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Document:	TU78 Magnetic Tape Transport Technical Manual Volume 2
Order Number:	EK-2TU78-TM
Revision:	OO1
Pages:	274
Original Filename:

OCR Text

EK-2TU78-TM-O0O1

TU78 Magnetic

Tape Transport
Technical Manuadl

Volume 2

EK-2TU78-TM-001

TU78 Magnetic
Tape Transport
Technical Manual

Volume 2

Prepared by Educational Services
of
Digital Equipment Corporation

=
|

1st Edition, May 1981

All Rights Reserved
The material in this manual is for informational
purposes and is subject to change without notice.
Digital Equipment Corporation assumes no respon-

sibility for any errors that may appear in this manual.

Printed in U.S.A.

The following are trademarks of Digital Equipment

Corporation, Maynard, Massachusetts.
DECnet
DECsystem-10

IAS

DECUS
DIGITAL
Digital Logo

DECSYSTEM-20
DECwriter

PDP

DIBOL

RSX

UNIBUS
VAX

EduSystem

VMS

OMNIBUS

DEC

MASSBUS
PDT
RSTS

OS/8

3/83-15

CONTENTS

CHAPTER 1

GENERAL DESCRIPTION

Applicable Documents ........ [P 1-11

p—

INtrodUCtioN . . .o oot
e
e e
e
e 1-1
Physical Description . .. ...
i
e
e
e
e 1-2
Functional Description . . ..................... e
e e e 1-6
Mechanical and Electrical Specifications

CHAPTER 2
2.1

2.2

................ [ 1-11

OPERATION

Controls and Indicators

.............
... . u..... e

e e e e

e e | 2-1

Operating Procedures .............
... .ol P 2-3

2.2.1
2.2.2
2.2.3
2.2.4
2.2.5

Power .......
... ... .. .. ..., e e 2-3
Autoload/Manual Load Selection . ......................... P 2-3
Autoload . ...
e
e
e 2-3
Manual Load ......... ... . . i e e 2-5
Probable Causes of Load Failure ..........
.. ... 2-7

2.2.6
2.2.7

Midreel Load . ... ..o
2-9
Unload ... .
e
e
e e
e 2-9

2.2.8
2.2.9

ReWINd . . .o
e
e 2-9
On-Line/Off-1ine . .. ..ot 2-9

CHAPTER 3

INSTALLATION

3.1
3.1.1
3.1.2
3.1.3
3.2
3.2.13.2.2
3.3
3.3.1
3.3.2
3.4

Site Planning . ... ..
e
e 3-1
Space Requirements ... .................... e
e e e 3-1
Power Requirements . . ... ... . . . e 3-1
Environmental Requirements . . ................ e 3-2
Unpacking and Inspection . ........ ... . i 3-2
Unpacking ................... e
e
e e 3-2
InSpeCtIOn . . o
e
e
e
e 3-4
Single Transport Installation . ... ... ... .. . . . i, 3-5
- Mechanical Installation . . ...
.. . . . e 3-5
Powerand Cabling ............
... ... ... ... . . ...e e 3-6
Multiple Transport Installation............ e 3-12

- 34.1
3.4.2
3.5
3.5.1

Mechanical Installation . ......... T ee 3-12
Powerand Cabling ............
... ... ... .. .... e 3-16
Acceptance Testing . ..........
.
i, e 3-18
Turn-On and Loading Checkout ... ... ... ... . . . .. ... 319

3.5.1.1

Power On . ... 3-19

3.5.1.2

Load Sequence Without Tape . ... .......... e e, 3-20

3.5.1.3

Inhibited Autoload Sequence ... .......... . 3-20

3.5.1.4

Autoload Sequence

3.5.1.5

Manual Load Sequence . . .........

3.5.1.6

3.5.1.7

. ... ... 3-20

- Manual Load Repeatability

3.5.1.8

... .. D 3-20

Unload Sequence ............ e
Autoload Repeatability

3-20

...............ST 3-20

.. ....... ... . . . . .

3-21

3.5.2

Subsystem Quick Check . ... .. SRS

3-25

3.5.3

TM78TU78 System Level Diagnostics

.. .... e 3-26

3.5.3.1

DECsystem 10/20 Diagnostics .............. AU e 3-27

3.5.3.2

VAX 11/780 DiagnostiCs . . ..ottt
e e e e e 3-28

CHAPTER 4
4.1

CUSTOMER CARE AND PREVENTIVE MAINTENANCE

Customer Responsibilities

. ........
... .. ...
....
... ... e SR 4-1
............c i,e
e, 4-1

4.2

Magnetic Tape Care

4.3

.................
.... e 4-2
General . ........... S, SN T
O A 4-2
Preventive Maintenance .......... S R e 4-2
Magnetic Tape Transport Cleanmg K1t ........... FE
4-2
TUT8 Tape Transport . . ... .o oot e
e e
e e
4-3
Ordering Supplies, Accessories and Documentation ......................... 4-4

Preventive Maintenance

4.3.1
4.3.2

433
4.3.4
4.4
CHAPTER 5

THEORY OF OPERATION

2.1
2.2
3
3.1
3.2
3.3
3.4
4

General . ...... ... .. ... .. . S 5-1
Theory of Operation Symbology e T
5-2
Functional Block Diagram Symbology ........... - £2
Schematic Diagram Symbology . .................. II e 5-2
TU78 Cabling/Interconnections . ................... .
£
Input/Output Cabling and Connectors ...... S
5-4
Interconnect DIPCBA . ............... e
e e e B
5-5
Interconnect F1 PCBA . .........
... ... ...... P e ... 55
Internal Interconnections . ..................... e e 5-5
Power Supply and Distribution .................. e e e e T
o

4.1
4.2

Primary Power Connections and Controls . ............... .. ... . .. . .... 5-9
Blower/Compressor Motor Power. . .............. e
5-9

4.3

ACPower .................... T P e 5-9

4.4
4.5

Unregulated DC Power Supphes ................ e
e e e e 5-9
DC Power Regulation . ............... [R e 5-13

4.5.1

4.5.2
453
4.5.4
4.5.5
45.6

+5 Vdc Regulator . .. ...

5-13
15Vde ......... S B 5-13
+5/—6Vde .. e
e e 5-13
36 VA (C) ..o e e 5-13
+36 Vde(S) .......
... ..., R e F
5-15
36 Vde(T) .......... S e, PR .' ......... 5-15

4.6

Regulated
Power Distribution

4.7

Power Reset (NPORST), Enable (ENBL, NENBLE) and Master Reset Pulse
(NMRSTP) Generation . .. .. ... e, 5-15

o0.

.............
.. . ..
i 5-15

Power Indicator .................S

SR e e e

e 5-16

—
NN

R, R, R, R
Y R
Y
Y R
R
R

B
W N —

N
00 -1 O\
O

o e ool

DO 1O DO MO B — =

1 0 10 0 Do 00 00 00 00 D0 00 00 00 1 O O O O

BN~
DD

T U 5-26

Control System Overview . .. ... e R
e
e e
e 5-26
Manual Controls . ... it i
e
ee e e
05227
LED Status Indicators ................. I e e e e e e e e 5-29
Control System Inputs/Outputs ................. S
N- 5-30
General Modes of Operation.. .. .............. e
e
e e e 5-30
Control System Timing ........ e

e e e e
e e e e e e 5-33
Transport/Massbus Port Selectlon e e e e e e e e e .. 5-34
Modes of Operation ......... e B 5-36
Reset/Preset State ... ..ot A 5-36
|
Interlock State (NINTLK, INTLK INTLKl DINTLK NDINTLK,

NINTLKPI, NINTLKP2) ........... A 5-37
9-Track State 5-38

"PE/GCR State ........... S
oA
T [ 5-38

Beginning of Tape Interlock (BOT INT) State ....... e

e 5-38

Unit Selected State (NSLTA) .. ..... ... oot e
e e 5-38
Air Load/Control ..........
... ... ...... SR e T 5-38
Tape Load, Unload, andRewmeperatlon RN
-§|
Load/Unload Sequences . .. ............... e ... 541
TapeLoad ............ e T
P
.
£ §|
TapeUnload . ........
... ..
.e [P 5-43
Load/Unload/Rewind Circuit Operation ..............
.. ... .. ..5-43
Tape Control Presetting by Power-On Sequence . . ................. L... 544
Circuits Involvedin Tape Load/Rewind/Unload Procedures.............. 5-45
Tape Load/Unload Procedure Counters ................ e e 5-48
Automatic Tape Loading Sequence R
AR T e
.0 5550
Reel Servos.......e e
e e e 5-52
Reel Servo Overview . . ... oo ittt i i i e et e e e
e e 5-52
Reel ServoPCBA
. ................. e e I 5-52

Capstan SEIVO . . . oo e R e . 5-55

W
—

System Control ............
..
i P

Capstan Servo OVEIVIEW . . ...ttt
ittt
e s e . 5-55
Capstan Servo PCBA .. .... e e e e e e PR 5-57
DataPaths ...........
... ... ...... e e S
5-58
e e P 5-58
oot
. . . .. .o uction
Introd
Write Function . . .............. R
S A PO 5-58
Read Function ............... e P S 5-60

G IRV, IRV, RV, IRy
RV RO R

Re N N e S R RV RV RV RV RV RV RV RV RV RV RV RV RV RS
AW W W —
AW
— LM
'
o=

N
RGN
R
R
R
R

Command/Status Register Descriptions . ...... ST S e 5-18

Circuit Description .. .........
... .o ... e e
e e e e
e 5-22
Commands and Command Timing . ................... e B 5-22
G ALUS . ot e st e e e
e
e e
e e
e
e 5-24
Write Data .. .... P
PRI S N e RIS ...5-25
Read Data .. .ot
e e
e 5-25
Amplitude Track In Error (AMTIE) Bits . . ... e
e
e e L. 5-25
Diagnostic LoOPS v v v it
e e 5-25
Switches and Indicators ............
... ... .. ... e e e e 5-25
Test Pattern Generation .............. e P 5-25

ControlM2PCBA .......
.. ... ...... e . e 5-33

oo e N N
OO

mmmmmmmmmmmmmmmmmmmmmmmm

Interfacing and the Multlple Interface Adaptor (MIA) PCBA ................ . 5-16
£
P
e
e
General . . ..o
516
...
.
..
.
.
.
Physical Description
enn. P 5-16
Interface Connections . ..... ...
e e .5-16
.......e
Slgnals
Bus)
(TU
Interface
MIA
Formatter to
e e . 5-18
e
.........
Signals
Interface
Transport to MIA

=
N
W

Write CIrCuitry . .. ..o 5-66

Amplitude Track In Error (AMTIE) Circuits ....................... ... 5-68
. ..
5-70
Read PCBA Control and Power Circuits . ... ... oo, 5-70

Read PCBA
L RO

ek
ek
i

pd fed
ek

ek
ek

Write Control and Power Circuits . .. ....
.
e,
..... 5-65

Read Amplifier CirCuits ... ... 5-71
Automatic Gain Control (AGC) Circuits . ......... o 5-73

GCR/PE Preamp 1 PCBA .............. e

CHAPTER 6

e e e

e e 5-75

MAINTENANCE AND TROUBLESHOOTING

SCOPE .o v
U
S
6-1
TU78 Maintenance Philosophy . . .. ...
o
e
e
6-1
Test Equipment .. ... ... ...
6-1
Preventive Maintenance ........
...
....... 6-1
Daily Preventive Maintenance . . . ..........
... .
.... 6-1

AW
—

o) e

o) e)

£ WO

0 0 00
n 0 n
2
R
TSI e

e Neo)Weo) We) e )We We)

Semiannual Preventive Maintenance . .. .. ... 6-1
Adjustment Procedures ..............
. ... . ... .. R 6-4
Power Distr
.. ibuti
... . .
on

6-5

EOT/BOT Adjustment . ............. . . 6-7

Low-Tape Sensor Adjustment (Pack Sense Assembly) .................. ...6-10
Vacuum and Air Pressure Adjustments. . ..................... A 6-11
System Vacuum Adjustment .................... e P 6-11
Takeup Reel Vacuum Adjustment . ................
.. .........
......6-11
Air Bearing Pressure Adjustment . ....
......
..
... 6-13
Thread Block and Cartridge Pressure Adjustment . .......
.......
... .... 6-16

Capstan Servo Adjustments

.............. PP e 6-18
Reel Servo Adjustments .. ........ i
e e e e
e
et e
e 6-25
Reel Servo Offset Adjustment . ...... ... .. ... . . ..
i, 6-25

Supply Reel Load Speed Adjustment ... .......
...
......
. ... .. .. ...6-26
Takeup Reel Load Speed Adjustment ........ e e
e e e e 6-27
Tape Loop Position Adjustment . . .................... e 6-28

Read/Write Adjustments

. ......... ...

. .

Read Skew Adjustment (Azimuth) . .............

6-31
... . . . . .

6-32

Write Current Adjustments . .. ... 6-35

(W]

[E—

Functional Description . . . ... ... ... .
6-40
UseProcedure...........................; ............ e 6-41

Using the PCBA Extender (DEC P/N 29-23218) . . ... ...
i
. 6-42
Power Supply Troubleshooting ..........
.. ...
.... ...6-44

Troubleshooting Rules ... .................... P 6-44

Troubleshooting Hints . .. ........ ... . . .. .
6-44
Troubleshooting Charts . ....
... ......
i,
... 6-44
Load Cycle Troubleshooting . ....
... ...
....
..
...
. 6-44

Load Faults ................ U e e
e
.. 646
Pneumatic System Troubleshooting ... .....
... .....
... ... . ... .......
. 6-46
Reel Servo Troubleshooting . ... .................... e
e e
e e 6-54
Dynamic Brake Check ..................... T 6-58

Data Paths Troubleshooting .................. e
Introduction and Pre-checks............ e
e e

e
e

6-58
e

e 6-58

NANDNNNARN
DD AR
e
e
e e e O O
NNV
AR W WWW DD =

Phase Encoded Gain Adjustments .. ....
... ....
.... 6-38
Troubleshooting .. .....
... .....
... ... ........ e
e
e e
e e 6-40
Using the Multiple Interface Adapter (MIA)PCBA .....
.. ... . ...
...
..., 6-40

6.6.7.2
6.6.7.3
6.7
6.7.1
6.7.2
6.7.3
6.7.4
6.7.5
6.7.6
6.7.7
6.7.8
6.7.9
6.7.10
6.7.11
6.7.12
6.7.13
6.7.14
6.7.14.1
6.7.14.2
6.7.14.3
6.7.14.4
6.7.14.5
6.7.14.6
- 6.7.14.7

6.7.14.8
6.7.14.9

... . ... 6-59
... .. ... ...
Write Path/Read Preamp Troubleshooting . ........
Read Path Troubleshooting . ... ....... ., 6-64
e e [ 6-72
Removal and Replacement Procedures . ... ...... e
.. ... 6-72
...
.. ... ...
Head Wear Check and Replacement Procedure . . .......
Tape Cleaner Removal, Cleaning, and Alignment ......................... 6-76
Air Guide Disassembly and Cleaning .............. P 6-76
Air Bearing Removaland Cleaning .. ......... ., 6-77
e 6-77
e
Capstan Motor Replacement ............... e
i, 6-82
... .. .....
Supply Reel Motor Replacement . .....
- Vacuum Reel Assembly Replacement and Take-up Reel Motor Replacement ... 6-83
oo, 6-84
.
... ... .......
Cartridge Actuator Motor Replacement . ......
... .... 6-85
... .. ... ...
Control Assembly Removal and Replacement . ........
.. ..... 6-85
Blower/Compressor AC Motor Replacement ................. . .
Blower Removal and Replacement .. ......... ... .. .. . .. 6-87
Compressor Removal and Replacement . ................. e 6-87
Air Valve Solenoid Replacement . ........ ... ... i, 6-88
Printed Circuit Board Assembly (PCBA) Removal and Replacement .......... 6-88
... 6-88
... ... ot
Multiple Interface Adapter PCBA (Slot 1) . .......
i e e e e e A 6-89
i
Read PCBA (SIot 2) ..o oot
Write PCBA (Slot3) .......... e P e 6-89
6-90
Control M2 PCBA (Slot4) ............ S
Capstan Servo PCBA (Slot5) ...............S 6-90
L..690
e
Reel Servo PCBA (SIot 6) . . . oo ot
GCR/PEPreamp 1 PCBA . ...... ... L, e 6-91

e e e 6-92
Interconnect F1 PCBA . ... . o
e 6-92
e
Interconnect D1 PCBA . . . . .. o i

APPENDIX A

GLOSSARY

A-1

General NOTES . . o v ot e

APPENDIX B

FLOWCHART GLOSSARY

e e et e e

e e

APPENDIX C TAPE UNIT MIA COMMAND / STATUS. REGISTER BIT DESCRIPTIONS
APPENDIX D

INTERFACE WIRE LIST AND TRANSPORT INTERCONNECTIONS

=t bt

ek ek e

S hLo—a9awm Ao
—

DD DO

DO DD D

FIGURES

Basic System Configuration ....... e o,

TU78 Master Tape Transport .. ... .. e |
Base Assembly ............. e e e
e
e
Card Cage ATCa . .. oo ittt
ePower Pack Assembly . . ..ot
Possible TU78 Configurations . ... ... .. ..

Master TU78 Functional Block Diagram .............e
TU78 Control Panel ..................... e PR .
i,
Autoload/Manual Load Selection ... ...........
Tape Content Limit ...................... e

e e e
Autoload Sequence with Operator Troubleshootmg ............... e

... e
... . ......
Tape Path and Controls ......
Manual Load Sequence with Operator Troubleshooting .. ............ I |

Vil

00 ~J O\ N WD
—

-PQIJJUJUJUJUJUJUJUJUJ

............... 3-15
Radial TU Bus Connections . .............. R 3-17
Cable Orientation on TU78 MIA PCBA ..... e
e eT 3-18

TM78 Maintenance Keypad ................... T
Load Sequence Without Tape . ......... SR F

Inhibited Autoload Sequence .. . . .. e

3-21

e e

e e e e 3-25

s
W
W
W

.................. e

S e 4-3

e e ek e et 5-3

e
e e eI
TU78 Interface Connections .......... N
R 5-5
Interconnect D1 PCBA; Front View . . .................. PR PR 5-6
Circuit Card Interconnections .............. e e
e
e e e 5-7
Power Supply Simplified Block Diagram .......... R T o

Primary Power Hookup and Control

..........
... .. . @.... 5-10
Blower/Compressor Motor Power and Control . ............... e e Lo..05-11
Unregulated Power Distribution CirCuits . .............. o' . 5-12

DC Power Regulation and Distribution . ................ .. 5-14
-MIA Basic Block Diagram . .. ..., ... .
5-17
MIA Detailed Functional Diagram ............ e S
Command Timing Loglc e
e
e e
e
Command Timing .
....... e
e
e
e
e e
Test Data Tape Format ........... e
et et e e
e
e

... 523
5-24
e

524

e 5-26
Control Logic Block Diagram ........... e
e
e
P
R, T
Control Signal General Routing .. ......
....
...
i
.... 5-28

Manual Control Switching

. ........
... . .
..... ... 529
Front Panel Indicator Connections . .. ..............
5-30

Control M2 PCBA Inputs and Outputs . . . .. e e L [ 5-34

Air Load/Control Function

.............0.
... B 5-39
Tape Loop In Takeup Buffer Box ..... e e [P 5-40

Positive Air Supply System

. ............ ... IR e L 5-41

Load Sequence . .... R e e e 5-42

Unload Sequence ....... eP e
Reel Servo Block Diagram

e e
S 5-44
........ e e e 5-53

Capstan Servo Block Diagram . .................... e
e e e e e e 5-56
Capstan Servo Wavefrom for Forward Start and Stop ............. P 5-57
TU78 Data Paths . ...... A e e
e e 5-59
Write Function Block Diagram . .................. e
e e
5-61

Read Function Block Diagram ................ e e
e e 5-62
Write PCBA Block Diagram. ............ e e e 5-63

v1il

:
:
-

O 00O O\
Wn
U

[SHNY

N— OVOIANUNPARWN—OWOIAWUDAWN—O

e
A
R
R
R
I
A
R

e e 3-22

——

Unload Sequence ..................... P e
Transport Items for Daily Cleaning .......... P
Schematic Diagram Symbology

NN PO DO D

e 3-20

Autoload Sequence ........ e e e e e B
3-23
Manual Load Sequence . .......... e eEEPR e 3-24

D LN ooy
Dn

TU Bus Cable Routing for a Multlple Transport Configuration

D U D o

874-E Power Controller .................... A S
3-8
Rear of Power Pack with Pulley Cover Removed ............. . 3-9
Cabinet Placement for Maintenance Dlsplay V151b111ty ..... e e
e e 3-13

Top Cover Fastener ......................... e e
e
e 3-13
Cabinet with Side Panels and Top Cover Removed A e, 3-14

DN DN DI DD M

D U D D D L

Location of Stabilizer Arm and Leveler Feet ............. S 3-6
............... R
e
A e e e e 3-7
TU78 Power Distribution . ........ e R
e 3-8

PCB Shipping Bracket

- Functional Block Diagram Symbology . . .. ... PR e e

L L U L

Space and Service Clearance ........... e e e 3-1
Unpacking the TU78 ............. e e e e e e
e e
e P 3-3
TU78 Mounting for Shipment ........... P e e e
e e 3-4

5-33.

Write Amplifier Circuitry ........... U e e

534

AMTIE Generator . ..................... S
e 5-69
Read PCBA Functional Block Dlagram S
5-72
AGCT1m1ng......................‘.'.._.‘ ..... e
e e e e e e 5-74
Power Supply Fuse Panel .. ....................... T
6-6
Capstan/Regulator PCBA Ad]ustments and Test Pomts ...................... 6-8
Interconnect F1 PCBA Adjustments and Test Pomts e
e ... 69
Base Assembly, Front Components . ......................... S 6-10
Vacuum Valve and Pressure Valve . ........
... .
i 6-12
Control M2 PCBA Adjustments and Test Points . . . .. T e
e e e 6-14
Reel Servo PCBA Adjustments and Test Points . . ... B
F
6-15
Cartridge Pressure Check Point . . ... ... .. e e e
e e e 6-17

5-35
5-36
6-1
6-2

6-4

6-7
6-8

6-9
6-10

6-11
6-12
6-13
6-14
6-15
6-16
6-17
6-18

6-19

6-20
6-21
6-23

6-24
- 6-25
6-26

6-27

628
629

6-30

6-31
6-32
6-33
6-34

6-35
6-36

6-37
6-38
6-39
6-40
6-41
6-42
643

6-44

\u .

6-45
6-46

6-47
6-48
6-49

GCR/PE Preamp 1 PCBA Test Pomts ........ P

e e 5-66

S P 6-21

Forward Start Ramp .............. ST e
ee
e e. 6-22
StopRamp............;....‘....‘....‘..._..-..... e
e e e e e e 6-23
Buffer Column Part Zone ............ e e R e
6-29
Loop Travel Limits . .. ........... P PRREE . e
e e e 6-32
Multiple Interface Adapter Controls, Indicators, and Connectors .............. 6-33
Read PCBA Test Points, Adjustments, and Connectors .. ................... 6-34
Read Skew Adjustment Waveforms ........................ . 6-35
Location of Read Skew/Azimuth AdJustment ........... e e 6-35
Write PCBA Test Points, Adjustments, and Connectors . .................... 6-36
Pedestal Voltage Adjustment .................... R P e 6-39
PCBA Extender . ......... ..., P 6-42
PCBA in Extended Position . ................. e e e e e 6-43
Autoload Timing Diagram .................... e
e e e e 6-47
Load Fault O Flow Diagram ...............
.. .. . ... e 6-48
Load Fault 1 Flow Diagram ............ e
e e S 6-49
Load Fault 2 Flow Diagram ................ e
e e e e
e e e e e e 6-50
Load Fault 3 Flow Diagram .......... RITA e
e
e e 6-51
Load Fault 4 Flow Diagram .. ... e e
e e
e e 6-52
Load Fault 5 Flow Diagram .... .. R
e e e e s e e 6-53
Load Fault 6 Flow Diagram ............... S
6-54
Pneumatic Troubleshooting Flow Diagram .. ................... e 6-55
Supply Reel Simplified Schematic Diagram .................. ee . 6-55

Write Path One Function Block Diagram ............ S

6-60

Read Preamplifier Output Waveform ...... R
S
6-61
Normal Read Head Output While Reading .. . ... O
N T AT UR
6-63
Normal Read Head Output While Writing . . ..
. .. e
e
e
... 663
Write Amplifier Output With No Load ................ R .. 6-65
Write Data at Input to Write PCBA . . . .. ... o
6-65
Write/Erase Head Plug (P6) Test Points .................... e ie e 6-65
Read Path One Function Block Diagram ............... e
e e e 6-66

Automatic Gain Control (AGC) Waveform
—GCR Mode . ........S 6-68
Read Data Output . ........cci
... R R 6-69
AMTIE Generation Circuitry ........ . e
e e e e
6570

+VAM Test Point on Write PCBA . . . ... o
+VAM AMTIE Threshold Voltage e

it
e

AMTIE Signal Switching ......... e e e

i 6-71
e

e e e 6-72

e e .. 6-73

Read/Write Head, Tape Cleaner, and Air Gulde Removal and Replacement ...... 6-73
Air Bearing and Ceramlc Guide Orlentatlon .............................. 6-78
Capstan Motor Mounting ................R
L
S
S 6-79
Capstan Tape Tracking Adjustment Studs ........ ..., 6-81

6-50

Cartridge Actuator Motor . . .. .. ..

C-1

i
6-84
Blower and Compressor Pulley Alignment ..........
...
.......
00 vu . ... 6-86
Flowchart Glossary ......................... e P B-1
Tape Unit Command/Status Byte Format ................. e C-1

C-2

TU Command/Status Summary .......... T

6-51
B-1

C-2

6-13
C-1
C-2
D-2
D-3

D-4

D-5

D-6
D-7

D-8

D-10

...

e 2-1

Primary Power Connections ... ......... .ot A 3-10

Pulley/Belt Part Numbers for Altitude Changes .............e e 3-10
TM78/TU78 Diagnostics for Acceptance Testing . . . . .. P . 3-27
Maximum Error Rate PerPass .....
... ... ...
....
.. ........... I 3-28
TU Bus Signal Summary . . ... ... .. .
5-17

Transport to MIA Interface Signal Summary ........................ e 5-19

Basic Timing Frequencies . ......... ..

i e 5-35

Load/Unload Sequence Control Count Applications

..............
... .. .... 5-49

- Try Counter OQutputs .......... ..., e e 5-50

Reel Servo PCBA Inputs . . ... ..
Reel Servo PCBA Outputs

o
e e, 5-53
. ... .., . 5-54

Write PCBAInputs ............... R 5-64
Write PCBA Outputs
Read PCBA Inputs . .

........ ... e, e 5-65
...

5-70
e e
e
e, 5-71
Standard Tools and Test Equipment Required ................e 6-2

Read PCBA Outputs . . ...

Special Tools and Test Equipment Required .........
.........
... .. 0 .. ... 6-2
Preventive Maintenance Schedule . ....................... e 6-3
Required Prerequisite/Corequisite Adjustments .. .. .. e e 6-5

Power Supply Voltage Readings . ................... e e 6-6
Vacuum and Pressure Valve Components . .. ..., 6-13

PE Gain Test Points and Adjustments
MIA LEDs

................ e 6-40
..
6-41

MIA Switch Functions ........... e AT 6-41
Power Supply Troubleshooting Chart . . ... ... 0. 6-45
Load Fault Categories

... ...... ..., 6-48
Reel Servo PCBA Operating Voltages ... ... i, 6-56

Parts Replacement/Adjustment Cross Reference ............. e e e 6-73
TU Command Register Descriptions . ......... A C-3

TU Status Register Descriptions . . .........
... ... ......e
..
Major Plug/Jack Reference Designations ................. e
TU Bus Interface Signals ....................... e
e
e
e e
AMTIE Cable Signals .....................e e

C-5
D-1
D-2
D-3

MIA PCBA to Transport Interface .....
... ... ...
.....
... ... ... ....... D-4
Power Distribution on Interconnect DI PCBA ...................... I . D4
Deck Interface Ribbon to Interconnect D1 PCBA . ...........
. ..
....
..., D-6
Internal Control Signals on Interconnect DI PCBA ........................ D-7
Interface Control Signals on Interconnect D1 PCBA ................... v... D-8

Interface Read Signals on Interconnect D1 PCBA ................
... ... ... D-8
Interface Write Signals on Interconnect D1 PCBA .......
...
.....
.. .. .. ... D-9

)

6-11
6-12

TU78 Controls ...

TUT8 Indicators
. . ... oo e, .22

6-10

Related Documents . .. ... ... . . . . e, 1-11
Mechanical and Electrical Specifications . ............
..
.. 1-12

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TABLES

TU78 Magne’nc
-

Tape Transport

Techmcal Manual
-

Volume 2

TM~
10140-8

——

CHAPTER 1
:
GENERAL DESCRIPTION

1.1

INTRODUCTION

The TU78 magnetic tape transport writes and reads data in 9-track phase-encoded (PE) or group code

recording (GCR) format. Bit density is 1600 bits per inch (bits/in) for the PE format and 6250 bits/in
for the GCR format. The transport can read data in the forward or reverse direction. The read/write
tape speed for both directionsis 125 inches per second (in/s). Nominal rewind time for a 731.5 m (2400
ft) reel1s 65 seconds.

The TU78 interfaces with the system processor via the MASSBUS, a MASSBUS controller, and a
TM78 tape formatter. Up to four TU78s may be driven by a single TM78 formatter. Figure 1-1 illustrates the basic TU78 system configuration. The TM78 tape formatter and its power supply (H7422-

AB) are housed in the TU78 cabinet, an H9500 corporate cabinet. (The specific model of the H9500
cabinet series used for the TU78 is H9602-KA. However, this manual refers to the cabinet as the
H9500.) The TU78s containing a TM78 are called master units; TU78s without the TM78 are called
- slave units. Both master and slave units contain an 874-E power controller. Earlier TU78 models contain an 872-E power controller. The two types are electrlcally identical, but differ slightlyin the location of remote control jacks.

'
]

vasseus

CPU

i TU78

:
+

ASTER TRANSPORT

CONTROLLER

)

MASSBUS

TM78
TAPE

’

TU78 TAPE

TRANSPORT
10

FORMATTER | :

TO1-7

OTHER

TM78

FORMATTERSI

*1, DECSYSTEM 20 (KL10 & RH20 )
2. PDP-11/780 VAX & RH780

SRR
'

| I
OTHERTU78
TRANSPORTS
MA-7012

Figure 1-1

Basic System Configuration

1-1

TU78
BASE ASSEMBLY

874- EPOWER

CONTROL

FORMATTER

‘M |

(

| Ft_ __:EV

1.2

TM78 TAPE

Figure 1-2

#
- '

TU78

\\POWER

Oce |||

TU78 Master Tape Transport (Sheet 1 of 2)
a. Front View

PHYSICAL DESCRIPTION

Figure 1-2 illustrates the locations of the major subassemblies of the TU78. They are listed below.
TM8 tape formatter (master TU78 only)
H7422-AB power supply (master TU78 only)

874-E power controller

TU78 transport (base assembly, card cage area, and power pack assembly)

1-2

=0 15—

o
0
o} —

ClVAl

EXHAUST /
FANS (2)

O
o

BLOWER
FAN

O
o

r@ o)

H7422- AB

w—

—

POWER SUPPLY—-'”“‘|l

‘

(A (PN
A (AN
A A\

EXCHANGER —_—E @ .((({%\-?))). .
HEAT

X/,

PULLEY
|

COVER

BLOWER

/MUFFLER

i
o]

=
YA

L
b. REAR VIEW

Figure 1-2

MA-7013

TU78 Master Tape Transport (Sheet 2 of 2)
b. Rear View

Figure 1-3 identifies the components of the base asserribly. They are listed below.
Control assembly (PN 29-23771)
Reel sense assembly (PN 29-23216)
Backwrap defeat switch (PN 29-23297)
Reel hub assembly (PN 29-23475)
Buffer box door assembly (PN 29-23215)
Tape in path (TIP) assembly (PN 29-23243)
|
EOT/BOT assembly (PN 29-23242)
Head (PN 29-23767)
Cartridge interlock switch (PN 29-16280)
Upper restraint (PN 29-23225)
Lower restraint (PN 29-23224)

1-3

UPPER RESTRAINT

CARTRIDGE

BUFFER BOX DOOR

INTERLOCK SWITCH

ASSEMBLY

' Al i

Q—

VAN

REEL SENSE

ASSEMBLY

BACKWRAP

REEL HUB ASSEMBLY

Jis= TIP ASSEMBLY

DEFEAT SWITCH\_

\W_, EOT/BOT ASSEMBLY

LOWER RESTRAINT —————

/v'
CONTROL .~
ASSEMBLY

& —— HEAD

MA-2636A

Figure 1-3

Base Assembly (Sheet
1 of 2)
a. Front View
S

Cartridge motor (PN 29-23280)
|
Pressure switch (pneumatic interlock) (PN 29-23239)

Pressure valve assembly (PN 29-23249)
Interconnect F1 printed circuit board (PCB) (PN 29-23770)
Reel motor assemblies (2) (PN 29-23236)
o

o
|

Write protect assembly (PN 29-23235)
Vacuum valve assembly (PN 29-23248)

Pressure switches (vacuum) (2) (PN 29-23238, 29-23239)

Pack sense assembly (PN 29-23217)

Capstan motor assembly (PN 29-23768)
Service lock
Preamp PCB (PN 29-23766)

|
|

Vacuum transducer assembly (PN 29-23246)
Pressure switch (column limit) (4) (PN 29-23238)

.
|

f
|

Figure 1-4 illustrates the card cage area containing the folloWin

g items.

Multiple interface adapter (MIA) PCB (PN 29-23769)
Read PCB (PN 29-23762)
-

Write PCB (PN 29-23763)

Control M2 PCB (PN 29-23764)

1-4

|
S

PRESSURE SWITCH
(PNEUMATIC INTERLOCK)

INTERCONNECT F1
PCB

PRESSURE VALVE
ASSEMBLY

[

m\rfi? T |e

%
/

1NC

1ajjaya figfi

‘éfl.-_;
mElHHHHHHHHHJ

)
’mflll
'/_\g\_'%
;‘Jy

PRESSURE
SWITCH

| REEL MOTOR ASSEMBLY

(SUPPLY REEL)

(COLUMN LIMIT):

WRITE PROTECT
|~

ASSEMBLY

CARTRIDGE

MOTOR

VACUUM

Y J

g &

‘@é\\\
/
g
= “ ‘i—‘\.\

TRANSDUCER —_
ASSEMBLY

==X

év

PREAMP PCB —

N — A

)

LOCK

U
CAPSTAN MOTOR
ASSEMBLY

(VACUUM)

ASSEMBLY

«%D

194

:
-

\"’
\

| ]

SERVICE

PRESSURE SWITCH (2)

===\
(|_vAcuumVALVE

' s /

=
N
\ 4t Q,

5)))S SN
=
PACK SENSE ASSEMBLY
(NOT SHOWN)

'REEL MOTOR ASSEMBLY
(TAKE UP REEL)

MA-2664

Figure 1-3
|

Base Assembly (Sheet 2 of 2)
b. Rear View

Capstan/regulator PCB (PN 29-23765)
Reel servo PCB (PN 29-23231)
Exhaust fans (2) (PN 12-17916- 02)

Interconnect D1 PCB (not shownin Flgure 1 4) (PN 29-2321 1)

Figure I-S”illustrates the power pack assembly containing the following items.
Rectlflers (3) (PN 29-23311, 29 23312)
Vacuum hose
Fuse panel

Air filter (PN 29- 23259)

" Blower with serial number below SP002386 (PN 29-23298)
Blower with serial number SP002386 and above (PN 29-24013)
Pulley cover

Power transformer terminal strip

Compressor (PN 29-23257)

Motor (PN 29-23287)
Transformer (PN 29-23258)
~ Muffler (PN 29-23220)
Heat exchanger fan (PN 12-17916- 02)

1-5

MIA PCB

EXHAUST FANS (2)

A
IN 7N
.

‘

lREAD PCB

Fg&o_m\OOmmfin eI
_—

7\ I
LMY
& @,

CONTROL

'-""'—" TR

O
55

eh
I

WRITE PCB

{4 A EE Y
>

A E

CAPSTAN SERVO
PCB

REEL SERVO PCB

Figure 1-4

Wi E

//fl7)

M2 PCB

‘

MA-2664A

Card Cage Area

1.3
FUNCTIONAL DESCRIPTION
Figure 1-6 illustrates the various TU78 configurations possible from the MASSBUS. The TM78 tape

formatter interfaces with up to four TU78 transports to the MASSBUS. Additional TM78s may be

added (a maximum of eight), with each formatter interfacing up to four additional TU78s. Thus, the

maximum configuration interfacing

TU78 transports.

CPUs.

a MASSBUS controller consists of 8 TM78 formatters and 3?2
A TM78 may also be dual-ported so that each subsystem can be driven by two host

The TM78 tape formatter is housed in the TU78 cabinet. Those cabinets containing a TM78 (énd its

H7422-AB power supply) are called master transports. Those cabinets without
the TM78 and H7422AB are called slave transports. The TU78 master transport is identical to the TU78 slave transport.

Figure 1-7 is a functional block diagram of a TU78 master tape transport. During a write operation the
TM78 accepts write data from the MASSBUS and formats it into 8-bit data characters for the TU78
transport. MASSBUS data is in the following formats: PDP-10 compatible, PDP-10 core dump, PDP-

10 high-density compatible, PDP-10 high density dump, PDP-10/11/15 image, PDP-11 normal or
PDP-15 normal. The TM78 disassembles Massbus data under control of the CPU which specifies the

data format. During a read operation, 8-bit characters received from the transport are formatted into
data words and placed on the MASSBUS. The TM78 assembles the data characters into the MASS-

BUS format specified by the CPU. The TM78 rwrites and reads data in either 1600 bits /in PE or 6250
bits/in GCR formats.

During a write operation, the TM78 assembles 8-bit tape characters and sends them to the TU78 over
the TU bus. Error detection is accomplished by parity checks (PE and GCR modes), and (GCR mode

only) by cyclic redundancy checks (CRC) and auxiliary cyclic redundancy checks (ACRC). Error detection occurs for both read and write operations. During a write operation, a read-after-write function

COMPRESSOR

RECTIFIERS (3)

RANSFORMER

_/9‘/,//‘

MOTOR

7.77»"'5@: ¥

VACUUM HOSE

FUSE PANEL

T
—

POWER TRANSFORMER
TERMINAL STRIP

(UNDER COVER)

RIEERY

PULLEY COVER

Figure 1-5

BLOWER

E BLOWER MUFFLER

MA-2643A |

Power Pack Assembly (Rear View)

is performed: the TM78 reads data just written and performs error checking. During a read operation
the TM78 can perform automatic error correction. Single-track errors can be corrected in PE; and using a special error correction character (ECC) double-track errors can be corrected in GCR.
The TM78 also controls and monitors tape transport operation. It receives operational commands from
the host CPU, selects the desired transport, and issues functional (data transfer) and motion (non-data
transfer) commands. It monitors transport operation and provides error and status information to the
host CPU.

The H7422 power supply provides regulated £5 V and +15 Vdc operating voltage for the TM78.
Power fail signals AC LO and DC LO are also supplied to the TM78.

The 874-E power control supplies ac power to the transport cabinet. It provides filtering for the ac input
power supplied to switched outlets when the remote power on/off line is enabled from the host CPU via
the remote switching control bus. There is no power on/off control on the TU78 control panel, transport
power is controlled by the host CPU. The switched ac is supplied to the H7422 power supply and TM78
cooling fan (master TU78 only), the transport power pack, the three cabinet cooling fans, and the compressor heat exchanger.

1-7

TU78BB ( 60 Hz)
TU78-BD
(50 Hz )

ROH

CPU

N | S|

[

I\,

E out| *
I

TM78 - BB
A

IN | ©

ouT

—

e v

TRANSPORT

FU78 SINGLE PORT MASTER

TU78 SLAVE

I TU78- AF(60 Hz)

TU78- AJ (50 Hz)

TU78
TAPE

— i — —

U80sT

8 | o | V1

| ' “I7] B

TU78
TAPE

TRANSPORT
1

]

TU78AB (60 Hz)

RH el
CPU

0 \,_J
|

TM78- AB
N |S

I A

RH1 <MASSBUS1J I

~our

;

TUBUS 1

* MASSBUS TERMINATOR (DEC PN 70- 09938- 00 )

Figure 1-6

TU78
I
TU78 SLAVE
TRANSPORT l TU78- AF (60 Hz)

J TAPE

TU78- AJ (50 Hz)

|
TU78
TAPE
TRANSPORT

MA-7014

Possible TU78 Configurations

The basic TU78 transport contains the following seven functional areas (Figure_ 1-7).

Capstan servo subsystem
Reel servo subsystem (2)

Pneumatic subsystem
Read/write subsystem
Control logic and manual controls
MIA interface
Power supply and distrib-ution

The capstan servo subsystem controls the speed and direction of tape movement past the read/ write
heads. The subsystemis a velocity servo that receives command signals from the control logic specifying forward, reverse, or rewind motion. The capstan motor responds with the appropnate velocity.
The capstan tachometer generates a feedback signal proportional to speed. This signalis summed with

the basic command signalin order to maintain the correct capstan velocity at all times.
The reel servo subsystems control the speed of the tape reelsin order to maintain optimum tape tension

between the supply and take-up reels. The supply reel and take-up reel servos are similar but separate
subsystems. The path followed by the tape (in either direction) between thesupply and take-up reels
contains two tape loops in the buffer box (supply loop and take-up loop). The separately formed loops
are maintained by a vacuum in conjunction with automatically controlled reel motor speeds. In effect,

- the reel servos function to feed tape into and remove tape from the buffer box at the rate required to
maintain the correct loops.
1-8

/}M\‘\

TU78- AD (50 Hz )

NdD WOHH

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1-9

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fi

Signals developed within the pneumatic subsystem initiate servo operation. The subsystem senses that
the tape loop position has changed as a result of forward or reverse tape motion. Air is drawn from the
closed ends of the two buffer boxes creating a vacuum and causing the tape loop to form in
each box.
The differential between the positive pressure inside the loop and the relatively negative pressure at the
closed end of the buffer box (outside the loop) maintains the proper tension on the tape during
the tapeloaded state.
There is a separate chamber behind each buffer box, connected to the box by a series of holes. The
spacing and arrangement of these holes is such that, if the loop becomes larger, more holes are exposed
to the positive (atmospheric) pressure inside the loop, and fewer to the lower pressure (vacuum) area
outside the loop. This causes pressure in the chamber to rise. Conversely, if the loop becomes smaller,
the pressure in the chamber decreases.
Pressure transducers are connected to the supply and take-up chambers. They interpret pressure variations in order to provide the supply and take-up servo feedback signals. The pressure sensitive signals

feed back to the reel servos to adjust the velocity of the reel motors for the proper loop in the two buffer
boxes. The uppermost and lowermost holes in each buffer column are limit ports. These connect to
supply and take-up limit switches which feed back to both the supply and take-up servos. If the tape

crosses a limit port in either the supply or take-up columns, a disabling signal couples back to the servos, stopping both reel motors before tape damage occurs.
|
A pneumatic interlock shuts down the capstan servo and reel servos if a pneumatic failure is detected.
The pneumatic subsystem contains a blower which creates the vacuum for the tape columns, and a

The read/write subsystem processes data and transfers it to and from the magnetic tape. The read func-

tion processes data picked up from the tape by the read heads. It translates information from the recorded PE or GCR format to digital data acceptable to the external controlling circuits. The function

includes the read-after-write capability that permits the formatter to verify execution of write command while writing is in progress. The write function prepares incoming data for recording in PE or
GCR format and writes the information on the tape in the selected format. The read /write subsystem
also develops amplitude track in error (AMTIE) status signals. It sends nine AMTIE signals to the
formatter, one for each track, which become active when the strength of the analog signal read from
tape falls below a specified threshold. During a write function this causes the operation to be retried.
During a read function, AMTIE signals assist the formatter in developing pointers for the error correc-

tion process.

The control logic and manual control circuit interfaces other TU78 subsystems. The control logic trans-

fers read/write data to and from the read/write subsystem. It also transfers the operational commands
to the capstan servo. During the autoload sequence, logic circuits control the sequence steps by issuing

appropriate commands to the reel servos. The control logic monitors and controls timing of the autoload
sequence steps and other operational sequences, such as rewind. It processes commands generated by

the manual controls and applies them to the appropriate subsystem. Control logic also senses transport

status (e.g., transport selected, on-line, EOT, BOT, etc.), and modifies signals to the read/write and
servo subsystems. Logic lights the appropriate control panel indicators to indicate transport status.
Transport status is sent to the TM78 formatter via the MIA interface module.

The MIA module couples control/status, read/write, and AMTIE signals from the tape unit bus (TU

bus) to the transport. The MIA adapts signals on the TU bus to the format required by the transport,
and vice versa. This includes multiplexing, de-multiplexing, signal gating, latching, and timing.

stopping the servo motors before tape damage occurs.

/(mm_,“\\ N

compressor which generates pressure for the tape path bearings. Sensing devices monitor vacuum and
pressure. If either is lost, the sensing device sends a VAC/PRES signal to the three servo subsystems,

Power supply functions include ac rectification, filtering, dc regulation, and distribution of power to the

various subsystems.

1.4 APPLICABLE DOCUMENTS

Table 1-1 lists documents applicable to the TU73 tape transport.

Table 1-1

Related Documents

Title

Doc No

Contents

TM78 Magnetic Tape

EK-0TM78-UG

Description, programming,

Formatter User Guide

- and installation
information

EK-0TM78-TM

TM78 Magnetic Tape
- Formatter Technical
Manual

Theory of operation,
programming information,
installation, and main-

tenance of the TM78
formatter and H7422 power

supply

EK-1TU78-TM

Schematics and logic

TU78 Magnetic Tape
Transport Technical
Manual (Volume 2)

EK-2TU78-TM

Description, installation,
operation, theory and
‘maintenance of TU78

TU78 Subsystem Pocket
Service Guide

EK-0TU78-PS
|

Summary of troubleshooting
and maintenance procedures

TU78/TM78 Magnetic Tape
Transport/Formatter IPB

EK-0TU78-1P

Exploded views and parts
lists of TU78 AND TM78

TU78 Field Maintenance
Print Set

MPO01061
|

Engineering drawings for
TU78 mechanics and

TU78 Magnetic Tape

‘

Transport Technical

prints of TU78

Manual (Volume 1)

TM78 Field Maintenance
Print Set

874 Power Controller

IPB

MPO01061

cabinet

Engineering drawings and

parts lists for TM78

mechanics and logic

EK-00874-1P

Exploded views and parts

lists of 874

1.5 MECHANICAL AND ELECTRICAL SPECIFICATIONS
Table 1-2 details the mechanical and electrical specifications of the transport.

Table 1-2

Mechanical and Electrical Specifications

Tape (computer grade)

Width

12.6492 mm + 0.0508 mm (0. 498in £ 0.002

in)

Thickness

0.0381 mm (1 5 m1l)

Tape tension

2.780 N (10.0 oz +0.0/
— 1.0 0z) nominal

Réel diameter (autoload)

266.7 mm (10.5 in) maximum (note 1) and
Easy-Load cartridge 1 and 2

Recording modes

1600 bits/in (3200 FCI) PE
6250 bits/in (9042 FCI) GCR

Magnetic head

Dual stack (with erase head)

Tape speed

3 2 m/s (125 1in/s)
-

*=3 percent

Long term speed

Rewind time for 731.5 m
(2400 ft) tape

max1mum)

65 seconds nominal (80 seconds

+ 2 percent (reverse)

+ ] percent (forward)

variation

/’WN .

Instantaneous speed
variation

" Dual blade type connected to vacuum

Tape cleaner

supply

Interchannel displacement
error

Read

3.81 um (150 uin) maximum (note 2)
8.89 um (350 pin) maximum (note 3)

Read-after-write

Start/stop time

1.1 ms £ 0.1 ms

Start

1.3ms £ 0.1 ms

Stop

1.1 ms £+ 0.1 ms

Start distance

Stop distance

Beginning of tape (BOT) and
end of tape (EOT) detectors

1.91 mm +0.25/—0.38 mm
(0.075 in 4+0.010/ —0.015 in)
-

2.16 mm +0.25/—0.38 mm
(0.85in +0.010/—0.015 in)

‘Photoelectric

(note 4)
Tape creepage
Pneumatic interlock

" None
Tape motion disabled when vacuum is lost
in vacuum column

1-12

Table 1-2

Mechanical and Electrical Specifications (Cont)

Load time

No greater than 10 seconds without a
retry, and 20 seconds with a retry for
10.5 in reels

Unload time

Less than 7 seconds for 10.5 in reels

Write gap to read gap
distance

0.381 cm =+ 0.013 ¢cm (0.150 in = 0.005 in)

Weight

286 kg (630 Ibs) (master unit)

Cabinet dimensions
Height
Width
Depth (from face of
front door to rear of
cabinet)

67.3 cm (26.5 1n)
81.9 cm (32.3 in)

Operating temperature
Nonoperating temperature

15° t0 32° C (59° to 90° F) (note 5)
—46°to71° C (—50° to 106° F)

Operating altitude

0 m to 2134 m (0 ft to 7000 ft) (note 6)

Nonoperating altitude

9100 m (30,000 ft) maximum

Power

Volts ac
Frequency

152.4 cm (60.0 in)

188 Vto 264 V at 60 Hz
198 V to 264 V at 50 Hz
50Hz + 1 Hzor 60 Hz = 1 Hz

Kilo volt amp (kVA)

Standby (loaded)
Start /stop

1.5 kVA maximum (note 7)
2.4 kVA maximum (note 7)

NOTES

177.8 mm (7 in) and 216.0 mm (8.5 in) reels may be used but cannot be autoloaded.

The maximum displacement between any two bits of a character when reading a master tape using
the read section of the read-after-write head.

The maximum displacement between any two bits of a character on a tape written with all ones
“using the write section of the read-after-write head.

Approximate distance from detection area to write head gap is 35.6 mm (1.40 in).

For data transfer, the operating temperature is dictated by the nature of the tape material.

Operation above 610 m (2000 ft) in 610 m (2000 ft) increments, requires installation of high
altitude pulleys and belts in TU78 power pack.

Slave unit only. Add 700 W for master units.

CHAPTER 2

OPERATION

2.1
CONTROLS AND INDICATORS
|
The TU?78 operational controls and indicators are located on the transport control panel. The controls
and indicators are illustrated in Figure 2-1. The controls are described in Table 2-1, the indicators in

Table 2-2.

AUTO
BACKWRAP

_— DEFEAT

—

MAN

[

power O

bot O

PORT

LOAD/REW

on line O
ON LINE

file protect O
UNLOAD

2-A/B

RESET

3TEST

—

1600 O

load fault O

TU78

/
MA-2662A

Figure 2-1

Table 2-1

TU78 Control Panel

TU78 Controls

Control

Function

Port Select Switch

Selects the MASSBUS 1/0 port(s) allowed to send commands to this tape

transport.

Switch
~

Position

Function

Transporvt connected to MASSBUS port A

Transport connected to MASSBUS port B

TranSport connected to both MASSBUS ports A and B

Transport disconnected from both MASSBUS ports and

placed in maintenance mode (available to TM78 formatter
maintenance panel)

2-1

Table 2-1

TU78 Controls (Cont)

Control

Function

LOAD/ REW |

Initiates one of three sequences.
1.

With no tape in path, initiates a load sequence.

With tape in path but not tensioned, initiates a midreel load sequence.
In a midreel load sequence the tape loads and runs in reverse d1rect10n
|
to BOT

With tape in path and tensroned and the transport off-hne the tape
rewinds to BOT. If the tape is already at BOT or if the transport is online, no action occurs.
P

ON LINE

Switches the transport off-line or on-line.

- UNLOAD

If the TU78 is off-line, causes the tape to rewind and unload.'lf the tape is

already at BOT, it unloads. If the TU78 is on-line, button has no effect.

RESET

Terminates all functions and clears a load fault.

BACKWRAP

AUTO (automatic) position: Allows a backwrap and retry for 10.5 inch reel,

DEFEAT

with or without a cartridge.

MAN (manual) position: Inhibits a backwrap and retry for 10.5 inch reel
without a cartridge.

Table 2-2

T_U78 Indicators

Indicator

Meaning

Power

Presence of dc and secondary ac power.

BOT
On Line

Tape 1s at BOT.
-

TU78is on-line. The transport reverts to the off—hne mode if any of the
following occur.
1.

ON LINE button is pressed.

2. External rew»ind unload command 1S recerved.

3. Vacuum celumn inrerleck is broken.

4. ACpoweris los‘r. |
5.

File protect

‘

RESET button is pressed.

Tape reel withouta ,’w_rite enable ring has been loaded onto the transport.

Table 2-2

TU78 Indicators (Cont)

Indicator

Meaning

Load fault

Load fault has occurred.
1.

Autoload sequence has failed to load a tape from a 267 mm (10.5 in) reel

after two tries.

Load sequence has failed to load tape from a 216 mm or 178 mm (8.5 in or
7 in) reels.

1600

6250

Tape transpoft set to read or write at 1600 bits/in (PE mode).

Tape transport set to read or write at 6250 bits/in (GCR mode).

2.2

OPERATING PROCEDURES

2.2.1

Power

When the system CPU is turned on, power is applied to the TU78. The CPU remotely enables the 874E power control, which in turn applies ac power to the TU78 cabinet.

2.2.2

Autoload/Manual Load Selection
Figure 2-2 illustrates various conditions and interlock settings that determine the selection of an auto-

load or manual load procedure.

The manual loading procedure must be used for a 216 mm or 178 mm (8.5 in or 7 in) reel. If a 267 mm
(10.5 in) reel in a cartridge is used, the cartridge engages the cartridge interlock. This bypasses the
autoload interlock and makes the autoload procedure necessary.

A full reel of tape must be used for an autoload sequence. Automatic loading requires that the outer
turn of tape is between 1.59 cm and 0.64 cm (0.63 in and 0.25 in) from the outer edge of the reel

(Figure 2-3). Thus 267 mm (10.5 in) reels which do not contain sufficient tape, must follow the manual
load procedure.
»
2.2.3

Autoload

Follow the steps below in order to perform the autoload procedure.
1.

Check that the tape path is clean. (Refer to Paragraph 4.3.4 for cleaning procedure.)

Check that the tape is a 267 mm (10.5 1n) reel, and that it has a full reel of tape.

Check that the end of tape has a clean edge and is not bent, torn, or frayed. If necessary, trim
the end with the tape crimper (PN 47-00038).

NOTE
Do not crimp the tape unnecessarily. Each crimping
shortens the tape leader and could eventually lead to
failures in the autoload sequence.

)

START

267

MM (10%
IN)
REEL

TAPE

REEL IN A

YES

CARTRIDGE

NO
—<_

MANUAL LOAD

FULL

REEL OF TAPE

PROCEDURE

AUTO LOAD
PROCEDURE

(PARAGRAPH 2.2.4)

(PARAGRAPH 2.2.3)
MA-2763B

Figure 2-2

Autoload/Manual Load Selection

LAST TURN OF TAPE

15.875 MM: 6.35 MM

(0.625 INCH: 0.250 INCH

MA-2654

Tape Content Limit

2-4

Figure 2-3

Check that static charge is not causing end of tape to stick to reel. End of tape must be free
of reel to accomplish autoload.
If a write operation is to be performed, install a write enable ring onto the rear flange of the

tape reel.

Place the supply reel in position on the 'upper hub. Rotate until it slips easily into place, and

press the reel retaining actuator. The reel should
be positioned so that the tape unwinds if it

is turned clockwise.

NOTE

The supply reel may be contained in an Easy-Load®
wraparound cartridge. It is not necessary to remove
or open the cartridge. It opens automatically during

the autoload sequence.

Carefully close the buffer door. Make sure it is closed securely.

Close the transport front door.

Check that power is applied to the tape transport (power light on).
10.

fore maintenance personnel are called. Refer to Figure 2-5 to identify tape path components.

.
Pt

Follow the instructions and check for the events specified in Figure 2-4. If the tape fails to
load properly, the figure contains some operator troubleshooting hints that can be tried be-

2.2.4

Manual Load

Follow the steps below in order to perform the manual procedure.
1.

Check that the tape path is clean. (Refer to Paragraph 4.3.4 for cleaning procedure.)

If a write operation is to be performed, install a write enable ring onto the rear flange of the

tape reel.

Place the supply reel in position on the upper hub. Rotate until it slips easily into place, and
press the reel retaining actuator. The reel should be positioned so that the tape unwinds if it

is turned clockwise.

Manually place the tape leader between thread block 1 and air bearing 1 (Figure 2-5).

- NOTE

Make sure that there is no tape slack or sag between

the supply reel and thread block 1.

Close the transport front door.

Check that power is applied to the tape transport (power light is on).
Follow the instructions and check for the events specified in Figure 2-6. If the tape fails to
load properly, the figure contains some operator troubleshooting hints that can be tried before maintenance personnel are called. Refer to Figure 2-5 to identify tape path components.
®Easy-Load is a registered trademark of IBM, Inc.

2-5

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AIR BEARING NO. 3

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/

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/ AIR BEARING NO. 4

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—" POCKET

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EOT/BOT SENSOR

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—————TAPE IN PATH

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UNLOAD

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T————__TAKE UP
BUFFER BOX

RESET/

6250 IN.DICATOR/

VACUUM

1 CAPSTAN

1600 INDICATOR/

PACK SENSE/
LOW-TAPE SENSOR
7
TABS (IN REEL)_“rake UP REEL
LOW-TAPE SENSOR

(BEHIND REEL)

— ACCESS LATCH

/
HEAD

h
AIR BEARING NO. 5

TAPE CLEANER

SCREW

MA-2640A

Figure 2.5 Tape Path and Controls

2.2.5 Probable Causes of Loadu Failure

The following is a list of procedures for repairing load failure.

Check that the buffer door is closed ahd sealed properly.
2.

Check that the front door is closed securely.

Check for ripped, Creased, or damaged tépe leader. This 1s especially critical if an autoload

failure has occurred. If necessary crimp the end of the tape with a tape crimper.

Check that the write enable ring is inserted in the tape reel if a write operation is to be performed. (File protect indicator should be out.)

If an autoload is being perfdrmed, check thc followi'ng.v
a.

A 267 mm (10.5 in) tape reel is on the supply hub

The supply reel has a full reel of tape. The tape must be between 0.64 cm and 1.59 cm
(0.25 in and 0.63 in) from the outer edge of the reel.

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Midreel Load

2.2.6

A midreel load is usually required after a power failure or a lost interlock. Follow the steps below to
1.

perform a midreel load.

Rotate the take-up reel to remove all slack in the tape.
CAUTION

Do not attempt midreel load until all slack is manually removed from the tape between the reels.

Press the RESET button.

Close the front door.

Press the LOAD/REW button.

The transport loads the tape and starts a reverse operation to BOT. To stop the transport, press the
RESET button. Any other command may now be given.
Unload

2.2.7

Follow the steps below to unload a tape.

2.2.8

Press the RESET button to terminate any current operation and place the transport off-line.

Press the UNLOAD button. If the tape 1s at BOT,- it backwinds onto the supply reel. If the

tape is at midreel, it rewinds to BOT and then unloads (backwinds onto the supply reel).
:

Rewind

Press the LOAD/REW button, with tape tensioned and the transport off-line, to rewind the tape to
BOT. When the button is pressed with the tape at BOT, no action occurs.
On-Line/Off-Line

Press the ON LINE button to place the transport on-line. This lights the on-line indicator. While online, the transport can accept external commands provided it is selected and ready. If the ON LINE
button is pressed again, the transport goes off-line. The on-line indicator goes out. Also, the transport
automatically goes off-line when any of the following conditions occur.

2.2.9

An external rewind unload command is received
Vacuum column interlock is broken
AC power is lost

RESET button is pressed
Front door opens

2-9

CHAPTER 3
INSTALLATION

3.1
3.1.1

SITE PLANNING
|

Space Requirements

Figure 3-1 illustrates the space and service clearances required for the TU78 cabinet. There must be
~enough space to swing the TM78 out of the cabinet for servicing and open the front and rear doors on
|

the TU78 tape transport.

|
|
3.1.2 Power Requirements
Vac,
256
to
Vac
198
or
Hz,
60
at
Vac
The TU78 tape transport can be operated from 188 Vac to 256
+10
within
to
maintained
be
50 Hz, with proper connections on the power chassis. Line voltage should

——

69.2 CM

‘

(27.25 IN.)

1~
—

6a1 o

(25-1/4 IN.) /

144.8 CM

REAR DOOR

(67 IN.)

76.2 CM

REMOVABLE SIDE.PANEL

(30 IN.)

LEVELER

+,,/ 4 PLACES

BASE ASSEMBLY

MA-2641

Figure 3-1

Space and Service Clearance (Top View)

3-1

percent of the nominal value. Frequency should not vary more than £1 Hz.

3.1.3

Environmental Requirements

The TU78 transport should be located in an area free of excessive dust, dirt, corrosive fumes, and va-

pors. The bottom of the cabinet, and the air vents in the front panel and rear door of the cabinet, must
- not be obstructed. The operating environment should have cool, well-filtered, humidified air. A temper-

ature range of 15° to 27° C (59° to 80° F); and relative humidity of 40 to 60 percent should be main-

tained.
3.2

UNPACKING AND INSPECTION

3.2.1
Unpacking
|
|
The TU78 cabinet (H9500) comes mounted to a shock absorbing wooden shipping skid that measures

approximately 76 cm (30 in) wide, 107 cm (42 in) long, and 15 cm (5.75 in) high. The cabinet comes
packed in an extra strong corrugated cardboard container that measures approximately 76 cm (30 in)

wide, 89 cm (35 in) long, and 147 cm (58 in) high. (Units shipped outside the continental United States
~have an additional wooden container around the cardboard carton. The side panels of the container are
bolted together.) Also mounted to the shipping skid are two wooden ramps which are repositioned during the unpacking procedure so that the cabinet may be rolled off the skid.

To unpack the TU78 from its shipping container, and remove the shipping skid, perform the following

Cut the tape on the top and sides of the container.

Remove and dispose of the container. (It is not reusable.)

Remove the plastic bag from the cabinet.

Two hex head bolts hold the wooden ramps
to the shipping skid. Unfasten the ramps by re-

Cut and remove the plastic bands around the cardboard container. Remove the angle boards.

’

procedure. (Refer to Figure 3-2).

moving the bolts and associated washers. Both ramps are positioned between the TU78 cabinet and the shipping skid, and are visible from the front of the cabinet.

Slide the ramps out from under the cabinet and set them aside for assembly (step 9).

Unbolt the cabinet from the shipping skid. Remove four hex bolts that hold the cabinet
frame to the skid deck (Figure 3-3). Discard the bolts, washers, and nuts.

Remove and discard the three wooden block spacers located between the cabinet frame and

the skid deck (Figure 3-3).

Attach the two wooden ramps to the skid deck. Four tee nuts have been driven into the top of
the skid deck on the left side for this purpose. (Refer to the exploded view of Figure 3-2
showing mounting details.) Position the aluminum bracket of one mounting ramp underneath
the skid deck so that the holes in the bracket are lined up with the tee nuts. Fasten the
bracket to the skid deck with two 1/4-20 X 3/4 hex bolts. (The bolts are shipped in the
accessory package ) Attach the second ramp to the skid deck in the same manner.

3-2

@
CONTAINER,

REMOVE AND DISPOSE

BANDS,
PLASTIC
CUT, REMOVE, AND DISPOSE

PLASTIC BAG,
REMOVE AND DISPOSE

f
|

|
A

ANGLE BOARD,
REMOVE AND DISPOSE
(4 REQUIRED)

POLYESTER TAPE,
CuT

RAMPS, ATTACH TO

SKID DECK

HEX 4&1
SCREW

MA-7015

Figure 3-2

Unpacking the TU78

CAUTION

The following step requires two people to roll the
TU78 down the wooden ramps. The majority of the
weight of the TU78 is situated in the upper half of
the cabinet, making it top-heavy. Do not attempt
this procedure with only one person.

10.

Roll the TU78 toward the left side of the side deck by pushing gently on the right side of the
cabinet. With one person bracing a shoulder against the left front and the other person brac_ing a shoulder against the left rear of the cabinet, allow it to roll off the skid deck, down the wooden ramps and onto the floor.

11.

Unfasten the wooden ramps. Discard them and the shipping skid.
3-3

TU78 CABINET

NYLOCK NUT

ASSSSRNSUNTER

SQUARE WASHER

‘

HEX BOLT
MA-7016

TU78 Mounting for Shipment

the local DIGITAL sales office. Perform the inspection according to the following
steps.

shipper and

Inspect all switches, indicators, and panels for damage.

Open TU78 front door. Fully depress the upper and lower release buttons and open the
buffer box door. Check that the buffer box door is tightly secured to the cabinet. Inspect
for
foreign material, loose or damaged components, and for glass damage.

3.2.2
Inspection
o
;
'
After unpacking the TU78 transport, inspect it and report any damage to the responsible

’/M'\\

Figure 3-3

Check the 'transport for any foreign material that may have lodged in the take-up reel or

other moving parts.
4.

Rotate the supply hub and take-up reel. Check for binding and physical damage.

Rotate the capstan. Check for binding and physical damage.

~
CAUTION
The capstan is fragile. Do not touch the capstan rub-

ber surface and do not apply pressure to the capstan
- Which might cause it to deform.
|

Check tape path for any_shar.p‘e,dgé_s; |

Close the buffer box door by pressing the two release b»utt(_v)ns using moderate pressure. (The

buttons will not catch if pressed too hard.)

conre

Close the TU78 front door.

3-4

3.3

SINGLE TRANSPORT INSTALLATION

3.3.1

Mechanical Installation

- After the shipping container and skid have been removed and visual inspection has been performed, roll
the transport cabinet into position and proceed as follows.

NOTE
\
If the TU78 is placed next to another system cabinet, do not remove the adjoining side panels and bolt

€

the cabinets together. Rather, leave the side panels
on and position the TU78 side panel tight against
the other cabinet’s side panel. This maintains proper
air flow in both cabinets.

An array of vertical slots constitutes the venting in the cabinet front panel. A quick release

latch is located approximately 2.54 ¢cm (1 in) behind each end of this array. Insert a thinbladed tool (such as a small steel rule) into one of the end slots, and push on the latch while
simultaneously pulling forward to release one corner of the front panel. In the same manner,
while continuing to pull forward, release the latch at the other end of the array to free the
front panel. Remove the front panel and set it aside. Do not disconnect the ground strap from
the panel.

Remove the two leveler pads and four leveler feet that are bhster wrapped wrap and taped to

the inside of the front panel.

Raise the interlock rods on each side of the cabinet. Remove the two stabilizer arms from the
stabilizer sleeve assemblies (Figure 3-4).
|
Screw the leveler pads into the stabilizer arms.

Raise the interlock rods. Reinsert the stabilizer arms into the stabilizer sleeve assemblies.
Install the leveler feet in the lower corners of the cabinet frame (Figure 3-4).

Using a 9/16-inch wrench, lower the levehng feet until they make contact with the floor
~

stabilizing the cabinet.

Using a level, adjust the feet until the cabinet is level.

Extend the two stabilizer arms and lower the leveler pads until they justtouch the floor yet

- can easily slide along the floor. Do not place any weight on the leveler pads.
10.

11.

Insert a 5/32-inch Allen wrench into the rear door latch, and turn one-quarter turn in a

counterclockwise direction. Open the door.

Open the transport front door and the buffer box front door. Using a screwdriver, release the
service lock locatedin the lower right corner of the base assembly Swmg the base assembly
open.

NOTE

The base assembly does not swing open unless the
stabilizer arms are extended (step 9).

12.

Remove the PCB shipping bracket by pushmgin on the lower front and pulling down from
underneath (Figure 3-5).

3-5

INTERLOCK

/
PO

@@QS@SSSQS@%S@@G\

ROD

STABILIZER
ARM

PAD

l%
|

<« LEVELER

FOOT

11-5612
MA-7017

Figure 3-4

Location of Stabilizer Arm and Leveler Feet

13.

Check seating of PCBs in their sockets.

14.

Replace the PCB shipping bracket.

3.3.2 Power and Cabling
Figure 3-6 shows the TU78 ac power distribution system. Refer to this figure while making the follow- | )
ing checks.

Check the following internal power cabling connections.
a.

Power cable from 874-E power controller switched outlet to transport power pack (Fig- -

ure 3-6).

Power cable from 874-E switched outlet to cabinet exhaust blowers.

Power cable from 874-E switched outlet to pneumatic system heat exchanger blowers. |

Power cable from 874-E switched outlet to H7422 power supply (master TU78 only).

Power cable from 874-E switched outlet to TM78 logic cage blower.

DC power cable harness from H7422 power supply to TM78 logic gate (master TU78
only).

3-6

/PAD DING

MIA PCB

READ PCB

WRITE PCB

CONTROL M2PCB

)
.

capsTaN sERvO PCB

REEL SERVO PCB

|
MA-2645A

Figure 3-5

PCB Shipping Bracket (Side View)

Check that the power on/off circuit breaker on the 874-E is on and the remote /local switch is
set to remote (Figure 3-7).

Check fuses on power pack fuse panel (Figure 1-5). It is necessary to swing the TM78 logic

gate out on its hinge. The fuses can be seen from the front of the cabinet.

Remove the cover from the power transformer terminal strip (Figure 3-8). (The ac input plug
on power pack must also be removed.) Check that the blue, brown, and white/red wires are
connected to the lower terminals (Table 3-1). The terminals are numbered 1 through 9, from
left to right. Replace the cover and connect the power pack connector.

Check that the circuit breaker on the rear of the powér pack is in the on (up) position.
Remove the pulley cover from the rear of the transport power pack (Figure 3-8). Spin the ac
motor pulley by hand, and check that the blower and compressor belts are tight and track

properly.

REMOTE SENSE CABLE

(70-08288-30F ) IN
FROM HOST CPU

N o

REMOTE SENSE CABLE (70 - 08288 - 8F )

OUT TO NEXT TU78

’| CABINET EXHAUST

PNEUMATIC
{ SYSTEM HEAT

{)

b S 7,@,

(ool

_|BLOWERS

EXCHANGER

FRONT

’

/’

POWER PACK
¢

)

REAR
874- E

POWER
)

, CONTROLLER

DC POWER CABLE
POWER CORD

(15 FT/4.6 M)
PLUG

(NEMA L6 - 30P )

|
|

I.__._.
= FAN

'
l——

TU78 MASTER ONLY

MA-7018

Figure 3-6

TU78 Power Distribution

(

'POWER
ON / OFF

POWER AVAILABLE .

REMOTE SWITCHING

CIRCUIT

I/NDICATOR

BUS JACKS

I O

[Jooo]] [[ooo]] [Tooo]] looo]]
O

O
REMOTE
ON

a. FRONT PANEL

REMOTE / LOCAL

874-E Power Controller (Sheet’l' of 2)

a. Front Panel

LOCAL

OFF ON

SWITCH

Figure 3-7

o
[

MA-7019

UNSWITCHED OUTLETS

SWITCHED OUTLETS

MA-7020

REAR PANEL

874-E Power Controller (Sheet 2 of 2)

Figure 3-7

- b. Rear Panel

POWER TRANSFORMER
TERMINAL STRIP

TERMINAL NO.1

\/OOOOO'OO

TERMINAL NO. 9

CIRCUIT

BREAKER

S
0]

|
’

AN\

N~
QL
%:@

MOTOR
PULLEY

NN
|

;

‘

3
Q

LOWER

PULLEY

MA-2663A

Figure 3-8

Rear of Power Pack with Pulley Cover Removed |

Table 3-1

Primary Power Connections
Brown Wire and

Input Voltage

Blue Wire

198 — 205

TB1-4

TBI1-7

206 — 215

TB1-3

TB1-7

216 — 225

White/Red Wire

226 — 235

TB1-4

TB1-8

TBI-3

236 — 245

TBI1-8

TB1-4

TB1-9

246 — 255

TB1-3

TB1-9

NOTE
All TU78 transports are manufactured to operate in

the 0 to 610 m (0 to 2000 ft) range. If the transport

you are installing is to operate at higher elevations,
you must install one of the optional high altitude kits
listed below. If not, replace the pulley cover.

The following optional high altitude kits are available.
e

610 to 1220 m (2000 to 4000 ft)

60 Hz
|

S50Hz

(PN A2W-0476-11

|
e

(PN A2W-0476-10
or 29-23985

1220 to 1830 m (4000 to 6000 ft)

or 29-23982)

60 Hz

(PN A2W-0477-10

or 29-23986)
50 Hz

(PN A2W-0477-11
or 29-23983)

)

1830 to 2133 m (6000 to 7000 ft)

60 Hz

(PN A2W-0478-10

‘
50 Hz

or 29-23987)
(PN A2W-0478-11
or 29-23984)

Refer to Table 3-2 for a list of parts and associated part numbers for each kit.

Table 3-2

Pulley/Belt Part Numbers for Altitude Changes

Blower
Altitude

Compressor

Freq.

Belt

610-1220 m
(2000-4000 ft)

60 Hz

108479-03
108479-05

1220-1830 m
(4000-6000 ft)

60 Hz

1830-2133 m
(6000-7000 ft)

60 Hz

50 Hz

AC Motor

Compressor

Pulley

108479-01
108479-08

108478-06
108479-12

102635-03
102635-03

108479-03
108479-12

108479-01
108479-08

108478-07
108478-11

102635-03
102635-03

108479-11
108479-12

108479-01
108479-01

108478-08
108478-13

102635-05
102635-05

Note: Vendor part numbers shown

3-10

NOTE

If the altitude kit is being installed on a TU78 with a
serial number lower than SP02386, you must also
install a new blower assembly (PN 29-24013).
Install the high altitude kit in the following way.

Turn transport power off at the cabinet power controller: Disconnect the | ac line at the

rear of the power pack by pulling the plug straight out.
CAUTION

Do not attempt this or any other removal or replacement procedure within the power pack assembly
without first removing the 220 V power cord.

clockwise,
Remove the belt guard. Remove both belts by manually rotating the pulleys
any compressor

and slipping the belts off the larger pulleys. It is not necessary to loosen
or blower mounting SCrews.

pulley (hub) for the
Remove the pulley set from the ac motor shaft. Save the smaller
from the high altipulley
reinstallation. Replace the larger pulley with the appropriate
tude kit. Reinstall the pulleys on the motor shaft.

Remove the pulley from the compressor shaft and replace it with the proper high alti|

tude compressor pulley.

the belts clockwise by
Replace the belts with the appropriate high altitude belts. Rotate
larger pulley. If too
the
onto
it
placing a belt around the smaller pulley and rotating
sor.
tight or too loose, adjust the position of the blower or compres

" Check that both belts track completely on the pulleys. If not, some shift of the motor
pulleys may be necessary.

| Replace the belt guard and the power cord.

leave it in the base of the
Package the old belts and pulleys in a marked container, and
to a lower altitude in the fu-

transport. It is possible that the transport may be moved
ture.

NOTE

For the following two steps, refer to the procedures
found in the installation section (Chapter 3) of the
TM78 User Guide or Technical Manual.

Connect the BC06S round MASSBUS cable to the input port connector.
Connect a MASSBUS terminator to the output port connector.

Connect the remoté switching control bus from the CPU to one of the front jacks on the 874E.

10.

Using the green/yellow ground cable provided, ground the TU78 cabinet frame to the CPU
cabinet frame. The grounding studs for the TU78 are located on the lower side frame members (Figure 3-11).

3-11

12.

Check that system power is off _at the »CPU. Connect the ac power cable from the 874-F to

the power source.
13,

3.4

—

Replace the front panel. Close the rear door.

11.

Perform acceptance testing (Paragraph 3.5). -

MULTIPLE TRANSPORT INSTALLATION

3.4.1
Mechanical Installation
When an installation requires more than one transport, only the master transport

is shipped with the
side panels. During installation, remove one of the side panels, and bolt the
master and slave transport(s) together. Then mount the removed side panel onto the end slave transport.
After removing the shipping containers and skids, perform the visual inspection

of the transports. Then
transport to the left (facing front) of all other transports. This allows the TM78 keypad/display to be seen
from the other transports in the line when the logic gate is swung out (Figure 3-9).
roll the transport cabinets into their approximate positions. Place the master

NOTE

If the TU78 on either end is placed next to another

system cabinet, do not remove the adjoining side
panels and bolt the cabinets together. Rather, leave

the side panels on and position the TU78 side panel

» );mn«\\

tight against the other cabinet’s side panel. This
maintains proper air flow in both cabinets.

Unless otherwise s’pecified, perform the installation of each cabinet as follows.
An array of vertical slots constitutes the venting in the cabinet front panel.
A quick release
latch is located approximately 2.54 ¢cm (1 in) behind each end of this array.
Insert a thinbladed tool (such as a small steel rule) into one of the end slots, and push on
the latch while
simultaneously pulling forward to release one corner of the front panel. In the same
manner,
while continuing to pull forward, release the latch at the other end of the array
to free the
front panel. Remove the front panel and set it aside. Do not disconnect the ground
strap from
the front panel.

Remove the two leveler pads and four leveler feet that are blister wfapped and taped to the

inside of the front panel.

Raise the interlock rods on each side of the cabinet. Remove the two stabilizer
arms from the
stabilizer sleeve assemblies (Figure 3-4). :
'

Screw the leveler pads into the stabilizer arms.
Raise the interlock rods. Reinsert the stabilizer arms into the stabilizer sleeve assemblies.
Install the leveler feet in the lower corners of the cabinet frame (Figure 3-4).

Extend the two stabilizer arms from each cabinet and lower the leveler pads until they just

touch the floor. Do not place any weight on the leveler pads.

Open the master transport front door. Using a screwdriver, release the sérvié_egvlock located in

the lower right corner of the base assembly. Swing the base assembly open.
3-12

( TOP VIEW
)

TU78 UNIT O
(MASTER)

\
\

TM78 LOGIC

\_‘

GATE OPEN

(SLAVE)

- VIEWING
ANGLE ’
T T T ———
-

TU78 UNIT 3

TU78 UNIT 2

TU78 UNIT 1

L
T
.

| 'M_AI-NTENANCE

/ DISPLAY
KEYPAD
MA-7021

Figure 3-9

Cabinet Placement for Maintenance Display Visibility
NOTE

The base assembly will not swing open unless the
stabilizer arms are extended (step 7).

Locate the fastener attached to the underside of the master transport top cover (Figure 3-10).
Release the top cover by turning the fastener one- quarter turn in a counterclockwise direc-

tion. When it is released, the fastener hangs by a wire from the top cover. Pull the top cover
forward approx1mately 1.27 cm (0.5 in) and lift it off. Rest the cover on top of the cabinet,
leavmg the ground wire connected

MA-2533

Figure 3-10

Top Cover Fastener

MOUNTING BOLTS

O
=
—

FRONT TRIM
I

——

i r__mg

a1l

/4\
e

GROUNDING

STUDS

MOUNTING BOLTS
MA-2661

Figure 3-11

10.

Cabinet with Side Panels and Top Cover Removed

Remove the end panel on the right side by grasping it on both sides and lifting.it off the four

mounting bolts. If the side panel does not lift off, it may be necessary to loosen the mounting

bolts. In this case, remove the front panel trim to gain access to the upper front mounting
bolt. To remove the trim, lift it up and out (Figure 3-11).
11.

Disconnect the side panel ground strap from the cabinet frame and set the panel aside.

12.

Remove the four exposed mounting bolts from the master transport.

13.

Push the cabinets together so they are in adjoining positions with the mounting bolt plates

side by side.
14.

15.

Using the short ground strap included with the slave transports, ground the master and slave
cabinets together.
Using the green/yellow ground cable provided with the master, ground the master TU78
cabinet frame to the CPU cabinet frame.

16.

Using a 9/16-inch wrench, lower the leveling feet of the highest cabinet until they make contact with the floor stabilizing the cabinet.

17.

18.

Using a level, adjust the feet until the cabinet is level.
Level and adjust the adjoining cabinet(s) so that the bolting (middle) holes on the four corner

bolting plates are aligned.

3-14

—

miA
|

|
I
I
|
I

A
e
G

|
|

TUO ( MASTER )

— o

I
I

— e

|
|

——

[

[ MIA Jfl

a—

cun S ee =

( FRONT VIEW )

TU 2 ( SLAVE))

TU 1 (SLAVE)

|
i

TU 3 ( SLAVE))

NOTE:

ROUTE CABLES

UP THROUGH SPACE
BETWEEN CABINET

MA-7022

FRAMES.

Figure 3-12

TU Bus Cable Routing for a Multiple Transport
Configuration

NOTE

Before performing the next step, the TU bus cables
for all slave transports must be laid in loosely between the master and first slave (Figure 3-12). There
are two 4.6 m (15 ft) cables (PN 70-17382-15) for
each slave. Orient the cables so that the red stripe on
the side faces the rear of the cabinet. Do not tape the
cables together since this would inhibit the replacement of a single cable in the event of failure.
19.

20.

21.

22.

Insert 1/4-inch bolts into the holes and secure them with kep nuts. Bolting the cabinets in this

manner provides good horizontal alignment.

Readjust the leveler pads on the stabilizer arms until each pad touches, yet easily slides along

the floor. Do not place any weight on the leveler pads.

Install the four mounting bolts from the master cabinet into the mounting bolt plates of the

end slave transport. Remove front panel trim if necessary.

Open the base assembly of the end slave transport. Release the top cover fastener, remove
the cover, and rest it on top of the cabinet, off to one side. Do not disconnect the cover
-

ground strap.

23.

Set the side panel from the master transport next to the slave transport. Connect the panel
ground strap to the cabinet frame. Mount the panel onto the side of the slave transport.

24.

Replace the top cover and secure the cover fastener.

25.

Insert a 5/32-inch Allen wrench into the rear door latch. Turn it one-quarter turn in a

counterclockwise direction and open the door.

3-15

26.

Open the base assembly of each transport. Remove the PCB shipping bracket by pushing in
on the lower front and pulling down from underneath (Frgure 3-5). Check seating of PCBsin
their sockets. Replace the PCB sh1pp1ng bracket.

3.4.2

Power and Cabling

Flgure 3-6 shows the TU78 ac power distribution system Refer to th1s flgure while making the following checks.

Check the following internal power cabling connections for all the transports.
a.

Power cable from 874-E power controller switched outlet to transport power pack (Fig-

ure 3-6).
b.

Power cable from 874-E switched outlet
to cabinet exhaust blowers.

Power cable from 874-E switched outlet to pneumatic system heat exchanger blowers.

Power cable from 874-E switched outlet to H7422 power supply (master TU78 only).

Power cable from 874-E switched outlet to TM78 logic cage blower (master TU78
only).

DC power cable harness from H7422 power supply to TM78 logic gate (master TU78
only).

Check that the power on/off circuit breaker on the 874-E

is on and the remote /local swrtch1S

set to remote (Flgure 3-7).

Check fuses on power pack fuse panel (Figure 1-5). The fuses can be seen from the front of
the cabinet. (On the master transport, it is necessary to swing the TM78 logic gate out on its

hinge.) A closer view can be obtalned from the rear of the cabinet by looking over and down
onto the fuse panel.

Remove the cover from the power transformer terminal strip (Figure 3-8). (The ac input plug
on the power pack must also be removed.) Check that the blue, brown, and white/red wires

are connected to the lower terminals (Table 3-1). The termrnals are numbered 1 through 9,
from left to right. Replace the cover and connect the power pack connector.

Check that the circuit breaker on the rear of the power pack is in the on (up‘) position.‘

Remove the pulley cover from the rear of the transport power pack (Figure 3-8).
NOTE
All TU78 transports are manufactured to operate in

the 0 to 610 m (0 to 2000 ft) range. If the transport
~

you are installingis to operate at higher elevations,
you must install a high altitude belt and pulley Kkit.

Refer to Paragraph 3.3.2, step 6 for instructions.

Spin the ac motor pulley by hand and check that the blower and compressor belts are tight
o

,,/’/\\~

and track properly. Replace the pulley cover.

3-16

NOTE

For the following two steps, refer to the procedures
found in the installation section (Chapter 3) of the
TM78 User Guide or Technical Manual.

Connect the BC06S round MASSBUS cable to the input port connector.

Connect a MASSBUS terminator to the output port connector.
Install the TU bus cables between the TM78 in the master transport and the slave transport(s). Figure 3-12 shows the positioning of the cables relative to the cabinet frames. The
TU bus for the master transport is prewired at the factory. Figure 3-13 shows the electrical
connection for each TU bus cable. Start at the TM78 end of the cable and work toward the
MIA (multiple interface adapter) end.

i
SF
—
Z 7]
1 |
TUO MIA
L{EJ___;J—1=DDDD

TU1 MIA
. —

N pe—

J3 | J2i

‘

| fi:'JZi
.

| TU BUS 1A

fi:‘ff

—

]

TU BUS 0B

TU BUS 1B

r js J

l I
]

Dbooo

U_'L_l_‘l_..l_—l-‘

TU 2 MIA
—

TU BUS 2B

]

Gooo

IJ'_\_I_'L_J—\-‘

TU
3 MIA

_TUBUS 3A _

[fJ
-

| |

TU BUS 3B ) F ] J
J8

| 'gaooo

5 TM78 BACKPLANE
MA-6172

Figure 3-13

TU BUS 2A
r ] J
»
( L w]

Radial TU Bus Connections

NOTE

The procedure for connecting the cable to the TM78
is found in the installation section (Chapter 3) of the
TM78 User Guide or Technical Manual.

3-17

RED STRIPE T——E
L IIIIIIIIIIIIIIIIIIII
X

AN N
N

I
]

[

FOLDING

CABLESIN

DETAIL

[

MA-7023

Figure 3-14

Cable Orientation on TU78 MIA PCBA (Slave Only)

10.

The TU bus cables should exit up through the space between the frame members of the mas-

ter and first slave transports. (Refer to note after Step 18, Paragraph 3.4.1). Fold all cables
over and thread them through the space between the cabmet frame and the transport card
cage side panels. The cables should lie flat over the MIA PCBs.

11.

Dress and bend the cables as shown in Figure 3-14. Note the orientation of the red stripe.

Plug the appropriate cables into the two MIA jacks (J2 and J3). Any slack in the cables

should be taken up, folded, and tie-wrapped.

12.

Repeat this procedure for each set of cables going to each slave transport. The cables for
each succeeding transport should be layed over the preceding transports MIA card (Figure 3-

12).
13.

Daisy chain the remote switching control bus by connecting the bus from the CPU to one of

the jacks on the front of the master transport’s 874-E power controller. Using another cable,

connect the bus from one of the other jacks on the 874-E to the 874-E in the next transport.

Continue the daisy chain until all the TU78s are connected to the remote switching control

bus.
14.

Check that system power is off at the CPU. Connect the ac power cable from each 874-E to a
power source.

15.

Install cabinet front panels, and close and secure all base assemblies.

16.

Perform acceptance testing (Paragraph 3.5).

3.5 ACCEPTANCE TESTING
This section describes all the acceptance tests required for the TU78 transport and the TM78 tape
formatter. If they are performed satisfactorily, then the units have been installed and are operating
properly.

3-18

Acceptance testing is divided into three categories: turn-on and loading checkout, subsystem quick
check, and system level diagnostics. The turn-on and loading checkout verifies only basic functions of
the transport and formatter. The subsystem quick check involves calling certain microcoded test routines from the TM78 maintenance panel. The system level diagnostics treat the formatter and transport
as a subsystem, and exercise them to the fullest extent.

If unfamiliar with interlocks and other conditions affecting autoload/manual load selection, refer to

Paragraph 2.2.2.

Turn-On and Loading Checkout

3.5.1

The turn-on and loading checkout applies power to the subsystem in order to observe the state in which
the formatter comes up running and the transport comes up idle. This test also loads the transport under
various conditions in order to check for the proper responses. The checkout utilizes flowcharts to show
the proper sequence of events for each loading operations. The flowcharts include minor troubleshooting aids to help locate simple problems caused by bad tape or improper loading procedures. Perform the following operations in order.

3.5.1.1.

Power On - Follow the instructions and check for the events specified.

Remove the lower front panel of the master transport to gain access to the TM78 formatter.

Turn both TM78 MASSBUS ports off-line by flipping TM78 backplane DIP switches 1 and

Turn on power. This may be done remotely by turning on the host CPU, or locally by flipping

Check for the following.

5 to the right (0) position.

the REMOTE/LOCAL switch located on the 874-E to LOCAL ON.

All fans in subsystem turn on.

The following indicators on the TU78 control panel light: Power, File Protect, 6250. All

The internal microcomputer exercises the TM78 maintenance panel display. This exercise consists of rotating the following characters through all six LEDs in the display: 0,
1,2,3,4,5,6,7,-, H E, L, P. The rotating display allows you to check that each LED
can produce each available character. It also indicates that the internal microcomputer

other lights on the TU78 control panel remain unlit.

1S running.

If the display does not rotate the characters, press and release the TM78 master reset

button, located on the backplane just to the right of the DIP switches. If the display still
does not rotate the characters, this indicates that there is a TM78 logic or power supply
malfunction (assuming that the TM78 is off-line). Refer to the troubleshooting procedures found in Chapter 5 of the TM78 Technical Manual.

Perform the TM78 maintenance keypad tests. Press each key (except ENA) independently in
order to produce its keypad matrix location in the display. The second LED digit indicates
the column number and the fifth LED indicates the row number. The other LEDs display
hyphens. Figure 3-15 illustrates the keypad with the assigned column and row numbers.
When no key is pressed, the display reverts to the rotating character test.

COLUMNS

ROWS

4
|

)

B0
@ ®®

= @0 CE &

clalalalc)
J | =@
@TM

E
R
)
MA-7024

Figure 3-15

TM78 Maintenance Keypad

3.5.1.3 Inhibited Autoload Sequence — Install a write enable ring on a 267 mm (10.5 in) tape reel.
Tape
the leader to prevent magnetic tape from coming off the reel. Mount the reel onto the supply hub.
Close
the transport front door. Follow the instructions and check for the events specified in Figure
3-17.
3.5.1.4 Autoload Sequence — Remove the tape from the leader allowing the magnetic tape to
come off
the supply reel. Check that the leader has no creases or rips. If necessary, crimp the end of the
tape

with the tape crimper (PN 47-00038)
Do
. not remove the write enable ring. Close the transport front
~door. Follow the instructions and check for the events specified in Figure 3-18.
3.5.1.5
Manual Load Sequence — Install a write enable ring on a 216 mm or 178 mm (8.5 in or 7 in)
tape reel. Mount the reel onto the supply hub. Check that the leader has no creases
or rips. If necessary,

‘crimp the end of the tape with the tape crimper. Insert 8 cm to 10 cm (3 in to 4 in) of tape into the
threadblock column. Close the transport front door. Follow the instructions and check for the
events
specified in Figure 3-19.

3.5.1.6

Unload Sequence
— Follow the instructions and check for the events specified in Figure 3-20.

3.5.1.7 Manual Load Repe_atability — Perform the following steps.
1.

Mount a 216 mm or 178 mm (8.5 in or 7 in) tape reel onto the supply hub.

Check that the leader has no creases or rips. If neCeSSary, crimp the end of the tape with the

tape crimper.

3-20

_/"M“:-.

3.5.1.2 Load Sequence Without Tape — With no tape reel mounted on the supply hub, and
the front
door closed, follow the instructions and check for the events specified in Figure 3-16.

running the maintenance display/keypad tests and display HELLO in the LEDs.
Now the
keypad is enabled and the microcomputer is waiting for a command. Press ENA again
and
the microcomputer disables the keypad and the display goes blank.
»

‘Now press the ENA (enable) key firmly for one second. This stops the microcomputer from

PRESS RESET
~

BUTTON..

SUPPLY HUB STOPS.
'
PRESSURE AND

VACUUM SOLENOIDS
DE-ENERGIZE.

PRESS LOAD/REW

BUTTON. .

SUPPLY HUB
ROTATES CCW.

AC MOTOR STARTS.

TAKE UP REEL TURNS

CW. (NO SUPPLY HUB

PRESSURE AND

MOTION.) CARTRIDGE

VACUUM SOLENOIDS

MOTOR OPENS.

ENERGIZE.

PRESSURE AND

TAKE UP REEL STOPS.

VACUUM SOLENOIDS

SUPPLY HUB STOPS.

ENERGIZE.

AC MOTOR STOPS.

PRESSURE AND VACUUM SOLENOIDS DE-

ENERGIZE. LOAD FAULT

SUPPLY HUB

LAMP FLASHES ON

ROTATES CW.

AND OFF.

TAKE UP REEL
COMPLETES ABOUT

PRESS RESET

TEN REVOLUTIONS.

BUTTON.

CARTRIDGE MOTOR

CLOSES, LOAD FAULT:
LAMP GOES OFF,
MA-2639

Figure 3-16

Load Sequence Without Tape

Insert 8 cm to 10 cm (3 in to 4 in) of tape into the threadblock column.

Close the transport front door.

Initiate a manualy load by pressing and releasing the LOAD/REW button.

If the tape loads successfully, press the UNLOAD button to unload the tape.

Repeat steps 3, 4, 5, and 6 eight times. If a failure occurs within the 8 tests, continue manual

loading up to 20 tests. There should be no more than 3 failures among 20 successive tests.

After completing the manual load repeatability test, check the tape for damage caused by
the tape transport. The tape should not show damage sufficient to cause a load failure or data

eITors.
3.5.1.8

Autolead Repeatability — Perform the following steps.

Mount a 267 mm (10.5 in) tape reel onto the supply hub.

Check that the leader has no creases or rips. If necessary, crimp the end of the tape with the
tape crimper.

3-21

PRESS RESET

BUTTON.

PRESSURE AND

;

VACUUM SOLENOIDS

ENERGIZE.

;

PRESS LOAD/REW
BUTTON.,

SUPPLY REEL

TURNS CW,

;

FILE PROTECT LAMPGOES

OFF. AC MOTOR

TAKE UP REEL

STARTS. CARTRIDGE

COMPLETES ANOTHER

MOTOR OPENS. TAKE-

TEN REVOLUTIONS.

UP REEL TURNS Cw,

(NO SUPPLY REEL
MOTION.)

SUPPLY REEL STOPS.
PRESSURE AND

VACUUM SOLENOIDS
DE-ENERGIZE.

SUPPLY REEL

TURNS CCW.

SUPPLY REEL
TURNS CCW.

PRESSURE AND

VACUUM SOLENOIDS

ENERGIZE.

PRESSURE AND

VACUUM SOLENOIDS

ENERGIZE.

SUPPLY REEL

TURNS CW,

PRESSURE AND VACUUM SOLENOIDEDS
TAKE UP REEL

ENERGIZE. SUPPLY

COMPLETES ABOUT

REEL STOPS. TAKE-UP
REEL STOPS. AC MO-

TEN REVOLUTIONS.,

TOR STOPS. LOAD FAULT

LAMP FLASHES ON

AND OFF. FILE PROTECT

SUPPLY REEL STOPS.

LAMP COMES ON.

PRESSURE AND

VACUUM SOLENOIDS

DE-ENERGIZE.

PRESS RESET
BUTTON.

TURNS CCW.

CARTRIDGE MOTOR
CLOSES. LOAD FAULT
LAMP GOES OUT.

SUPPLY REEL

MA-2649

Figure 3-17

Inhibited Autoload Sequence

3-22

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*'SNOILNTOATY N3IL

‘NOL1iNngd

m:o_mws_flaug salo

1dV3NL4
a
a

]
i
i

-PIVL IHL

3-23

ANV SAV3IHHL

HOLOW S0 PV

"S1HVIS3DQaAI4LHVD | WNNSINVHANLSA"IMOINND3IT0S

S*JZIN9HYINNLTa‘MID IHNSAS1NdH3NHNLdSAM7NO3V4

SOd(WN‘3N)N0NO1DAAII311LJ‘dOdV4WANS0NNSDAHVI77NO33LNH3O44"ILM1DO0SW pA—dN—SqaaS ;734.
L
i

dVNL

104

PRESS RESET

BUTTON.

TAKE UP REEL

COMPLETES ABOUT
TEN REVOLUTIONS.

PRESS LOAD/REW

BUTTON.

‘

SUPPLY REEL STOPS.

FILEPROTECT LAMP

GOES OFF. AC

HAS A BOT

TAPE

MOTOR STARTS.

MARKER.

PRESSURE AND

VACUUM SOLENOIDS

;

DE-ENERGIZE.

CARTRIDGE MOTOR

INSTALL A BOT

OPENS.TAKE UP REEL

MARKER 4.6M (15 FT.)

TURNS CW. (NO

FROM THE BEGINNING

SUPPLY REEL MOTION).

OF THE TAPE. REPEAT

l
PRESSURE AND

PROCEDURE,

HAS PASSED BOT

‘
PRESSURE AND

VACUUM SOLENOIDS

SENSOR AND IS ON

ENERGIZE.

TURNS CCW,

THE MANUAL LOAD

BOT
MARKER

VACUUM SOLENOIDS

:
SUPPLY REEL

ENERGIZE.

BOT MARKER IS TOO

FAR FROM BEGINNING

SUPPLY REEL

OF TAPE. MARKER

ROTATES Cw.

SHOULD BE FROM 4.3
REPEAT THE MANUAL

TAPE

THREADS AND

WRAPS ONTO
TAKE UP
REEL.

BOT

LAMP FLASHES

TO 4.9M (14 TO 16 FT.)

LOAD PROCEDURE

FROM BEGINNING OF

WITH ANOTHER REEL

TAPE. REPOSITION THE

OF TAPE. IF THE LOAD}

MARKER AND REPEAT

SEQUENCE IS STILL

THE MANUAL LOAD

UNSUCCESSFUL, RE-

PROCEDURE. IF THE

FER TO TROUBLE-

SAME PROBLEM OCCURS AGAIN, REPEAT
THE PROCEDURE WITH

CHAPTER 6 OF THE

ANOTHER REEL OF

TECHNICAL MANUAL.

TAPE.|F THE LOAD SE-

QUENCE IS STILL UN-

SUCCESSFUL, REFER

l
LOOPS ARE SET

CEDURES IN CHAPTER

6 OF THE TECHNICAL
MANUAL.

PRESSURE AND

VACUUM SOLENOIDS
DE-ENERGIZE.

ENERGIZE. AC MOTOR

STOPS. FILE PROTECT

LAMP COMES ON.

i
CHECK PARAGRAPH

2.2.5 FOR PROBABLE
CAUSE. ATTEMPT

ANOTHER MANUAL
LOAD.IF THE MANUAL

TO TROUBLE-

SHOOTING PRO-

CUUM SOLENOIDS DE-

LOAD FAULT LAMP

PROCEDURES
IN

SUPPLY REEL STOPS.

PRESSURE AND VA-

FLASHES ON AND OFF,

SHOOTING

ONCE.

TAKE-UP REEL STOPS.

LOAD PROCEDURE

FAILS AGAIN, REFER
TO TROUBLESHOOTING PROCEDURES IN CHAPTER
6 OF THE TECHNICAL

TO BOT AND STOPS.

;

MANUAL.

BOT LIGHT

TAPE ENTERS
VACUUM COLUMNS,

:
Figure 3-19

e D

MA-2655A

Manual Load Sequence
Fa

3-24

PRESS RESET
BUTTON.

l
PRESS UNLOAD

BUTTON.

l,
AC MOTOR STOPS.

SUPPLY REEL TURNS
CCW. TAKE UP REEL
TURNS CW AND
THEN CCW,

TAPE UNLOADS AND
WRAPS ONTO SUPPLY
REEL.

SUPPLY REEL
STOPS.

l
' CARTRIDGE MOTOR
CLOSES.

TAKE UP REEL STOPS
~

FILE PROTECT LAMP

COMES ON.

Figure 3-20

Unload Sequence

Close the transport door.

the LOAD /REW button.
Initiate an autoload by pressing and releasing

If the tape loads successfully, press the UNLOAD button to unload the tape.

If autoload fails; the tape automatieal‘ly tries to load a second} time. If the second attempt

fails, the load fault lamp flashes. This is counted as one failure.

Repeat steps 4, 5, and 6 nine times. If a failure occurs within the 9 tests, continue autoloading up to 20 tests There should be no more than 2 fallures among the 20 suceesswe tests.

After completmg the autoload repeatab111ty test, check the tape for damage caused by the

tape transport. The tape should not show damage sufficient to cause a load failure or data
: GI'I'OI'S

Subsystem Qllle Check

3.5.2

Perform this test using the TM78 formatter for each TU73 transport one at a time.

Load a write enabled scratch tape on the desired transport. Place the transport on-line.

3-25

Place the transport port select switch in the number 3 position (maintenance mode).

Enable the TM78 maintenance keypad by pressing the ENA key. The display should respond
with HELLO.

Select the transport as folloWs.
e

Press 0 (parameter item #0).

Press PAR. (The display should flash parameter item 0, then display its contents.)

Enter the TU number to be exercised by pressing 0, 1, 2, or 3.

Press DEP. (The display should flash the new contents of parameter item 0).

Issue a Write GCR command to the transport.
e

Enter 63. (The display should show 63).

Press EXE.

The subsystem executes the write GCR command, puts the results in the display, and waits
for the next command. The results are in the format II-FF, where II is the interrupt code and
FF 1s the failure code. The only two acceptable results are 01-00 (done with no errors), or

01-01 (done with a correctable error). Any other results are not acceptable, indicating a
problem somewhere in the subsystem. Refer to the interrupt code/failure code cross-refer‘ence and troubleshooting sections of the TM78 Technical Manual.

The write GCR command may be executed again by pressing EXE, or repeatedly by
-

pressing REP. To halt a repeated operation, press CLR.

Repeat the quick check (steps 1, 2, 4, and 5) for each transport in the subsystem.

Disable the keypad by pressing the ENA key. The display should go blank.

Turn both TM78 MASSBUS ports on-line, by flipping TM78 backplane DIP switches 1 and
5 to the left 1 position.

Verify each TU78 vacuum and pressure setting by performing the procedures in Paragraph
6.5.4. This 1s especially important if a high altitude belt/pulley kit has just been installed.

Adjust any setting that is out of tolerance.
3.5.3 TM78/TU78 System Level Diagnostics
Mount and load a write enabled 267 mm (10.5 in) tape reel. Place the transport on-line and check that
the on-line indicator lights. Set the transport port select switch to 0 or 1, depending upon the MASS-

BUS port being driven. If exercising a single port subsystem, set the switch to 0.

Table 3-3 lists the TM78/TU78 diagnostics for DECsystem-10/20, and VAX 11/780 systems. Load and
run the appropriate diagnostics. Refer to the instructions in the diagnostic documentation and use the
parameters specified in the following paragraphs.

3-26

Table 3-3

TM78/TU78 Diagnostics for Acceptance Testing

Title

DECSYSTEM-20

VAX

Description

Control

DFTUI

EVMAE

Tests MASSBUS
controller and TM78

Logic Test

formatter logic. Also
tests subsystem
basic command
functions while
checking for proper
tape motion timing.
Must be run from each
CPU separately,
through both MASSBUS
ports (if dual port
option present).
Provides error
information to user
via console or line
printer.
Data

DFTUJ

Reliability

EVMAA

Tests TM78 circuitry

and TU78 circuitry

by writing and
reading predetermined data
patterns and
recording modes.
Provides error
information to user
via console or line
printer. May be run
in dual port mode
(from dual CPUs)
driving two or more
transports.

3.5.3.1

DECsystem 10/20 Diagnostics

DFTUI (Basic/Control Logic Supervisor)

1.
=

Run one pass of test “accept” (TM78 acceptance) with all manual intervention tests enabled.
Allow one pass with no errors.

Run “accept” for five passes with manual intervention tests disabled.

_"-

Allow five passes with no errors.

3-27

DFTUJ (Data Reliability)

Allow one pass in default mode with the error criteria listed in Table 3-4.

Table 3-4 Maximum Error Rate Per Pass
Error Type

Write

Status Errors

Non-recoverable

Media

|
|
|

Others

NOTES

Read Reverse

Double track corrections

Single track corrections
Data compare

Read

—
-~

5
0

‘

One pass consists of writing and reading from BOT to EOT twice, once in each density mode.

If the TU78 does not meet these specifications, further passes are necessary to determine the validity of
errors.

3.5.3.2

VAX 11/780 Diagnostics

Standalone Mode (Level 3)

Control Logic Test (EVMAE) — Boot the diagnostic supervisor (ESSAA) and configure System (select drives, RHs, etc.) to run TM78/TU78.

Run the control logic test (EVMAE) for one pass with all manual intervention tests enabled.

After loading the diagnostic supervisor, in order to print the subtest header information, type
in SET TRACE.

Proceed as follows after the supervisor prompt.
DS>SET TRACE

DS>RUN EVMAE/SEC:MANUAL
Allow one pass with no errors.
Run the control logic test again for five passes without the manual intervention tests as fol-

lows.

'DS>START/PASS:5
Allow five passes with no errors.

Data Reliability (EVMAA) — Run the data reliability exerciser (EVMAA) for one pass. A
pass comprises two complete tape passes (to EOT), once for PE format and once for GCR

format.

3-28

Proceed as follows after the supervisor prompt.

DS>RUN EVMAA
or in conversation mode

DS>ST/SEC:CONVER

Allow one pass with the error criteria in Table 3-4.

On-Line Mode Under VMS (level 2)
1.

Boot the VMS operating system and load the diagnostic supervisor (ESSAA). Run the data
reliability test (EVMAA) for one pass, preferably with other users (jobs) running simultaneously.

Allow one pass with the error criteria in Table 3-4. Make sure that the TU78 tape subsystem
does not degrade total system performance in the on-line mode.

3-29

CHAPTER 4

4.1

CUSTOMER CARE
|
AND PREVENTIVE MAINTENANCE

CUSTOMER RESPONSIBILITIES

The following is a list of maintenance procedure for which the customer is responsible.
1.

Obtain operating supplies, including magnetic tape and cleaning supplies.

Supply accéssories, including cabinetry, tables, and chairs.

Maintain the required logs and report files consistently and accurately.

Make the necessary‘ documentation available 1n a‘ location convenient to the system.

Keep the exterior of the system and the surrounding area clean.
Make sure that ac plugs are securely plugged in each time equipment is used.
Perform specific equipment care operations described in Paragraph 4.2 and 4.3 at the suggested frequencies, or more often if usage and environment warrant.
4.2

MAGNETIC TAPE CARE

The following is a list of steps necessary for properly maintaining magnetic tape.
1.

Do not expose magnetic tape to excessive heat or dust. Most tape read errors are caused by
dust or dirt on the read head; it is imperative that the tape be kept clean.
Always store tape reels inside containers when they are not in use. Keep the empty containers

tightly closed to keep out dust and dirt.

Never touch the portion of tape between the BOT and EOT markers. Oil from fingers attracts dust and dirt.

Never use a contaminated reel of tape. This spreads dirt to clean tape reels and could have an
adverse affect on tape transport reliability.

Always handle tape reels by the hub hole. Squeezing the reel flanges could lead to tape edge
damage in winding or unwinding tapes.

Do not smoke near the tape transport or storage area. Tobacco smoke and ash are especially
|
damaging to tapes.
Do not place magnetic tape near any line printer or other device that produces paper dust.

Do not place magnetic tape in any location where it might be affected by hot air.
Do not store magnetic tape in the vicinity of electric motors.

4-1

4.3

- 4.3.1

PREVENTIVE MAINTENANCE

General

Digital Equipment Corporation tape transports are highly reliable precision instruments that provide

years of trouble-free performance when properly maintained. A planned program of routine inspection
and maintenance is essential for optimum performance and reliability. The following information assists

the customer in caring for his equipment and maintaining the highest level of performance and reliabil-

ity.

4.3.2
Preventive Maintenance
’
|
To ensure trouble-free operation, a preventive maintenance schedule should be kept Thrs involves
cleaning only a few items, but the cleanliness of these items is very important to proper tape transport

operation. The frequency of the cleaning varies with the environment and degree of use of the transport.
Therefore, it is difficult to define a general schedule for all machines. Daily cleaningis recommended
for TU78 units in constant operation in ordinary environments. This schedule should be modified if

CAUTI()N

Do not use acetone or lacquer thinner, rubbing alco-

‘hol, or excessive cleaner. Be extremely careful not
to allow the cleaner to penetrate ball bearings and
motors.

4.3.3

Magnetic Tape Transport Cleaning Kit

A magnetic tape transport cleaning kit (TUCO1) has been prov1ded Its material do not harm tape
equipment and do not leave any residue behind to interfere with data reliability. The following paragraphs contain hints to make sure that the very best results are obtained.

The Freon TF113TM

cleaning fluid in this kit is one of the safest and best degreasing agents available.

It does not adversely affect any part of DIGITAL’s tape equipment. To ready the can, unscrew the top
and punch a small holein the metal seal covering the pour spout
WARNING
TK113 is a non-restricted, non-hazardous substance.
However, avoid excessive skin contact. Do not allow

it to come in contact with the eyes, and do not swallow it. Use only in a well-ventilated area.

Never d1p a contammated cleanmg swab or wipe into the can. To transfer fluid onto the swab, pour a
little into the cap and dip the swab into the cap. Dlscard the fluid remalmng in the cap when the clean-

Ing operation is complete.

Always keep the can tightly closed when not in use because the fluid evaporates raprdly when exposed

to air.

Use the cleaning materials containedin the kit to clean tape heads, air bearings, tape guide blocks, the
tape cleaner, eapstan reel hubs, and any part of the transport where a dirty residue mrght contact the
\

TMTrademark of Dow Chemical Company

Before performing any cleaning operation, remove the file reel and store it properly. All items in the
tape path should be cleaned on a daily basis. It is important to be thorough yet gentle and to avoid
certain dangerous practices. Some tape cleaners are strong cleaning agents and should not come in contact with painted surfaces or plastic.

experience shows other periods are more suitable. Paragraph 4.3.4 contains the cleaning instructions.

tape. To clean other parts of the transport (such as the exterior surfaces of doors) use any reasonably
clean, lint-free material, with or without cleaning fluid.
NOTE

For an unusually stubborn dirt deposit that appears
to resist TF113, try a mild soap and water solution
to dislodge it. After using soap, be sure to wash
down the affected area thoroughly with TF113 to remove soapy residues.

TU78 Tape Transport

4.3. 4

Perform the followmg steps to clean the TU78 tape transport.

Dismount the tape from the unit.

Clean the following components of the transport using a foam- tlpped swab soakedin cleanmg
Thread blocks (6)

Read/write head

Capstan

Erase head
Tape cleaner
“Air bearings (6)

Buffer boxes (2)
Pucker pocket

Buffer box glass, pocket glass, door overlay

Spring-loaded ceramic tape guldes (2)
THREAD BLOCK

AIR BEARING NO. 1

~ AIR BEARING

—

NO.
3

flu1d (Figure 4-1).

AIR BEARING

2
NO.

SUPPLY

__
THREAD BLOCK

1L~ BUFFER BOX

AIR BEARING

BUFFER
BOX GLAS_S\ °

PUCKER

4
NO.

1L~ POCKET
TAKEUP

/(/

AIR BEARING

POCKET

L~ BUFFER BOX

NO. 5 AND

SPRING LOADED
TAPE GUIDE

GLASS

|__.TAPE CLEANER

|| ERASE HEAD

READ/WRITE
HEADS
THREAD

BLOCKS -

Y
_______—d

AIR BEARING NO. 6

SPRING LOADED

TAPE GUIDE

PART OF DOOR

VACUUM

| CAPSTAN

MA-2638

Buffer Box Door

Tape Path Items

Figure 4-1

MA-2637

Transport Items for Daily Cleaning

NOTE
Only use the foam-tipped swabs. Do not touch any
part of the tape path since oil from fingers attracts
dust and dirt. Also, excessive physical pressure on
the capstan could affect its alignment.

When cleaning the thread blocks, be sure to clean the air guide ports. Every thread block has
air guide ports except the metal block containing the spring-loaded tape guide.

When cleaning the spring-loaded ceramic guides, be sure that the washer is pressed firmly
against the tape guide surface and not hung up on its shaft.

When cleaning the inner surface of the vacuum door, use a lint-free wipe and cleaning fluid.
Pass another lint-free wipe over the head using a polishing action to remove any remaining

deposits.
4.4

ORDERING SUPPLIES, ACCESSORIES AND DOCUMENTATION
For information about supplies, accessories, and additional documentation for your TU78 tape trans-

port (or for any DIGITAL equipment), contact your local sales office or call DIGITAL Direct Catalog

Sales.

Continental US, 8:30 am to 6 pm (EST), call 800-258-1710
New Hampshire, 8:30 am to 6 pm (EST), call 603-884-6660

Chicago, 8:15 am to 6 pm (CT), call 312-640-5612
San Francisco, Alaska, and Hawaii, 8:15 am to 6 pm (PT), call 408-734-4915.

Terms and conditions include net 30 days and F.O.B. DIGITAL plant. Freight charges are prepaid by

DIGITAL and added to the invoice. Minimum order is $100.00. (Minimum does not apply when full
payment is submitted with an order). Checks and money orders should be made out to Digital Equip-

ment Corporation.

Purchase orders for supplies, accessofies, and documentation should be sent to the following address.
Digital Equipment Corporation\
Accessories and Supplies Group
P.O. Box CS2008
Nashua, New Hampshire 03061

Purchase orders must show shipping and billing addresses and state whether a partial shipment will be
accepted.

4-4

In addition to the hardware documentation listed in Table 1-1, the following accessories and supplies

may be purchased to support the TU78 tape transport.
Part No

Description

TUM24-A

732 M (2400 ft) magnetic tape 1n

Magnetic Tape

TUM?24-AL

10 TUM?24-A tapes

Magnetic Tape

TUM24-AM

50 TUM24-A tapes

Autoload Belts

TUM24-AX

10 autoload belts for 26.7 cm
(10.5 in) diameter tape reels

Cleaning Kit

TUCO1

Magnetic tape transport cleaning
- kit containing fluid, swabs,
‘wipes, and cleaning instructions

Markers

90-09177-00

Magnetic tape foil sensing

Item

Magnetic Tape

autoload belt

markers for re-creating EOT/BOT

points

CHAPTER 5
THEORY OF OPERATION

GENERAL

This chapter describes basic functioning of the TU78 magnetic tape transport and detailed circuit oper— |
ation of the printed circuit board assemblies (PCBAs). Chapter 1 contains an overall functional description of the transport. Refer to Chapter 1 for a general deserrption of the TU7S. Thls chapter picks up
|

where Chapter 1 leaves off.

The text is supported by applicable sehematics Simplified detail diagrams and other conventional illus.O\S":“S'J!\-’t—"

trations. In addition, the following block diagrams for major functions are providedin the TU78 Magnetic Tape Transport Technical Manual, Volume 1.
System functrons 1ntegrated

- Power supply and distribution
System controls
Capstan servo subsystem
Air load/control function
Reel servo subsystem

‘Diagrams two through six each present one essential function‘, such as the reel servo function. Each

diagram’s subject is covered completely, if necessary for clarity, from input signals to outputs, regardless of circuit location in the hardware. This distinguishes the functional block diagram from the sche-

matic, whichin most cases is confined to a single PCBA or other hardware unit. Schematics provrde

greater detail and are identified by hardware references on the functional block diagrams. TU78 eng1neering drawmgs are locatedin Volume 1 along with the six funct1onal block diagrams

TU78 funct1ons are shownin detailin Figure 1, Volume 1 and d1V1ded for d1scuss1on into the followmg
major categories.
Power supply and distribution
System control
Air load/control
Reel servos
Capstan servo
Write function

- Read function
F1gure 1 1llustrates the relationship between transport functions and interface connections to the mul-

tiple 1nterface adapter (MIA) module

_Interface 1nputsand outputs are 1dent1f1ed by connector and pin designations and mnemonic terms for
the signals. These terms are defined in the glossary. Signal flow between the six internal functions is
also shown. These functions (control, capstan, reel servo, write, read, and power distribution) are covered separately. Therefore connectors are not identified in Figure 1.

5-1

5.2

THEORY OF OPERATION SYMBOLOGY
Spec1f10 symbols and mnemonic standards are usedin the text and drawmgs of this chapter. An exception is the paragraph on the multiple interface adaptor (MIA) interface module. The following explanations refer to other TU78 transport areas.
5.2.1

Functional Block Diagram Symbology
Symbols used in the functional block diagrams (Volume 1) are shown in Figure 5-1. Parts of signal
paths confined to hardware assemblies are placed within boundaries which indicate the subassembly
level. One level of hardware (such as a PCBA) is included within boundaries of the next level assembly

(such as the card cage).
The block diagrams illustrate the purpose of the modules, cards, assemblies, or components involved in
the overall operation. Active components in each block are shown to link the block diagram to the schematic. Interconnecting wires, plugs, jacks, terminal boards, adjustments, controls, meters, and test
points are shown. Signal hnes are coded by special arrowheads and identified by s1gna1 flags The
weight of the 51gnal lines show the significance of the signalin the discussion.

Hardware references are printed in the upper left corner of the area representing that hardware. Controls and control nomenclature visible when the equipment is mounted and operating under normal con-

ditions (dust covers, doors closed, etc.) are considered front panel controls. The diagram shows front
panel controls in a line art window in the function and hardware on which they are located.

Signals generated in one function, and used in another, are interfaced by terminating the signal in a
shadow box area representing the other function using the signal. Since all functions are located in
hardware, all pins of plugs and jacks through which the signal passes are shown. This provides an easy
method of tracing signals from one functional block diagram to another. Signal flags (mnemonic terms)

help the user locate the desired signal faster. Mnemonic terms, and abbrev1at10ns are definedin the
glossary.

The text provides a description of the functional block’s operation within the overall function. The text
is written to establish how one portion of the function interplays with other portions of the function.
References to engineering drawings, schematics, etc., include document number and a zone code
formed from the document sheet number, vertical coordinate number, and horizontal coordinate letter

(for example, zone 2-4 F).
5.2.2

Schematic Diagram Symbology

Interface voltage levels between the MIA and the transport (at interconnect D1) are as follows.

Low (true) =0V
High (false) = 43V
A true signal from the MIA will be 0 V (nominal) at the input to the transport’s receiver circuits. Similarly, a true signal from the transport to the MIA will be 0 V (nommal) at the output of the transport’s

driver circuits. Therefore, at interface low
= true, and a mnemonic term with a prefix I for interfaceis
always interpreted as low
= true. This applies whether the interface signalis an input or output.

At other points in a circuit, a true s1gna1 may be low. For example, ISIGNAL applied to a NOR gate or
inverter produces SIG, Wthhis high
= true. If SIGis srmllarly inverted, it produces NSIG, whichis

low
= true. As far as voltage levels are concerned, NSIGis the same as ISIG. ISIGis known to be low
= true without the N because the I indicates an interface signal, whichis always low
= true.

5-2

HARDWARE BOUNDARIES
.

[ N

—]

/_HARDWAREASSEMBLY)

1ST LEVEL (COMPLETE

]

2ND LEVEL (MAJOR SUB

u/_ASSEIVIBLY)

[ J

3RD LEVEL (INTERMEDIATE

e I

. .| :

: 'AI//_ 4TH LEVEL (PCBA, ETC.)

/_SUBASSEMBLY)

L—— oo

I l—oo

[]

’...—JE:./

o0 -

[]

REFERENCE TO OTHER FUNCTIONS

SIGNALS BEGINNING OR ENDING
POWER

IN OTHER FUNCTIONAL BLOCK

DISTRIBUTION

DIAGRAMS ARE CONNECTED TO
A
AS SHOWN
SHADOW BOX IDENTIFIED

‘

IN THIS EXAMPLE.

SIGNAL PATH

<€

FEEDBACK PATH

5.
B

>-P
e

INDICATOR SIGNAL

——— e

— ——

MECHANICAL LINKAGE

7. V/// SCREEN TYPE Am

VACUUM LINE OR AREA

PRESSURE LINE OR AREA

777777777 ///

Lol
Ll L Ll 8 8L

CREEN TYPE

NUMBER IN PARENTHESIS DESIGNATES

SHEET NUMBER OF APPLICABLE ENGINEERING
:

DRAWING WHERE CORRESPONDING LOGIC CAN
BE FOUND.

10.

ENGINEERING DRAWING ZONE FORMAT

e
l

:
Figure 5-1

LOGIC GATE SHOWN AT COORDINATES (ZONE) C3 OF

SHEET 2. AREA DEFINED

IN TEXT AS (ZONE 2-3C).

TITLE

DWNG. NO.

2 OF 4
SHEET

NEN

MA-3646

Functional Block Diagram Symbology

An interface signal that appears to be irregular in regard to voltage level is the high /low density select
signal. This is because the signal is essentially true in either high or low state, depending on whether
high or low density is selected. To simplify understanding the logic, this is considered a high density
select signal. It is true (high density mode is selected) when the voltage level is low. If the voltage level
is high, the high density signal is false and the system operates in low density mode.
Standard symbols are used in all schematics, logic drawings, etc. Mnemonic terms are defined in Appendix A. The alphabetic character I is used as the first letter of a mnemonic term to indicate an interface signal. When necessary for clarification, a D (driver) or an R (receiver) is added at the end of the
expression to indicate output and input signals, respectively.

5-3

PULL UP

}1KOHM

TERMINATION
+5

22052

33002

+3TO

LOGIC

OPEN COLLECTOR
GATE IN OUTPUT

BUFFERED INPUT FOR INCREASED
CURRENT
HANDLING CAPABILITY
4.

GROUNDS

| %R

REGULATOR
GROUND

%s | %c

SERVO

CHASSIS

GROUND

LOGIC DC
GROUND

* REFERS TO SPECIFIC GROUND ETCH CONNECTING TO PCBA JACK.
MA-3012

Figure 5-2

Schematic Diagram Symbology

" An N is used in the beginning of a mnemonic term to indicate a NOT (low voltage level) state. In some

documentation thisis expressed by the overline or bar symbology (for example NSIGNAL A = NOT
SIGNAL A = SIGNAL A). The N pertains only to the voltage level; it does not imply that the signal
is logically false.

Other symbols used on the schematic drawings are explained in Figure 5-2.

53 TU78 CABLING/INTERCONNECTIONS
5.3.1

Input/Output Cabling and Connectors-

All input /output signals between the TM78 tape formatter and the TU78 transport are via the multlple
interface adaptor (MIA) PCBA (Figure 5-3). The MIA receives the TU bus from the TM78 and plugs
into J1, J2, and J3 on the interconnect D1 PCBA. The transport interface signals are also coupled to

two other sets of connectors on interconnect D1. These are J101, J102, and J103 located on the top edge

m—

of the interconnect D1 PCBA, and J201, J202, J203, and J204 located on back of the interconnect D1
PCBA (Figure 5-4). Both sets of connectors are not used but can serve as test points for the transport
interface signals. The functional block dlagramsin Volume 1 of the Technical Manual show these connectors and identify thesignals on each p1n

5-4

TUBUS (N)A

-2

MULTIPLE

,
S

TM78

TAPE

FORMATTER

INTERFACE

|
TU BUS (N) B

ADAPTER

MIA)

[J—3'

MA-3011A

Figure 5-3

TU78 Interface Connections

5.3.2 Interconnect D1 PCBA
|
The interconnect D1 PCBAis the vertical board which prov1des the 1nterconnect10ns between the various logic boardsin the card cage. The interconnect D1 PCBAis shownin Figure 5-4 and connections
provided by the PCBA are listed in Appendix D. The interconnect D1 PCBA also connects to the inter-

connect F1 PCBA, via a cable, through jack J24 (Figures 5-4 and 5-5).
5.3.3 Interconnect F1 PCBA
The interconnect F1 PCBA, mounted on back of the transport base assembly, provides interconnections
‘between the card cage logic circuits and the controls, sensors, and indicators on the base assembly.
Circuits for the interconnect F1 PCBA are shown on Schematic Number 107307. The interconnect F1
PCBA connects to the interconnect D1 PCBA, via a cable, through jack J21 (Figure 5-5). Terminal
boards one through four allow connections to base assembly components.
5.3.4

Internal Interconnections
Interconnections between various functional PCBAs (control M2, write, etc. ) are provided by the interconnect D1 PCBA, into which the other boards are plugged (Flgure 5-4). Conductors on the interconnect D1 PCBA interconnect the logic signals, distribute power, and route commands. Conductor

connections on the interconnect D1 PCBA are listed in Appendix D. The few logic interconnections
made by cable are shownin Figure 5-5. Primary and secondary power circuit cables are descrlbed in
|

Paragraph 5.4.

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8.5VAC (POWER RESET) |

I CARD CAGE ASSEMBLY

+12, + 24,

INPUT

TRANS-

BREAKER

NREGULATED DC

| RECTIFIERAC

8.5VAC CAPSTAN/ K

36V (©)

—

—8

INTER-

CONNECT

'L be

JUNREGULATED

oces |

ClRCUITS

REGULATED

PCBA

r——-"E
'

| B

REGULATED

DC DISTRIBUTION

BLOWER/

GCR/PE

PREAMP

PCBA

— — — #» (FURTHER REGULATION OF

MOTOR

REGULATOR §

o | voirace |

) /_M\\

]

POWER PACK

ASSEMBL

‘

'
36V (S,R) DC

PCBA

UNREGULATED
MA-3658A

Figure 5-6
5.4

Power Supply Simplified Block Diagram

POWER SUPPLY AND DISTRIBUTION (Refer to Figure 2 in Volume 1 of the Technical

Manual)

The transport derives all power from a smgle ac input (shownin simplified formin Figure 5-6). Prlmary

ac power 1s used for the motor which drives the blower and compressor. A transformer T1 secondary
winding output provides 8.5 Vac to the power reset (NPORST) circuits. Other secondary winding out-

- puts are rectified and delivered to the capstan/regulator PCBA, where they are regulated. Reel servo
- unregulated +£36 Vdc power is supplied to the reel servo PCBA. Power used for the read, write, and

The following paragraphs describein detail the power supply and dlstrlbutlon circuits for a TU78 trans—
port operating on 210 V 60 Hz power. For equlpment using voltages and frequenc1es other than 210 V
60 Hz, you must determine that the input receptacleis properly connected to the primary winding taps.

'Varlous connections are listedin Table 3-1. These are detailed furtherin the following paragraphs. For
“clarity, the subject matter is divided into the followmg topics.
Prlmary power connection and controls
Blower /compressor motor power

Unregulated dc power supplies
DC power regulation and distribution

5-8

erase headsis regulated on the GCR/PE preamp 1 PCBA

5.4.1
Primary Power Connections and Controls
The transport derives all necessary power from a single ac input. The input voltage is optional between
190 and 250 Vac, in 10 V increments, but the input must correspond to the connections between power
circuit breaker CB1 and the transformer’s primary winding taps. These taps are available at power

supply terminal board A1TB1 (Figure 5-7). The transport can also be prepared for either 50 or 60 Hz

power. This requires a different ac motor pulley and a different blower drive belt. Figure 5-7 shows that
ac power is available to the transport when circuit breaker CB1 is closed.

5.4.2 Blower/Compressor Motor Power
The blower/compressor ac motor operates directly on ac input as shownin Figure 5-8. It is turned on
automatlcally when solid-state switch S3 closes the circuit between A1TB1-1 and A1TB1-2. Switch S3
is controlled by +12 Vdc at S3-3 and a low (0 Vdc) pneumatic return PNU RET at S3-4. The +12
Vdc is supplied by rectifier CR2 when the transformer T1 secondary winding is energized. S3-4 goes
low during load operation and stays low unless interlock is lost, or air or vacuum pressure is inadequate.

The motor has an internal thermal switch which interrupts power to the motor windings when the temperature is too high. The switch contacts close when the motor temperature returns to normal.
5.4.3

AC Power

AC power is used in the transport to operate the blower/compressor drive motor and to initiate the
power-on reset process (NPORST) via power supply rectifiers and power-on reset logic (Paragraph
5.4.7). The voltage applied to the motor is 210 V, as long as the input taps on the transformer match the
applied voltage.
|

The power-on reset requirement is 8.5 Vac derived directly from the transformer T1 secondary winding.
The connection to the secondary tap is physically made at the input to rectifier CR2, which 1s connected to A2TB1-10. A2TBI1 is located at the rear of the card cage and prov1des direct 1nputs to vertically mounted interconnect D1 PCBA, to which it is attached. The 8.5 Vacis delivered to pin 40 of J11
to generate the power-on reset signal (NPORST)in the capstan/regulator PCBA.
5.4.4

Unregulated DC Power Supplies
.
Power for the dc circuits is derived from various taps of the transformer T1 secondary winding (Figure
5-9). These ac voltages are rectified by CR1, CR2, and CR3 to produce nominal +12 Vdc +24 Vdc,
and +36 Vdc unregulated voltage.

Actual rectifier outputs are listed as follows.

Nominal

Rectifier Output

+12

9.0 to 11.0 Vdc at 10 A, 2 V peak-to-peak maximum ripple at 10 A |

124

21.5 to 24.5 Vdc at 5 A, 2 V peak-to-peak maximum ripple at 5 A

—24

—21.5to —24.5 Vdc at 5 A, 2 V peak-to-peak maximum ripple at 5 A

+ 36

33.0 to 37.0 Vdc at 15 A, 43 Vdc maximum at no load, 2 V peak-to-peak max-

imum ripple at 15 A

—36

—33.0to —37.0 Vdc at 15 A, —43 Vdc maximum at no load, 2 V peak-to- peak
~

maximum ripple at 15 A

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Rectifier outputs are routed through the respective fuses to terminal A2TBI1, attached to the rear of
interconnect D1 PCBA (Figure 5-9). They are connected through interconnect D1 PCBA conductors to
the capstan/regulator PCBA for regulation and further distribution. However, the PNU RET line is
|

routed to the control M2 PCBA.

Supply reel and takeup reel 436 Vdc unregulated power is routed directly from the respective fuse to

the reel servo PCBA. It does not go through the interconnect D1 PCBA. Similarly, —36 Vdc unregulated power is also routed to the reel servo PCBA.

All dc return lines terminate at the dc common bus mounted on the top of the capacitors. The bus is
B

connected to the center tap of the T1 secondary winding.

o
|
5.4.5 DC Power Regulation
The +12 and +24 Vdc unregulated power outputs are later regulated to provide the required +5,
+15, and +5/—6 Vdc power (Figure 5-10). This is described in the following paragraphs.

5.4.5.1 +5 Vdc Regulator — The + 12 Vdc unregulated voltage is received by the +5 V regulator on
the capstan/regulator PCBA. The +5 V regulator uses a type LM305-IC to control the series power
and has an 8 A full load capacity. TP11 (on capstan/regulator PCBA) is used to monitor the
transistor
:
o
'
|
JERN
regulated +5 Vdc output.

The +5 V is used primarily in the logic and lamp drive circuitry. Current is limited in the +5 V supply
by current foldback techniques. This provides over-current protection.

Over-voltage protection is provided on the +35 V lines. A voltage over 6.2 V fires an SCR and crowbars

the output voltage to zero. Primary power must be removed for a short period of time in order to reset
the crowbar circuitry.

Separate +5 V regulation 1s prbvided on the reel servo PCBA for its internal logic circuits and amplifier circuits, +5 Vdc (S) and +5 Vdc (A) respectively.

The MIA interface logic uses +5 V (L) from the transport via P3-11, 12, 13, 23, 29, and 30. Write,
read, and control M2 modules are made gompatible with MIA logic by obtaining their terminator voltage {+5 V (T)} from the +5 V (L) source via jumper W1 on the interconnect D1 PCBA. W1 is used
to connect the +5 V (L) at J11-22, 23, 62, and 63 to J5-7, 43; J7-21, 57; and J8-37. After the inter-

“connection the signal source name changes to +5 V (T).

is received by the =15 V regulator on the cap5.4.5.2 15 Vdc - The =24 Vdc unregulated voltage
= 15 V regulator uses a type LM325 IC to
The
Vdc.
+15
into
converted
and
PCBA
stan/regulator
capacity. TP15 is used to monitor reguload
full
A
2.5
a
has
and
transistors
power
series
the
~control

‘lated
+ 15 Vdc output, and TP18 to monitor regulated —15 Vdc.

54.53 +5/—6Vdc-The +5V and —6 Vdc used in preamp circuitry are derived from the +15V
and — 15 Vdc by voltage regulators U13 and U14 on the GCR/PE Preamp 1 PCBA. The GCRE preamp 1 is mounted on back of the transport drive base assembly behind the read/write head area. The
regulated + 15 Vdc used for this purpose is supplied through the read PCBA.

5.4.5.4 +36 Vdc (C) — Unregulated +36 Vdc (C) for the capstan motor is connected from fuse F4 to
A2TBI1 on the interconnect D1 PCBA, through the PCBA conductors to J11 and the capstan/regulator
PCBA. Unregulated —36 Vdc (C) is routed from fuse F5 in the same way.

MIA

PCBA
CARD CAGE

A2T81

PNU RETURN

DC COMMON

BUS

F3
-

¢
7

+12VDC*

-36VDC (C)*

DC COMMON 2

BUS

- —

= —

— —

—

_______

DC COMMON 1
|

.
-

-24VDC*

VOl

—_———t

I
——

POWER (+)

[

——

|
]

-1

+5 415 =15 +24VDC

—

J1, J3, J101 ¢— —

CONTROL

L"°]

P11

REGULATED DC

-15VDC**

~15VDC**
+15vDCEr

‘L «L

+5VDC (L)**

[

124

INTERCONNECT

REEL

PCBA

GCR/PE

SERVO

F1PCBA

—{
-36VDC (5)*

PREAMP PCBA

PCe

REGULATES

t 15VDC

TO +5/-6VDC
J16

FROM J6 ON

INTERCONNECT
D1

Vye

(RIBBON CABLE)

FUSEF6 ———d \_p— roevbe ()

CR3-3

CABLE)

+15VDC**

o
|
e 1§

RECTIFIER

(RIBBON

CAPSTAN/ R .

———

————d \_pP—

PCBA

REGULATOR

——— _)

FUSEF7

INTERCONNECT D1

Mm2rcBA

+36VDC ($)*

—

-Th——--—

INTERFACES

PACK

J21 FROM

+36VDC (C)*

POWER

)

PCBA

POWER (-)

WRITE

——~|————,—\

CAPSTAN
CONTROLLED DRIVE

— — —

CONTROLLED DRIVE

F1PCBA

)

+24VDC*

CAPSTAN

—y

P5
INTERCONNECT

DC COMMON

READ

PCBA

g svac

A1T1-12

BASE ASSEMBLY

INTERCONNECT D1 PCBA

A1S3

J20

-36VDC (T)*

)
|

HEADS

* UNREGULATED
** REGULATED

Figure 5-10

MA-3668A

DC Power Regulation and Distribution

5-14

NOTE

A2TB1-2 and A2TB1-3 serve as connecting points
for controlled capstan motor drive power (negative
and positive, respectively). These are part of the cap-

stan circuits and not part of the power distribution

system.

5.4.5.5 =36 Vdc (S) - Unregulated +36 Vdc (S) for the supply reel motor 1s connected from fuse F7
directly to J13 on the reel servo PCBA. Interconnect D1 PCBA circuits are not used. Unregulated —36
Vdc (S) is connected from rectifier CR3-3, without fusing, to J16 on the reel servo PCBA.

5.4.5.6 +36 Vdc (T) - Unregulated +36 Vdc (T) for the takeup reel motor 1s connected directly
from fuse F6 to J17 on the reel servo PCBA. Unregulated —36 Vdc (T) is connected from CR3-3,
|

without fusing, directly to J20 on the reel servo PCBA.
Regulated Power Distribution

5.4.6

All 5 Vdc and 15 Vdc power is regulated on the capstan/regulator PCBA and distributed to other
boards via J11 and conductors on the interconnect D1 PCBA. Internal connections of the interconnect
D1 PCBA are listed in Appendix D. Regulated power distribution is shown in Figure 5-10.

The reel servo PCBA contains voltage regulators on thé same board for the 4+5 Vdc (L) and +5 Vdc

(A) used in the logic and amplifier circuits, respectively. Similarly, the +5 /—6 Vdc used by the pre-

amp circuitry is regulated internally on the GCR/PE preamp 1 PCBA.

'5.477 Power Reset (NPORST), Enable (ENBL, NENBLE), and Master Reset Pulse (NMRSTP)
|

Generation

Restoring power after an interruption initiates pulses that reset or preset various flip-flops, etc., before
starting operation. The following unregulated power at inputs to the capstan/regulator PCBA is involved.

+24 Vdc input at P11-16, 56
—24 Vdc input at P11-20, 60
+12 Vdc input at P11-15, 55
8.5 Vac input at P11-40

of the power, and Schematic Number 104757 shows circuits on the capFigure 5-10 shows the source
the resetting pulses and enabling conditions. The +24 Vdc and —24
develop
that
PCBA
or
stan/regulat
and —15 Vdc, respectively, by LM235N (Ul) and transistors
Vdc
+15
to
reguiated
are
inputs
Vdc
Q32 and Q35 (zones 3-8E, F).

Resistors R114 and R121 (zones 3-7E, F) provide for dividing the difference between +15 Vdc and
— 15 Vdc at approximately —5 Vdc. However, this point is regulated by VR4 (zone 3-6E), inverted to
nominal +5 Vdc at Ul1-11 (zone 3-5H), and applied to adjacent Ul1-4. Resistors R115 and R122
(zones 3-7E, F) provide a +5 Vdc level, which is connected directly at U11-5 (zone 3-5H). When 415
'Vdc and — 15 Vdc supplies are functioning, U11-6 is high, turning on Q29 (zone 3-4G) and delivering a
high through diode CR7 and the 3.9 V voltage regulator VR2 to Q31 (zone 3-3G). Q31 conducts, drop-

ping Q30 base input to 0 V. This turns Q30 off, applying a high to Q55 and a low to Q56. Q56 is turned
off and Q55 conducts sending a high = false NPORST through P11-37, 77 and to the base of Q51.
Q51 conducts turning on Q50 and Q52, making the enable (ENBL) signal low = false.

The preceding conditions are valid when power is applied after a brief delay. The delay provides the low
— true NPORST and high = true ENBL pulses. After the pulses, the previously described false conditions are sustained as long as the 8.5 Vdc, entering at P11-40 (zone 3-10E), maintains a charge in the
5-15

C20 network (zone 3-5G, 3-4G) between diodes CR8 and CR9. When power 1s disconnected,
the 8.5
Vdc is disconnected. This allows the input to VR2 (zone 3-4G) to bleed through CR9 and R110,
disabling the above circuits. The 8.5 Vac feature protects circuits from damage by rapidly discharging
the

power pack capacitors whenever power is switched off or disconnected.

5.4.8
Power Indicator
R
:
|
|
The Power indicator is lit by lamp driver U15 when power is on. This is one of the indicator drivers

the control M2 PCBA which are enabled and, in this case, switched
on by NPORST

stan/regulator PCBA.

5.5
-

INTERFACING AND THE MULTIPLE INTERFACE ADAPTOR (MIA)

from the capS

PCBA

5.5.1
General
SRR
Interfacing between the TM78 formatter and TU78 transport circuitry is accomplish
ed through the
multiple interface adaptor (MIA). The MIA translates signals between the
formatter interface (TU
bus) and the transport interface. Figure 5-11 shows a basic functional block diagram
of the MIA. The
formatter interface (TU bus) is shown entering at the left and the transport interface
is shown entering
at the right.
|
|
|
5.5.2
Physical Description
|
|
|
|
The TU bus connects to the MIA via two jacks, J2 and J3. The MIA plugs into J1, J2, and

J3 on the
interconnect D1 PCBA. A separate cable connects the MIA to the transport’s write PCBA (refer
to
Figure 5-5). Three sets of eight miniature DIP switches are mounted on the MIA. Two of these
sets are
used for setting a hardware serial number, which is used as a signature in status reporting. The
third set
is used for creating a special off-line test data pattern for maintenance purposes. Four toggle
switches
used in manual (maintenance) mode, set the density, tape direction, and read or write. Two
LEDs indicate manual mode and wrong parity on the incoming command word.
5.5.3 Interface Connections
|
~
This section contains a summary of the interface connections (formatter and transport) for the

brief description accompanies each signal name.

5.5.3.1

NPORST is gated with NINTLK (zone 2-8H) to produce CAPSTAN ENABLE. It 1s
delivered
through J11-37 and J11-77, via the interconnect DI PCBA to the write PCBA (J7-11), control
M2
PCBA (J8-61), reel servo PCBA (J12-9, 26), and as MIA PCBA (J1-1). NPORST
is used to reset and
enable various circuits as required after a power interruption. The master reset pulse (NMRSTP)
is
initiated by either NPORST or the manual RESET switch output, as applied to J8-61
or J10-25 respectively, on the control M2 PCBA (Schematic No. 106875, zone 4-8C, D).
ER
-

Q29, CR6, and R99 (zone 3-4G) are connected to the +12 Vdc supply, after regulation to
+5 V by
LM305 (U2) in zone 3-8G. Therefore, all the power pack outputs except =36 Vdc contribute
to the
reset/enable (NPORST/ENBL) network. These supplies must be in operating order to provide
appropriate reset/enable signals, which effectively check supplies before transport operation. ENBL
is used
on the capstan/regulator PCBA to enable the cartridge motor drive circuits (zone 3-8C).

MIA. A

Formatter to MIA Interface (TU Bus) Signals — The TU bus signals are listed in Table 5-1. A

signal line is true when low (<<1.0 V) and false when high (>2.8 V) except for the present
line. The
present line is true when HI. TU bus timing is explained in detail in Paragraph 4.4.1.2 of
the TM78
Magnetic Tape Formatter Technical Manual EK-0TM78-TM. The TU bus signals are listed
by cable
and pin number in Appendix D.
|

MIA INTERNAL CIRCUITS

INTERFACE

(TU BUS)

|
WRITE DATANy IR
o
COMMANDS
|
——————- —
wes
VER

—

STATUS MODE

STATUS

STATUS REGISTERS

__ fr
_

READ COMMAND

WeS DATA

—

LOOP WRITE TO READ/

AMTIE

COMMAN

"WCS DATA

POWER

WCS PARITY CHECK

NALS
|IAMTIE SIGNAL

paTA
—{reap
B

jTACHOMETER

Figure 5-11

!STATUS

J_—'fi

NETWORK

'LOOP WRITE TO

AMTIE SIGNALS P f

CMD PE L

COMMANDS

CONTROL
PROCESSING

STATUS REQUEST

|sTATUS

SRESENT H

l
I
v
|

READ DATA

COMMAND

COMMAND MODE_§

MA-7077

MIA Basic Block Diagram

TU Bus Signal Summary

Signal Name

Function

Elght write /command /status lines are b1—d1rect10nal and multlplexed for

WCS 7.0 L

the three different functions. Information on the WCS linesis determined
by the assertion of the WDS, CMD or STAT control lines. The WCS
lines are asserted by the formatter during a write data or command transfer and asserted by the tape transport durlng a status transfer

ANt

"WCSPL

TRANSCEI

STATUS

Table 5-1

S
J
ol WRITE DATA

INTERFACE

TRANSPORT

‘

FORMATTER l"-' _—

A single b1—d1rect10nal mu1t1plexed WCS hne — It carries the odd parity

bit for command/status transfers, and the parity channel for a write data
transfer. WCS P is asserted by the formatter during command or write
data transfers and by the tape transport during status transfers.

Table 5-1

TU Bus Signal Summary (Cdnt)

Signal Name

Function

WDS L

Write data strobe indicates that the WCS lines contain data to be written
on tape. WDS is asserted by the formatter.*

CMD L

Command indicates that the WCS lines contain a command byte. CMD
is asserted by the formatter.*

STAT L

Status enables the tape unit to place a status byte on the WCS lines.
STAT is asserted by the formatter.*

CMD PE L

The command parity error line indicates that a CMD/STAT address or
command byte has been received by the tape transport with even parity.
CMD PE is asserted by the tape transport. This line remains asserted until a clear command is received with odd parity. While CMD PE L is set,
motion and density signals are not released to the tape transport.

TACH L

Tachometer i1s a line which reflects the digital output of the tape transports capstan servo motor tachometer.

PRESENT H

Present 1s asserted by the tape transport when it is connected to the TU
bus and has power applied.

RD7:0L,RDPL

The nine read data lines are asserted by the.t‘ape transport when read enabled. They can also be asserted during the tape transport loop-write-toread diagnostic mode.

AMTIE 7:0 L, AMTIE P L The nine amplitude track in error signals can be asserted by the tape
transport when read enabled. They indicate, independently, that the read

back amplitude, on the track for which they are named, has not come up
to a predetermined threshold value. They can also be asserted during the
tape transport “‘loop-write-to-read” diagnostic mode.
*The WDS, CMD and STAT lines are mutually exclusive. That is, only one of the three (indicating one of three
types of information on the WCS lines) can be logically true at any time.

5.5.3.2 Transport to MIA Interface Signals — The transport interface signals are listed in Table 5-2. A

signal line is true when low (<<0.8 V) and false when high (>3.0 V) unless indicated otherwise The

transport interface signals are listed by plug/pin number in Appendix D.

5.5.4 Command/Status Register Descriptions
The formatter sends commands to the MIA PCBA in order to control the tape transport and acquire
status information. It sends commands over the WCS lines. Because of bidirectional and multiplexed
traffic on these lines, command and status information is handled by specifically addressable registers.

Instantaneous status information is constantly updated at the registers and available upon request by
the formatter. The MIA registers and bit descriptions are listed in Appendix C.

5-18

Table 5-2

Transport to MIA Interface Signal Summary

Signal Name

Description

Signals from the transport to the MIA.

ISLTO

ISLTO is a signal which, when low, indicates that the operator panel port select

ISLTI1

Same as ISLTO except switch position 1*

ISLT2

Same as ISLTO except switch position 2*

IONL

switch is in the O position.*

is a level which is low when the on-line flip-flop is set. When low, the
IONL

transport is under remote control; when high, the transport is under local
control.

ILDP

ILDP is a level which is low when the transport is ready and on-line and tape is
at rest with the BOT tab under the photosensor. The signal goes high after the
tab leaves the photosensor area.

IFPT
IEOT

IRWD

IRDY

IFPT is a level which is low when tape is loaded and under tension in the vacuum

column, and the supply reel has the write enable ring removed.

IEOT is a level which, when low and the transport is ready and on-line,

indicates that the EOT reflective tab is positioned under the photosensor.

IRWD is a level which is low when the transport is engaged in any rewind

operation.

IRDY is a Ievel which is low when the transport is ready to accept any external

command, i.e., when:

Tape is under tension in the vacuum column.

Aload or rewind command has been completed.

Thereisno unload command in progress.

The transpdrt is on-line.

IDDI

IDDI is a level which is low when the PE density mode is selected.

ITACH

ITACH is a pulse (1 us) which is triggered by the positive and negative

transitions of the capstan optical tachometer. The tape movement between
alternate pulses is 0.254 mm (0.01 in).

*In order for ISLTO, 1, 2 to reflect their true levels, MIA command register 3, bits 3, 4, and 5 must be
loaded with 1s by the formatter.

Table 5-2

Transport to MIA Interface Signal Summary (Cont)

Slgnal Name

Descrlptlon

IARA ERR

The IARA ERRsignal is generated on the read PCBA and sent through the write
PCBA to the MIA via cable. Itis effectivein write mode only and notifies the
system that the automatic read amplifier burst expected at the transport for
recording has failed to record properly within the allotted time.

WRT STAT H

Write status is 1ndlcated by a hlgh
— true WRT STAT srgnal to the MIA via

cable from the write PCBA.
MOTION H

The MOTION high
= true 51gna1 via cable from the write PCBA to the MIA

indicates that the tape transport is in motion.

;

WRT BIN indicates that the tape transport is writing binary data. It is routed

WRT BIN H

from the write PCBA to the MIA via cable. ThlS informationis arbitrarily

derlved from the WD4 channel.

NPORST

NPORST initiates resetting and presetting of circuits when power is applied.

IAMTIE 7:0, P

An AMTIE signal is generated for each of the nine tracks on the basis of the
amplitude of the data as received from the GCR /PE preamp 1 PCBA. An

‘unsatisfactory channel output causes the Write PCBA AMTIE circuits to issue a
low
= true IAMTIE signal to the MIA via cable. IAMTIEPis not generated as a
parity bit for the other eight channels, but reflects the amplrtude status of

~the IAMTIEP track.
IRD 7:0, P

The nine IRD channels provide the MIA with data read from the tape.

Signals from the MIA to the transport

IDDS

IDDS is a level which, when low, conditions the read electronics to operate in
the 63 ¢/mm (1600 cpi) density mode. In addition, the Data density line (IDDI)
to the controller /formatter goes low and the 1600 indicator becomes illuminated.
Conversely, when IDDSis high, the read electronics operate in the 246 ¢/mm
(6250 cpi) density mode, the 6250 indicator becomes 1llum1nated and IDDI goes
high.

ISFC

ISFC is a level which, when low and the transport is ready and on-line, causes
~

ISRC

tape to move forward. When the level goes high, tape motion ceases.

ISRC is a level which, when low and the transport is ready and on-line, causes
tape to move in reverse. When the level goes high, tape motion ceases. An SRC

is terminated upon encountermg the BOT tab, or ignored if glven when tape is at

load p01nt

5-20

Table 5-2

Transport to MIA Interface Signal Summary (Cont)

Signal Name

Description |

ISWS
|

ISWS is a level which is low for a minimum period of 20 us after the front edge
of an ISFC when the write mode of operation is required. The front edge of the
delayed ISFC is used to sample the ISWS signal and sets the write/read flip-flop
in the transport to the write state.

If read modeis required the ISWS signalis high for a minimum period of 20 us
after the front edge of an ISFC (or ISRC), in which case the write/read

flip-flop will be set to the read state

IRWU

IRWU is a level which resets the on-hne flip-flop and initiates a rewind
operation. Upon completion of the rewind, an unload sequence is automatically
|
executed.

IRWC -

"IRWCisa level which, if the transport is selected, ready, and on—line, causes

IRTH?2

Not used

NLTH

"NLTH and STDTH ferm a field which establishes the threshold of the read |

STDTH

tape to move in reverse, moving at rewind speed unless a low tape (LT) condition
has been sensed. In this case, movement is at reverse speed until it comes to
rest at BOT. An IRWC is ignored if tape is already at BOT.

electronics for the nine AMTIE signals as follows:

NLTH
low
low
high
high

STDTH

low
high
low
high

Threshold
10%
- 10%
25%
- 20%

Mode

IRG check
IRG check
write
read

IWINH

IWINH is a level which, when low, prevents the write head from being energized,

IWD7:.0,IWDP

IWD7:0, P are write data signals Wthh when low at IWDS time resultin a flux

IWDS

Thisis the trailing edge of the IWDS s1gna1 strobes the write data hnes to the

while allowing the erase head to operate normally.

reversal being recorded on the correspondmg tape track.

write PCBA circuits.

NTSTR

Not _used

5-21

5.5.5

Circuit Description

- The MIA is essentially a switching and routing device for signals between the TM78 formatter and the
tape transport, in which the MIAis installed. Generally, the MIA performs the following three groups
of functions.

It accepts commands and write data from the formatter and relays them to the transport in a

form compatible with transport circuits.
2.

It accepts read data, amplitude track in error (AMTIE) signals, and status indications from
the transport and relays them to the formatter in a form compatible with formatter circuits.

It participates in certain system-checking functions, such as looping WCS signals from the

formatter into the read data lines or, through registers, into the AMTIE lines back to the
formatter. These functions are called loop-write-to-read (LWR).
With reference to the transport interface, each signal uses a dedicated path. However, in dealing with
the formatter interface (TU bus), some of the signals (i.e., write data and most of the command and

status indications) use the same conductors on a time-sharmg basis. The MIA’s basic functionis multiplexing/demultiplexing signals on the write/command /status lines.

Figure 5-12 shows a detailed functional view of the MIA PCBA. The various signal paths are described
in the following paragraphs.
5.5.5.1

Commands and Command Timing — Two types of command formats may be sent over the

WCS lines by the formatter, as shown in Appendix C. They are the command /status address specifier

byte and the actual command byte. The address specifier byte always has bit 7 = 1 and the command
byte always has bit 7 = 0. Both bytes are strobed to the MIA by the CMD L line. Figure 5-13 shows
the MIA logic associated with command tlmlng and Figure 5-14 shows the timing associated with both
types of command formats.
|

The formatter places the command /status address specifier byte on the WCS lines during the trailing
(rising) edge of CMD L. The rising edge of CMD L also triggers the 500 ns CMD one shot. When the
CMD one shot times out, its Q output latches the byte into the CMD/ADR latch, whose outputs MTC
7:0 now become stable. The Q output strobes MTC 4:0 to the CMD/STA ADR register whichis enabled by CMD 7=1. The CMD/STA ADR register now holds the lower five bits of the com-

mand /status address specifier byte. The four low bits of its output (ADR 3:0) input to the MIA register
address decoder, which asserts a select line (SEL 0-5, 7) to the associated command and status register
pair. The next step in the process is a formatter initiated command write into the addressed command
register, or a status request from the addressed status register. The high bit output of the CMD/STA
ADR register (ADR 4) is not an address bit, but rather the pattern generator enable (PGE) bit. The
PGE bit enables the test data pattern, written prior into command register 7, to be placed on the transport interface IWD lines.
When the formatter writes a command byte to the MIA, the byteis latched into the CMD/ADR latch
as described in the previous paragraph. However, because bit 7 = 0, the CMD/STA ADR register
input 1s disabled and it retains its previous contents. Signal MTC 7 enables one input of the execute
(EXEC) one shot. On the trailing edge of the CMD one shot, the EXEC one shot is fired. The one shot
output (EXEC H)strobes MTC 6:0 into the addressed command register on the trailing edge of its 500
ns timeout. The output of the command register is routed to the transport interface or internally within
the MIA, depending upon the register. Figure 5-12 shows the routing for each command register.

5-22

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5-23

LAY (€)

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oLEr sNlna

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(6:0)

>WORD

COMMAND

SEL
0

ADR 4 (PGE.)

L
.

CMD/

WCS 7:0

CMD/

STA

ADR

(4:0)

LATCH

SEL 1

ADR

ADR 3:0

REG

SEL3
. REGISTER

DECODER|SEL4

(7)

—J

COMMAND

SELECT

SEL 5

CMD L

SEL2

REG

ADR

STR

SEL7

(CMD H)

CMD

0.S.

500NS

—O

EXEC H

EXEC

. COMMAND

~ STROBE

0.S.

500 NS

MA-7068

Command Timing Logic

soons

WCS 7:0

CMD 0.8
|

)

CMD L

mOMMAND ON TU BUS

\\| 500 NS

MTC 7:0

Figure 5-13

{ LATCHED

| X

\\ STROBE
ADR 4:0

X NEW CMD/STA ADDRESS

EXEC H

(REGISTER N)

500NS

1
STROBE

OLD COMMAND

|
IF MTC 7=1

IF MTC 7=0

X NEW COMMAND
MA-7069

Figure 5-14

Command Timing

Command parity is ‘checkedin both command byte formats by inputting MTC 7:0 and WCSP into a
~ parity checker. The checkeris strobed on the trailing edge of the CMD one shot. If wrong (even) parity

was received at the MIA, the CMD PE TU bus lineis asserted back to the formatter, and the command
1s not gated to the transport interface. A command parity error also causes the CMD PE LED on the
- MIA to light.
|
3.5.5.2

Status — The formatter can examine the contents of any status register in the MIA, after it

selects the desired register with an address specifier command (refer to Paragraph 5.5.5.1). Transport
status, from the transport interface, is input to certain status registers while others receive inputs from
sources on the MIA. The formatter requests status by asserting the TU bus STAT L line. Signal STAT

L clocks the transport interface lines to the registers and enables the selected register outputs from the

5-24

MTS lines to the WCS lines. The trailing edge of STAT L clocks the status byte into the formatter

circuitry. Status parity is generated by examining MTS 7:0 and asserting WCS P as required to maintain odd parity on the WCS lines. While the tachometer signal (TACH) is input to the TU DIAG register, it is also transferred from the transport interface to the TU bus with no gating. This i1s done so the
formatter may examine it in real time during a data transfer operaton to guarantee constant tape velocity -and ramp times within specification.

5.5.5.3 Write Data— Once the formatter has commanded the transport to move tape, and enabled the
write circuitry, it asserts nine bits of write data on WCS 7:0, P along with the WDS strobe pulse The
datais gated through the MIA to the transport interface IWD 7:0, P lines, and the strobe pulseis gated
to the IWDS line. Another source of write datais from within the MIA PCBAin test mode. This source
is discussedin greater detailin Paragraph 5.5.5.8.

'5.5.5.4

Read Data — Data from the transport’s read electronics enters the MIA from the transport

interface as IRD 7:0, P. The read data passes through nine independent digital filters that condition the

waveforms, and is gated to the TU bus RD 7:0, P lines. Before, the data transfer, the formatter specified a read enable command by setting bit 6 of the threshold command register.

5.5.5.5 Amplitude Track In Error (AMTIE) Bits - AMTIE status information enters the MIA card
from the transport interface (via cable from the write PCBA) as I AMTIE 7.0, P. AMTIE status 1s
gated out to the TU bus as AMTIE 7:0, P, assuming the MIAis read enabled. Read enableis set and
AMTIE bits are generated, in read and write mode, for both PE and GCR formats.

5. 5 5.6 Dlagnostlc Loops — The formatter can conflgure MIA 01rcu1try in loop write-to- read dlagnostic mode to check the TU bus and portions of the MIA circuitry, independent of the transport. It does
this by resetting the read enable bit (bit 6 of the Threshold command register), and setting the loop
write-to-read (LWR) bit (bit 2 of the TU CMD A register). In this diagnostic loop mode, data can be
sent from the formatter, looped aroundin the MIA, and sent back to the formatterin two ways. First, a
data byte plus parity is sent out on the WCS lines and immediately looped around to the RD lines. In
this case the WCS datais not accompanied by an enabling pulse on the CMD or STAT TU bus lines.
Second, the formatter can loop data around from the WCS lines to the AMTIE lines. It does this by
writing a full nine bits into the AMTIE loop command register (bits 6:0) and the TU CMD A register
(bits P, 7). After writing data into these registers, the formatter can read it back on the nine AMTIE
lines.

5.5.5.7 Switches and Indicators — Three sets of eight DIP switches, four toggle switches, and two hght
emitting diodes (LEDs) reside on the MIA PCBA. Two of the DIP sw1tches set the four d1g1t transport
serial numberin BCD format. The third DIP switchis used to create a write data pattern in off-line
(manual) mode. One of the toggle switches functionally removes the transport from the formatter
(auto), and places it in off-line test mode (manual). When the transport is in manual mode the remaining three toggle switches set tape direction (rev-off-fwd), data mode (read-write), and density (1600" 6250). The two LEDs indicate manual mode and command byte parity error.
5.5.5.8 Test Pattern Generation — Test data patterns can be created and written to the transport over
the transport IWD linesin any of three ways. First, the formatter can write test data through the MIA
in the conventional manner any datais written to tape. Thatis, strobing data from the TU bus WCS

" lines to the IWD lines. Second, the formatter may write a pattern into MIA command register 7, the

test pattern register. Then the pattern
is shifted out to the IWD lines by formatter generated WDS
strobe pulses. And third, a maintenance engineer place the transport in manual mode and create a test

data pattern in the appropriate onboard DIP switches. In this case, data is strobed to tape by an os-

cillator on the MIA PCBA pulsing the transport interface IWDS line.

3-25

MIA COMMAND REGISTER 7

o
)
e
e

mmd
e
)
e
)
e
-—

I (DATA PATTERN EXAMPLE 356g)

NOTE:

)

)
)
eed
)
)
e
med
emd
)

)
e
e

)

)
)
—

aNeNeNololoNeNolo

)

e
)

)

)
)

)

eed

e
)

———

—_—ee)

-t

ol eNoNoNeNeNolleNa

—

LT[l

)

ETC.

cooococoocoo \

-t o)

7*
6

\_‘ .

OR TEST DATA SWITCHES

TEST DATA ISWRITTEN ON

TAPE IN NRZI FORMAT

REGARDLESS OF CHOSEN

DENSITY.

TEST DATA
EIGHTHBYTE OF

GROUP ““N”

FIRST BYTE OF

TEST DATA

GROUP “’N-1"

GROUP "N+1”

*MIA COMMAND REGISTER 7,BIT 7 IS ALWAYS A 1
MA-7070

Figure 5-15

Test Data Tape Format

The manner in which the second and third methods actually write the test data is much different than
the first, however. When register 7 or the switches are used, the pattern in the register or switches is not
the pattern written to tape for each character. Rather, each bit of the 8-bit test pattern byte corresponds to a full 9-bit character on tape, for a total of eight tape characters. If a given bit in the test
pattern is a 1, the corresponding 9-bit character is written to tape as a flux change in all tracks. Similarly, if the test pattern bit happens to be a 0, the tape character has no flux changes in all tracks. In
this method of writing test data, parity and recording format on tape is not observed. The pattern of
eight bytesis written repetltlvely on tape until commanded to stop. Figure 5-15 shows an example of the
test data tape format.
5.6
5.6.1

SYSTEM CONTROL (Refer to Figure 3 in Volume 1 of the Technical Manual)
Control System Overview

The control logic circuitry manages transport operation through commands received from the host Sys-

tem and /or manual commands entered by means of switches provided on the transport. Figure 5-16is a
simplified block diagram of the control logic.
Most of the control circuits are mounted on the control M2 PCBA, which is plugged into connector J8
on the vertical interconnect D1 PCBA. The control M2 PCBA circuits are described in detail in Para-

graph 5.6.6. The following text describes the control system in general.

Inputs and outputs from the host system are connected via the MIA, which plugs into J1, J2, and J3 on
the interconnect D1 PCBA.

Figure 5-17 shows the general routing of control signals throughout the transport assembly.

5-26

o
DRIVERS

LOAD

CONTROL

———» TO REEL

SERVOS

AND

Y |

RECEIVERS

MODE/

MOTION
CONTROL

| TO CAPSTAN

TIMING

SERVO

CONTROL

STATUS

——

CONTROL

——

‘—————

MANUAL

REWIND

CONTROL

CONTROLS

L READ/
WRITE

TO DATA

CONTROL

ELECTRONICS
MA-3654

Figure 5-16

Control Logic Block Diagram

Manual Controls

5.6.2

’

Manual controls (Table 2-1) include the port select thumbwheel switch, LOAD/REW switch, ON
LINE switch, UNLOAD switch, and RESET switch. Manual switching is shown in Figure 5-18. The
power circuit breaker switch, mounted on the rear panel, is discussed in the power supply and distribution text.

In addition to the operating switches mentioned the following switches are provided for maintenance
purposes.

Tape motion switch (on control M2 PCBA) Reel servo disabling switch (on reel servo

Test write switch (on the write PCBA).

AGC exerciser switch (on the read PCBA).

PCBA).

‘The thumbwheel switch (S8) located next to the POWER indicator sets the MASSBUS port select
code so the formatter may determine which MASSBUS (or both, or neither) to logically connect the
transport to. Positions 0, 1, 2, and 3 are used. Contacts 0, 1, and 2 are connected to the MIA module via
the control M2 module. SLT COM on P10-4 is connected to ground. The switch grounds one of the four
select lines which connect to the MIA module via the control M2 module. Which select line is grounded
depends on the MASSBUS port selected by the switch. SLT COM is grounded by jumper W3 on the
control M2 module (Schematic Number 106875, zone 3-7C.) Jumper W3 also asserts SLT and SL'TA
which enables the various transport circuits involved in host system operation.

LOAD/REW, ON LINE, UNLOAD, and RESET switches S2 through S5 (Figure 5-18) are momentary push button devices which normally hold one of their two contacts at low (neminal 0 V) level.
When depressed, they remove signal ground from the contact and momentarily connect ground to the
other contact. Circuits operated by these switch commands are located on the control M2 PCBA, described in Paragraph 5.6.6.

5-27

FROM INTERFACE

| CONNECTORS
r

MODE SELECTION

® DENSITY

INTERCONNECT
D1 PCBA

TO INTERFACE

I—»—_—fi

® READ/WRITE

® TAPE STATUS

]

@ FILE PROTECTED

—‘l

' COMMANDS

STATUS

| ® READY/ON LINE

r—-—— — — —

| CONNECTORS

DENSITY MODE

AMTIE SIGNALS

® TACH PULSE

| ®© PORT SELECT CODE

)

]

I TO TRANSPORT

[

—’»‘

READ PCBA

® UNIT SELECTED
®

DENSITY MODE

® READ/WRITE MODES

® BEGINNING OF TAPE
|

| FROM TRANSPORT
l

e ———
®

FILE PROTECTED

l' ® TAPE STATUS
® TACH PULSE

|
I

P?2]

J24:

A2TBI
® PNEUMATIC RETURN

—_— e ——

® PORT SELECT CODE
®

MANUAL COMMANDS

CAPSTAN/REGULATOR PCBA

READ/WRITE MODE

® TAPE
MOTION COMMANDS
—— —— i

FRONT PANEL CONTROLS

——

CARTRIDGE STATUS

r— _

® DENSITY MODE

® AR STATUS
®

WRITE PCBA

1
o

‘

MOTION

Y
»

PNEUMATIC CONTROLS

CARTRIDGE COMMANDS

MOTION COMMANDS

® TACH PULSE

—
SRV

® SPEED INFORMATION
.

CONTROL M2 PCBA

[

REWIND STATUS
INTERLOCK STATUS

REEL SERVO PCBA
P12||

REEL MOTION COMMANDS

® AMPLIFIER ENABLE
P10

INTERLOCK STATUS

DIRECTION MODE
I INDICATORS -

_j |

® ON LINE

® BEGINNING OF TAPE

L' DENSITY

’
MA-3661A

Figure 5-17

Control Signal General Routing

5-28

,—..\\

CONTROL M2 PCBA
P10

PORT SELECT

CODE SELECTOR
S8

O-

st
[sLT2

17|

UNLOAD }— 9

sS4 fil

|sLTO

16|

RESET

SLT COM (GROUND)

| LOAD/REWD

ON LINE.

‘ <{

| SLT3 (NOT USED)

LD/REW N.C.

LD/REW N.O.

ONL N.C.

ONL N. O.

UNL N.C.

UNL N.O.

RST N.C.

{25

RST N.O.

MA-3656A

Figure 5-18 Manual Control SwitChing
5.6.3

LED Status Indicators

Panel LED indicators include power, bot (béginning of tape), online, file protect, load fault, 6250, and
1600. All indicators are connected to system circuitry through connector P10, whichis mounted on the
control M2 PCBA (Flgure 5-19). The bot indicator lights to indicate that the BOT marker has been
sensed and the tape is in the begmnmg-of-tape position. On-line indicates that the transport has been
switched to the host system. (Itis not an active part of the host system, however, until selected by the
system and the transport is in ready status.) File protect (FPT) lights to indicate that the write enable
ringis not in place and the fileis protected against writing. When illuminated, the Load fault (LDF)
indicator cautions the operator that the tape failed to load. The 6250 indicatoris illuminated when the
system is set for high density (GCR) operation; the 1600 indicator lights when the system 1s set for low
density (PE) operation.

5-29

CONTROL M2 PCBA

P10

+5V

IND

}

COM

POWER

BOT

ON LINE

FILE PROTECT

LO DENSITY

*
’

POWER

@
(X

BOT

@ o @
(Y

FILE PROTECT

Loap L A*

|0@

FAULT(X

@D 1600

" (GCR)
PE

LOAD FAULT

MA-3666A

Figure 5-19

Front Panel Indicator Connections

5.6.4

Control System Inputs/Outputs

Inputs and outputs to the control system are generalized in Figure 5-17. Interface connectors are

mounted directly on the interconnect D1 PCBA, which routes command/status signals between the
MIA interface module and the control M2 PCBA edge connector, P8.

Manual control switches and associated LED indicators are connected directly to J10 on the control
M2 PCBA. Status sensor information is connected through interconnect F1 PCBA J21 to J24 on interconnect D1 PCBA. It is then routed to the control M2 PCBA. Outputs from the control M2 PCBA to
various other card cage PCBAs (read, write, capstan, reel, servo, etc.) are all routed via the interconnect D1 PCBA. This 1s shown in Figure 3 in Volume 1 of the Technical Manual.
5.6.5 General Modes of Operation
Transport operational modes may be divided into two categories: off-line modes and on-line modes.
Off-line operation includes tape loading, unloading, and some maintenance/test procedures. Front panel control switches are used to select and run off-line operations. In addition to these controls, maintenance test procedures involve using a manual switch (located on the control M2 PCBA) to control tape
motion, and a similar switch (located on the reel servo PCBA) to disable reel motion. Additional man-

ual switches are located on the MIA interface board.
On-line operation essentially includes read /write and motion procedures under host system control. Initiation of on-line operation requires the following conditions: tape has been loaded; all interlocks have
been made; and the transport has provided the selected, ready, and on-line (SRO) signals (Schematlc
Number 106875, zone 3- 3E)
When system power is turned on, an ac voltage (8.5 Vac) is apphed to the capstan/ regulator PCBA
which generates a power-on reset pulse (NPORST) to the control logic. NPORSTin turn develops a

5-30

/_«—m\

The indicator common (IND COM) provides +5 V to the indicators whenever transport power is on.
Any of the LEDs conduct and emit light when the controlling input to the LED is low = true.

master reset pulse (NMRST) which clears the control M2 logic before receiving the manual load command (LD/REW N.O.). Until the tape is loaded and the necessary interlocks are made, the logic ignores all other commands except reset. Reset stops the load operation and prepares for another load
command (in addition to its normal clearing and resetting functions).

After completing a successful load operation, the control logic accepts all other commands except a
|

load command.

When the tape is loaded and positioned between the BOT and EOT (end of tape), a Rewind command
may be initiated via the interface or manual operator control.

When the rewind control logic receives the rewind command, the following things occur.
1.

A rewind command is initiated.

A high speed reverse signal is sent to the capstan servo.

The tape slows to synchronous revefse speed.

3. Tape is‘ wound ontc the supply reél at high speed vuntil Iow tape is sensed.
5.

Tape continues to wind onto the supply reel until it reaches the BOT tab, where it‘ stops.

An unload command may be initiated from the control panel (off-line) or the interface (on-line). If the
tape is not at BOT, a rewind is executed, then the unload operation is executed. If the tape is at BOT,

- only the unload operation is executed.

Jumper W3 on the control M2 module asserts SLT and provides SLTA to the output logic. The output
logic provides NSLTA to the read function via J8-23. Jumper W3 also grounds SLT COM on J10-4.
SLT COM routes to the select switch on the front panel control unit. The select switch connects ground
to one of the ISLT lines which routes to the MIA module via J10 and P8 of the control M2 module and
the interconnect D1 PCBA.

Once power is on, the reset signal (NPORST), the input and output logic, and the front panel switches
are enabled. These provide transport control provided system power is on (NPORST false). If system .
power is interrupted, NPORST goes low (true) causing logic to provide the master reset signal
(NMRSTP) to the rewind generator and the air load/control function. Pressing and releasing the RESET button also generates the master reset pulse (NMRSTP). NMRSTP clears the rewind generator
and logic in the air load/control function. When NPORST goes high it initiates enabling of the front
panel indicators.

Refer to Figure 3 in Volume 1 of the Technical Manual. The +5 V and logic return lines are connected
to the EOT/BOT assembly via TB2 on the interconnect F1 PCBA. The EOT/BOT assembly provides
the off-tab voltage and either the EOT or BOT voltage depending on which tab is detected. These voltages are supplied to the EOT/BOT amplifier. The EOT/BOT amplifier provides the NBOT or NEOT
signals, via P24, to the input logic. R22 on interconnect F1 PCBA adjusts NBOT and NEOT voltages.

When power is applied to the transport (NPORST false), IDDS on J8-19 of the control M2 PCBA

generates a high density signal (NPE high) on P8-25, and a data density signal (DDI) to the PCBA’s
output logic. The output logic provides either a low LO DENSITY* or a low PE to light the 6250 or
*The control M2 PCBA is a multi-purpose PCBA and in this case the LO DENSITY signal indicates high density or 6250
mode.

5-31

1600 indicator respectively depending on the interface signal, IDDS. The input logic also provides the
~ density signal (NPE) to the read and write function. The NPE density signal becomes NHID to the
read function on J5-10 and the write function on J7-61. At the same time, the write function provides a
file protect signal (FPT) to the output logic via J8-60. The output logic provides a low FILE PROTECT
to light the file protect indicator if the write-enable ring is not installed.

When the air load/control function detects a load command, it provides a low load status “signal

(NLDS) to the ready generator (control M2 PCBA). The low NLDS disables

ing a load sequence.

the ready generator dur|
|

After the loops are set in the buffer boxes, the air load /control function initiates

(INTLKT1) to the rewind generator, no more than one second after interlock

an interlock signal
is detected. Approximately

one second after INTLK1, the delayed interlock signals (DINTLK
and NDINTLK) and the interlock
pulse (INTLKP1) are generated (control M2 PCBA). Signal DINTLK is applied
to the rewind generator, the ready generator, and the input logic. At the same time,
NDINTLK and INTLKPI are
coupled to the input logic. If interlock is lost, the function provides
a loss of interlock pulse
(NINTLKP2) to the rewind generator. Signal NINTLKP?2 disables the
rewind generator.

The high DINTLK from the air load/control function to the rewind generator
causes the generator to
produce rewind signals REV, RWS, and NRWS. REV is applied to
the capstan servo function and
causes the transport to rewind to BOT. At the same time, the low
NRWS disables the ready signal
(RDY). If either NMRSTP from the input logic or NINTLKP? from the
air load /control function are
low, the rewind generator provides a reset signal (NRST1) to the input
logic.
When the BOT tab is detected, NBOT is sent from the EOT /BOT amplifier
to the input logic (J8-52).
The input logic applies NBOT to the rewind generator and the motion
control. NBOT resets the rewind

generator and provides a low REV which removes the drive from

the capstan servo function. The high

NRWS enables the ready generator. The input logic also provides BOT

and BOT to the air load/control function. The output logic provides the

and NBOT to the output logic
drive signal, BOT, which lights

the BOTindicator on the front panel. The output logic also provides the
BOT INT signal to the read
function via J8-48.
o
|
|

When DINTLK, NLDS, and the unload signal (NUNL1) are high from the

and NRWS is high from the rewind generator, the ready generator provides

air load /control function,

the ready signal (RDY) for
the motion control and the input logic. TP24 (control M2 PCBA)
is used to monitor the ready signal.

- The ONL N.O. (normally open) and ONL N.C. (normally closed) are provided

to the input logic from
When ONL N.O. is low, a flip-flop is set which provides three online signals (an output from U25-5, NONL, and a delayed signal, DONL).
The high output from U25-5
provides on-line which lights the front panel on-line indicator. At the
same time, NONL is sent to the
motion control and air load/control function. The delayed on-line signal,
DONL, is sent to the output
logic. If the transport is ready and on-line, the input logic provides the
SRO signal to the output logic.

S3, the front panel ON LINE switch.

The status lines reflect the transport state. Because the transport is always

S
e

certain interface lines are always enabled. If the transport:

Is file protected, IFPT is low
Is rewinding, IRWD is low
Is on-line, IONL is low
|
Is in motion, ITACH is pulsing
Is in PE mode, IDDI is low.

5-32

selected (jumper W3 in),

If the transport is ready and on-line, the SRO signal enables the remaining three interface lines whrch
~

functron as follows If the transport is:

1.
2.
3.

A-t BOT, ILDP is low |
At EOT, IEOT is low
Not having power reset, IRDY is low.

When the input logic detects a forward command (ISFC low) or a reverse command (ISRC low), the
input logic provides a low NSFC or a low NSRC to the motion control.

The motion commands are enabled by a low NONL from the input logic and a high RDY from the
ready generator. If the transport is at BOT (NBOT low), NSRCis inhibited. When a valid NSFC or
NSRC is detected by the motion control, it provides the motion signals (NGOP, NMOT, and MO-

TION) and the direction signal, REV (REV high
= reverse, REV low
= forward) dependrng on the
state of NSRC and NSFC. Motion is supplied to the read and write functions via J8-28. The output
from U32-6 (TP21) is coupled to the stop pulse generator. NGOP is provided to the input logic. NMOT
is applied to the capstan servo function via J8-51. REVis also sent to the capstan servo function and the
reel servo function via J8-66.
When NONLis high, the maintenance switch (Sl on control M2 PCBA)is enabled. Thrs switch allows
off-line testing of the transport. S1 moves tape in a forward and reverse direction. TP21 is used to mon-

itor motion. TP22is used to monitor reverse and TP23is used to monitor forward. TP30 and TP31 are
for applying a clock (CLKE or CLKG) to test the manual FWD/REV circuits.

When the motion control output (TP21 control M2 PCBA) goes high, it 1n1t1ates the output of a high
stop pulse on the NDRYV line at P8-65. This causes NMOT and the stop pulse to apply dynamic braking
to the transport mechanism for a specified time determined by the duration of the pulse
5.6.6 Control M2 PCBA
The control M2 PCBA integrates, develops, and applies commands received from the host system man-

ual control switches, or MIA test switches.*

External commands are delivered frorn the interface to the control M2 PCBA via the interconnect D1

PCBA, connector J8. Manual commands from the control panel are connected via J10 on the control
M2 PCBA.

Internal signals used in the control process include feedbacks and status signals. These arrive at the
control M2 PCBA via the interconnect F1 PCBA (J24) and J10 on the interconnect D1 PCBA. Timing
is provided by a 1 MHz oscillator and a battery of frequency dividers, which are part of the control M2

PCBA.

Inputs and outputs are detalledin Frgure 5-20. The followrng text describes control M2 PCBA circuits
that develop input signals into control outputs for other transport circuits and the host system. Refer to
Chapter 1 for the theory of operation of the entire control subsystem external to the control M2 PCBA.

Refer to Figure 4 in Volume 1 of the Technical Manual for the source of sensor feedbacks.

5,6.6.1 Control System Timing— Control M2 PCBA clocks are der1Ved from the 1 MHz oscillator

~circuits associated with crystal Y1 (Schematic Number 106875, zone 2-6H.) The 1 MHz prime fre~quency is referred to as clock A (CLKA), which may be monitored at TP20.

*The transport must be on-line to use MIA test switches.

5-33

OUTPUT

P8
ISLTO

P8
‘

NTSFC
NTSRC

(Not Used)

ISFC
‘ ISRC
‘

From Capstan/

Regulator

Rewind Command
Rewind and Unload Command

PE/GCR Mode
Write Status

9-Track Mode Selected

ILDP

IONL

6
44

ITACH
IEOT .

BOT INT

NHID (NPE)
NWRT

9TK

‘

NXFR

NCCC

‘

IDDI

> ToMIA

1RWD

Beginning of Tape (internal signal)

Transport Selected

IRDY

45 |

NSLTA

25
| 26

To Read PCBA
To Read/Write

61 :

Power On Reset Signal

Pressure on Command

NBOT

' 52 :

Beginning of Tape Sensed

Prneumatic Return

PNU RETURN

NEDT
TACH

. 50 ,
153 |

End of Tape Sensed
-

Reverse Command

REV

To Write, Reel &
Capstan/ Regulator

| 65 |

NDRV

To Reel & Capstan

NTEN

;

TAGH COM

TORN.O.
TLUMITN.O.
SLUIMITN.O.
VAC N.O.
ABP N.O.

NSMRL

LOWTAPE

CON.O.
CCN.O.

CABLE TO CONTROL PANEL

Tape In Path Sensed

54 !\

Tachometer Circuit

Motion

Vacuum Sensed
Pressure Sensed

Small Reel Sensed

Tachometer Enable

Speed Greater Than80%

|42 | Low Tape Sensed

Cartridge Closed Sensed

Rewinding

P10

( SLT COM

NCOC
NPOL

To Capstan/

Reguiator PCBA
To A2TB1-11

o
o
28 | MOTION

| 67 |

N >80%

Tachometer
Pulse 2 | 62
| NMOT
NTAP2
51
Motion Command

Cartridge Open Sensed

| 10

Capstan Drive

Tape On Reel
Takeup Loop Limit
Supply Loop Limit

3.
4

Open Cartridge

Close Cartridge

g '
: 2,
| 1
i
|

Vacuum Transfer Command

File Protect (no write enable ring)

;49 i

Data Density Select Line

NPORST

From Sensors via
424 & Interconnect
1 PCBA

19 |

( FPT

)

47 |

14 . Set Write Status Command

IDDS

IFPT

Rewinding

(low=PE; high= GCR)

Synchronous Forward Command
Synchronous Reverse Command

16
13

I ISWS

Select Line 3

Data Density Status

Test Write/ Read Command

20
18

IRWC
IRWU

46 .

Tach Pulse
End Of Tape

Test Rewind Command

36 . Test Mode Set

NTWRC

From MIA

Test Synchronous Forward Command
Test Synchronous Reverse Command

l NTEST

ISLT3

File Protect

Transport On Line

24
35

NTRWC

SelectLine 0

Sepctiine )

Load Point { Beginning of Tape)

—

Test Signals

ST | a0l
Transport Ready

Reel Servo Amplifier Enable

| 33

NRWR

| 34 |

NRSAE

MRL

PCBAs

ToRegulator
Capstan/
To Reel Servo &

Capstan/ Regulator

SLTO

4 |

Select Common
Seiect Line 0

Supply Reel Forward

SRF

SLT2

Select Line 2

Takeup Reel Forward

TRF

Interlocks achieved

<19|

NINTLK

P10

CABLE TO CONTROL PANEL

SLT3

Mid-Reel Load

Regulator PCBAs
|
To Read/ Write

Select Line 3

Takeup Reel Reverse

PCBA

TRR

To Capstan/

Marua! Switche

‘

COM

rom Manual switches
on Control Pane!

LD/REWN.O.
LD/REWN.C.

12 |

18
Co

|23,
' 8 i

ONL N.O.
ONL N.C.

7
24

UNLN.O.
UNLN.C.

9
i 10

Switch

Common

SLT COM

Ov (L)
.

Load Rewind Switch (normally open contacts)
Load Rewind Switch (normally closed contacts)

On Line Switch {normally open contacts)
On Line Switch (normally closed contacts)

Servo PCBA

6250 CP! Density
5 | LOWDENSITY (GCR)
1600 CPi Density | 21 | HI DENSITY (PE)
6
19

ON LINE
LOAD FAULT

To Front Panel

Write Enable Ring Absent

FILE PROTECT

Indicators

3
20

PWR
BOT

+5v—— 13
30

RSTN.O.
RST N.C.

4 | Select Common (Groun

Transport On Line
Load Fault Sensed

"
Power On
Beginning Of Tape

Unload Switch (normally open contacts)
Unload Switch (normally closed contacts)

Regulator & Reel

INDICATOR
COMMON
3

Reset Switch {normally open contacts)
Reset Switch (normally closed contacts)
—w~+0A

Figure 5-20

Control M2PCBA Inputs and Outputs

The oscillator output is cascaded through a series of decade dividers and one final flip-flop to provide

the required additional frequencies. The available frequencies, including oscillator output, are listed in
Table 5-3. Load/unload sequence counter outputs are described in Paragraph 5.8.2.
5.6.6.2 Transport/Massbus Port Selection — The common contact of the MASSBUS port selector
switch (SLT COM) is grounded by jumper W3 on the control M2 PCBA (Schematic Number 106875,
zone 3-7C). This ground supplies a low input to U102-9 (zone 3-6C), producing SLT and SLTA signals.
SLT is applied to the motion command circuits (zone 3-5E) as one of the enabling inputs. SLTA is
routed to U143-5 (zone 4-2H) to produce the NSLTA control signal at P8-23. NSLTA is applied to
other transport circuits through interconnect D1 PCBA.

The selector switch ground common contract is returned to the MIA PCBA via P8-15, 39 and 40 as
ISLTO:2. ISLTO corresponds to switch position 0, ISLT1 to position 1 and ISLT2 to position 2. ISLT3

5-34

CONNECTOR ON INTERCONNECT D1 PCBA

CONNECTOR ON INTERCONNECT DI PCBA

—

CONTROL M2PCBA

INPUT

is not used in the MIA because it is assumed that if a ground is not present on ISLTO (1 or 2) the switch |

must be in position 3. Table 2-1 lists port selector switch positions and functions.

Table 5-3

Basic Timing Frequencies (Refer to Schematic Number 106875)

[
\

Name Frequency

Test
Point

CLKA 1 MHz

TP20

CLKB 100 KHz

TP15

Distribution

Sheet
and
Zone

Primary Use

Associated
Signals

Ul2-3,11

6-4,5H

Tachometer

TAPEN, TACHP,

U52-3,11
U53-3,11

5-4G,H
5-3G,H

GO pulse
generation

NGOP

U35-11,
U25-11
U35-3,
U34-3,11
U6l1-3

4-6D

Master reset
generation
Load reset
pulse, load
pulse and

NMRSTP

4-3/6F

pulse
generation

NTAP2, NTEN,
NRWR, N>80%

NLRSTP, NLDP
NREWP

rewind pulse
generation

(

CLKC 10 KHz
|

TP39

CLKD 100 Hz

TP17

CLKE 10 Hz

TP19

)

U225-12,

Stop pulse
generation

NDRV

Not used

U63-9

4-3B

U54-13

5-7G

Ul14-11

4-11B

Ul8&83-5
U216-11,

5-6B

U226-11

7-7C
7-5,6B

Load fault

LOAD FAULT

indicator
control

(LDES)

GO pulse
stop pulse

NGOP, NDRU,
NMOT

‘generation

Load fault

LDFS

Vacuum control
Reel motion

NXFR
SRF, SRR, TRF,
TRR

Thread signal
Set tape loops

THDS
STL

signal

Ul15-9

8-6A

command

Load fault 6

LDF6

CLKF 1 Hz
|

U184-11,3

7-3G

U101-14

9-6F

Interlock
circuits

INTLKI1, DINTLK,
NDINTLK, INTLKPI

CLKG 0.5 Hz

U64-13,

5-6,7F

Forward/

NGOP, MOT

U74-1

Load fault O

reverse
motion

5-35

LDFO

5.6.6.3

Modes of Operation — The control M2 PCBA processes internal and external commands to

establish the required modes of operation.
transport is to be used, are as follows.

The major modes, determined by the purposes for which the

Read Only, Forward
Read Only, Reverse

Write and Read Forward
Low Recording Density (PE)

High Recording Density (GCR)
Load Tape
|
Rewind Tape

Unload Tape
Some of these modes are effective simultaneously with each other and with certain transport states that
define conditions required to enable the major modes of operation. The transport states are as follows.
PN

Reset/preset
Interlock
9-track
PE/GCR
Beginning of tape Interlock

Unit selected
These states are discussed in the following paragraphs.
Control M2 PCBA circuits which process various commands and the operational task operations (load,

etc.) are discussed later in this chapter.
5.6.6.4

Reset/Preset State — The reset/preset state clears and resets the transport’s circuits for a new

operation. It is initiated automatically when power is applied after an interruption. The operator can
initiate it at other times by momentarily pressing RESET.

The circuits that check condltrons (adequate power, etc.) and develop the reset/preset signals

(NPORST and ENBL) are located on the capstan/regulator PCBA. They are discussed on a system

basisin Paragraph 5.4.7. The control M2 PCBA uses RST N.O., RST N.C., and the NPORST signals
which are described in the text.
NPORSTis a low
= true pulse produced when power is applied. The pulse input is at P8-61. (Schematic Number 106875, zone 4-8B.) NPORSTis used to enable the front panel indicators (zone 4-3C). Itis
also applied to NOR gate U3 (zone 4-4C) as one of three inputs which will produce NMRSTP at the
output of NAND gate (U13-11). NMRSTPis the low
= true master reset pulse usedin various circuits

on the control M2 PCBA (as hstedin zone 4-1C).

RST N.C. (J10-26) and RST N.O. (J 10-25) inputs establish the state of flip-flop output U26- 9 As the
mnemonics imply, the RESET pushbutton switch contacts normally close the U26-13 clear (CL) in-

verted input circuit to signal ground (0 V), and Q output (U26-9)

is low. The preset (PR) input (U26-

10)is kept high by U6-10.

When the RESET switch is pressed, RST N.O. contacts are closed to ground and RST N.C. contacts
are opened. The preset input U26-10 is pulled down momentarily, and the Q output (U26-9) applies a
high to flip-flop U35-12. At clock B time (applied at U35-11), the Q output (U35-9) applies a high to
NAND gate U24-13 and to flip-flop input U25-12. The Q output of the flip-flop goes high, and U25-8

sends a high to NAND gate input

U24-12. NAND gate output U24-11 goes low and initiates an

5-36

NMRSTP low
= true pulse from Ul3 11. The pulse continues approximately 10 us after the pushbutton is released

The low= true master reset pulse (NMRSTP) whether generated manually br automatically when
power is applied, is usedin the following networks on the control M2 PCBA.
Usedin Pr-oducmg

(Sheet and Zone)

- NRST1
PNU RETURN UNLl

-~ NLDFS

Schematic Number 106875

-~
-

NLRST
RST, NRST
NCOC, NCCC

5-8E
9-5G
9-7C
71-5E
8-8F
| 9-5A

NRST1 goes to U81-4 to preset the fl1pflop (zone 5-7D) that eontrols rewrnd status, and to U83 5 to

“clear the flip-flop that initiates the on-line signals (DONL, NONL).

The PNU RETURN signal (9-1G)is used to turn on thecompressor/blower motor. Itis enabled by the
appllcat1on of NMRSTP to U156-1 (zone 9- SG)

~ The load fault status (NLDFS) flip-flop (zone 9- 7C) 1s cleared by the apphcatlon of NMRSTP to
U166-13. This enables motion and other physical command outputs through P8 as shownin zones 9-2A
through 9-2G. The PNU RETURN signal goes to A2TB1-11 for blower control. NXFR, NCOC,
"NCCC, and NPOL are connected to the capstan/ regulator PCBA. NRSAE, MRL SRF SRR, TRF |
and TRR are connected to the reel servo PCBA.

NLRST (zone 7- 4E)is produeed either by NMRSTP at Ul94 9 or by the interlock (NINTLK) s1gnal
at U194-10, 11. NLRST resets the tape loading procedure flip-flops (zones 7-3A through 7-3E). RST
and NRST (zone 8-3E) are initiated by NMRSTP at OR gate U64-5 or by other inputs to the same
gate (zone 8-8F). RST resets the try counter (zone 8-6C) which issues a load command from U195-11,
and the load sequence counter which produces the load counts (NC1,2; CI, etc.). Refer to zone 8- 6H
from where the count srgnals fan out to ether areas of sheet eight.

The preceding paragraphs descrlbe distribution of the master reset pulse NMRSTP and, in general
circuits on the control M2 PCBA where the signal used. Complete functions of the various circuits are
descrrbed separatelyin the approprlate paragraphs a

-5_.6.6.5 Interlock State - (NINTLK, INTLK, INTLK1, DINTLK, NDINTLK, NINTLKPI,
NINTLKP2) - The interlock state circuits are designed to inhibit and/or enable various modes on the
basis of monitored air and tape conditions. The basic interlock signal is the low = true NINTLK level

found at TP62 and P8-69 (Schematic Number 106875, zone 9-1F), and at NAND gate output U184-8
(zone 7-5F) where the signal originates. The NAND gate requires a high level at inputs 9, 10, 12, and

13 to produce a low
= true NINTLK output level at U184-8. The inputs are controlled by the pressure
switches that sense the supply and takeup reel loop limits (SLIMIT N.O. and TLIMIT N.O.), vacuum
pressure (VAC N.O.), and positive pressure (ABP N.O.).

The switches are each connected (via interconnect F1 PCBA, J24, interconnect ‘Dl PCBA, and J8) to

their respective pins (J8-1,2,3, and 4) as shown in zones 7-8G and H. A satisfactory condition causes the
corresponding switch to close its circuit to signal ground. This pulls down the level at the respective
input to J8.

5-37

5.6.6.6 9-Track State — The 9-track signal is hardware-selected by means ofjumper W1 (Schematic
Number 106875, zone 4-3H). The
jjumper pulls down the inverted input to U201, causing it to produce
a high = true 9TK signal at P8-27. Thisis connected via conductors on the interconnect D1 PCBA to
J5-11 (read PCBA) for data reading circuits. Jumper W4is alwaysin.
5.6.6.7 PE/GCR State — Control M2 PCBA output NPE (low
= true) at P8-25 (zone 4-1G) selects
low density phase encoded (PE) operation. When NPEis high=false, the high density GCR modeis
effective.
Density selection is normally accomplished by the host system software through the formatter (write

operation) or the formatter alone (read or spacing operation). If the formatter applies a low = true
IDDS at the interface, P8-19 (zone 3-8B) is low. This applies a low at U65-9 (zone 4-4G), causing the
OR gate to place the transport in PE mode (NPE low = true).
The other input to OR gate U65-10 is normally held high since jumper W4 (zone 4-6H) is removed.
Therefore NAND gate U65-12 (zone 4-4H)is disabled. This circuit also initiates the DDI signal (zone
4-1G) which produces the interface IDDI signal through P8-17 (zone 3-1D). The interface driver

(U161)is enabled by transport selection (SLTA) from U142-6 (zone 3-5B), whichis always asserted by
jumper W3. (The IDDI output on P8-17 is returned to the MIA as a density status signal.)
5.6.6.8

Beginning of Tape Interlock (BOT INT) State — The BOT INT output at P8-48 of the control

M2 PCBA (Schematic No. 106875, zone 4-1H) is a high = true level, initiated when the beginning
marker on the tape is in register with the BOT optical sensor. At this time a low = true level (NBOT)
appears at P8-52 (zone 4-8B) via interconnect D1 and F1 PCBAs. The latched NBOT signal is also
applied to various circuits on the control M2 PCBA as shown or referenced on the schematic (zone 44B).

5.6.6.9

Unit Selected State (NSLTA) The NSLTA output at P8-23 of the control M2 PCBA (Sche-

matic No. 106875, zone 4-1H)is always at a low = true level. This circuit is descrlbedin Paragraph
5.6.6.2.

5.7 AIR LOAD/CONTROL
The air load/control subsystem includes air and electronic provisions which control and monitor the
tape path between the reels (Figure 4 in Volume 1 and Figure 5-21 in this volume).

The speed at which the tape passes the read and write heads is controlled by the capstan servo subsystem. The speed of the supply and take-up reels must vary according to the quantity of tape on the
reels. For example, when the supply reel is full and the take-up reel nearly empty, the take-up reel must
rotate much faster than the supply reel in order to transfer the tape past the read/write head assembly
at a constant 3.2 m/s (125 in/s) rate. Each of the reels is driven by a separate motor controlled by a
servo system that adjusts the speed as required to maintain proper tape transfer. The air load/control
subsystem provides tape loop status signals to the reel servo circuits, which use the information to regulate power applied to the reel motors.
The input port of the blower
is used as the source of vacuum (minus atmosphere) pressure that forms
the tape loops. Vacuum is applied to the buffer boxes, loop pocket, corner pockets, and capstan. Energizing solenoid K3, on the vacuum valve, switches vacuum to the takeup reel hub to facilitate threading. A typical tape loop formation is shown in Figure 5-22. The complete tape path is shown in Figure 2-

Pressure (positive atmosphere) is developed by a pump located in the power pack/pneumatic assembly.

5-38

INTERCONNECT

INTERCONNECT D1

_reeA_

| P21r

—]

}_ PLE |

| { CRV'XS | i

CAPSTAN/

)

CARTMTR+

COMMANDS
INVOLVING

TAPE
|

MOTION
M PCBA

PNU RET

L r1 |
a2te

DISTRIBUTION

‘

runcrion | |

BLOWER/

MOTOR

COMPRESSOR

SWITCHES

TAPE ON

]

REEL SWITCH

]

- VACUUM

|
A |
oo
| |

|
1

POSITIVE .

PACK SENSE

SENSOR

PRESSURE SENSOR

|
I

l TAPE-IN-PATH
SENSOR ASSEMBLYI
+5v ——»{
|| |i TP |i |l | | NSWR | '

ssv———

REEL SENSE

[ | SLIMIT |l |!

SUPPLY
LIMIT
PRESSURE SWITCH

| | TtumiT | E

T spoS | |

;

‘

| |
|

P12

—

TPOS |

J1a

REEL J15

SERVO

PCBA 118

*PACK SENSE SIGNAL FROM LOW-TAPE SENSOR

Figure 5-21

[ TOR | |

| | vac | |
‘

MOTOR

POSITION

CRIPPLED

T |

POWER

CARTRIDGE

| PRSNT L

PeBA

ID I
1 — K3 SOLENO

‘

| |
'
| |

CONTROL

’ —{K1 SOLENOID I

| | |

| I

| t o N0 | | —l
IL | Con.0 % % -

-—

(

]

T EART MR

REGULATOR

PoBA

9 b—

.
'

SM ()

W0
TTM (+)
MO

TAKE-UP LIMIT
.

PRESSURE SWITCH

TRANSDUCER 1
PRESSURE

ASSEMBLY

SUPPLY

REEL

MOTOR
TAKE UP
REEL

MOTOR
MA-3669

Air Load/Control Function

{

5-39

/—— LIMIT SWITCH

‘

UPPER PORT

FORWARD
RUN ZONE

PARK ZONE

REVERSE
RUN ZONE

TAPE

CRIPPLED REEL

\ SWITCH PORT

- LIMIT SWITCH
-~

LOWER PORT

CAPSTAN

TO TAKE UP REEL

MA-3655

Figure 5-22

Tape Loop In Takeup Buffer Box

5-40

POSITIVE AIR
OUT TO PRESSURE
VALVE

\
} FILTER
IR

MUFFLER

]
f_fifi; |

Figure 5-23

7a\
HEAT

EXCHANGER

\\"/} \\"//

Positive Air Supply System

Air 1s drawn through an acoustic muffler by the pump and cooled in the forced air heat exchanger. The
cooled air is filtered and delivered to the pressure valve located on the base assembly. Figure 5-23
shows a schematic of the positive air supply system.
5.8

TAPE LOAD, UNLOAD, AND REWIND OPERATION

5.8.1

Load/ Unload Sequences

5.8.1.1

Tape Load - During a load operation, the following series of events occur (Figure 5-24).

When the LOAD/REW buttonis pressed, the blower (Vacuum) and compressor activate and
the reel servos are enabled.

If tape is in the tape path at this time, a midreel load situation is assumed, and the unit sets
loops and starts towards BOT.

3.
4.

If tépe was not in the tape path, the cartridge motor opens the cartridge, the take-up reel

turns clockwise (CW), and a normal load is initiated.

With the transport front door closed, the supply reel backwraps for approximately two turns

before starting the threading process.

5-41

ENABLE PNEUMATICS

THREAD
MID REEL

LOAD

ENABLE REEL

AMPLIFIERS

BOT

YES

{

SET LOOPS

OPEN CARTRIDGE I

LOAD POINT

\\‘

TAKE UP REEL (CW)

YES

- NO

BACKWRAP

SUPPLY REEL

MA-3662

Load Sequence

/‘“" '~

Figure 5-24

5-42

NOTE
If the diameter of the outside turn of tape is too
small, it is necessary for the operator to manually
place the tape in the tape path and to load with the

transport front door open. The outer turn of tape
must be between 1.59 and 0.64 cm (5/8 and 1/4 in)
from the outer edge of the reel to accomplish autoload (Figure '3-2) Also, 216 and 178 mm (8-1/2 and
7 in) reels require the operator to place the leader

over thread block 1.

After backwrapping, the supply reel starts forward and tape threads through the tape path.

When beginning of tape (BOT) is detected, vacuum is applied to the buffer boxes and the
reel motors turn so that tape loops are set in the buffer boxes and interlock is made.

The transport is then ready for controller commands and data operation.

When the tape is satisfactorily loaded, the transport is ready to make data runs, etc., as commanded by
the controller. When a motion command arrives at the interface, the system control sends a drive
(NDRYV) and direction (REYV, true or false) signal to the capstan servo subsystem. This initiates tape
movement across the read /write head assembly. Pressure transducers in the air load/control subsystem
sense tape loop position and feed signals to the summing logic in the reel servo subsystem. The output of
the summing logic is applied to the power amplifiers that drive the reel motors.

5.8.1.2 Tape Unload
- The same auxiliary circuits employed to load tape into the vacuum chambers
(load operation) are used during an unload operation (Flgure 5-25). When the UNLOAD button is
pressed while the unit is at midtape, the following sequence is initiated.
1.

Tape rewinds to BOT

Blower (vacuum) motor is turned off causing the pneumatic interlock to be broken

Tape is wound onto the supply reel

Reel motors are stopped

Cartridge is closed

The unload procedure with tape at BOT is identical but without rewind operation.
- 5.8.2 Load/Unload/Rewind Circuit Operation
The tape loading procedure involves all steps that result in tape being installed and brought to the beginning-of-tape (BOT) position. The steps include motion in either or both directions, and may include
cartridge and pneumatic system control. If a tape reel is installed on the supply reel spindle, but sensors

‘determine the tape has not been threaded through the guides to the take-up reel, normal load conditions

exist. Pressing the LOAD/REW button initiates the automatic threading process, which connects the

tape to the take-up reel, forms the loops, and stops at BOT. The tape is then ready for a read or write
operation.

If tape is sensed between the supply and take-up reels when the LOAD/RE button is pressed, a situation called a midreel load condition exists, and rewind mode is initiated. Rewind mode also terminates

at BOT. Tape sensor feedbacks are shown in Figure 4 in Volume 1 of the Technical Manual.

5-43

e T—
o

REWIND

INTERLOCK

,’l/

DISABLE PNEUMATICS

»
YES

UNWIND TAPE I

TAPE IN PATH

DISABLE REEL SERVO
AND CLOSE CARTRIDGE
MA-3663

Figure 5-25

Unload Sequence

Note that when the UNLOAD switch is pressed, rewind mode is also initiated if the tape 1s not at BOT.

Unload mode causes tape to be completely wound on the supply reel. Unload mode then causes the
supply reel cartr1dge to close.

Schematic Number 106875, sheets 10 and 11, contain a flowchart for reel-motion logic by manual con-

“ trol. The flowchart includes motions commanded by means of the LOAD/REW and UNLOAD switches. The following text describes the preliminary power-on sequence and the load sequence with reference to the flowchart and various zones on other sheets of the same drawing. The power-on sequence 1s
included here because it prepares the subject circuits for tape procedures.

5.8.2.1 Tape Control Presetting by Power-On Sequence — When power 1s apphed (zone 11-8H), the
power-on reset signal (NPORST)is produced (Paragraph 5.6.6.4). NPORSTis applied to control M2
PCBA J8-61 (zone 4-8B). Thisis distributed as shown at zone 4-4B and gated with the manual reset
circuits (zone 4-4C) to produce the master reset pulse (NMRSTP) at NAND gate output U13-11.

5-44

If the tape sensors find tape in the tape path, a high
= true TIP signalis rece1ved at J8-49 (zone 4-8A).
This signal informs the circuits that a load command, when received, will be under midreel load conditions. TIP and NTIP initiate midreel load signals MRL and NMRL (zone 7-1D). NTIP, from zone 44A, is applied to NAND gate U202-4 to inhibit a close cartridge command (NCCC). MRL goes to
P12-28 of the reel servo PCBA, where, when high = true, it asserts NSRF2. This supplies additional
torque to the supply reel servo. NMRL is applied to U124-10 (zone 7-2F) to turn pressure on (PSOL)
and U125-10 to preset the air control flip-flop (zone 7-7F).

MRL (zone 7-1D)is also applied to NAND gate U194-2 as one of the conditions that preset the first
delay flip-flop (U216-4, zone 7-6B). After a delay, U226-9 clocks the flip-flop that produces the set tape
| loops (STL) command

When no tape is foundin the path a normal load condition exists. NTIPis high = false and NAND
gate U202-4 (zone 9-5A) is enabled for a high output at U182-5 (zone 9-5A) of the cartridge control
flip-flop. The other condition for issuing a close cartridge command is the input CC N.O. at U202-5
from the cartridge open sensor. The NCCC output at P8-70 sets the cartridge mechanism in closed
position for installing or removing a reel on the supply hub.

The tape in path signal (NTIP) is also applied to OR gate input U194-3 (zone 9-8E) as one of the
conditions for sending the supply reel reverse (SRR) command to the reel servo PCBA. Other conditions are sequence counts (NCO, NC1), a false load fault status signal (LDFS) and/or backwrap
(BKW), and cartridge open (CO N.O.), unload number 1 (UNL1) depending on the mode of operation.
SRR also is inhibited by the suppression of BKW when the set tape loops (STL) process is initiated.
These signals are shown on the right side of sheet 9, zones 9-6G and 9-4E through 9-2C.

5.8.2.2 Circuits Involved in Tape Load/Rewind /Unload Procedures — Circuits involved in load, rewind,
and unload control are shown in Schematic Number 106875 and are described as follows.

Clocks — Basic system clocks (zones 2-1A through 2-1H) are based on a crystal oscillator

Load/Rewind Command Pulsing— Load/rewind command and pulsmg circuits (zones 4-8F
through 4-1F) are initiated by LOAD/REW momentary switch outputs.

(Paragraph 5.6.6.1).

Load reset pulse (NLRSTP)
Load pulse (NLDP1)
Rewind pulse (NREWP)

U24-6, zone 4-4F
|

U46-6, zone 4-1F
U46-12, zone 4-1F

Unload Commands — Unload command circuits (zones 4-8E through 4-1D) process either a
manual command from the control panel UNLOAD switch or a logic command (IRWU at
interface, zone 3-8E, NULC at U192-12, zone 3-5E). They produce unload command number 2 NUNLC?2 at U56-12, zone 4-2E.

Reset Commands — Reset command circuits are located in zones 4-8D through 4-4C. This is

the only command that interrupts a load procedure. Output is master reset pulse NMRSTP.

Load Status — The load status flip-flop provides the load-in-progress condition for the system.
The load status (LDS) level (U135-9, zone 7-1E) participates in setting the backwrap flipflop (zone 7-2B), sets the thread- mode flip-flop (zone 7-2A), and the set-tape-loops flip-flop
(zone 7-2B). These flip-flops then wait for their respective clock inputs. LDS also enables
tape and reel motion command gates, etc. via U115-13 (zone 8-2G), U126-8 (zone 8-1D), and
U166-8 (zone 9-7B) provided no load fault exists as decided at gate output U165-11 (zone 96B).

5-45

Load/Unload Counts — Load/Unload step sequence count control circuits are located in
zones 8-6C through 8-6H, and 8-7H. Counter outputs (U215-12,9,8,11) are decoded and pro-

duce counts NC 0,1, 2, 3, 4, and 7, at outputs U205-1, 2, 3, 4, 5, and 9, respectively. The
~counter 1s incremented at input U215-14 by the output of U195-11 (zone 8-6C). This reflects

the low tape sensor input pulses (P8-42, zone 8-8C) divided by five. The divided count is
provided by U185-11 (zone 8-6C). Sensor pulse inputs at U185-1 are inhibited if a load fault
exists (NLDFS at U136-2). The divider output is not applied to the load counter unless the
transport is in load status (NLDS at U195-9, zone 8-6C). Or, if tape-in-path signal (NTIP) is

high = false at U195-2 and unload command UNL1 is high = true at U195-1.
Load Fault Recovery — Load fault flip-flop (zone 9-7B) issues a high load fault status
(LDES) level at Q output U166-9 and a low load fault status level at Q output U166-8 whenever conditions warrant aborting the procedure. The flip-flop is cleared by master reset pulse
NMRSTP at U166-13. In load status (LDS at U166-12) it is set to produce fault status by

the input at U166-11 from fault NOR gate output U126-8 (zone 8-1D). Low inputs to the
NOR gate which clock U166-11 are as follows.

U126-1

Load status terminated by end of count

(TP41)

output to U186-11 (zone 8-2F)

Ul126-3

Try counter outputs U1»12-12, 9 are high

(TP42)

indicating two attempts have already been

made to load tape, these outputs cause NAND
gate output U122-6 to produce a low

Ul126-6

System is at the set-tape-loop mode and

(TP28)

tape loop timer outputs U123-9, 8, 11 are

all high, indicating that time has run out
for setting the loops.

U126-11
(TP14)

Failure to load count (NLDC from U195-11,
zone 8-6C) at start count timer flip-flop
input U125-3 (zone 9-7E) and timer inputs

U101-2, 3 (zone 9-6F), causing U102-10 to
send load fault zero (LDFO) to U126-11
U126-5

(TP32)

Failure of cartridge to open by count C3
as determined by NAND inputs U136-4 and 5

(zone 8-2E)

Ul126-4

Failure to get proper air pressure and

(TP35)

vacuum condition by count C3 as determined
by NAND inputs U136-12 and 13 (zone 8-2F),
is provided by output

NAOK input at U136-13

of U173-3 (zone 7-6F) on basis of Vac N.O.
and ABP N.O. sensor inputs to P8-3 and P8-4
U126-12,2

(TP27)

Cartridge problem as determined by NAND
output U132-6 when load pulse (NLDP2) is
received at U131-5, these signals are
inverted and applied to U132-4, 5 (zone

8-5B)

5-46

Tachometer Circuits — Capstan tachometer signal processing and application circuits shown

on sheet 5, provide tape speed information feedbacks for optimum speed control. TACH signals generated by capstan rotation arrive via interconnect F1 PCBA, interconnect D1 PCBA,
and P8-53. Signals are shaped to form the tachometer pulse (TACHP) at U104-2 (zone 62G). Then they are sent to the interface ITACH driver (zone 3-2E) provided the tachometer
pulse circuits are enabled (TAPEN at U116-12, zone 6-3G). The tachometer pulses are also
obtained from U13-8 (zone 6-4G) and applied to flip-flop clock inputs U95-11 and U93-11,
and preset input U92-10 (zone 6-3B-D). They are also squared and applied to the velocity
decoder and time constant circuits at U85-14 (zone 6-7E).

After a 20 us delay, the output U116-8 (zone 6-6D) clears the tachometer pulse number 2
flip-flop (zone 6-3B). This provides a squared pulse 20 us long (NTAP2) at P8-62. After a 64
us delay, the output at U104-10 (zone 6-6C) clears the rewind enabling flip-flop and produces
a high at U93-6 (zone 6-2C). The inputs that produce U105-8 output (zone 6-5D) are all
connected to pull-up resistors U96 which produce high inputs to U105 except those input
lines with jumpers installed. The TU78 has jumpers W8 and W10 installed. Therefore, when
time constant counter U86 has a high output on pins 11 and 9, all the U105 inputs are high
and the U105-8 output goes low.

The low output at U105-8 changes the state of outputs at U95-9 (zone 6-3D) and U92-5 (zone
6-2D). When the latter output is low, the rewind ramp is terminated (NRWR, zone 5-1B).
When the N>80 percent signal is high = false, indicating a tape speed greater than 80 percent has not been achieved, the tachometer enabling signal NTEN is high = false. When 80
percent speed is achieved, these states are reversed. These signals are used in both states
(true or false) in the application of acceleration and deceleration (start and stop) ramps, and
steady synchronous motion.

Note that circuits on the capstan/regulator PCBA (Schematic Number 104757, zones 212C,D through 2-9C, D) convert the tachometer frequency pulses (NTAP2) to analog voltage signals used in the capstan servo summing amplifier.

Unload Control — Unload procedure control circuits are shown in zones 9-6G through 4-6B.
NUNLC2 (refer to item 3) presets the first stage (rewind) unload command flip-flop (zone 96G). Output U146-5 (UNL1) is applied as a condition to various NAND gates, as shown in
the schematic, and to enable the load counter (zone 8-7C). Q output U146-6 (NUNL1) provides the reel servo amplifier enable output at P8-34 by presetting flip-flop output U226-5.

NUNLI1 is also used in the mode circuits (zone 3-6C) and to initiate the rewind pulse circuits
(4-7G). NULRW from U133-12 (zone 9-5H) is applied to U71-11 (zone 5-8E) to establish
the state of the rewind status circuits. The output of U82-6 (zone 5-5D) is applied to the
motion control circuits at U72-9 (zone 5-5E) to start tape motion.

When BOT is sensed (BOT at U131-13, zone 9-5H), the rewind part of the process ends, but
unload rewinding motion continues until interlock is broken (INTLK low = false at U133-1,
zone 9-5SH). BOT also is applied to the PNU RETURN flip-flop at its presetting input
NAND gate (U145-10), and clock input U146-11 (zone 9-5H). At C4 count, flip-flop input
U146-13 (zone 9-5G) clears the flip-flops disconnecting the PNU RETURN line, which
turns off the blower/compressor motor. When interlockis broken (NINTLK high
= false at
U225-5, zone 9-3F), U226-9 changes state, disabling the reel servo amplifiers (NRSAE high
= false).

5-47

5.8.2.3

Tape Load/Unload Procedure Counters — The tape loadmg procedure employs two counters: a

try counter and a sequencmg counter.

The try counter provides an automatic second attempt at starting the loading sequence if the first attempt falls, but inhibits repetitious recycling. The try counter is cleared and reset by an input at U112-2
~and 3 (zone 8-3D) from NOR gate output U164-6 (zone 8-8F). Inputs to the NOR gate are the master
reset pulse (NMRSTP), load reset pulse (NLRSTP) unload s1gnal (NUNLCZ) and delayed interlock

(NDINTLK).
The try counter is incremented by a low input at UllZ 14 which primarily reflects the output of
NAND gate U115-6 (zone 8-4D). At sequence count one output (C1), the inputs to the NAND gate are

Cl1, try counter zero (NT2), and the inverted NSMRL input. This increments the counter to T1. At
NC3 time from the sequencing counter, AND gate input U155-12 is low, U155-11 is low, and the try
counter is incremented to T2. When counter outputs are high (at T3) at U112-12 and 9, the output at

NAND gate U122-6

is low and reports a load fault 4 at load fault NOR gate U126-3. Thrs prevents a

third try The NSMRL input at P8-8 1nh1b1ts a second try when a small reelis loaded.
The sequencing counter is reset by the reset (RST) input to the counter at U215-2, 3 (zone 8-TH). It is
incremented by pulses from the low tape sensor P8-42 (zone 8-8C) after these pulse counts have been

divided by five at divider output U185-11 (zone 8-6C). Application of the pulses are on the condition
that no load fault has occurred. For example, the load fault status signal NLDFS at Ul36 2 (zone 81C)18 h1gh
= false.

The pack sense assembly A4 located on the base assembly (Schematic Number 107307) contains an
optical detector that senses a low-tape condition on the take-up reel. The pack sense assembly output
are pulses (PKSN) coupled via TB2 and J21-30 to control M2 module J8-42 where they become low
tape sensor. The optical detector senses two reflective tabs placed on the inside of the take-up reel

flange. The detector looks at these tabs through two slotsin the side of the reel opposite the tabs. Each
time the reel turns, the two tabs are sensed. This produces two low tape sensor counts per reel revolution, provided thereis not enough tape on the reel to block the path between the detector and the tabs.

In rewind mode, when tape on the take-up reel is down to about 9.525 mm (0.375 in), the low tape
sensor begins issuing pulses. The first pulse is used to slow tape motion so the reels can stop at BOT. In
forward motion, the pulses are sent to the logic until tape on the take-up reelis sufficient to intercept
the sensor path. These pulses, at the rate of two per turn, are sent through P8 42 to U136-1 (zone 8-7C).

During the load process, if no load fault exists, NLDFS
-

is high = false at U136-2 and U136-3 applies

the inverted pulses to U185-1. The output of U185-11 of the divider is one pulse per five inputs, or one

per two and one half turns of the reel, at NAND gate input U195-12. If the transport is in load status
(NLDS at NOR gate U195-9) then U195-11 issues low load count pulses These are applied to the
sequencrng counter incrementing 1nput U215-14.
L3

The outputs of the sequencing counter are applied to decoder inputs U205-12, 13, 14, and 15. Decoder
outputs are low at times corresponding to the count, which is the chip pin number minus one (For ex-

ample, U205-1 is low at the zero count, U205-2 is low at the first count, etc.). These counts are low
=
true NC1, NC2, etc. When inverted they are C1, C2, etc. The counts are used to cue the various load-

ing process steps {backwrap (BKW) thread (THD) set tape loops (S'EL) etc.} (Tables 5-4 and 5-5).

5-48

,'/‘—\\\

Table 5-4

" Load/Unload Sequence Control Count Applications (Schematic No. 106875)

Decoder Pin
(Zone 8-6H)

Count*®
(N = Low)

Distribution/
Zone

Mode

U205-1
|

NCO

U222-11/9-8E

Load

Opens cartridge if not open
and no fault exists.

U194-4/9-8E
|
|
-

Unload
|

Commands supply reel reverse
if interlocks are not made

U222-10/9-8E

Load/

Opens cartridge if not open,

U205-2

NCl1

unload

U125-11/7-7F
-

Load
-~

U194-5/9-8E

Unload

Ul115-4/8-4D
|

(after BOT is reached)

tape is in path, and no fault
exists

Effect

Starts supply reel reverse if

interlocks are not made

Load
|

Increments try counter ifa
small reel has been sensed

(after BOT is reached)

|
Load

U144-3/7-2B

If air pressure is correct,
issues PSOL command

and if one try has not

already been made

Starts backwrap if in load

status, small reel has not
been detected, and there is
no tape-in path (not a

midreel load)

U205-3

U222-9/9-8E

NC2

Load/

Opens 'cartridge if not open

Load

- Trailing edge starts threading

unload

Ul144-11/7-2A

process if in load status

Load

“Clears backwrap flip-flop

Load

- Increments try counter

U205-4

'NC3

- U155-4/7-3B
U155-12/8-4D

an_d no fault exists

*Counts are produced only under the following conditions (zone 8-6/7C)
Mode

Load
Unload

NLDFS (U136-2)

NLDS (U195-9)

high = false
high = false

low = true

N/A

high = false

5-49

NTIP (U195-2)

UNLI (U195-1)

N/A

high = true

Table 5-4

Load/Unload Sequence Control Count Applications (Schematic No. 106875) (Cont)

Decoder Pin

Count*

Distribution/

(Zone 8-6H)

(N = Low)

Zone

Mode

Effect

U136-12,4/8-2F

Load

Initiates load fault status
if cartridge is not open or if
air is not correct

U145-13/9-6B

Unload

Closes cartridge if unload is

complete, there is no tape in
path, and cartridge is open

- U205-5

U156-13/9-6F

Unload

Terminates process if in unload
status

Table 5-5

Try Counter Outputs (Schematic Number 106875, zone 8-3D)

Try No.

U112-12

TO (reset)
T1 (first)

low
high

T2 (second)
T3 (third)

low
high

U112-9

U122-6

Effect

low

high

enable

low

high

high
low

permits try
permits try

high

inhibits try

Note that low tape counts at U215-12, 1 (zone 8-7H) are applied to U115-1 (zone 8-2G), as well as to
the decoder. Similarly, counter output U215-11 is inverted and applied to clock flip-flop (U186-11,

zone 8-2G). Flip-flop output U186-9 is applied to NAND gate input U115-2 (zone 8-2G). If BOT is

reached, load status ends (LDS low), so U115-12 cannot issue a load fault 5 output. If counts stop
before BOT is reached, U115-12 goes low, producing a load fault. Also, counter outputs to the decoder
are binary; A = 1, B = 2, C = 4, D = 8. D clocks the flip-flop so that output U186-9 goes high at

count 16 (the next binary order). This allows for about 92 m (30 ft) of tape to pass while searching for
BOT, without signalling a time-out load fault.
5.8.2.4 Automatic Tape Loading Sequence - When issuing the load command by pressing the
LOAD/REW switch, the logic goes through a series of steps based on feedbacks from status sensors
and cued by the sequencing counter. The hardware circuits that make decisions are shown in Schematic
Number 106875, sheets 2 through 9. The logic flowchart for the procedure is in the same drawing,
sheets 10 and 11. Sensor feedbacks are shown in Figure 4 in Volume 1 of the Technical Manual.
If tape is in the path and air status is satisfactory for operation after the LOAD/REW button is
pressed, interlocks will have been made (Paragraph 5.6.6.5). NDINTLK is applied (zone 7-1G) and
rewind mode is commanded by the resulting low = true rewind pulse NREWP (zone 4-1F). The tape

stops at BOT, and the load is completed.

- If interlocks are not made when the LOAD /REW command is processed, the automatic load sequence
is initiated by the low = true load pulse NLDP1 (zone 4-1F).

Pulsing is developed by the series of flip-flops (zones 4-7F to 4-3G) activated by the LOAD/REW

switch. While the momentary switch is pressed, J10-23 is connected to ground, which presets the first
flip-flop in the series. The resulting Q output (U26-5) sets the next flip-flop (435-5) at clock B (CLKB)

5-50

time. (Refer to Paragraph 5.6.6.1 for system timing details.) When the switch is released, J10-23 is
disconnected from ground, U26-4 goes high, and U26-1 goes low. This clears the first flip-flop while the
second stays in the set state until cleared by an unload (NUNLI1) or load status (NLDS) signal at NOR
gate U145, inputs 2 or 1, respectively.

The Q output at U35-5 applies a high at NAND gate input U24-4 while the Q output at U34-6 applies

a high to NAND gate U24-5 producing a load reset low = true output (NLRSTP) at U24-6. This is
sent to EXCLUSIVE NOR gate input U164-4 (zone 8-8F) to reset the load sequence counters and
control circuits. At clock B time, the output of U35-5 (zone 4-6F) causes the next flip-flop to change
state. This terminates the NLRSTP pulse (U24-6) and applies its high Q output to NAND gate U54-2,
which, while Q output at U34-8 is high, causes NAND output U54-3 to initiate a low load pulse
(NLDP1) at U46-6 (TP18). This pulse is terminated when the Q output at U34-8 changes state at the
next clock B time. NLDP1 is sent to U135-10 (zone 7-2E) to preset the load status (LDS) flip-flop and
U134-10 (zone 7-2C) to preset the thread status (THDS) flip-flop. It is also inverted and used as a
condition for output of NAND gate U133-6 (zone 8-3D).

If no cartridge is in place or, if the cartridge is sensed as neither open or closed, U132-6 (zone 8-5B) is
low. This causes a load fault 1 signal at U126-2, 12 (zone 8-2D) and a load fault status level (NLDFS)
at the Q output (U166-8) of the load fault flip-flop. NLDFS is applied to U136-2 (zone 8-7C) as one of
the conditions in the network that issues the load count signal to U215-14 to increment the sequence
counter U215 and decoder U205 (zone 8-6/7H). If NLDFS is true=low at U136-2, the reel-turning
pulses from the low tape sensor are prevented from entering the divide-by-five chip at U185-1 (zone 86C).

If the cartridge is in place, U205-2 (zone 8-6H) issues count C1, which clocks backwrap (BKW) flipflop U144-3 (zone 7-2B), and NC1, which clocks the air control flip-flop (U125-11) at zone 7-7F. Since,
during normal load sequence, interlock is not made (NINTLK at U184-8, zone 7-5F, high = false),
U124-8 (zone 7-2F) issues the pressure solenoid command (PSOL).

If no load fault exists, U166-8 (zone 9-7B) is highand U165-11 (zone 9-6B) is low, clearing the car-

tridge command flip-flop (zone 9-5A). This causes Q output U182-6 to initiate the NCOC command to
|

open the cartridge.

At NC1, the backwrap flip-flop is enabled to be set (by the output of U143-8, zone 7-3C), provided the
inputs (U133-9, 10, and 11) are high. This indicates that load status (LDS) mode is set (U135-9), a
midreel load condition does not exist (U134-6), and the try counter output (U112-9, zone 8-3D) in|

dicates no more than one previous try has been made (U112-9 high).

Load sequence count NC2 is applied to thread command flip-flop U144-11 (zone 7-2A). The NTHD

output (U144-8) is sent to U154-9 (zone 9-7D) to initiate the supply reel forward (SRF) command and
continue the take-up reel forward (TRF) command.

Load sequence count NC3 (zone 4-14D) applied to OR gate U155-4 (zone 7-3B) initiates clearing of
the backwrap flip-flop. NC3 at U204-1 (zone 8-3H) is inverted to C3 and applied to NAND gate Ul364, which checks the cartridge open signal CO N.O. for a possible load fault. U136-11 (zone 8-2F) similarly checks for air system faults.

When tape appears in the path (BOT or NAOK), U196-12 (zone 7-5C) presets flip-flop U216-4 (zone
7-6B). The succeeding two flip-flops, clocked by CLKE, provide a delayed output at U226-9, which sets
the tape loop command (STL) flip-flop. This delivers STL (zone 7-1B) to the reel servo motion commands at U222-13 (zone 9-4D). The take-up reel reverse (TRR) and supply reel forward (SRF) com-

“mands provide slack tape to form the loops.

5-51

When loops are set and interlock is made (NINTLK at U233-13, zone 9-6F), take-up reel reverse
(TRR) and supply reel reverse (SRR) are commanded (zone 9-1C D) When BOTis sensed, U131-13
(zone 9-5H) goes high and output U133-12 terminates motion.
|
3.9
- 5.9.1

REEL SERVOS (Refer to Flgure S in Volume 1 of the Technical Manual)
Reel Servo Overview

The reel servo subsystem controls tape reel speed as required to maintain optimum tension on the tape

between the supply and take-up reels. (The tension is interpreted from the positions of the tape loops.)
Figure 5-26 illustrates the basic signal flow as applied to each reel servo. The servo loop monitors the
power interlock signal and disables the reel servos if the interlock is broken. While loading and unload-

ing tape, the reel motors are controlled by forward and reverse signals from the control logic. When
tape is loaded, servo loop control is assumed by the loop position signal from the position transducer.
During normal run operations, a loop offset generator generates a signal which offsets the tape loops.
~ The direction of the offset is determined by the direction and type of motion (forward, reverse, or re-

wind). During rewind, a larger offset is used to allow for the higher tape speed.
If the supply reel is properly loaded, the air system in operation and interlock circuit status is acceptable, reel motion begins. The reel rotation speed is subject to feedback information from the air
load /control subsystem. This information includes the tape loop position transducer output for the appropriate servo (supply or take-up) and an offset input. The offset input pertains to adjusting reel mo-

tion to achieve a different loop configuration for different tape motion directions.

The supply and take-up reel servo networks are identical except for the polarity of the position transducer outputs. The crippled reel s1gna1in the take-up reel servo system 1S applied to the capstan servo
circuitry.
'

During load and unload operations, at which times the tape path has not stabilized, the reel speedis

totally a function of voltage specified by the control electronics. Load and unload sequenees are described 1in Paragraph 5.8.
5.9.2

Reel Servo PCBA

The reel servo PCBA, plugged into J12 on the interconnect D1 PCBA, contains the supply reel and
take-up reel power amplifiers. These control the speed and direction of reel motion (Schematlc Number

106925).

While the speed and direction of the capstan drive motor determines the motion of tape across the

heads, reel motion is a critical factor in tape transport management. Reel motion is determined by tape
loop position. Reel speed is adjusted to maintain the proper tape loop thereby maintaining the proper
tape tension. In doing so the reel speeds change according to the quantlty of tape on the reel. A tape

loop offsetis placed into the reel servo loops. The direction of the offsetis determined by the direction
and type of tape motion (forward, reverse, or rewind). Reel servo PCBA inputs and outputs are detailed
in Tables 5-6 and 5-7. Power amphfiers and outputs to the reel motors are shown on sheet 4 of Schematic Number 106925.

Drive power unregulated+ 36 V inputs to the reel servo PCBA are through J13 vand J16 (supply reel
posmve and negatlve) and J17 and J20 (take-up reel positive and negative,) respectively (zones 4- lG 4-

1A).

Outputs to the reel motors are, respectively: supply reel motor positive SM(+),J 14 supply reel motor
negative, SM(—), J15; take-up reel motor positive, TM(+), J18; take-up reel motor negative, TM( ),
J19.

5-52

INTERLOCK

CONTROL {
LOGIC

h FORWARD *

|
SERVO
LOGIC

§| REVERSE
*

POSITION
TRANSDUCER

% LOOP POSITION

SUMMING
AMPLIFIER

POWER
liffiiiffi

REEL MOTOR

FORWARD

CONTROL{ REVERSE
LOGIC

OFFSET

GENERATOR

REWIND

OFFSET

MODE ONLY
* IN LOAD/UNLOAD
MA-3648

Figure 5-26

Reel Servo Block Diagram

Table 5-6 Reel Servo PCBA Inputs
Input

Connector

From

Purpose

' +36 V(S)

J13

Supply reel motor power

—36 V(S)

J16

C5(—)

| Supply reel motor power return

+36 V(T)

J17 |

—36 V(T)

J20

C5(—)

REWR

J12-13

J11-78

REV

J12-33

J8-66

Reverse command from control M PCBA

NRSAE

J1 2—1 1 |

J 8-34

Reel servo enable Signél

NPORST

J12-9,26

J11-37,77

Power-on reset signal

N‘TINTLK o J1231 |
J12-30
NSINTLK

J 2-1 0
12146

Take-up 1oop interlock (TLIMIT signal)
Supply loop interlock (SLIMIT signal)

J12-15

J8-31

Take-up reel forward command

TRF

o Take—up reel motor power" .
Take-up reel motor power return

Rewind ramp éignal from capstan/regulator ranip

generator

5-353

‘

Table 5-6

Reel Servo PCBA Inputs (Cont)

Input

Connector

From

Purpose

TRR

J12-14

J8-32

Take-up reel reverse command

SRF

J12-17

J8-29

Supply reel forward command

SRR

J12-16

J8-30

Supply reel reverse command

MRL

- J12-28

J8-5

Midreel load signal

SPOS

J12-20

J21-37

Supply loop position signal

TPOS

J12-3

121-21

Take-up loop position signal

NDRYV

J12-27

J8-66

+15 V(L)

J12-6,23

J11-21,61

Regulated dc from capstan/regulator PCBA

0 V(L)

J12-4.5,

J11-26,27,

DC ground

21,22

66,77

J12-7,24

J11-14,54

Regulated dc from capstan/regulator PCBA
Power for position transducer

—15 V(L)
+15 V(R)

J12-32

Interconnect

0 V(R)

J12-34

F1 PCBA

Drive reel command

Table 5-7

Reel Servo PCBA Outputs

Output

Connector

Purpose

Supply reel motor

Drive power

Take-up reel motor

Drive power

SM(+)

J14

SM(—)

J15

TM(+)
TTMM(—)

J18
J19

Input signals to the reel servo PCBA are through interconnect D1 PCBA and J12, shown on the leftside
of sheets 2 and 3 of Schematic Number 106925.
Both supply and take-up reel amplifiers are enabled by low = true reel servo amplifier enable
(NRSAE) at J12-11 and high
= false power-on reset (NPORST) at J12-9,26 (after reset pulse) (zones
2-8F and 2-8E). Gate U10-6 (zone 2-6E) produces amplifier enable (NAE) when low and, when high,
initiates the dynamic brake outputs for both reelsin both dlI‘@Cthnb (SFBRK, SRBRK, TFBRK, and
TRBRK) (zones 2-1D and 2 1E).

5-54

The brake signals are sent to the amplifiers (zones 4-8F, E, B, and A, respectively). The NAE signal is
routed as shown at zone 3-4E as one of the conditions for development of the drive signals, NSDA,
NSDB, NTDA, and NTDB (zones 3-1G,F,C, and B, respectively). These are routed to the amplifier
circuits as shown in zones 4-8F and G (for supply reel signals NSDA and NSDB) and 4-8C (for corre-

sponding take-up reel signals).

Mode control circuits are shown in zones 2-8E through 2-6C. They interpret supply reel (SR) and takeup reel (TR) motion commands (SRF, SRR, TRF, and TRR) with respect to whether the tape interlocks (NSINTLK and NTINTLK) are set, and whether a midreel load (MRL) operation is in progress.
The outputs of the mode control network are applied to the corresponding mode switches shown in
~

zones 3-5B,6B,5F, and 5G.

Reel load speed adjustment circuits are shownin zones 3-5H, 6H and 3-5C, 6C. The supply loop position feedback signal (SPOS)is applied to the summing amplifier network through J12-20 (zone 3-8G).
Take-up loop position signal feedbackis applied to the corresponding take-up reel summing network
through J12-3 (zone 3-8B). The offset factor is introduced into the summing networks (zones 3-8F and
3-8A) to reproportion the supply and take-up loops during a rewind operation.
|

The offset signal is developed on the basis of reverse motion signal (REV) J33, and rewind ramp signal
(REWR) J13, shown in zones 2-8F and 2-8H, respectively. REWR is developed on the capstan/regulator PCBA and REV is provided by the control M2 PCBA. Normal offset adjustment circuits are shown in zone 3-5D, where resistance of potentiometer R76 contributes to the T-wave generator circuits controlled by the park loop gain switch (shown near the NDRYV input J12-27 in zone 3-8E).
The reel servo inhibit switch (zone 2-6F) allows disabling reel servo circuits for maintenance purposes.

The 5 V regulator nétwork produces the +5 V (A) (zone 2-3C) for the amplifier circuits and the +5 V
(S) (zone 2-3D) for all reel servo logic requirements. Zones 2- 8B through 2-6A show the +15 V and
—15 V inputs to the reel servo PCBA circuits.

5.10 CAPSTAN SERVO (Figure 6 in Volume 1 of the Technical Manual)
5.10.1

Capstan Servo Overview

The capstan servo is a velocity management system. It acts as the tape mover that pulls tape across the
magnetic head assembly for data recording or reproduction. The capstan servo consists of the functional blocks shownin Figure 5-27.

The heart of the servo is the summing amplifier which receives current signals from three sources, sums
them, and forces the power amplifier to the proper voltage. The power amplifier applies this voltage to
the capstan motor. which responds with the appropriate speed. The capstan tachometer is shaft-coupled
to the capstan motor and produces a frequency output proportional to the speed of the capstan motor.
This frequency is converted to voltage, which is the tachometer feedback required for constant velocity
operation.

The primary inputs to the capstan servo are the logic control signals. These signals initiate either a

positive or negative ramp for forward and reverse operation, or a long rewind ramp used to accelerate
“the capstan motor to rewind speed. The ramp slopes and final velocities for forward and reverse are
adjusted to achieve the desired start/stop characteristics.

5-55

]

FREGUENCY.

VOLTAGE

OPTICAL

TACHOMETER
,

{—_@:}—-

CONVERTER

LOGIC
CONTROLS

}
SPEED

SUMMING

REFERENCE -

AMPLIFIER

—

POWER

MODE

AMPLIFIER

CONTROL

CAPSTAN
_

MOTOR

REWIND RAMP I
GENERATOR

CURRENT

SENSE

MA-3653

Figure 5-27

Capstan Servo Block Diagram

Flgure 5-28 illustrates typlcal capstan Servo waveforms The following sequence of events descrlbes nor-

mal capstan servo operatlon

With power applied and tape loaded interlock made, the capstan power amplifier is enabled.
2.

Upon receipt of an ISFC command, capstan drive current is appliedin the forward direction.

The magnitude of the current is constant and determlnes the constant rate of acceleratlon

As the capstan approaches synchronous speed, the dlfference between the commanded speed
and the actual speed decreases as does the capstan drive speed.
A small error signal determined by the loop gain is required to overcome running losses.

When ISFCis terminated, the polarity of the drive current is ‘reversed. ThlS reverse current
is maintained at a constant level for a fixed time.

At the end of the reverse current pulse the capstan motor drive voltageis brought to, and
held at, ground level to produce a dynamic braking effect.

NOTE
The synchronous reverse mode (ISRC) procedureis
identical except the direction and drive current is reversed.

Each time power is applied to the unit, the power distribution block generates a reset signal (NPORST)
to the velocity decoder on the control M2 PCBA and the capstan control logic on the capstan/ regulator
PCBA. After tape is loaded into the vacuum column, the interlock signal (NINTLK) from the air

load/control function goes low and enables the capstan amplifier.

The system control function, upon receipt of a motion command, supplies the following signals to the
capstan mode control logic: drive (NDRYV), direction (REV), motion (NMOT), and speed greater than

80 percent (N>80%). (N indicates low = true.)

5-56

INTERFACE-

SYNCHRONOUS

FORWARD

COMMAND
MOTOR

CURRENT

—

=== —_—

CAPSTAN
VELOCITY

|
o
*__l—'“-__*Jr*"

MA-3664A

Figure 5-28

Capstan Servo Waveform for Forward Start and Stop

The power amp11f1er prowdes drlve to the capstan motor via J11 and TB1-3 on the interconnect D1
PCBA
|

-Tachometer pulses, from the optlcal Sensor mounted on the capstan shaft, are amplified on interconnect
F1 PCBA. The signal is routed through interconnect D1 PCBA to control M2 PCBA where it is
squared and sent to the velocity decoder and the interface (TACHP). The velocity decoder generates a

20 us pulse for each tachometer pulse input. This is called NTAP2 and is sent to the capstan/regulator

PCBA. There it is converted by the tachometer frequency/voltage converter to the feedback analog

(ANALOG TACH) 31gnal for the capstan summing amphfler
5.10.2

Capstan Servo PCBA

The capstan /regulator PCBA develops the capstan drlve motor power inputs CM(—) and CM(+), provides primary regulation of dc voltages, develops rewind power ramps for the reel servo system, converts capstan tachometer frequency output to proportionate voltages, controls cartridge motor power,
and processes vacuum, pressure, and write protect solenoid signals. Capstan/regulator PCBA circuits
are shown on Schematic Number 104757.

Capstan motor drive power is developed from the =36 V unregulated input by the power amplifiers
(zone 2-3B) on the basis
of inputs through capstan/regulator edge connector P11, (shown at the left
side of sheet 2. The amplifiers are enabled by the interlock signal (NINTLK) from the control M2
PCBA and power-on reset (NPORST) from the regulator circuits (zone 3-1G to 2-8H).
Application of the start ramp, forward stop ramp, or reverse stop ramp (zone 2-7B, C) is controlled by
the output of the mode control circuits (zone 2-7E through 2-7F). Direction of the application is determined by the forward-reverse switch (zone 2-7D) output on the basis of the reverse (REV) signal input
(zone 2-12F) as inverted at U7-8 (zone 2-9E). The start ramp is terminated when capstan speed reaches
80percent of nominal tape speed. (N>80% input at P11-25 is low = true.)

Capstar-i drive speed is determined by summing amplifier output U9-6 (zone 2-7D) on the basis of tach-

ometer feedback pulse (NTAP2) through P11-57 (zone 2-12D) when the tachometer circuits are enabled (NTEN mput at P11- 17)

In rewind mode, the rewind ramp (NRWR) command at P11-38 (zone 2-12B) initiates the rewind ramp
~ generator (zone 2-8B,9B), the output of which is also integrated in the summing amplifier output. The
crippled reel signal (CR N.O.) at P11-80 disables the rewind ramp generator 1if the tape loop excursion
in the take-up reel buffer column becomes too short.

5-57

Circuits which execute the cartridge open command (NCOC) and cartridge closed command (NCCC)
are shown on sheet 3, starting with the command inputs at zone 3-10D. The active command is applied

to the cartridge motor driver amplifier (zone 3-8D). When the driver is enabled (ENBL at Q53, zone 3-

8C), the amplifier output is applied to the bases of Q37 and Q38. If the output is high, Q38 is turned
off, and Q37 turned on. This pulls down the base of Q36, causing it to connect +24 V to the CART
MTR (+) output at P11-30 and 70 (zone 3-1D). While Q36 is switched on, Q43 is off.
If the amplifier output is low, the states of Q36 and Q43 are reversed, in which case the —24 V source
is connected to CART MTR (+) output. The positive sign at the output in this case means more nega-

tive than the return line designated as CART MTR (—). It may be convenient to think of the CART
MTR (+) line as the output line (its electrical polarity indicating the direction of motion with positive
(+) for forward) and the CART MTR (—) as the return line.
Vacuum transfer command (NXFR) input at J11-39 (zone 3-10B) is a command to redirect application

of the vacuum source by controlling the vacuum valve solenoid. When NXFR is low = true, Q44 (zone
3-4C) is switched off. This causes Q45 base to be pulled down. This turns Q45 on, which connects the
vacuum solenoid return (VAC SOL RET) to ground.
The reel servo amplifier enable (NRSAE) command provides a low at J11-58, which is inverted and

cuts off Q54 (zone 3-6C). This low output of Q54 then turns on Q46. This applies a high to NOR gate
inputs Ul1-1 and U11-2. The inverted output at U11-3 is a low = false file protect (FPT) status signal.
The high output of Q46 also turns on Q47, connecting the write protect solenoid return (WP SOL

RET) line to ground. If the write-enable ring is in place, WP1 N.O. input at J11-69 (zone 3-10B) is
high. The high input is regulated in VR7 (zone 3-7B) and applied to the base of Q46. This turns Q46
off, causing a low at NOR gate inputs Ul1-1, 2 and a high = true FPT output at J11-19 (zone 3-1B).
The Q46 low output also turns Q47 off, which disconnects the write protect solenoid return line from
ground. This causes the WP1 N.O. input at P11-69 to continue until the circuits are reset. P11-79 input
is not used.
The upper half of sheet 3 contains the regulation circuits (covered in Paragraph 5.4.5).
5.11

DATA PATHS

This section outlines the data paths utilized in write operations, and traces the flow of data onto tape
and back through the read recovery chain. For an understanding of the group code recording and phase
encoded tape formats, refer to Paragraph 4.1, Recordmg Formats, in the TM78 Magnetic Tape Formatter Technical Manual (EK- OTM78-TM)
5.11.1
Introduction
Figure 5-29 shows an overview of the read /write data paths. Write data originates
in the formatter and

is placed on the TU bus. The MIA PCBA gates the write data through to the write PCBA where it is
conditioned before going through the preamp PCBA to the write head.

Data picked up by the read head is amplified in the preamp PCBA and input to the read PCBA. The
read PCBA further amplifies the read data and passes it on to the MIA PCBA where it is gated to the
formatter over the TU bus. The read PCBA also establishes a gain control voltage for each track that is
fed back to the preamp PCBA. Read data from the preamp PCBA passes through the read PCBA and
is input to the write PCBA. The write PCBA generates an AMTIE signal if the read data amplitude
falls below a predetermined threshold level. AMTIEs are gated through the MIA PCBA and sent to the
formatter over the TU bus.

5-58

|SOMd'0:2zr——fezd|doLami_ALdor|HO)(d'0:L—]eo6r!——a—.

—— _3ANLITdAY)MOVH1 A|—aTvadvEd |

31dILTINW__

~3L1um—)(Vivad—31idm){vlva/(1\—e314m)(V1va"S
I

vad

_OILINDVIN _ev814dvy3ad

5-59

5.11.2
Write Function
The write function records formatted digital information on tape. The recording format and den31ty are
compatible with ANSI and IBM, 9-track PE or GCR. Figure 5-30is a simplified block diagram of the
write function.

Assume power is applied, and a reel with a write enable ring is installed on the supply reel. Switch S8,

on the base assembly, closes and supplies write power (WP1 N.O.) via P21-29 and 32 to the capstan/regulator PCBA (J11-69) and to the write PCBA (J7-24 and 60), where it is designated as WRT
PWR. If the write enable ring is not installed on the reel, WP1 N.O. is not applied to the circuitry.

The density signal (NPE) from the control

M PCBA (J8-25) is input to the write control logic on the

write PCBA at P7-61. The density command is received from the formatter via the MIA PCBA. Signal
NPE is used to select either PE or GCR format (high = GCR, low = PE).
When a load command is detected, the air load/control function provides a low reel servo enable signal

(NRSAE) to the capstan/regulator PCBA via J8-34. The WP1 N.O. signal from S8 (P21-29 and 32)

and NRSAE from the air load/control function (J8-34), are applied to the write driver on the capstan / regulator PCBA. The write driver provides a low file protect signal (FPT) to the system control
function via J11-19, and a low holding path feedback write lock out signal (W.P. SOL RET) to WLO
solenoid, K2 via J 11-33 and 73.

Signal W.P. SOL RETis coupled through the interconnect F1 PCBA (P21-27 and 28) and energizes
the WLO solenoid K2 which holds S8 closed and maintains WP1 N.O. If WP1 N.O. is not present, the
write driver provides a high FPT signal to the system control function (J11-19), and a high W.P. SOL

RET to the WLO solenoid (J 11-33 and 73). The high W.P. SOL RET does not energize the WLO

solenoid and no WP1 N.O. is available. TP51 (capstan/ regulator PCBA) is used to monitor the file
protect signal and TP58 (Capstan/Regulator PCBA)is used to monitor the write lockout feedback signal.

If the transport is selected, ready, and on-line, and the system control function detects both interface
write and interface motion commands, the system control function provides a high motion signal (MOTION) via J8-28 and a low write signal (NWRT) via J8-26 to write control logic jacks J 7- 26 and J7-25,
respectively.

The interface input data lines (IWDP, IWDO-IWD?7) are routed to the write data buffers via J2 of the
MIA PCBA. The MIA PCBA also provides the write data strobe (IWDS) to the write strobe logic via
J7-47.

5.11.3

Read Function

The read function recovers digital information from magnetic tape in either the forward or reverse direction. The formatis compatible with ANSI and IBM, 9-track GCR or PE. Figure 5-31 is a simplified
block diagram of the read function.

The density signal (NPE) from the control M2 PCBA (J8-25) is applied to the read control -logic on the

read PCBA. The density command is received from the formatter via the MIA PCBA, Signal NPE is
used to select either PE or GCR format (high = GCR, low = PE).
|

When the system control function detects a read command and an interface motion command, the control M2 PCBA provides a high motion signal (MOTION) via J8-28 and a high write signal (NWRT)
via J8-26 to the read PCBA. NWRTis used to select either a read or write operation (high
= read, low
= write).

5-60

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5-61

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pre

|
WRITE

—

IWD 7:0,

‘

DATA

REGISTERS | AMPLIFIERS
(3,4,5)

(3,4,5 )

IWDS

WRITE

» STROBE

MOTION

CLK 1,CLK 2

PCBA

WRITE

DATA

GENERATOR | RESET 1, RESET 2

+10V

|
|

—_

jWRITE

$HEADS
ERASE

HEAD

(2,3)

NPE

)

STEP/

PEDESTAL

GENERATOR

V STEP

|V PED

PE/GCR

(2)

IWINH

V WRT

NPORST

WRT CUR WPTN.O.)

NWRT

CONTROL

CIRCUITRY
(2)

FERHRLO

WRT STAT

TO MIA

DIFFER-

PO7:0,P

ENTIATOR | DETECTOR

NLTH

NORMTH (STDTH)

(6,7,8)

AMTIE

THRESHOLD
GENERATOR

(6,7,8)

+ VAM

PCBA

ENVELOPE

AMTIE 7:0,P

NOTE:: NUMBERS IN PARENTHESIS INDICATE
CIRCUIT SCHEMATIC PAGE NUMBER

(2)
MA-7073

Figure 5-32
.

Write'PCBA Block Diagra‘m

Because of the read-after-write feature, the transport reads in both read and write modes. Selection of
the read-only function is essentially a suppression of the write mode.

Data retrieved by the read heads is preamplified on the preamp PCBA and routed directly to J4 on the
read PCBA. There it is processed and presented to the interface in binary form as required by the
formatter. The read data is also sent to the write PCBA as pointers (P07:00, POP) for development of
the AMTIE signals. Here the read data is examined for signal amplitude against a reference threshold.
S5.11.4

Write PCBA

The write PCBA processes data received from the MIA PCBA, controls the write/erase heads, and

checks the read data to provide the amplitude track-in-error (AMTIE) status signals.

The write PCBA plugs into J7 on the Interconnect D1 PCBA. Figure 5-32 is a block diagram of circuits
on the write PCBA. Circuit details are provided in Schematic Number 107860. Write PCBA interface

signals are listed in Tables 5-8 and 5-9.

Sheet 1 of Schematic Number 107860 shows hardware commonality and general notations. Sheet 2
shows the general mode control and power circuits, including the development of the pedestal-and-step
waveforms used for greater recording efficiency. Sheet 3 shows the write data inputs, registers, and
data strobe clock development (upper areas) with the parity bit channel and erase head circuits (lower
areas).
Sheets 4 and 5 shows circuits for amplifying and preparing data for recording in channels 0 through 7.
Sheets 6, 7, and 8 show amplitude track-in-error (AMTIE) signal development.
The following paragraphs provide more details on the circuit theory for each of these circuit groups.
5-63

Write PCBA Inputs

Mnemonic

Connection

From

WP1 N.O./
WRT CUR
NPE

~ Purpose
o

J7-60,24
-

P21-29,32

Write power

J7-61

J8-25

Density select

NWRT

J7-25

J8-26

Write command

MOTION

J7-26

J8-28

Specifies that tape is rolling

IWINH

J25-4, J7-49

MIA J1-4

Write inhibit

NPORST
NARA

J7-11
J7-32

J11-33,77
J5-17
|

ARA burst error

Power-on reset

NTEST

J7-56

J1-22

Test mode (not used)

'NTSTR
IWDS

J7-20
J7-47

J3-19
J2-34

Test data strobe (not used)
Write data strobe

IWDO

J7-44

J2-24

Write data

IWD1

J7-23

J2-23

IWD2

J7-42

J2-22

IWD3

- J7-41

IWD4
IWD5
IWD6

J7-40
J7-39
J7-38

J2-21
- J2-20
J2-19
J2-18

IWD7

J7-37

J2-1

IWDP

J7-45

J2-25

POO
PO1

J7-65
J7-66

J5-50
J5-51

PO2
PO3
PO4
PO5
PO6

J7-67
J7-68
J7-69
J7-70
J7-71

+5V(T)

J7-21,57

J5-54
-

J5-55
J5-56
J5-57
J5-49
INT. DI

J7-18,19,

J11-22,23

+15V

54,55
J7-22.58

62,63
J11-21,61

-15V

J7-23,59

J11-14,54

STDTH

- J25-5

J25-15

B
|
Termination voltage (not used)

WI1-2,W2-2.

+5V (L)

NLTH

Logic power
Power for erase head amplifier

Power for erase head amplifier

MIA J1-5

Establishes AMTIE threshold

MIA J1-15

Establishes AMTIE threshold

.\\\

J7-64

."’

J7-72

POP

J5-52
J5-53

PO7

‘Read data bits used as pointers — used for
developing AMTIE signals

Table 5-8

5-64

Table 5-9

Write PCBA Outputs

Mnemonic

Connection

Purpose

J25-11
J25-16

MIA J1-11
MIA J1-16

ARA burst error
Specifies tape is rolling

J6-7,19
- J6-6,18
J6-4,16
J6-10,22
J6-2,14
J6-9,21
J6-3,15
J6-5,17

J23-7,16
J23-6,15
J23-4,13
J23-10,19
J23-2,11
J23-9,18
J23-3,12
J23-5,14

NARA

(I ARA ERR)
MOTION

WRT STAT
WRT BIN
(CHO)*
(CHI1)*
(CH2)*
(CH3)*
(CH4)*
(CH))*
(CHo6)*
(CHT7)*
(CHP)*

VWRT
ERHD LO

WRT REG
AMTIE 0
AMTIE 1
AMTIE 2
AMTIE 3
AMTIE 4
AMTIE 5
AMTIE 6
AMTIE 7
AMTIE P

J25-14
J25-9
J6-8,20

J6-1,23
J6-24

J6-11
J25-18

J25-19
J25-20
J25-12
J25-3
J25-2
J25-13
J25-1
J25-17

MIA Ji-14
MIA J1-9
J23-8,17

Transport in write mode
~ Status of write data bit 4
Write head current

J23-1,20
E2

Write head center tap
FErase head current

El
MIA J1-18

MIA J1-19
MIA J1-20
MIA J1-12
MIA J1-3
MIA J1-2
MIA J1-13
MIA J1-1
MIA J1-17

- Erase head current
Amplitude track-in-error status
|

*Mnemonic not shown on prints

5.11.4.1 Write Control and Power Circuits
e

Control Circuits
Control circuits are shown in the upper left area of Sheet 2, Schematic Number 107860.
Inputs involved are IWINH, NWRT, NPORST, and WRT CUR (zones 2-8F,G,H). Signal
WRT CUR orlglnates on the base assembly as WP1 N. O

The control circuits are reset when the power-on reset 51gna1 (NPORST)is momentarily low
= true. This opens Q1 (zone 2-7G) and Q3 (zone 2-8H). When Q1is not conducting, Q2 and
QS are also open. When Q3is not conducting, Q4 and Q6 are similarly open. This terminates
= false
any prev1ous mode until NPORST goes h1gh

= true), U112-12 (zone 2- 8G)is high, U122| When the write command arrives (NWRT low
of Q2 is pulled down. This causes Q2 to
base
the
Q1,
through
and,
low
is
6 (zone 2-7G)
then conducts, enabhng write current
QS
Q5.
of
base
the
to
high
a
apply
conduct and
(WRTCUR) circuits.

5-65

|
T

+10V

WRTREG

?) TP2

V PED

—N_——

WRITE

CURRENT | \ sTEp

SOURCE
NPE

TP3

TP5

TP1
@

IWDS _ CLK 1

STEP

CLK2

WIDTH

IWD (N)

EDGE

DELAY

]

DETECTOR

WRITE

BUFFER

»{cK

WRITE

HEAD

NWRT

IWINH

NPORST

|
TP4

BASE ASSEMBLY
15V

WPIN.O.

WRITE

|(-)

WRT

CUR

V WRT

)

PROTECT

SWITCH

MA-7075

Figure 5-33

Write Amplifier Circuitry

PE/GCR Modes

Phase encoded (PE) mode is commanded when the NPE input to the write PCBA is low =
true and group coded recording mode is commanded when NPE is high = false. This input is
shown on Schematic Number 107860, zone 2-8E.
- When NPE is true, U112-10 (zone 2-8E) is high, producing the PE1 mode control signal,
distributed as shown in zone 2-7E.
|

When NPE is high = false, GCR mode is effective. GCR1 (zone 2-5E) »and GCR3 (zone 2SF) are distributed as shown to set up the circuits for GCR-formatted data.

Write Power
|
!
The +15 V dc input to the write PCBA for J7-58, 22 on the interconnect D1 PCBA (zone 2-

8C, D), is reduced by diodes CR11 through CR14 (via jumper W4) and regulated by VR3
(zone 2-5C, 6C). The write power regulated (WRT REG) is applied to the voltage step
(VSTEP) and voltage pedestal (VPED) circuits at zones 2-2H and 2-2E respectively.
5.11.4.2 Write Circuitry — The write circuitry comprising the current source, step delay, edge
detector, write buffer, and amplifier is shown in simplified form in Figure 5-33. Refer
to Figure 5-33 and

Schematic Number 107860 while reading the following discussion.

5-66

Write Current Source (VPED/VSTEP) Circuits

The terms voltage pedestal and voltage step refer to the shape of the write current waveform
of a data bit. Theoretically, a series of 1s and Os would involve a simple squarewave signal
composed of square pedestal-like waves in alternating upright and inverted position. In practice, greater efficiency is achieved by overshooting the pedestal level at the beginning of each
wave. This produces a waveform composed of squarewaves, with an added step more positive
than the pedestal amplitude of positive waves and more negative than the pedestal amplitude
of negative waves.

In GCR mode, pedestal amplitude is adjusted by trimming R39 (zone 2-1D) and step ampli-

tude is adjusted by trimming R22 (zone 2-1G).

In PE mode, R36 (zone 2-1E) is used to trim pedestal' amplitude and R19 (zone 2-1H) is used
|

to trim step amplitude.

Which PE and GCR adjustment described in the two preceding paragraphs is used, is determined by operational mode selection. In PE mode, the base of Q10 (zone 2-4E) is high, which
turns Q10 off. This applies the low = true NPE2 signal to the various circuits listed in zone
2-3F, and also to CR8 (zone 2-3G) and CR10 (zone 2-3D). CRS8 and CR10 then conduct,
pulling down the gates of the FET Q14 (zone 2-3G) and Q15 (zone 2-3D), respectively. Q14
and Q15 then open the circuits adjusted by R22 (zone 2-1G) and R39 (zone 2-1D).

In GCR mode, a low is applied to the base of Q10 (zone 2-4E). Q9 is then turned off, which
selects the GCR adjustment circuits (R39 and R22). The circuits involved operate-on the
same theory discussed in the previous paragraph for PE mode VSTEP and VPED adjust-.
|

ments.

Write Data Buffers and Strobes

Input data IWD7:0, P are input to the write PCBA through J7 of the interconnect D1 PCBA
(zone 3-5D-5H). Data multiplexers Ul1, 31, and 41 always select the A inputs because the
test mode is not employed. The write data strobe (IWDS, zone 3-7H) is made available
through U41-11 and U41-9 as clock 1 (CLK1) to U99-2 (zone 3-3G) and U99-10 (zone 3-3E),
where the signal is low when true. At the trailing edge, when the CLK1 signal goes high, it
triggers either the GCR or PE one-shot, depending on the state of the GCR1 and PE1 mode
inputs, to form the step width delay. If PE1 at U99-1 (zone 3-3G) is low = false, the GCR
one-shot output at U99-4 is high for a period determined by the values of C11 and R48. Conversely, if GCR1 at U99-9 is low = false, the PE one-shot output at U99-12 is high for a
period determined by the values of C12 and R50. These one-shot outputs are applied to
NAND gate inputs U102-5 and 4 (zone 3-2G), respectively. The NAND acts as an OR function to produce a high if either of the inputs is low. This high 1s inverted at U92-10 to produce
data strobe clock 2 (CLK2) at zone 3-1G.

CLK1 (zone 3-3G), which is high = true (equivalent to the IWDS strobe) from U41-9 (zone
3-5G), is applied to the pedestal (VPED) flip-flop of all data channel and the parity channel
amplifiers (e.g., U52-3, zone 3-7C). CLK2 (zone 3-1G) is applied similarly to the step
(VSTEP) flip-flop (e.g., U52-11, zone 3-7C).
Write Current Driver Circuits

All write current drivers and head control networks, including the parity bit channel network,
operate on the same theory. In this discussion the parity bit circuits are referenced as an
example. These circuits are in the lower part of Sheet 3, Schematic Number 107860.

5-67

Write voltage (VWRT) is applied to the center tap of the head winding (zone 3-2C and 3-

3B). This is approximately -15 V dc. The direction of the magnetic flux then depends on
whether the circuit through the coil is toward head connector pin 5 or pin 14. This is deter-

mined by the state of Q19 (zone 3-4B) and Q18 (zone 3-4C). If the data bit at U52-2 (zone 3-7C) 1s low at CLK1 time, U52-5 is low and Q18 conducts. If the data bit is high, U52-6 is
low, and Q19 conducts.

Flip-flop U52-9 and EXCLUSIVE OR gate U53-6 ’togethér form thé.edge detector which

determines the VSTEP pulse width. The VSTEP level is applied during part of the pulse

- time by the EXCLUSIVE OR gate output at U53-6 (zone 3-6B). This output is buffered and
applied to the base of Q17 (zone 3-5G), which gates in the VSTEP level. The U53-6 output is
low at all times unless one and only one of its two inputs (U53-4 or U53-5) is high. The output
at U52-5 (zone 3-7C) is applied to U53-4 and also to adjacent U52-12. If U52-5 is high, U536 also is high until CLK2, when U52-9 and U53-5 go high, producing a low at EXCLUSIVE
OR gate output U53-6. If U52-5 is low, at the next CLK2 time U52-9 and U53-6 is high until
-

the succeeding CLK2 time. For each bit, 1 or 0, there is consequently a discrete time when
EXCLUSIVE OR gate output U53-6 applies a high to the base of Q17 (zone 3-5D) to gate in

the VSTEP voltage level.

Each of the other input data bits, IWD0-7, are processed in the same manner as the parity
bit, IWDP, discussed in the previous paragraph, provided also that the write inhibit (IWINH) signal is not low = true.

When IWINH is true, a low applied at J7-49 (zone 2—8H) causes U51-8 to gd high, U122-10

to go low, and U122-8 to go high. If Q3 is conducting, this applies
a high to the base of Q4,
turning off Q4 and consequently, Q6. This enables the write status (WRT STAT) signal to go
high if Q5 is off, and prevents writing regardless of the previously mentioned write command

and power inputs by removing the negative voltage to the center tap of the heads (VWRT).

The MOTION input to the write PCBA (zone 2-8E) is also required to establish the write
mode. When

MOTION is low = false, RESET1 and RESET? (zones 2-1C,B) are also low
= false. They are applied to the write buffers, such as U52-4 (zone 3-7C) and the edge detec-

tors, such as U52-10 (zone 3-7B) for the parity channel. When the motion input is high =
true, it provides the motion status output to the MIA PCBA at J2 (J25)-16 (zone 2-4G).

~ Erase Head Circuits
The erase head circuits are shown on Schematic Number 107860, zones 3-2A,B through 3-

4A, B. The regulated write voltage (WRTREG) is available at diode CR25 (zone 3-3A) and
passes through the erase head winding when the erase head low (ERHDLO) line is low. ER-

HDLO 1s developed in the write/write inhibit mode circuits (zone 2-4G) and is high during
read only mode, to prevent erasing existing data unless new data
is to be written.

5.11.4.3

Amplitude Track In Error (AMTIE) Circuits — Amplitude track in error (AMTIE) signals

are generated on the write PCBA from read data. They are used to notify the error checking and correction circuits in the formatter of marginal data.
B
B
:

Threshold Selection
|
The threshold selection circuits are shown in zones 2-4B and 2-5B of Schematic Number
- 107860. These circuits regulate the + VAM to a level determined by the threshold selection
(NLTH or NORMTH at J2-5 and J2-15, respectively). When NORMTH (normal threshold)

1s high = true, VR6 regulates the + VAM at approximately 6.0 V. When NLTH (low
threshold) is low = true, VRS regulates the + VAM at approximately 2.7 V. VR4 regulates

VAM to assure approximately 7.5 V maximum. The regulated voltage is applied to the AM-

TIE circuits.

5-68

THRESHOLD

(+VAM)

READ DATAIN

(PO7:0,P)

AMPLITUDE TRACK
IN ERROR OUT

(AMTIE 7:0,P)

PE/GCR
GAIN
CONTROL

MA-7074

Figure 5-34 AMTIE Generator
|

AMTIE Generator Circuits

Data received by the read PCBA for processing is also routed through the interconnect D1
PCBA to J7 into which the write PCBA is plugged. At the write PCBA inputs, the data from
the channels are labeled as pointers (POP, POO0-7), as shown at the left side of Sheets 6, 7,
and 8 of Schematic Number 107860. The following discussion uses the parity channel as an
example starting with POP (zone 6-8G). A simplified Vlew of the AMTIE generator 1s also
shownin Figure 5-34.

POP data bits are applied through C13 and R153 to differentiator input U132-1 (zone 6-7G).
The differentiator operates in either GCR or PE mode, depending on the circuitry set up
between U132-4 and U132-7. The circuit selection is made by mode selection signals NPE2
= true, GCR mode signal NGC
and NGC (zones 6-2F). When PE mode signal NPE2 is low
= false. These inputs cause Q44 (zone 6-6G) to stop conducting and turn Q45 (zone
is high
6-6F) on. This electrically connects the PE gain determining components between differen= false
~ tiator pins U132-4 and U132-11. Similarly, whenin GCR mode, s1gnal NPE2is high
= true, allowing Q44 to conduct, therefore bringingin the GCR gaindeterand NGCis low
mining components |

Differentiator outputs U132-8 and U132-7 correspond to the voltage differential in time
(DT/DV) of the input at pins 1 and 14. Positive (pin 8) and negative (pin 7) transitions are
input to the threshold detector (U134) where they are compared with the threshold voltage (+ VAM). The output of the threshold detectoris applied to the input of two open collector
gates (U138-1 and U138-13). Each open collector gate forms the input to the envelope detec—
tor stage. Separate envelope detectors are provided for PE and GCR modes.
The peaks of each bit transition cause the threshold detector to produce an output, causing
the open collector gate to conduct. Using the phase encoded threshold detector as an example, current would be conducted through gate U138-2 and resistor R171. During the time

when a transition peakis not being detected, U138-2 is not conducting and capacitor C23
charges up through R171. In normal operation read data transitions occur at a frequency that
does not allow capacitor C23 to charge up to a value equal to or greater than the input threshold of NAND gate U148-1. In other words, the NAND gate always is inhibited. However,
should a 51gnal dropout or incorrect data format appear on tape for a sufficient amount of
time, C23 is not discharged and charges up to a value sufficient to enable the NAND gate.
NAND gate output U148-3 disables NAND gate U148-5, whose output pin 6 enables the
= true IAMTIEP to the MIA
- AMTIE driver U149-1. AMTIE driver U149 3 sends the low
PCBA via J2 (J25) -17.

IAMTIE 7:0 signals are similarly generated in the appropriate circuits shown on Sheets 6, 7,

and 8 of Schematic Number 107860.

5-69

5.11.5

Read PCBA

The read PCBA accepts signals from the read heads via the GCR / PE preamp 1 PCBA and decodes the
signals to provide the formatter with read datain usable form. It also provides the preamp with a feedback gain control voltage. Finally, it routes the read signals to the write PCBA for use in generation of
AMTIE signals. Table 5-10 lists inputs and Table 5-11 lists outputs for the read PCBA.

Table 5-10

Mnemonic

Read PCBA Inputs

Connection

From

Purpose

- NPE |

J5-10

J8-25

PE/GCR density select

NWRT
BOT

J5-47
J5-12

J8-26
J8-48

Write /read mode
Beginning of tape

POO
PO1
PO2
PO3
PO4

J4-6,22
J4-7,24
J4-9,25
J4-42,28
J4-3,19

GCR/PE
Preamp 1

Analog read data

PO5S

J4-31,32

PO6

J4-4,21

PO7

PCBA, J902

J4-13,30

POP

J4-10,27

+15

J5-5,41

J11-21,61

Regulated precision voltage

-15

J5-6,42

J11-14,54

Regulated precision voltage

The read PCBA plugs into J5 on the interconnect D1 PCBA. Read PCBA circuits are shown in Schematic Number 107855, which is referenced in the following paragraphs. Also,
a simplified functional

block diagram of the read PCBA is shown in Figure 5-35.

Sheet 1 of the schematic provides general hardware and commonality information. Sheet 2 covers mode
control and power circuits. Sheets 3, 4, 5, and 6 show automatic gain control and AGC timing circuits

for each of the nine channels. Sheets 7, 8, and 9 show the main decoding, amplifying, and processing
circuits for each of the nine data channels.
The following text gives further details on the circuit theory for each of these circuit groups.
5.11.5.1

Read PCBA Control and Power Circuits — The following discussions of various read PCBA

control and power circuits refer to zones of Schematic Number 107855.

Phase Encoded (PE) and Group Coded Recording (GCR) Mode Control
PE and GCR modes are applied to the read PCBA circuits as shown on Sheet 2 of Schematic
Number 107855. The input command is NPE (zone 2-8G) from the control M2 PCBA. NPE
is basically the PE mode command. When low = true, PE mode is selected. When high =
false, GCR mode is selected.
In PE mode, the inverted output at U15 2 (zone 2-7G)is high. Thisis applied to the base of
Q5 (zone 2- 2D) This turns off Q5 and produces the low
= true NPE1. NPE]1 is distributed
to various parts of the read PCBA, listedin zone 2-1C, to set up the circuitry for PE mode.

5-70

Table 5-11

Read PCBA Outputs

Mnemonic

Connection

Purpose

+15

J4-16,33

GCR/PE preamp 1

-15

J4-15

PCBA, J902

Regulated voltage

(IARA ERR)
Late AGC
AGCO
AGCl1

J5-17
J5-37
J4-5
J4-23

J1-11
—
GCR/PE preamp 1
PCBA, J902

ARA burst error
not used
Automatic gain voltage
-

AGC2
AGC3
AGC4
AGCS
AGC6
AGC7
AGCP

J4-8
J4-11
J4-2
J4-14
J4-20
J4-29
J4-26

POO

J3-50

J7-65

Read data for AMTIES

PO1
PO2
PO3
PO4
PO5
PO6
PO7

J5-51
J5-52
J5-53
J5-54
J5-55
J5-56
J5-57

POP
- IRDO

J5-49
J5-70

J7-66
J7-67
J7-68
J7-69
J7-70
J7-71
J7-72
J7-64

IRD1
IRD2
IRD3
IRD4
IRD5
IRD6
IRD7
IRDP

J5-69
J5-68
J5-67
J5-62
J5-61
J5-59
J5-58
J5-72

Y
Read data output

J3-32

J3-31
J3-27
J3-26
J3-21
J3-20
J3-18
J3-1
J3-34

\\\

NARA

When NPE (zone 2-8G) is high = false, GCR mode is effective. The output of U15-12 1s the
high = true GCR4. This is applied to the base of Q6 (zone 2-2B), which closes to produce
low = true NGCR, and also to the AGC timing circuits (zone 3-8D).
Read PCBA Power Circuits

Read PCBA power circuits are shown in the lower left corner of Sheet 2. The =15 V 1nputs
are reduced by diodes CR4 through CR13, and regulated by diodes VR1 through VRS to

produce voltages needed by the read analog circuitry. VR1 and VR3 (zone 2-7C) provide
+ 5.6 Vdc (£6 V) for the read differential amplifiers. VR2 provides +5.1 Vdc (4 VR) for
the AGC gain detect counter stages. VR4 provides -5.1 Vdc (-5 V) for the read zero crossing
networks. VRS provides +10 Vdc (+ VGR) for the AGC digital to analog (D/A) converters.

5.11.5.2 Read Amplifier Circuits — The read track output amplifier ciréuits for the nine channels are

shown on Sheets 7-9 of Schematic Number 107855. The following discussion of theory refers to the
parity channel network, which is typical of the nine channels.

5-71

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5-72

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Connector pins J4-10 and J4-27 (zone 7-8G) are connected to the GCR/PE preamp 1 PCBA, which
preamplifies the current flowingin the read head winding. The inputs at J4-10 and J4-27 are apphed
through C130 and C131 to differential amplifier 1nputs Ul101- 14 and U101-1, respectlvely

GCR or PE differentiation characterrsucs are. determined by the circuits between preamplifier pins

U101-4 and U101-11. These pins are connected through either Q131 (zone 7-5F) or Q130 (zone 7-6F),

depending upon mode selection signals NGCR or NPE1 (zone 7-5F). If NGCR is low = true, Q131 is

turned off and PE resistor R136 and capacitor C139 are effectively removed from the circuit between
U101-4 and U101-11. If NPE is low = true, Q130 is turned off and GCR resistor R137 and capacitor
C138 are ineffective.

‘The two amplifier outputs U101-8 and U101-7 (zone 7-6G), which are associated respectively with inputs U101-14 and U101-1, are input to U102 pins 1 and 2, the zero-crossing network comparator. The
output of the comparator is current amplified and presented to read PCBA connector P5-72 as IRDP.

ic Number 107855.

The same theory apphes to the 01rcu1ts for other data channels, shown on Sheets 7, 8, and 9 of Schemat-

The resulting low
= true IRD 7: 0 P bits are sent to the MIA PCBA via the 1nterconneet D1 PCBA. A
Jow
= true bit indicates a flux change away from the direction of the interrecord gap (IRG) magnetization. Similarly, a high
= false bit indicates a flux change toward the direction of the interrecord gap
magnetization. Whether a low
= true or high
= false bit should be interpreted as a 1 or a 0, 1s determined by the TM78 formatter.

5.11.5.3 Automatic Gain Control (AGC) Clrcults _ The read PCBA AGC function is initiated and
controlled by circuits shown on Sheets 3 through 6 of Schematic Number 107855. Refer to Figure 5-35
for a simplified functional block diagram of the AGC circuitry. Figure 5-36 shows the timing sequence
for AGC setup relative to information recorded at or near the BOT marker on a GCR tape. If unfamil-

iar with GCR recording formats, refer to Paragraph 4.1.2 of the TM78 Magnetic Tape Formatter
Technlcal Manual (EK OTM78-TM)

AGC, as an automatic gain setting function, is performed only in GCR mode. When in PE mode, the

AGC voltages sent to the preamp PCBA are fixed by a pre-set potentiometer, one for each track.

Initiation of the sequencing logic is accomplished by gates at zone 3-7D. Beginning of tape status
(NBOTis low
= true) generates the preset (PRST) signal which holds all track D/A counters reset.
Using the parity track as an example, PRSTis applied to U106-2, 12 (zone 4-G, H 4) which outputs all
low signals to the D/A converter. As the magnetic tape ramps up to speed, NBOT eventually goes high
— false and the preset is removed. Gate U27-13 (zone 3-6D) also removes the reset from the sequencing oscillator, allowing it to produce clocks with an 800 us period. These sequencing clocks are input to
the sequencing counter U30 (zone 3-5D, E).

The sequencmg counter and its associated decoding logic (zones 3-3C through 3-5D) express the number of counts in decimal terms. Three principal counts are produced by this network which represent
discrete amounts of tape travel. These counts are as follows.

Count
64

92
96

Gate
U309
U32-8
U32-3

Zone
3-5D

3-3D
35C

Amount of Tape Travel
16.3 cm (6.4 in)

23.4 cm (9.2 in)
244cm(96in)

5-73

BOT
HEAD

SENSOR

ARAID

U
D BURST

ARA BURST

'7G FIRST RECORD

TAPE

i
I

CAPSTAN

VELOCITY

N BOT

51ms

(= 16.3cm)

TP21

TP22 (ST1CLOCKS)

””””
FINAL LEVEL OF THIS TRACK

(N)
(N

LEVEL SET BY PE

GAIN ADJUSTMENT

’/’m\

AGC

TRACK 6

ANALOG DATA

ALLSET
A-7076

Figure 5-36

AGC Timing

The 64th count (TP21) enables NAND gate U29-2 (zone 3-5F) which outputs ST1 CLOCKSs to the
track D/A counters. The 64th count also allows the CLEAR signal at U31-2 (zone 3-4D) to go low =
false. With CLEAR false, the gain detect counters, U105 (zone 4-6G, H) are allowed to count up. Read

data (POP) enters the counter’s threshold detector at U33-5 (zone 4-7G). If the amplitude of the read
data ARA burst for this track is equal to, or greater than, 800 millivolts, the threshold detector outputs
a pulse for each bit transition. The gain detect counter is configured to count 128 ARA transitions, then
output a low logic signal from NAND gate U104-3 (zone 4-5F). If 128 transitions are not detected
immediately following the first ST1 CLOCK pulse, the second pulse arrives 800 us later and counts up
the D/A counter stage U106-1 (zone 4-4H). This counter incrementally adjusts the AGC P output voltage via the
D/A converter U107 and R107 through R111 (zone 4-3G, H) until the gain detect counter
is able to count 128 transitions. The AGC P signal is driven toward ground in a maximum of 32 steps by
the D/A converter, allowing the preamplifier stage (on the PE/GCR preamp 1 PCBA) to increase its
- gain.

When the gain detect counter reaches a count of 128, open collector gate U107-12 (zone 4- 3F) turns

off, releasing the low
= false ALLSET signal. Also, NAND gate U104-3 (zone 4-5F) inhibits NAND
gate U104-12 (zone 4-5H) and freezes the D/A counter.

When the gain detect counters for all nine tracks reach the 128 count, ALLSET is pulled up to high =
true by R42 (zone 3-4B). This causes the sequencing oscillator to reset and stop the AGC sequencing
cycle. Now the AGC voltages for each of the nine tracks are set and do not change for the tape duration.

If the sequencing counter reaches a count of 92 (D/A count of 28) before ALLSET is raised, the
LATE AGC status signal goes high = true at U31-8 (zone 3-4C). Signal LATE AGC is sent out of

5-74

connector P5-37, but is not used. If the transport was writing, LATE AGC enables NAND gate U26-3,
5 (zone 3-4C) and through U28-6 (zone 3-3C) and U23-3 (zone 3-26C) generates the status signal
NARA at connector P5-17. Signal NARA is sent to the MIA PCBA via the write PCBA and interconnect D1 PCBA, where it becomes IARA ERR. In write mode, it signifies that the ARA burst failed
to record properly within the allotted time. The formatter initiates a retry sequence and rewrites the
burst.

If the sequence counter reaches a count of 96 (D/A count of 32) before ALLSET is raised, while the
transport is reading, the other input of NOR gate U28-6 (zone 3-2C) is enabled and NARA is generated. This indicates to the formatter that at least one track counter has achieved maximum gain without recognizing 128 ARA burst transitions. Presumably the track(s) generates AMTIE pointers which
aid in error correction when reading the upcoming data records on tape.

5.11.6

GCR/PE Preamp 1 PCBA

The GCR/PE preamp 1 PCBA, located at the rear of the transport base assembly, provides first stage
amplification for read data, and acts as interconnection between the write and read PCBA and the
heads. The GCR/PE preamp 1 PCBA circuits are shown on Schematic Number 107850.
The GCR/PE preamp 1 PCBA regulates the =15 Vdc inputs from the capstan/regulator PCBA to
obtain +5 and -6 Vdc for its differential amplifiers. The £ 15 voltages are sent, via the interconnect D1
PCBA and the read PCBA, along the read cable, and enter the preamp PCBA at J902-16, 33 (+15)
and J902-15 (-15) zone 2-7B, C.

Write data enters the preamp PCBA through header J903 (zone 2-7D through H) and is sent directly to
the write head connector J23. Read data enters the preamp PCBA through read head connector J22
(zone 2-6A through H). The analog data signals are differentially amplified through two AGC controlled stages and output through connector J902 (zone 2-2A through H), where they are sent via cable
to the read PCBA.

5-75

CHAPTER 6

MAINTENANCE AND TROUBLESHOOTING

6.1

SCOPE

This chapter provides procedures necessary to perform functional alignments, parts replacement adJustments and troubleshooting for the TU78 Magnetic Tape Transport assembly. Although TM 78 testing is includedin some diagnostics, actual maintenance pertaining specifically to the TM78is contained in the TM78 Magnetic Tape Formatter Technical Manual (EK-OTM78-TM). The maJor TU78
assemblies referencedin this chapter are shownin Figures 1-3 and 1-4. Methods for gaining access to
these assemblies are outlined in Chapter 3.
|
6.2

TU78 MAINTENANCE PHILOSOPHY

The TU78 Magnetic Tape Transport is a reliable, high-performance unit which will provide years of
trouble-free operation when properly maintained. A program of routine inspection and maintenance 1s
required for optimum performance and relrablllty

A preventive maintenance (PM) Program for the TU78 transport is outlinedin Paragraph 6.4. A pro- |

gram of daily customer care should include head and tape path cleanings. Adjustments should only be
made when problems are encounteredin transport operation or during a regular PM cycle.

Correetlve maintenance involves troubleshooting at the system level using system dragnostrcs, and at
the subsystem level using TM78 microprogrammed maintenance routines and visual methods to localize the failure. System level diagnostics direct service personnel to the faulty functional area, not necessarily to the faulty module. Custom tailored read/write sequences may be created through the TM78
maintenance panel to further isolate the failure, or when the system is not available for maintenance.
Unit level troubleshootmg can be performed utilizing functional block diagrams, flow diagrams, timing
diagrams, and engmeermg logic drawings, together with troubleshooting aids given in Paragraph 6.6.
(Refer to the diagramsin Volume 1 of the Technical Manual and Chapter 5 of tl’llS volume)

6.3

TEST EQUIPMENT

All tools and test equrpment needed to facilitate transport operation and maintenance, aceordmg to
procedures describedin this manual, are listedin Tables 6- 1 and 6-2.
6.4

PREVENTIVE MAINTENANCE

6.4.1

Daily Preventive Maintenance

The recommended frequency for performing the PM tasks in this procedure are based on moderate
equipment use. If use exceeds 2500 vacuum-on hours in six months, the PM frequency should beincreased proportionally. Refer to Table 6-3 for preventive maintenance schedule.
|
Preventive Maintenance for the TU78 transport includes a dally cleaning of all tape path surfaces This
cleaningis required to prevent possible data errors that can be caused by contamination within the tape
path. For cleaning procedures refer to Paragraph 4.3, 4
6.4.2

Semiannual Preventive Maintenance

The semiannual PM tasks should only be performed by trained, qualified service personnel. Table 6-3
outlines individual tasks and references the appropriate paragraph for individual procedures. Perform

Table 6-1 Standard Tools and Test Equipment Required
Equipment

DIGITAL Part

Manufacturer’s

Number

29-23269
29-23271

=
=

Field service
tool kit

Domestic
European/GIA
Oscilloscope

—

equivalent

Digital multimeter

—

Fluke 8020A or

Table 6-2

equivalent

Special Tools and Test Equipment Required

Manufacturer’s

Equipment

DEC P/N

Number

Reel motor centering tool

29-23206

—

Reel flange locating bar
PCBA extender

29-23207
29-23218

—
—

Lower restraint tube fitting

29-23228

Differential pressure gauge

29-11650

Dwyer #2040

(0—40 inch H»,0)
Differential pressure gauge

:
29-11636

(0-5 PSI)
.
Portable accessory package for
gauges (two required)
Tachometer (decimal readout)
Tape crimper
|
Xcelite handle
7 inch extension
5/32 X 4 inch ballpoint
hex driver ,
#1 Phillips screwdriver shaft
Master skew tape (1200 ft)
Magna-see tape developer
50X microscope with graticule

29-11647
|
29-11635
47-00038

29-10562
29-11625
29-11630
29-11001
29-19224
29-16871 .
29-20273

Dwyer #2205
|
Dwyer #A-432
—
Xcelite #99-1
Xcelite #99-X10
Xcelite #99-25BP

Xcelite #99-821
—

=
—

Heat sink compound

90-08268

Inspection mirror (dental type)

29-19663

—

Cleaning kit

TUCO1

Standard output tape

29-11691

—

6-2

Tektronix 465 or

100 MHz/dual trace

Table 6-3

Preventive Maintenance Schedule

Frequency

Daily

Procedure

Clean read /write head, erase head,

Paragraph

Number

4.3.4

tape cleaner blades, ceramic guides,
air guide, air bearings, guide block,
buffer box (floor and sides), buffer
box glass, loop pocket, pocket glass,
and capstan.

CAUTION

Observe warnings and notes in Paragraph 4.3.

Semiannually

or 2500
vacuum on
hours

Remove and clean foam cabinet

filters; one on inside front dress
panel and four on inside rear door.
Perform general cleaning of cabinet

—_—

area.

Remove and clean air bearings, air
guide, and circular ceramic guide.

6.7.3,
6.7.4

Remove tape cleaner an_d clean blades.

6.7.2

Clean reel sense lenses and EOT/BOT
:
cavities.

—

Clean cartridge restraints.

—

Clean and check supply reel locking
hub friction ring. Check that reel
does not slip on hub.

Check for head wear and if necessary,

6.7.1

replace head.

Check all hoses and tubing for cracks
and tighten all connection clamps if

—

necessary.

Remove pneumatic belt guard and check

Fig. 6-51

Clean compressor intake muffler/

—

belts for wear and proper tracking.

filter element.

Replace compressor in-line filter.

—

Preventive Maintenance Schedule (Cont)
3

Frequency

Paragraph

Procedure

Number

"NOTE

Semiannually

If any of the following checks are out of tolerance,

or 2500
vacuum on

Table 6-3

perform the associated adjustment
|

hours

Check vacuums and pressures.

6.5.4

Check supply reel load speed.

6.5.6.2

Check take-up reel load speed.

6.5.6.3

Check loop positions.

6.5.6.4

Check cartridge limit switches.
|

6.7.8

(Steps

8,9, 10)

Check PE amplitudes.

Check read skew (azimuth).

6.5.73

6.5.7.1

the tasks in the order listed in the table. It is not necessary to alter any adjustment on the TU78 if it is
performing in a satisfactory manner, and the check being performed is within the allowable tolerance.
- While conducting the semiannual PM, perform a visual inspection of the equipment for loose electrical
connections, dirt, cracks, binding, excessive wear, and loose hardware.
6.5

ADJUSTMENT PROCEDURES

This section provides adjustments and alignments relatlve to the TU78 transport. The adjustments and
alignments are functionally grouped. Supportlng 111ustrat10ns are referenced where relative.

Some adjustments may require prerequ151te (performed before) and/or corequisite (performed with)
adjustments of other parameters (Table 6-4). Make sure the adjustments are made as specified in the
individual procedures.

Acceptable limits are defined in each adjustment procedure, assuming the specified test equipment is
accurate. When the measured value is within designated parameters, do not make an adjustment.

Should the value fall outside specified limits, make adjustments according to the relevant procedure.
Make the adJustment as close to the de51gnated value as p0531ble

Some adjustments require using the TM78 maintenance panel Procedures for operating the maintenance panel are provided in each alignment step that requires its use. For more information on the

TM78 maintenance panel and its functions, refer to Paragraph 5.5 in the TM78 Magnetic Tape For-

matter Technical Manual (EK-0TM7 8-TM). A complete listing of interrupt /failure codes which may

be shown in the maintenance panel’s display, are includedin Table 2-8 in the TM7S8 Magnetzc Tape
Formatter User Guide (EK-0TM78-UG) or the technical manual.

6-4

Table 6-4

Required Prerequisite/Corequisite Adjustments

Paragraph

Adjustment

6.5.1
6.5.2
6.5.3
6.5.4
|
6.5.4.1

Power distribution
|
EOT/BOT adjustment
Pack sense adjustment
Vacuum and air
pressure adjustments
System vacuum
-

Prerequisites

Corequisites

Paragraph
Number

6.5.1
6.5.1
—
|
—

—

6.5.4.2

adjustment

Takeup reel vacuum

6.5.4.3

adjustment
Air bearing pressure
adjustment

r'/

6.5.4.2

6.5.4.4

6.5.4.1
|

Thread block and

—

cartridge pressure
adjustment

Capstan servo
adjustments
|
Reel servo adjustments
Reel servo offset
=
Supply reel load speed
- adjustment
Takeup reel load speed

6.5.6.4

- adjustment
Tape loop position
adjustment

6.5.7

6.5.5
.
6.5.6
6.5.6.1
6.5.6.2
D
6.5.6.3
|

—

3
|

6.5.1

6.5.7

|
3

6.5.1
—
—

|
e

o
—

—
e
-

6.5.4.1

Read/write adjustments

434,651
-6_.5.-5?

Some adjustments also require that the front door be open and the 1nterlock switch be defeated. In

order to defeat the interlock switch, first open the front door. Then with a spring hook, or othér suitable
hooked tool, push down on the switch actuator arm while pulling out. This allows the reel servos to
operate normally. When the front door closes, the switch arm returns to its normal position.

If difficulties arise during any alignment procedure, refer to Paragraph 6.6 (Troubleshooting) for fault
isolation procedures.
6.5.1

Power Distribution

-The +5 V logic supply voltageis adjustable. All other power supplies and regulators are not adjustable.
The following procedureis given to direct service personnel to check, and adjust if necessary, the +5V
logic supply voltage, and
to verify that all operating dc Voltages are present.
| WARNING
|
Dangerous voltages are present in the power supply

Make sure the transport is plugged into the proper ac power source and that the transformer
primary taps are configured for the proper voltage range (jumpers on terminal block
A1-TB1). (Refer to Table 3-1 for proper jumper configuration.)

6-5

Fé

fe]

Jol

[o]

No N s N o N O B o

POWER SUPPLY PANEL

MA-3675

Figure 6-1

Power Supply Fuse Panel

Remove the lower front dress panel from the cabinet. Open the rear door. Pull the two front
stabilizer arms out of the cabinet. Release the service lock and swing the transport base assembly out to gain access to the card cage assembly.
»

Remove the four retaining screws from the left side of the TM78 logic gate and swing the
gate out on its hinge (master TU78 only.)
Make sure the 874 power control circuit breaker (front) is on as well as the power supply
circuit breaker (rear).
|
With a digital voltmeter (DVM) check all the unregulated dc voltages at fuses F1 through F7
with respect to chassis ground. The fuses are located on the power supply fuse panel. Refer to
Figure 6-1 for fuse locations and Table 6-5 for proper voltage readings. If the readings are
incorrect go to Section 6.6 for troubleshooting information.

Table 6-5

Power Supply Voltage Readings

Measured

Fuse

Circuit
Function

Type

Minimum

Nominal

Maximum

+12V

7AFB

+09.5V

- +105V

+11.5V

F2
F3

+24V
—24V

5AFB
5 AFB

+22.0V
—22.0V

+24.0V
—240V

+260V
—260V

F4
F5
F6
E7

+36 V(C)
—36 V (C)
+36 V(1)
+36 V (S)

20AFB
20 AFB
20
AFB
20 A FB

+35.0V
—350V
+38.0V
+38.0V

+37.5V
—375V
+40.0V
+40.0 V

+400V
—40.0V
+42.0V
+42.0V

6-6

e TN

Voltage (dc)

With a DVM, check all the regulated voltages by monitoring TP11, TP15, and TP18 with
respect to TP1 on the capstan/ regulator PCBA. Figure 6-2 shows the locatlons of test points
and adjustments.
a.

TP11

e
e

+5.15 Vdc nominal

+5.30 Vdc maximum

TP15
e
+14.0 Vdc minimum
e
415.0 Vdc nominal
e
+16.0 Vdc maximum

TPI18

e
e
e

,//_\\\.

+5.00 Vdc minimum

—14.0 Vdc minimum
—15.0 Vdc nominal
—16.0 Vdc maximum

If the voltage measured at TP11 is found to be outside specified limits, adjust potentiometer
R179 on the capstan/regulator PCBA (Figure 6-2).
6.5.2 EOT/BOT Adjustment
|
The following procedure describes sensitivity adjustment of the EOT/BOT amplifier on the base assembly interconnect F1 PCBA.
1.

Verify power supply voltages according to Paragraph 6.5.1.

On the interconnect F1 PCBA, connect a DVM with its positive lead to TP6 and its negatlve
lead to TP5 (Figure 6-3).

Open the transport front door and the buffer box door.

—-

On a work tape, attach an EOT reflective tab about one inch in front of the BOT tab.
Install the work tape reel on the supply hub. Thread the tape so the EOT and BOT reflective
tabs are not under the sensors (Figure 6-4). Maintain tension with one end of the tape by
holding the tape on the capstan. The tape must contact the head surface.

Monitor the DVM. The voltage displayed should be between +0.1 Vdc (maximum) —0.1
Vdc (minimum).
If the voltagein step 6 is out of tolerance, adjust potentlometer R22 on the interconnect F1
PCBA for 0 Vdc (Figure 6-3).

Pull the work tape to move the BOT tab under the sensor and monitor the DVM. The voltage
~display should be equal to or more negative than —2.0 Vdc.
Pull the work tape to move the EOT tab under the sensor and monitor the DVM. The voltage
display should be equal to or more positive than 4 2.0 Vdc.
10.

Remove the work tape and disconnect the DVM.

6-7

6-8

6L9€-VIN

\ LidOl1DINODYINI1dva2d

SUPPLY POSITION ADJUST

TAKE-UP POSITION ADJUST

R17

PACK SENSE (LOW TAPE) ADJUST

/—Rzz EOQT/BOT ADJUST
®

TP4 TP5|

TP2

TP3

4/-

®©
TP1

|TP6 Lo’

R31

SUPPLY GAIN

121

R30

TAKE UP GAIN

(Early Style)

~
<

REMOVE PIN 1

SUPPLY POSITION ADJUST

R30

SUPPLY GAIN

TAKE-UP POSTION ADJUST
TAKE-UP GAIN

R17

PACK SENSE (LOW TAPE) ADJUST

R22

EOT/BOT ADJUST

NELX L L
TP6

|
|

R31

TP4FTPS

‘TP1 TP2 TP3

BEFORE

INSTALLATION

.
o

TP7 o—o
W1

D
1©
J21
REMOVE PIN 1.BEFORE
INSTALLATION

(Current Style)
Figure 6-3

Interconnect

MA-3681A

F1 PCBA Adjustments and Test Points

6-9

MA-3681

SUPPLY REEL
|

AIR BEARING NO. 1

/THREAD BLOCK NO. 1

INDICATOR\

%4 , AIR BEARING NO.2

FILE PROTECT

/AIR BEARING NO.4

INDICATOR \
ON LINE

INDICATOR

BOT

AIR BEARING NO. 3

|/ CARTRIDGE MOTOR

LOAD FAULT

SUPPLY

)

/" BUFFER BOX

INDICATOR
\

PUCKER

INDICATOR

—~" POCKET

AIR GUIDE

PORT SELECT/

EOT/BOT SENSOR

LOAD/REW .

————TAPE IN PATH

ON LINE/]

SENSOR

___TAKE UP

UNLOAD/
y

BUFFER BOX

RESET

6250 INDICATOR?

VACUUM

1600 INDICATOR/

CAPSTAN

- ACCESS LATCH

LOW-TAPE SENSOR

(BEHIND REEL)

Figure 6-4

7 ',/M‘\\

PACK SENSSEéNOR
TABS (IN REEL%\KE ué REEL
TAPE CLEANER

Base Assembly, Front Components

|
NOTE
|
If either voltage is out of tolerance, the EOT/BOT
assembly may have to be cleaned or replaced.
6.5.3 Low-Tape Sensor Adjustment (Pack Sense Assembly)
The following procedure describes sensitivity adjustment of the low tape sensing circuit. The low tape
sensor detects the amount of tape remaining on the take-up reel. If the remainder is 1.27 cm (1/2 in) or
~less (measured radially), the sensor produces an output. The output is used to slow the tape speed down
during a rewind before sensing the BOT marker, and to develop sequencing counts during a tape loading operation.
|

Verify power supply voltages according to Paragraph 6.5.1.

On the interconnect F1 PCBA, connect a DVM with its positive lead to TP4 and its negative
lead to TP7 (Figure 6-3).

Open the transport front door.

Rotate the take-up reel until the sensor tab (located on the inside of the outer flange of the

reel) is in line with the low tape sensor behind the reel (Figure 6-4).

6-10

Monitor the DVM. The voltage displayed should be +0.50 Vdc maximum.

If the voltage -'is out of tolerance, adjust potentiometer R17 on the interconnect F1 PCBA

(Figure 6-3).

Rotate the take-up reel until the tab is off the sensor.
%

The voltage displayed should be equal to or more positive than +4.0 vdc.
NOTE
If either voltage is out of tolerance, the pack sense
assembly may have to be cleaned or replaced.

6.5.4

Vacuum and Air Pressure Adjustments

6.5.4.1
/

System Vacuum Adjustment — Refer to Figure 6-5 and Table 6-6 while performing this adjust-

ment.

Turn transport power on.

Mount and load a 267 mm (10-1/2 in) reel of tape.

Open the base assembly to gain access to the rear.

4.
[
L

Remove the red cap from the cripple reel measurement port and connect a differential air
gauge with a range of 0 to 1016 mm (0 to 40 in) of water. Use the low pressure input of the
air gauge to measure vacuum.

Place maintenance switch S1 on the control M2 PCBA (Figure 6-6) toward the front of the

transport to drive tape forward.
6.

Observe the air gauge while tape is running forward. Check for a system vacuum reading of
838 to 889 mm (33 to 35 in) of water.

If the reading is out of tolerance, loosen the butterfly valve lock nut (I) and turn the adjust-

ment screw (C) for a reading of 864 mm (34 in) of water. While holding the screw, tighten
|

]

the locknut and observe the air gauge to make sure the adjustment has not changed.

Stop the tape and unload it. Remove the air gauge and replace the red cap.

Check the take-up reel vacuum as describedin Paragraph 6.5.4.2,

6.5.4.2

Takeup Reel Vacuum Adjustment — Refer to Figure 6-5 and Table 6-6 while performmg this

adjustment
1.

Before attemptmg this adjustment, make sure system vacuum is within the spemfled limits

outlinedin Paragraph 6.5.4.1.
2.

Turn transport power off and remove tape from the supply reel.

Place disable servo switch S1 on the reel servo PCBA (Figure 6-7) toward the rear of the
transport.

6-11

N
/“\\\

PRESS.
VALVE

CARTRIDGE PRESSURE

— ADJUSTMENT SCREW

CRIPPLE
REEL
MEASUREMENT—_
S
PORT
O

/TAKEo

{

uP REEL

MOTOR

CAPSTAN
MOTOR

(A) VALVE ORIENTATION ON BASE ASSEMBLY

’

,,rw*q_‘

TM,

—

°'u?:1r 0

#E \I_
|

:fif:

(REAR VIEW)

(B) VACUUM
VALVE DETAIL

Figure 6-5

Vacuum Valve and Pressure Valve

Remove red cap from take-up reel vacuum port (F).

Connect a differential air gauge with a range of 0 to 1016 mm (0 to 40 in) of water to the
take-up reel vacuum port. Use the low pressure input to the air gauge to measure vacuum.
Turn transport power back on.

Press and release the LOAD/REW switch.

Immediately rotate the take-up reel three full turns to deactivate the load fault zero function.
Observe air gauge and check for a reading between 508 mm (20 in) of water (maximum) and
457 mm (18 in) of water, (minimum).

6-12

Vacuum and Pressure Valve Components

Table 6-6
Reference

Description

ZZOR==IQTWEDOUO & >

Figure 6-10

System vacuum test point
Reel motor connections
Butterfly valve adjustment screw
Take-up reel vacuum adjustment screw
Vacuum present switch
Takeup reel vacuum port

Tape on reel switch

Vacuum input (to pneumatic assembly)

Butterfly valve lock nut
Air bearing pressure adjustment screw

Pressure input (to pneumatic assembly)
Thread block pressure adjustment screw

Thread block pressure port
Air bearing pressure port

CAUTION

The specified duty cycle for vacuum and air pressure
solenoids is intermittent — three minutes on and nine
minutes off. Therefore, the unit should not be held in
this mode for over three minutes after which the coil
should be allowed to cool for nine minutes.
10.

of tolerance, loosen the take-up reel vacuum adjustment screw (D) and
If the reading is out
slide the friction plate forward or backward to obtain a reading of 483 mm (19 in) of water.

11.

Tighten screw while observing air gauge to make sure adjustment is not disturbed.

12.

PreSs and release RESET button.

13.

Remove air gaugé-and replace red cap. Place reel servo disable switch S1 forward (servo

enable position).

NOTE

The two vacuum adjustments (Paragraphs 6.5.4.1
and 6.5.4.2) are interactive, and after performing
one, the other should be rechecked.

6.5.4.3 Air Bearing Pressuré'Adjustment — Refer to Figure 6-5 and Table 6-6 while performing this

adjustment.

Turn transport power on.

Mount and load a 267 mm (10-1/2 in) reel of tape.

Open base assembly to gain access to the rear.

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6-14

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6-15

Remove red cap from air bearing pressure port (N) and connect a differential air gauge with
a range of 0-34 krlopascals (0-5 psi). Use the high pressure input of the air gauge to measure
pressure.

Place maintenance switch S1 on control M2 PCBA (Figure 6-6) toward the front of the transport to drive tape forward.

Observe the air gauge while tape is running foward and check for an air bearing pressure
reading between 27.6 krlopascals (4.0 psi) maximum and 24 kilopascals (3.5 psi) minimum.

If the readrngis out of tolerance, loosen the locknut and adjust the air bearing pressure adjustment screw (J) for a 25.8 krlopascals (3.75 psi) reading.

Tighten the locknut while observing the air gauge to make sure adjustment is not disturbed.

CAUTION

Excessive torque on the lock nut damages
threads. Exercise extreme care.

Stop the tape, remove the air gauge, and replace red cap.

10.

Unload the tape.

port

6.5.4.4
Thread Block and Cartridge Pressure Adjustment — Refer to Figure 6-5 and Table 6-6 while
performing this adjustment.

NOTE
Both the thread block pressure and cartrldge pressure must be adjusted at the same time since one adjustment directly affects the other.

Turn transport power off.

Place servo disable switch S1 on the reel servo
transport (servo disable position).

Remove the red cap from the thread block pressure port (M) and connect a differential air
gauge with a range of 0-1016 mm (0—40 in) of water. Use the high input to the air gauge to

PCBA (Figure 6-7) toward the rear of the

measure pressure.

Turn transpOrt power back on.

Press and release LOAD/REW on the control panel Immedrately rotate the take-up reel six
full turns by hand. This deactivates load fault zero and causes the pressure solenoid to energize.

CAUTION

The specified duty cycle for vacuum and air pressure
solenoids is intermittent — three minutes on and nine
minutes off. Therefore, the unit should not be heldin

this mode for over three minutes, after which the coil
should be allowed to cool for nine minutes.

6-16

'/CARTR!DGE PRESSURE PORT

LOWER CARTRIDGE RESTRAINT

____\.\-

MA-3484

* Figure 6-8

Cartridge Pressure Check Point

Observe air gauge and check for a reading between 660 mm (26 in) of water, maximum, and
-

559 mm (22 in) of water, minimum.

If the reading is out of tolerance, loosen the locknut on the thread block pressure adjustment
screw (L) and adjust the screw for 610 mm (24 in) of water. Tighten the llocknut»while' ob|

serving air gauge to make sure adjustment is not disturbed.
CAUTION

Excessive torque on the locknut damages the port
threads. Exercise extreme care.

Press and release RESET on the control panel.

10.

Disconnect air gauge and replace red cap on the thread block p'ressur'e port.
On the front panel, remove the hex soc_ket héad screw from the cartridge pressure port in the

11.

Connect the differential air gauge with a range of 0-1016 mm (0—40 in) of water, to the tube

12.

lower cartridge restraint (Figure 6-8), and install the tube fitting (DEC P/N 29-23228).
fitting using the high input to the gauge.

Press and release LOAD/REW on the control panel. Immediately rotate the take-up reel six
full turns by hand. This deactivates load fault zero and causes the pressure solenoid to energize.

'CAUTION

The specified duty cycle for vacuum and air pressure |
solenoids is intermittent — three minutes on and
nine minutes off. Therefore, the unit should not be
held in this mode for over three minutes, after which

the coil should be allowed to cool for nine minutes.

13.

Observe the air gauge and check fora reading between 76 mm (3 in) of water, maximum,
50.8 mm (2 in) of water, minimum.

6-17

14,

If the reading is out of tolerance, adjust the cartridge pressure adjustment screw (Figure 6-5)
for a reading of 63.5 mm (2.5 in)
of water.

15.

Press and release RESET on the control panel.

16.

Disconnect air gauge, remove tube fitting and replace socket-head screw.

Steps 3 through 16 may have to be repeated several times to ensure adjustment integration.
Observe all cautions.

NOTE
An alternate method to the preceeding steps would
be to acquire two differential air gauges. Connect
both gauges to the respective ports, and make adjustments while observing both gauges.

18.

6.5.5

Place the servo disable switch S1, on the reel servo PCBA, toward the front of the transport
(servo enable position).
Capstan Servo Adjustments

ramps. Capstan speed adjustment affects tape speed as it moves past the read /write heads. Start ramp
adjustment affects the amount of time it takes for the capstan servo to accelerate the tape from the rest
position to full data handling velocity (125 in/s). Stop ramp adjustments affect the amount of time it
takes for the capstan servo to decelerate the tape from full data handling velocity to rest position. You
must perform the adjustments in the sequence given.

The following are procedures for adjusting the capstan speed, start ramp, and forward and reverse stop

Verify power supply voltages according to Paragraph 6.5.1.

Load any write enabled 267 mm (10-1/2 in) tape to BOT.

Place the transport on-line and set the port switch to position 3 (maintenance).

Remove the lower front dress panel from the master TU78 to gain access to the TM78 maintenance panel. If the TU78 undergoing the adjustment procedure is not the master, remove

the TM78 logic gate retaining screws and swing the gate out on its hinge so the maintenance

display is visible to you.

Enable the TM78 maintenance panel by pres.sing ENA. The display responds with HELLO.

Enter the slave unit number in the following way.
e
e

Press 0 (parameter item zero)
Press PAR.

T_he display flashes the parameter item location (0) then shows the contents of that location.

e
e

Enter the slave TU number by pressing 0, 1, 2 or 3.
Press DEP.

The display flashes the parameter item location again, then shows the new contents.

6-18

NOTE

Steps 7 through 11 describe the procedure for adjusting tape speed.

Execute the speed test command in the following way.
e

Enter 32.

Press EXE (execute).

The formatter executes one speed test command sequence, stops the transport, and re|

sponds with a termination status code in the display.

If the code is 01-00, the capstan speed is within specification and you can proceed to step 12.
However,a code of 77-01 indicates an error and an adjustment is required.
Adjust the capstan speed as follows in the following way.
e

Press REP (repeat).

The maintenance display indicates the magnitude of the error in one of two ways. If the
display shows L EEEE, there is a gross maladjustment and the TM78 cannot determine
the direction in which to make the correction. If the display shows a number in the tens
and hundreds position, a pointer adjacent to the number shows you which way to make
the correction. The number may be any arbitrary value between 00 and 37:00 corresponding to correct speed, and 37 corresponding to maximum deviation.

Adjust potentiometer R47 on the capstan/regulator PCBA (Figure 6-2) while observing
the display, until it indicates L 00 . If the display shows L -nn (where nn = 01 through
37) the capstan speed is too high and R47 must be turned counterclockwise. If the display shows L nn- the capstan speed is too low and R47 must be turned clockwise.
NOTE

If the tape reaches end of tape while making the adjustment, the TM78 initiates a rewind, places L
EEEE in the display, and continues the test when beginning of tape is reached.
10.

Press CLR (clear)

The display should show a termination status code of 01-00 indicating done with no error.
|

NOTE

An alternate procedure for measuring capstan speed
is to measure the frequency of the tach pulses. Connect a scope to control M2 PCBA, TP40 (Figure 66). The time period from trailing edge to trailing
edge should be 80 us =0.8 us.

11.

If it was necessary to adjust capstan speed, then the PE gains must be adjusted (Paragraph
6.5.7.3).
NOTE

Steps 12 through 16 describe the procedure for ad-

justing the forward start ramp.

6-19

12.
13.

Check the forward start ramp by executing a 34-command, as in step 7.

Again, if the termination status code is 01-00 no adjustment is required and you can proceed

to step 17. Any other code indicates an error and an adjustment is necessary.

14.

‘Press REP. The display indicates the magnitude of the error similar to that shown in

15.

Adjust potentiometer R59 on the capstan/regulator PCBA (Figure 6-2) while observing
the
display, untill it indicates L 00. A pointer leading the displayed error value indicates the
capstam is ramping up too quickly and R59 must be turned counterclockwise. A trailing
pointer
indicates the capstan is ramping up too slowly and R59 must be turned clockwise.
- Press CLR.

The display should show a termination status code of 01-00 indicating done with

no error.

NOTE
The following is an alternate procedure for measur-

ing the forward start ramp.

Rewind the tape and place it on-line
Create a 3200 FCI pattern on the tape by executing a 26 command through the maintenance
keypad. (The TM78 must be off-line.) Rewind

the tape.

/,,/-*"“""‘"\\

16.

step 9.

Connect an o’scilloscope to the TU7S.

Vertical CH1 to GCR/PE preamp 1 PCBA R14
top lead (Figure 6-9).

Connect a jumper between
PCBA TP30 and TP25.

the

control

Set control M2 PCBA -ma-intenance switch S1 to

the front (toward you). The tape alternately

starts and stops.

“Refer to Figure 6-10a for a representative scope
waveform and settings.

. The forward start ramp rise time (0 to 95%)
should
be in the 1.1 to 1.3 ms range.

If it is out of a‘dj,uStment,» adjust cap-

stan/regulator PCBA R59 for 1.2 ms.

Return control M2 PCBA S1 to the center position.

Although there is no adjustment, you may want
to look at the reverse start ramp profile. The
start ramp may measure from 1.1 to 1.3 ms ex-

6-20

b5
——R13 | TRACK

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TRACK

JRQEOADTSCBA

ORIENTATION N
P6 TO

WRITE PCBA

2
R4

3
R7

R5°

R10

TM.
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WHITE ~TM© J905 @

J904

5/6

R13 R16

R19

R11 R14

(=)

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PREAMPLIFIER

R14 | OUTPUTS

e ceoccoe
R17

R22 R25

R20 R23 R26

u10

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&
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READ HEAD

WRITE HEAD

CONNECTOR

CONNECTOR
MA-68LE6A

Figure 6-9

GCR/PE Preamp 1 PCBA Test Points

cept there may be a small “forward hitch’ enve-

lope for a 1.7 ms duration preceding the ramp.
This forward hitch envelope is normal if there
has been no tape motion for approximately 10 to

20 ms or more before a reverse motion com-

mand. Refer to Figure 6-10b for a representative
scope waveform and settings.

NOTE
Steps 17 through 21 describe the procedure for adjusting the forward stop ramp.

17.

18.

Check the forward stop ramp by executing a 36 command as in step 7.
If the termination status code is 01-00, no adjustment is required and you may proceed to
step 22. Any other code indicates an error and an adjustment is necessary.

19.
20.

Press REP. The display indicates the magnitude of the error similar to that shown in step 9.
Adjust potentlometer R66 on the capstan/ regulator PCBA (Flgure 6-2) while observing the
dlsplay, until it indicates L 00. A pointer leading the displayed error value indicates the capstan is ramping down too quickly and R66 must be turned counterclockwise. A trailing pointer indicates the capstan is ramping down too slowly and R66 must be turned clockwise.

6-21

SLIGHT OVERSHOOT HERE IS DESIRABLE

95%

1.2 ms —»
PROBE:

X10

HORIZ:

0.2 MSEC/DIV

VERT:

50mV/DIV

CH1:

PREAMP R14

SYNC:

AC EXT POSITIVE

TP21 CONTROL M2 PCBA

NOTE:

FORWARD START RAMP

IS MEASURED BETWEEN

il L,

0% AND 95% OF

Uil

STEADY STATE WAVEFORM

(a) FORWARD START RAMP
0%

95%

|<—1.2ms—’: '
|

—

PROBE:

HORIZ:

VERT:
CH1

]

SYnNC:

thih
"
i

FORWARD
HITCH

:
|

!
:

NOTE:

HHEIH

10X

0.5,ec/DIV
0.1V/DIV

PREAMP R14

AC, EXT, POSITIVE

L
M2 PCBA
TP21 CONTRO

REVERSE START RAMP

IS MEASURED BETWEEN

0% AND 95% OF

STEADY STATE

WAVEFORM AFTER
FORWARD HITCH.

|‘———1.7ms——i
(b) REVERSE START RAMP

(SHOWING FORWARD HITCH)

Figure 6-10

21.

Forward Start Ramp

Press CLR.

The display should show a termination status code of 01-00 indicating done with no error.
NOTE
The following is an alternate procedure for measuring the forward stop ramp.

Rewind the tape and place it on-line
Create a 3200 FCI pattern on the tape by executing a 26 command through the maintenance

keypad. (The TM78 must be off-line.) Rewind
the tape.

6-22

-1

MA-7306

5%
1.08ms

PROBE:

X10

HORIZ:

0.2 MSEC/DIV

VERT:

50mV/DIV

CH1:

PREAMP R14

SYNC:

AC EXT NEGATIVE

TP21 CONTROL M2 PCBA

STOP

NOTES: 1.

BETWEEN 100% AND 5%
2.

ADJUST THE FALL

TIME FOR NO

a. CORRECT WAVEFORM

OVERSHOOT

OVE R/SHOOT

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i R

WLEICHECEER
'

b. INCORRECT WAVE FORM SHOWING OVERSHOOT
MA-7305

Figure 6-11

Stop Ramp

‘Connect an oscilloscope to the TU78. Vertical
CH1 to GCR/PE Preamp 1 PCBA R14 top lead
(Figure 6-9). External sync to control M2
PCBA TP21 (Figure 6-6).

Connect a jumper between control M2 PCBA

TP30 and TP25.

Set control M2 PCBA maintenance switch S1 to
the front (toward you). The tape alternately
|

starts and stops.

Refer to Figure 6-11 for a representative scope
waveform and settings.

The forward stop ramp fall time (100 to 5%)
should be in the 1.02 to 1.13 ms range.
If it is out of adjustment, adjust
stan/regulator PCBA R66 for 1.08 ms.

6-23

cap-

Return control M2 PCBA S1 to the center posi|

tion.

NOTE

Steps 22 through 26 describe the procedure for ad|

justing the reverse stop ramp.
22.

23.

Check the reverse stop ramp by executing a 40 command as in step 7.
If the termination status code is 01-00, no adjustment is required and you may exit the cap-

stan adjustment procedures. Any other code indicates an error and an adjustment 1S necessary.

24.

Press REP. The display indicates the magnitude of the error similar to that shown in step 9.

25.

Adjust potentiometer R78 on the capstan/regular PCBA (Figure 6-2) while observing the
display, until it indicates L 00. A pointer leading the displayed error value indicates the capstan i1s ramping down too qulckly and R78 must be turned counterclockwise. A trailing pointer indicates the capstan i1s rampmg down too slowly and R78 must be turned clockwise.

26.

Press CLR.

The display should show a termmatlon status code of 01— 00 indicating done with no error.

NOTE

The followmgis an alternate procedure for measuring the forward stop ramp.

Rewind the tape and place it on-line

Create a 3200 FCI pattern on the tape by executing a 26 command through the maintenance
keypad. (The TM78 must be off-line.) Rewind
the tape.

Connect an oscilloscope to the TU78. Vertical
~ CH1 to GCR/PE Preamp 1 PCBA R14 top lead
(Figure 6-9). External sync te control M2

PCBA TP21 (Figure 6-6).

Connect a jumper between control M2 PCBA
TP30 and TP2S.

M2 PCBA maintenance switch S1 to
Set control

the rear (away from you). The tape alternately
starts and stops.

Refer to Flgure 6-11 for a representatwe scope
waveform and settings.

e The reverse stop ramp fall time (100 to 5%)
should be in the 1.02 to 1.13 ms range.

6-24

27.

If it is out of adjustment, 'adjust cap-

Return control M2 PCBA S1 to the center posi|
tion.

stan/regulator PCBA R78 for 1.08 ms.

Unload the tape.

6.5.6

Reel Servo Adjustments
Reel servo adjustments provide for adjusting the reel servo offset, supply and take-up reel load speeds,
and tape loop position. The adjustments are interactive. Therefore they all should be performed togeth-

er (Paragraph 6.5.6 must be performedin its entirety). Refer to Flgure 6-7 for reel Servo adjustment
and test point locations.

6.5.6.1

Reel Servo Offset Adjustment
— The reel servo offset adjustment sets the dc reference level

of the triangle wave generator output. This mamtams balanced currents through the reel motors when
they are not commanded to turn.

Verify power supply voltages according to Paragraph 6.5.1.
Turn transport power off.

Disconnect the take-up reel servo motor leads at the motor.

Turn transport power back on.

Open the transport front door, disable the door interlock switch, and remove the supply reel
tape.

Press and release the LOAD/REW switch. Immediately turn the take-up reel three full turns
by hand ThlS defeats activating load fault zero.
CAUTION
The specnfled duty cycle for the vacuum and air
pressure solenoids is intermittent, three minutes on

and nine minutes off. Therefore, the unit should not
be held in this mode for over three minutes, after
which the coil should be allowed to cool for nine

minutes.

With no reel on the supply motor hub (making it as light as possible), check the supply motor

hub for motion. There should be no motion at this time because the logic sees a small reel and
does not activate the backwrap function.
If motion occurs, adJust potentiometer R76 on the reel servo PCBA for no supply reel hub
motion.

NOTE

If R76is adjusted, it should be set first at the point
where the supply reel hub just starts to turn in the
clockwise direction, then backed off untll the reel
hub stops tummg

6-25

Press and release the RESET control.

10.

Turn transport power off.

11.

Reconnect the take-up reel motor leads.

12.

Turn transport power back on.

6.5.6.2

Supply Reel Load Speed Adjustment

Using hand held tachometer

Turn transport power off.

Connect reel servo PCBA test points TP60 (NAE) and TP69 (NSRF1) to TP49 (ground).

Turn transport power on. The supply reel should be rotating in a clockwise direction.

Measure the supply reel speed directly in rpm with the hand held tachometer (DEC P/N 2911635). Make sure the tachometer is fitted with the rubber cone type adapter. To measure
the supply reel speed, place the tip of the tachometer cone into the small dimple at the rear
of the supply reel servo motor shaft and read the rpm directly from the tachometer LEDs.
The reading should be in the 50 to 60 rpm range.

If the speed is out of tolerance, adjust potentiometer R52 on the reel servo PCBA for 55 rpm.

Turn transport power off and remove the ground jumpers.

Without hand held tachometer

The following is an alternate supply reel load speed adjustment for instances when a tachometer 1s not
available.

On the supply hub, mount a 267 mm (10-1/2 in) reel of tape W1th the leader taped down to
the reel.

Place a short piece of masking tape at a convenient point on the front panel trim, adjacent to
the supply reel.

Place a short piece of masking tape on the supply reel adjacent to the masking tape affixed in
step 2.

Turn transport power off.

Connect TP60 (NAE) and TP69 (NSRF1) on the reel servo PCBA to TP49 (ground).

Turn transport power on. The supply reel should rotate in the clockwise direction.

Observe the masking tape on the supply reel. Using a stop watch, time ten rotations of the
NOTE
Be sure to start and stop the stop watch when the
two pieces of masking tape are coincident.

6-26

//ffl.»\\‘

supply reel masking tape as it passes the tape on the trim.

Observe the elapsed time indicated by the stop watch. The display time should be between
12.0 seconds maximum (50 rpm) and 10.0 seconds minimum (60 rpm).
~
If the time displayedis out of tolerance (step 8), adjust potentiometer R52 on the reel servo
PCBA for an 11 seconds (55 rpm) elapsed while performing steps 7 and 8.
10.

Turn transport power off.

11.

Remove grounds from the reel servo PCBA and remove the masking tape.

6.5.6.3

Takeup Reel Load Speed Adjustment

//"’\\ ,

Using hand held tachometer
1.

Turn transport power off.

Connect reel servo PCBA test points TP60 (NAE) and TP57 (NTRF) to TP49 (ground).
Turn transport power on. The take-up reel should be rotating in a clockwise direction.

Measure the take-up reel speed directly in rpm with the hand held tachometer (DEC P/N
29-11635). Make sure the tachometer is fitted with the rubber cone type adapter. To measure the take-up reel speed, place the tip of the tachometer cone into the small dimple at the
rear of the take-up reel servo motor shaft, and read the rpm directly from the tachometer
LEDs. The reading should be in the 162 to 198 rpm range.

If the speed is out of tolerance, adjust potentiometer R91 on the reel servo PCBA for 180
rpm.

Turn transport power off and remove the ground jumpers.

Without hand held tachometer

The followingis an alternate take-up reel load speed adjustment for instances when a tachometer1s not
available.
1.

Turn transport power off.

Connect TP60 (NAE) and TP57 (NTRF) to TP49 (ground) on the reel servo PCBA.

Turn trénsport power on. The take-up reel should rotate in the clockwise direction.
Connect an oscilloscope input lead to TP43 (low tape sensor input) of the control M2 PCBA
(Figure 6-6).

Observe the oscilloscope. The time between leading edges of two consecutive pulses should
be between 183.7 ms maximum (162 rpm) and 150.3 ms minimum (198 rpm).
If the time displayed is out of tolerance (step 5), adjust potentiometer R91 on the reel servo
PCBA for 167 ms (180 rpm).
.
Turn transport power off. Remove the grounds and scope leads.

6-27

6.5.6.4

Tape Loop Position Adjustment

~ 1.

NOTES
Check, and adjust if necessary, all vacuum and
pressure readings outlined in Paragraph 6.5.4
before attempting to adjust the loop positions.

If the loop positions are so far out of adjust-

ment that interlock (fail safe) is broken, then
proceed to step 1 and execute the entire procedure. Otherwise, proceed to step 23.

Turn transport power off.

Set control M2 PCBA maintenance switch S1 in the center position (Figure 6-6).

Set reel servo disable switch S1, located on the reel servo PCBA (Figure 6-7) toward the rear
(d1sable)

Connect control M2 PCBA test points TP62 (NINTLK) and TP71 (PNU return) to TP25
(ground)

D1sconnect one capstan motor lead

Mount a full 267 mm (10-1/2 in) reel of tape W1thout cartrrdge on the supply hub. Open the
buffer box door and hand thread the leader through the tape path. Wind approxrmately 9.1
m (30 ft) of tape on the take-up reel. Close the buffer box door.
Turn transport power back on. Vacuum and pressure comes on.

Manually rotate the supply reel clockwise to put tape into the supply buffer column. Rotate
the reel so the tape forms a loop and the end of the loopis locatedin the middle of the park
zone. The park zone is defined as the series of thirteen small holesin the center of the buffer
column, shownin Figure 6-12. Hold the reel and apply masking tape to the outer flange and
the transport to prevent the loop from being pulled down the buffer column by the vacuum.

Hold the tape»agamst air bearing Number 4 (Figure 6-4) with your finger and manually ro-

tate the take-up reel counterclockwise to form a loopin the take-up buffer column. Continue
rotatlng the take-up reel until the loopis in the middle of the park zone and then tape the reel
as in step 8. Release the tape at air bearing Number 4.

10.

Recheck that both loops are positioned in the middle of the park zone.

11.

Press RESET on the Control panel.

12.

Connect a DVM to the reel servo PCBA as follows pos1t1ve lead to test pomt TP55 (TPOS)
and negatwe lead to TP49 (ground).

13.

Observe the DVM. The voltage d1splayed should be between +0.2 Vdc maximum and —0.2

6-28

If the voltage is out of tolerance, adjust potentiometer R9 on the interconnect F1 PCBA for O
Vdc (Figure 6-3).
|

‘/,/

14,

Vdc minimum.

/—‘ LIMIT SWITCH
UPPER PORT

FORWARD

RUN ZONE

BUFFER BOX
CENTER BAR

PARK ZONE

REVERSE

RUN ZONE

TAPE

\ CRIPPLED REEL

\ SWITCH PORT

LIMIT SWITCH

LOWER PORT

CAPSTAN TO TAKE UP REEL

MA-3678

Figure 6-12

Buffer Column Park Zone (Take-up column shown)

6-29

Observe the DVM. The voltage displayed should be between +0.2 Vdc maximum and -0.2
Vdc minimum.

16.

)

Connect the DVM positive lead to reel servo PCBA TP66 (SPOS).

15.

17.

If the voltageis out of tolerance, adjust poten‘uometer R1 on the interconnect F1 PCBA for 0
Vdc.

NOTE
These voltages are produced on the base assembly by

the respective pressure transducers. Therefore, while
performing steps 12 through 17, it is imperative that
the air measurements are within specifications and

that the loops are positioned in the middle of the
park

zones

(refer

Note

under

Paragraph

18.

Turn transport power off.

19.

Remove ground wires from TP62 and TP71 on the control M2 PCBA.

20.

Enable the reel servos by placing reel servo PCBA switch S1 toward the front. Disable the
front door interlock switch.

21.

Reconnect the capStan motor lead.

22.

23.

- Remove the masking tape from both reels and rotate one of the reels to take up slack.
Turn transport power on and load a full 267 mm (10-1/2

in) reel of tape. If the tape fails to

load, refer to the reel servo troubleshooting procedures (Paragraph 6.6.6).
24.

Set gain potentiometers R30 and R31 on the interconnect F1 PCBA (Figure 6-3) fully clock-

wise. (The potentiometers have a range of approximately 28 turns.)
25.

Adjust the position potentiometers R1 and R9 on the interconnect F1 PCBA so that both
tape loops are within the park zones.

26.

Move the tape approximately 9 meters (30 ft) from BOT by placmg control M2 PCBA
sw1tch S1 toward the front of the transport for three seconds.

27.

Ground control M2 PCBA test point 31 to test point 25 to initiate a forward/ reverse shuttle.

28.

Adjust the take-up position potentiometer R9 on the interconnect F1 PCBA so the loop travel
is equal above and below the take-up column park zone.

29.

Remove the ground from control M2 PCBA TP31.

30.

Record the park position of the tape loop in the take-up column. You need this in step 32.

31.

Adjust take-up gain potentiometer R31 on the interconnect F1 PCBA approximately ten
turns counterclockwise.

6-30

, PN

6.5.6.4).

32.

Adjust the take-up position potentiometer R9 so the take-up loop park position is identical to
that recorded in step 30.

33.

Ground control M2 PCBA TP31 again to obtain a forward/reverse shuttle.

34.

Fine tune the position (R9) and gain (R31) potentiometers so the take-up loop matches the
boundaries shown in Figure 6-13. The position potentiometer moves the loop excursion up
and down in the column.

The gain potentiometer increases and decreases the length of the excursion. Rotating the
gain potentlometer counterclockwise decreases the servo loop gain and allows a longer loop
excursion. Rotating it clockwise increases the gain and allows a shorter loop excursion. Do
not allow the take-up loop excursion to extend beyond 24 cm (9-1/2 in).
NOTE
Because the gain and position potentiometers are interactive, it is necessary to alternate adjustments in
the fine tuning process.
35.

Remove the ground from TP31 on the control M2 PCBA.

36.

Place control M2 PCBA switch S1 toward the front of the transport and allow the tape to
move to the EOT point. When EOT is reached, move switch S1 to the rear for three seconds
and allow the tape to move 9 meters (30 ft) from the EOT point.
|

37.

Repeat steps 27 through 35 for the supply reel servo loop position. Use position potentiometer'

R1 and gain potentiometer R30 on the interconnect F1 PCBA. Do not allow the supply loop
excursion to extend beyond 25.4 cm (10 in) in step 34.
38.

When completed with the supply reel loop position, rewind the tape.to BOT. Move the tape
to EOT and rewind to BOT two more times. If interlock is broken, readjust the position and
gain potentiometers until an optimum point is reached.

6.5.7

Read/Write Adjustments

The read/write adjustment paragraph gives, in the proper order, adjustment procedures for the functions needed to ensure data integrity.
NOTE
Before starting the read/write adjustments make
sure the tape path is clean (Paragraph 4.3.4), the
voltages are correct (Paragraph 6.5.1), and the capstan servo adjustments are correct (Paragraph
6.5.5).

k%4

The following functions should now be checked or adjusted in the following order.
1.

Read skew adjustment (azimuth)

Write current adjustments

PE gain adjustments

6-31

o INTERLOCK

o INTER

o
o

°
°

o]
o]

(o]

]

0%8
o

°
(o]

;

MAXIMUM
TAKE-UP

o—7

o
o
o

PARK

MAXIMUM

°0— 1

SUPPLY

LOOP

ZONE

TRAVEL

o—1

PARK
ZONE

°0—1

(o]
4

o —©06

(o]

:
8

O INTERLOCK

LOOP POSITION MAY BE OFFSET UP OR
~

LOOP
TRAVEL

NOTE

LOCK

SUPPLY
TAKE-UP

0—9
o]
o

DOWN IN COLUMN BY UP TO ONE HOLE

BUT LOOP TRAVEL SHOULD BE NO MORE

THAN SPECIFIED.

0
(o]

O INTERLOCK
MA-7314

Figure 6-13

Loop Travel Limits

6.5.7.1 Read Skew Adjustment (Azimuth)
Mount and load a write protected master skew tape to BOT Place the transport on-hne Defeat the front door interlock switch.

Set MIA PCBA maintenance switches (Fig. 6-14) as follows:

///‘Cl.\“;

S2 Left Read
S3 Left 1600
S4 Right Manual

6-32

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6-33

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Gzcln

j\
W\

READ HEAD

CONNECTOR

CONNECTS TO J5 ON

INTERCONNECT

PCBA

—

Dagoooapog

Qooocgogoopoon

' U/U

[{e)

2 e 0o 000 00 o0 8
2

TRACKS 2 81 1 9] 8L
|5
|7
HHHHHHT

TP1-TP24

Ppl . PP[ '

7 6 543210P

ENA __ AGC

AGC

TEST

GAIN

S1 READ AMPLIFIER

GAIN SWITCH

(NORMAL)

PE GAIN

’

POTENTIOMETERS

FOR CHANNELS:
MA-7316

Figure 6-15

Read PCBA Test Points, Adjustments, and Connectors

Confiect an oscilloscope to read PCBA (Figure 6-15) test point 11. Set the scope to as follows.
Vertical

0.2V/div

- Horizontal

0.5 us/div

—

-+, int, dc

Sync

Set MIA PCBA switch S1 to the right (run forward).
Watch the oscilloscope. The overlapping step should not exceed 1.2 us (corresponding to 150
w inches of skew) as shown in Figure 6-16.

If the skew is out of tolerance, adjust the azimuth angle of the read/write head to obtain a
skew within the proper value. Adjust the head for minimum step width. The head can be
adjusted by inserting a 1/8-inch allen driver through the buffer box door and into the tape
cleaner cap-clip housing (Figure 6-17).
|
- Set MIA switch S1 to the left (run reverse). The step width must not exceed 1.2 us. If it does,
the capstan motor tracking may have to be fine tuned (Paragraph 6.7.5).
Allow the master skew tape to continue in reverse to BOT, then remove it.

Set MIA PCBA switch S1 to the center (stop), and S4 to the left (auto).

6-34

1. 2 u SEC MAXIMUM

(CORRESPONDING TO
1.50 u INCH OF TAPE)

Figure 6-16

MA-7317

Read Skew Adjustment Waveforms

ADJUSTMENT

_=—— ACCESS HOLE

MA-3483

Figure 6-17
6.5.7.2

Location of Read Skew Azimuth Adjustment

Write Current Adjustments

Verify power supply voltages according to Paragraph 6.5.1.

Load any write enabled 267 mm (10-1/2 in) tape to BOT. Leave the transport off-line.

Set the MIA switches as follows.
S1 = FWD (right)

S2 = WRT (right)
S3 = 1600 (left)
S4 = MAN (right)
Data pattern (U196) equals all ones (all switches forward)

6-35

CONNECTS TO J7
INTERCONNECT D1 PCBA

[eE23833228238)]

CONNECTS TO

GCR/PE PREAMP

1 CABLE

Figure 6-18

R36

R39

R22

R19.

R48

R50

- GCR

GCR

—

STEP

ADJUST

TEST POINTS

TP1-TP24

AMTIE CABLE

CONNECTS TO MIA J1

STEP TIME

PEDESTAL

ADJUST

Write PCBA Test Points, Adjustments, and Connectors

Phase Encoded Write Current Adjustments

Connect an oscilloscope to write PCBA (Figure 6-18) test point 6. Set the scope as follows.
Vertical chl

1.0 V/div, ac (X10 probe)

‘Horizontal

0.2 us/div

Sync

+,Chl1,dc

Place transport on-line. The tape starts moving forward.

Adjust write PCBA potentiometer R50 (PE step time) for a 1.25 us £.1 us positive pulse
width.

Place transport off-line. The tape stops moving.

Move the scope probe to write PCBA TP3. Change the vertical setting to 2.0 V/div, dc.

Place transport on-line.

Adjust write PCBA potentiometer R19 (PE step voltage) for a +8.75 Vdc =0 Vdc level.

6-36

Move the scope probe to write PCBA TP2.

Adjust write PCBA potentiometer R36 (PE pedestal) for a +6.2 Vdc =0 Vdc level.

10.

Place the transport off-hne and rewmd the tape to BOT

Group Coded Write Current Adjustments (Transport Off-line
Loaded, at BOT)

Coarse Adjustments

Connect an oscilloscope probe to write PCBA test point 6. Set the scope as follows.
= 1.0V/ d1V ac (X10 probe)

Vertical Ch 1
Horizontal

Sync

.05 us/div
Auto, +Ch 1, dc

Set the MIA switches as follows
S1 = FWD (right)

S2 = WRT (right)
S3 = 6250 (right)
S4 = MAN (right)

Data pattern (U196) equals all ones (all switches forward)

Place transport on-line. The tape starts movmg forward wr1t1ng all ones.

Adjust write PCBA potent1ometer R48 (GCR step tlme) for a 350 ns + 10 ns positive pulse

width.

Place the transport off-hne The tape stops moving.

the verti6. ‘Move the scope probe to write PCBA TP3 Leave the scope settmgs as is,but place graticule,
cal amplifier coupling switch to GND and position trace to the bottom of scope
‘

then place the coupling switch to dc.

Adjust write PCBA potentlometer R22 (GCR step voltage) for a 7. O Vdc, +0 Vdc level.

Move the scope probe to the write PCBA TP2.

Adjust write PCBA potentlometer R39 (GCR pedestal) for a +4.0 Vdc £0 Vdc level.

Fine AdJustment
|

Move the scope probe to GCR/PE preamp 1 PCBA R13 (upper lead) This 1s 51gnal POS3.

Set the scope to the following settings.
Vertical Ch 1
Horizontal
Sync

0.2 V/div, ac (X10 probe)
1.0 ps/div
“auto, +Ch 1, ac

6-37

Place the transport on-line. Tape moves forward and writes all ones.

Adjust R22 (GCR step voltage) on the write PCBA clockwise until the peak-to-peak ampli-

Place the transport off-line. The tape stops moving.

Check TP3 with the scope. It should be less than 70 Vdc and in the 6.7 — 6.9 Vdc range.

Mo»ve the scope probe back to R13 (step 1).

Change the scope sync coupling from AC to HF REJ.

Set the MIA data pattern switches to a 10010011 pattern. (U196 switches 1, 4, 7, and 8
forward, 2, 3, 5, and 6 rear)

10.

Place the transport on-line. The tape moves forward and the transport writes the 10010011
pattern serially on each track.

11.

Adjust write PCBA R39 (GCR pedestal) to obtain a waveform as shownin Figure 6-19A.

tude of the sine wave displayed on the scope just begins to drop.

Note the symmetrical shoulders for both sets of double zeros. Figure 6-19B and 6-19C show
examples of unsymmetrical waveforms.
|

12.

Place the transport off-line.

6.5.7.3 Phase Encoded Gain Adjustments
NOTE
The capstan servo adjustments (Paragraph 6.5.5)
affect PE gain. Make sure that these adjustments
are within tolerance before doing the PE gain ad-

justment.
1.

Mount and load a write enabled master output tape (DEC P/N 29-11691). Place the trans-

port off-line.

Connect an oscflloscope to GCR/PE preamp 1 PCBA R1 upper lead (Figure 6-9). Set the
oscilloscope as follows.
Vertical Ch 1

Horizontal

Sync
3.

.02 V/div, ac (X10 probe)

1.0 ms/div
auto, + Ch 1, ac

Set the MIA switches as follows.
i

S1 = FWD (right)
S2 = WRT (right)
S3
1600 (left)
S4 = MAN (right)
Data pattern (U196) equals all ones (all switches forward).
4.

Place the transport on-line. The tape moves forward.

6-38

SYMMETRICAL

Lil

LLL

pliblr

IRRE

SHOULDERS

.
\' FHHHH T
3

NI/

V|
T

MA-7307

Figure 6-19

Pedestal Voltage Adjustment

Adjust the track 1 read PCBA potentiometer R706 (Figure 6-15) so the read data envelope
measures 1.25 V peak-to-peak =0 V.

Refer to Table 6-7 for test points and adjustments and adjust the other eight tracks as done in

step .

NOTE

If the tape reaches EOT before you complete the adjustments, the MIA rewinds the tape automatically.
Upon reaching BOT, the write operation resumes.

6-39

PE Gain Test Points and Adjustments

Physical
Track

Preamp
~

Test Point

Read PCBA
Adjustment

R706

R906

R506

R10

R106

R13

R406

R16

R306

R19

R206

R22

R806

R25

R606

e w'-...\\\

Table 6-7

When finished adjusting all nine tracks place the transport off-line, unload, and remove the
master output tape.

Place MIA switch S4 to AUTO (left)

Verify proper transport operation by runnmg the keypad or host CPU data reliability diag-

nostic.

6.6

TROUBLESHOOTING

Troubleshooting the TU78 transport consists of using this section as a guidein conjunction with system

software on-line diagnostics, standalone diagnostics, and off-line maintenance features found within the

System software device errof log .‘reports

The theory discussion found in Chapte’r 5

TM78 maintenance instruction / status‘codesfound in the’Apoc-»ket service guide

Transport functional block diagrams and logic/ schemafic diagrams found in Volume 1

6.6.1

\\\

transport and formatter. Aids to the troubleshooting process include the following things.

Using the Multiple Interface Adapter (MIA) PCBA

This section describes how the MIA PCBAis used as an a1d in performing certain transport adjustments, alignments, and troubleshooting.
6.6.1.1

Functional Description — The MIA PCBA is the interface between the TM78 formatter and

the TU78 transport logic. It handles read/write data, command/status information and amplitude

trackin error (AMTIE) information. It also prov1des one of the points where field maintenance personnel can issue commands to the transport. Thisis in case the formatter and its maintenance features

are not available due to failure or heavy customer usage.

The MIA PCBA has four toggle type command switches, eight DIP switches and two LEDs for troubleshooting purposes. Figure 6-14 shows where these components are and Tables 6-8 and 6-9 list their
functions. A more detailed description
of MIA theory is found in Paragraph 5.5.

6-40

MIA LEDs

Table 6-8

CR Number

Function

CRI1
CR2

Command parity error
Manual mode

Table 6-9

MIA Switch Functions

Function

Switch

Number

Left Position

S2
S3

read
1600 mode

reverse

forward

write
6250 mode

manual (test)

auto (on-line)

Right Position

6.6.1.2 Use Procedure — When the MIA PCBA is in manual mode (switch number 4 to the right), all
data, command, AMTIE and status information is inhibited from crossing the TU bus interface. The
other maintenance switches on the MIA now provide command and data information. The source of
this information is transparentot the transport logic. Therefore, the transport under test must be placed
on-line with the control panel ON LINE switch in order to receive the MIA commands. Also, when in
manual mode, the port select switch on the control panel has no effect and can be placed in any posi'

tion.

eight charThe eight test pattern DIP switches (Figure 6-14, DIP U196) can be set to write a repeating
17, etc. is all 1s or
acter pattern to tape. Switch number 1 of U196 determines whether character 1, 9,
all 0s. Switch number 2 corresponds to characters 2, 10, 18, etc. and so forth to switch eight for charac-

“ters 8, 16, 24, etc. Refer to Paragraph 5.5.5.8 for a detailed description of test write data generation.

“The right LED (CR2) is illuminated when in manual mode. The left LED (CR1) is illuminated when
|

the MIA detects a command byte parity error from the formatter.
NOTES

1. When in test write mode, a tape must have a

write enable ring or the write/erase heads will be

Q-

disabled.

2. All MIA switches are dynamic; that is the user

may change densities, write/read, whether tape
|
|
|
is moving or not.

3. When creating a tape in manual mode, upon
reaching EOT, switch number 2 should be re-

turned to the read (left) position. If not, when
- performing a reverse/rewind to return to BOT,

the tape will be overwritten.

6-41

TO J7
WRITE

TO J5
READ

TO J8
CONTROL M2

EXTENDER PLUG FINGERS

TOPIN 30

TO PIN1

TO PIN 37

/ TO PIN 72

O————-0

-J

TEST

POINTS

o= ———-04

TEST

POINTS

DO NOT CROSS
CARIES

EXTENDER
JACK

PLUG FROM

<+——PCBA UNDER
TEST
MA-3498A

PCBA Extender

Switch number 4 must be placed in the auto
(left) position before returning the transport to
operating system on-line usage.

6.6.2 Using the PCBA Extender (DEC P/N 29-23218)
The PCBA extenderis used as an aidin troubleshooting the TU78 transport. The read, write, and con-

trol M2 PCBAs can be extended for access one at a time. The MIA can not be extended butis accessible by removing the cabinet top cover. The capstan/regulator and reel servo PCBAs can not be ex-

tended due to heat sinking requirements. Refer to Figure 6-20 for an illustration of the PCBA extender.
To extend a PCBA, first remove the PCBA retainer clip (Figure 3-6), then remove the PCBA to be
extended from the card cage. Insert the extender into the slot vacated and push it firmly into the interconnect D1 PCBA. The orientation of the extender must be observed as it can be inserted two ways.
The correct way depends on the PCBA to be extended.
The extender is etched on both sides near the plug fingers. One side is etched READ (TOP) and the
opposite side is etched CONTROL (TOP) and WRITE (TOP). Therefore, if the read PCBA is to be

extended, the extender must be inserted into the card cage with the READ (TOP) etch pointing up. If
the control M2 or write PCBAs are to be extended, the extender must be inserted into the card cage
with the CONTROL (TOP) and WRITE (TOP) pomtmg up. The extender jackis then pushed onto the
extended PCBA’s plug fingers.
Note that the extender jack is connected to the extender with two flat cables. Place the extender jack

with the two cables flat as shown in Figure 6-20. The jack must not be rotated 180 degrees (indicated
by twisted cables). This would not make proper connections between the extended PCBA and the interconnect D1 PCBA.

6-42

Figure 6-20

UPPER ANGLE BRACKETS

L
-

- f

—[r
O

~—amae 8N00

j Onn Annn

OOy £ Oy B

t‘

1 () ammam

o
r——r—

[

s Ve V.o I o}

=
e W

[ e Foan X e B e B = T =

oO b

S enF s P d
11

S ad e ke

-]_l_o

LOWER ANGLE

PCBA BOARD

é@

()

BRACKETS

LOWER

AND SUPPORT BAR/1

SUPPORT BAR

LOWER ANGLE BRACKET

(@)

BRACKET FITS
BETWEEN BOARD

9
MA-3481A

Figure 6-21

PCBA in Extended Position

The extended PCBA is supported at an angle within the card cage assembly by four nylon brackets
protruding from the side, so it is accessible to service personnel. The two bottom brackets are angled
out and up, and fit in between the PCBA board and the support bar running underneath
the PCBA'’s
test points. See Figure 6-21 for an illustration of a PCBA in the extended position.

The 72 test points on the edge of the extender connect to the 72 pins on the interconnect D1 jack.
Therefore, service personnel have access to all connector pins on the PCBA under testing. The leftmost
test point on the extender connects to pin 1 on the PCBA. The next test point connects to pin 2, and so
on from left to right across the extender, with the rightmost test point connected to pin 72 on the

6-43

PCBA. The test points are on both sides of the extender and have the same left to right orientation with

respect to the extended PCBA, regardless of which side of the extender is up (Figure 6-20).
6.6.3

Power Supply Troubleshooting

This section contains a failure analysis of the powersupply and power distribution. Refer to Paragraph
5.4 for theory, and Figures 5-6 through 5-10, and Figure 2 in Volume 1 of the Technical Manual for

functional block diagrams. With the exception of +5 V (L) individual power supply voltages are not
adjustable. And, if a particular voltage is found to be out of acceptable range, a subassembly component has to be replaced.
WARNING
Use caution when making measurements and adjust-

ments with power applied to the transport. Keep one
hand behind your back or in a pocket, and do not
come in contact with any metal parts on the transport.

Voltages in the 220 Vac range are present in the
power supply, pneumatic assembly.

6.6.3.1
Troubleshooting Rules — When troubleshooting power supply problems, be sure to adhere to
the following rules.

1.
2.

Make sure that po»Wer is off and the transport is unplugged before replacing any defective

components in the power supply/pneumatic assembly.

The capstan/regulator PCBA cannot be extended from the card cage for troubleshooting
with power applied since it requires heat sinking. If this PCBAis suspected, substitute a new
PCBA.

6.6.3.2 TroubleshootingHints
1.

Examine the circuitry for burnt printed circuit board etch/components/wiring, oil leakage

from capacitors, and loose connections. A good visual check can quickly determine the cause
of a malfunction.

The +5V,+4+15Vand —15V regulators -contain overvoltage Crow’bar'detection circuitry. A

supply may crowbar and bring the output down to zero volts due to an intermittent regulator.
Turning transport power off then back on usually releases the crowbar.

- 6.6.3.3 Troubleshooting Charts — In checking the various areas of the power supply/distribution system, refer to the following troubleshooting chart (Table 6-10). Refer to Figure 6-1 for fuse locations.

6.6.4

Load Cycle Troubleshooting

When a load fault occurs, specific test points can be checked for cluesto the trouble area. Seven test
points are specified and load fault troubleshooting flow diagrams are provided, one associated with each
of the test pomts The seven load faults are numbered 0 through 6 to correspond with the loading flow- chartin the engineering print set in Volume 1 (control M2 logic Schematic Number 106875, sheets 10
and 11 of 11).

6-44

control, capstan servo, and reel servo functional circuitry be operating. Before pursuing
a path through
these troubleshooting flows, the loading flowcharts and suggested corrections (Figures 2-4, 2-6, 3-18,

The autoload cycle requiresal‘l vacuums and pressures to be within spéci-fication, and all power supply;

Table 6-10 Power Supply Troubleshooting Chart

Problem

Check

Result

No operator

Fans and

Problem is in 874 power

lights /no

rear

functions

operating

yes

Breaker CB1 tripped

panel

blower at

- Cause

control or line voltage
|

Check +5V (TP11 of
capstan/reg PCBA)
Power jumpers incorrect at

A1-TB1

No +5 VTPI11
of capstan
(regulator

+12V at
A2-TB1-6
o

+ 5 V output
too low
|

PCBA)

No+12V

Troubleshoot +12 V
Bad capstan/regulator PCBA
Burnt etch on interconnect

D1 PCBA

—

Bad capstan/regulator PCBA
or out of adjustment
Bridge rectifier CR2
partially open

8.5 Vac at

(A2-TB1-6)
|

A2-TB1-10

No +15V
(TP15of

424 Vat
A2-TB1-7

capstan/
regulator

no
yes

yes

Fuse F1 blown

Bridge rectifier CR2 open
Capacitor C3 shorted

' no

~ Transformer T1 defective

no
yes

Troubleshoot +24
V
|
Bad capstan/regulator PCBA

PCBA)

No —15V

(TP18 of
capstan/

—24 V at

A2-TB1-8

Troubleshoot —24 V

yes

regulator

PCBA)

No +24 'V
<2

(A2-TB1-7)
|

Burnt etch on interconnect
D1 PCBA
-

—

Bad capstan/regulator PCBA
Burnt etch on interconnect
D1 PCBA

Fuse F2 blown

Bridge rectifier CR1 open
~ Capacitor C1 shorted
Bad transformer T1

No —24V
(A2-TB1-8)

—

No +36V

—

Fuse F3 blown
Bridge rectifier CR1 open
Capacitor C2 shorted
Bad transformer T1

—

Fuse F4 blown

(A2-TB1-1)

6-45

Table 6-10

Power Supply Troubleshooting Chart (Cont)

Problem

Check

No +36 V

Result

Cause

Fuse F6 blown

—

Fuse F7 blown

(Reel servo
PCBA TP12)

No +36 V
(Reel servo

PCBA TP4)

No +36 V

Bridge rectifier CR3 open

anywhere
No —36V
(A2-TB1-5)

Capacitor C4 shorted
—36 V at
reel servo
PCBA
TP10 and

yes
no

Fuse F5 blown
Bridge rectifier CR3 open
Capacitor C5 shorted

TP18

and 3-19) should be followed. Also refer to Schematic Number 106875 (control M2 PCBA), sheets 10
and 11 of 11, for a functional loading flowchart and Figure 6-22 for an autoload timing diagram. Figure
4 in Volume 1 of the Technical Manual shows the major signals necessary to accomplish a load cycle.
6.6.4.1 Load Faults - When a load fault occurs (flashing load fault LED on the control panel) it can
be categorized into one of seven possible load fault areas. In order to determine what area caused the
fault, and therefore correct the source of this problem, you must scope test points on the control M2
PCBA. Table 6-11 lists the load fault numbers and their associated test points. During a normal load
cycle the signal level at the test points remains high. Any test point that pulses low or goes low during
the cycle indicates the load fault area number and the troubleshooting flow diagram to be used. Figures
6-23 through 6-29 are the load fault flow diagrams.
6.6.5

Pneumatic System Troubleshooting
WARNING

If the ac motor in the power supply/pneumatic assembly has stopped because of overheating it will restart when the temperature is normal. Always turn
off or disconnect ac power before working near mo- tor pulleys and belts.

The pneumatic system located in the power supply/pneumatic assembly and distributed on the base
assembly provides positive (pressure) and negative (vacuum) air to accomplish loading and running op-

erations.

6-46

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Table 6-11

Load Fault Categories

Load Fault

Control M2 PCBA

Number

Test Point

- Category Description

TP14

No load count sequencing pulses from take-up reel

TP27

Cartridge fault (not sensed as being closed or open)

— TP32

Cartridge fault (nof sensed as being open) |

TP35

Air fault at sequence count C3 time

TP42

Two attempts (one attempt for small reel) have been made to
load tape without success

TP41

Tape leader fault

TP28

Set loops fault

( LOAD FAULT O )

-DOES
TAKE UP
NO

REEL TURN

YES

WHEN LOAD/REW

IS PUSHED

REEL SERVO
-

PKSN

DISABLE

MARKERS ON TAKE UP

PULSES

S‘éVl\'JT/'\CBHL'EN

POSITION

FLIP

SWITCH

AT INTERCONNECT F1

CHECK FOIL SENSING
REEL

® CLEAN OR REPLACE

TP 4

PACK SENSE

ASSEMBLY

ENABLE
IS

TRF SIGNAL

PKSN

CONTROL M2 PCB@
REPLACE

HIGH AT
CONTROL M2
TP 66

CHECK THE FOLLOWING:

PULSES AT

BAD INTERCONNECT F1

CONTROL M2

BADF1TO D1CABLE

TP 43

BAD INTERCONNECT D1

REEL SERVO PROBLEM

CHECK THE FOLLOWING:
1.. FUSE F6

REEL SERVO PCBA

REPLACE CONTROL

TAKE UP REEL MOTOR

M2 PCBA

ADJUST TAKE
UP REEL
LOAD SPEED
MA-3492A

Figure 6-23

Load Fault O Flow Diagram

6-48

‘

LOAD FAULT1 )
REMOVE

SUPPLY REEL
PRESS RESET

YES

CONTROL

M2
TP 54

CONTROL
M2 TP 55

LOW

(CO N.O.

YES

CAPSTAN/

REPL ACE

REGULATOR

CONTROL M

TP 71

PCBA

+ 24V

(CAR MTR+)

REPLACE
CAPSTAN/
REGULATOR PCBA

YES

FAULTY CARTRIDGE
MOTOR

FAULTY OR

MISALIGNED

CARTRIDGE MOTOR
SENSING SWITCHES
MA-3489A

Figure 6

-24

Load Fault 1 Flow Diagram

6-49

( LOAD FAULT2 )

YES

FAULTY OR
MISALIGNED
CARTRIDGE

MOTOR SENSING
SWITCHES

PUT SCOPE ON

CONTROL M2 TP 69

(NCOC)

PRESS LOAD/REW
AND ALLOW FAULT

TO OCCUR. DO NOT
PRESS RESET

REPLACE

CONTROL M2 PCBA

YES

PUT SCOPE ON

CAPSTAN/REGULATOR

TP 71 (CART. MTR.+)

CART. MTR.+

AT
—24V

REPLACE
CAPSTAN/REGULATOR
PCBA

@ FAULTY CARTRIDGE

MOTOR .

e FAULTY OR
MISALIGNED

CARTRIDGE MOTOR
SENSING SWITCHES
MA-3490A

Figure 6-25

Load Fault 2 Flow Diagram

6-50

C 'LOAD FAULT3 )
!
PUT SCOPE ON

CONTROL M2 TP 60

(VAC N.O.)

!
MOUNT TAPE.
PRESS RESET.

,,"’/_’—\\\g

PRESS LOAD/REW.

PNEUMATIC FAULT; CHECK:
e

BLOWER MOTOR

BLOWER BELT

BLOWER

VACUUM SENSING SWITCH

PUT SCOPE ON

CONTROL M2 TP 48

(ABP N.O.}

!
PRESS RESET.

PRESS LOAD/REW.

REPLACE

CONTROL M2
PCBA

PNEUMATIC PROBLEM
CHECK:

COMPRESSOR BELT

COMPRESSOR

AIR BEARING PRESSURE

SENSING SWITCH
MA-3486A

Load Fault 3 Flow Diagram

Figure 6-26

6-51

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6-52
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10V1d3y v49d

v4d0d

31V1S

30V1d3Y v89d

/ .ul»fu\..

( LOAD FAULT5 )
BOT NOT SENSED
IN TIME

DOES

TAPE HAVE

BOT POSITION-

CFIX

ED 15+ 1FT *

TAPE

FROM END
OF TAPE

BOT MARKER
SEEN GOING
ONTO TAKE-UP

CHECK:

e
e

BOT SENSOR
CONTROL M2 PCBA

REEL

TAKE UP REEL
TIMING TOO

FAST. ADJUST

TAKE UP REEL
LOAD SPEED

_
IF PROBLEMS ARE EXPERIENCED DUE TO LEADER BEING TOO LONG, CUT IT

*15 FT. IS OPTIMUM. TRANSPORT WILL LOAD AT UP TO 30 FT.
DOWN TO 15 FT.

MA-3493A

Figure 6-28 Load Fault 5 Flow Diagram

6-53

C LOAD FAULT6 )
LOOPS FAIL TO FORM IN BUFFER

—— ——

—1 COLUMNS WITHIN & 1.5 SECONDS
AFTER "SET LOOPS” COMMAND

ARE

LOOPS

YES

FORMING IN
BUFFER

COLUMNS
ARE
LOOPS
FORMING BUT THEN

MOVING UP OR

CONTROL M2

DOWN

TP3 (STL)

GOING

CONTROL M2

LOW

YES

TP62

(NINTLK)

GOING

REPLACE

LOW

CONTROL M2

RAPIDLY

REEL SERVO FEEDBACK
LOOP NOT FUNCTIONING
PROPERLY FOR ONE OR
BOTH REELS. CHECK:
REEL SERVO PCBA

POSITION TRANSDUCER

PCBA

ASSEMBLY
CAPSTAN SERVO

CHECK:

VACUUM
TRANSFER VALVE

POSITION

BOTH LIMIT

CONTROL M2 PCBA

LOOP

SENSING SWITCHES

VISIBLY MOVING

BACK TO REST

CHECK:
e

VACUUM TRANSFER
VALVE

CHECK SYSTEM

e CAPSTAN/REGULATOR

MENT.

e CONTROL M2 PCBA

PCBA

VACUUM ADJUST-

CHECK FOR:
®

HOSE LEAKS

CLEAN CAPSTAN

BUFFER BOX
DOOR CLOSED
PROPERLY
MA-3497A

Figure 6-29

Load Fault 6 Flow Diagram

The accompanying flowchart (Figure 6-30) is used to troubleshoot a major pneumatic system failure. In
order to track down more subtle failures, first inspect the system. Check for holes, cracks, or pinchesin
any of the hoses or tubing. Check the condltlon and tension of both drive belts. Check all positive and

negative air values as outlinedin Paragraph 6.5.4. Both the muffler filter and air filter at the input of
the positive air system are changed during semiannual PM. However, a particularly dlrty environment
could cause these filters to clog prematurely and should be suspected. Also refer to the air/load control
functional block diagram, Figure 4 in Volume 1 of the Technical Manual, for a schematic of the air
system.

6.6.6

Reel Servo Troubleshooting

All circuitry used to drive both the take-up reel and the supply reel is contained on one PCBA (reel
servo PCBA) located in the card cage assembly. Inputs to the reel servo PCBA are summarized in
Table 5-2 and consist of power, control signals, and feedback signals. If the reel servo PCBA is suspected, it must be replaced since it may not be extended for troubleshooting due to heat sinking requirements. (Refer to Figure 5 in Volume 1 of the Technical Manual for a reel servo functional block dia-

gram. Also refer to Figure 6-31 for a simplified schematic diagram of the supply reel servo.)

6-54

NO PNEUMATIC SYSTEM
MOTOR WON'T

AIR.

TURN ON

DOES
CONTROL M2

YES

TP71 (PN U

RETURN) GO
LOW
A

TURN POWER OFF AT
POWER CONTROL
REMOVE PROTECTIVE
COVER FROM POWER
JUMPER PANEL A1 TB1

ATTACH VOLTMETER

CAPSTAN/
REGULATOR

CHECK:
e CONTROL M2 PCBA

TP70 (NPORST)

® CONTROL PANEL

LOW

(>300VAC) TO TERMINALS

2 AND 7

TURN POWER BACK ON

TROUBLESHOOT
POWER SUPPLY

VOLTAGE BEING
APPLIED TO
-

DRIVE
MOTOR

!
REPLACE
SOLID

STATE

MOTOR CIRCUIT BREAKER
TRIPPED (RED RESET

RELAY

BUTTON ON REAR
OF MOTOR) OR
DEFECTIVE
MOTOR
MA-3501A

Figure 6-30

Pneumatic Troubleshooting Flow Diagram

ANV

+15V
(SPOS)

+36 V

SRF

66
—15V

TP71

VACUUM

T>o-

TRANSDUCER
|

SRR

67
w

RUN

OFFSETS

(FWD, REV d
'
OR REWIND)

INTLK

TP
65

TRIANGLE
WAVE

,
v

GENERATOR
=36V
MA-3499

Figure 6-31

Supply Reel Simplified Schematic Diagram

6-55

Table 6-12

Reel Servo PCBA Operating Voltages
-

Test Point
TP62

Voltage

Name
|

+15V

TP64

—15V

Voltage
Reading
+15

Voltage
Source
1.0

‘Capstan/regulator PCBA

+15 £1.0

TP12

+36 V(s)

+40 £2

TP18

—36 V(s)

—40 =2

Power supply/pneumatic
assembly

+36 V(t)

+40 =2

"TP10

TP4

—36 V(1)

—40 =2

TP53

+5V(s)

53 +.3

Reel servo PCBA

Check all input power sources and Voltages developed on the reel servo PCBA. Table 6-12 lists the test

points, Voltage names, and proper readings with allowable tolerances. Check the test points with a
DVM using test pomt 49 as a ground reference.

A servomechanrsmis more difficult to troubleshootin a dynamic condition than a quiescent condition.

The TU78 reel servo consists of the reel servo PCBA, reel servo motor, loop position transducer, and
~loose coupling (feedback) provided by the tape loopin the buffer column. (For a block diagram refer to
\\

element most prone to failure. If this fails to correct the problem, proceed to check the various feed-

Figure 5-26.) Therefore, when encountering a reel servo problem, with no indication of what element of

the loop is causing the problem, it is advantageous to initially replace the reel servo PCBA since it is the

back elements. Loop position feedback elements for each servo consist of position transducers, limit
sensors, and the crippled reel sensor (take-up reel only).

Use the following procedure to check reel servo loop feedback elements. Refer to Figure 6-12 for an

illustration of the take-up buffer column, its zones, and sensing switches. The supply buffer column is
similar but without the crippled reel switch port.

Check all system vacuum measurements (Paragraph 6.5.4).

Turn transport power off.

Set reel servo dlsable sw1tch Sl located on the reel servo PCBA, toward the rear (drsable)

Ground control M2 PCBA test pornts TP62 (NINTLK) and TP71 (PNU RET)

Disconnect one capstan motor lead.

Mount a 10-1/2 inch reel of tape on the supply hub (without cartridge).

7. | Open the buffer box door and hand thread the leader through the tape path. Wind approximately 9 m (30 ft) of tape onto the take-up reel. Close the buffer box door.

Turn transport power back on. Pneumatics should be enabled with vacuum applied to the

buffer columns and pressure to the air bearings.

6-56

NOTE

If either reel starts rotating at this point, replace the
reel servo PCBA.

Manually rotate the supply reel clockwise and allow a loop to form. Position the loop in the
park zone. Apply masking tape to the reel’s outer flange and the transport to prevent the loop
from being pulled down toward the source of vacuum.

10.

Hold the tape against air bearing number 4 (Figure 6-4) with your finger and manually rotate
the take-up reel counterclockwise to allow a loop to form. Position the loop in the park zone
and release your finger. Tape the take-up reel to prevent movement.

11.

//'A\\\L

12.

on the control panel.
Press RESET

With a scope, monitor control M2 test points TP57 (supply limit N.O.) and TP61 (takeup
limit N.O.) with reference to TP49 (0 V). Both test points should be at or near ground. Any
to +5 V indicate an intermittent limit switch or air leak in the associmomentary jumps up
ated tubing.

13.

14.

Connect the scope to reel servo TP66 (SPOS) and ground to TP49 (0 V). Set the scope to 1 V

per division vertical, and 20 ms per cm horizontal with the baseline in the center.

Remove the tape from the supply reel and rotate it so the loop in the supply column extends
down to the lower limit switch and observe the voltage on the scope. Note the reading and
~ rotate the reel so the loop extends to the upper limit switch and observe the voltage on the
scope. Note the reading and the unsigned value of the readings together. The result should be
in the 3.6 V to 4.2 V range.

NOTE

The 0.6 V tolerance is due to the system vacuum setting, the position adjustment setting on the interconnect F1 PCBA, and individual position trans.

ducer characteristics.
15.

14 for the
Retape the supply reel and remove the tape from the take-up reel. Repveat step

take-up reel and the take-up column while monitoring reel servo test point TP55 (TPOS).

16.

If the result in step 14 or 15 is out of range, and the buffer column vacuum is known to be
within tolerance, the fault is with either the position transducer or the interconnect Fl

17.

Place the scope on interconnect F1-TB1-13 with ground probe on TB1-14. With the take-up
loop above the crippled reel port (atmosphere) TB1-13 should be at +5 V. With the loop

below the crippled reel port, TB1-13 should be at or near ground. Anything else indicates a
defective crippled reel sensor or associated tubing.

18.

Turn transport power off and remove the jumpers. Connect the capstan motor lead and set
the reel servo disable switch to front. If, after eliminating the reel servo PCBA and the feedback element, the problem still exists, replace the reel motor.*

*Motors can develop shored windings due to overheating. Also, they have a life span associated with the brushes/
commutator.

6-57

6.6.6. 1

Dynamic Brake Check
— This procedure must be accomplished when the reel servo PCBAis

replaced, or when tape damage due to power failureis suspected.
1.

(

Open the transport front door and install 2 267 mm (10 1 / 2 in) reel of work tape. Load the

tape to BOT.

Set control M2 PCBA switch S1 towards the front of the transport. The tape should be mov-

ing in the forward direction.

Allow the tape to run to its midposition.

With tape running, turn transport power off.

Open the buffer box door. The tape should not have spilled excessively in either column.

Examine the tape in the tape path. It should not show any damage.

Replace the tape in the tape path and rotate one reel to take up slack.

Turn transport power on and perform a midreel load.

With ytape rewinding to BOT at high speed turn transport power off.

10.

Repeat steps 5 through 8.

11.

.
(

Unload the tape.

‘6.6.7 Data Paths Troubleshooting
6.6.7.1

Introduction and Prechecks — It is assumed you have localized the fault to the TU78 data

paths before entering this section. That is,
no fatal error codes are displayed in the formatter maintenance panel and the basic integrity of the MASSBUS controller and formatter has been established by
running the appropriate control logic diagnostic.

If the data reliability diagnostic shows a hard error on one of the nine tape tracks, skip the following

prechecks and go directly to the write/read troubleshooting paragraphs. Otherwise, perform the prechecks; especially if the system error log or the data rehablhty diagnostic shows more than an average
of ten read errors per 2400 feet of tape.
Data Path Troubleshooting Prechecks
1.

Clean the transport and try another tape (Paragroph 4.3.4).
Make sure the AGC test switch on the read PCBA is in the AGC enabled position (left).
Check all unregulated and regulated voltages (Paragraph 6.5.1).

Check all vacuums and pressures (Paragraph 6.5.4).
Check all capstan servo adjustments (Paragraph 6.5.5).

6-58

/
~

Check head wrap angle (forward/reverse differential) adjustment (Parégraph 6.7.1, steps 6

through 14).

Check tape tracking (Paragraph 6.7.5, steps 8 through 31).
8.

Check that air bearings are not installed wrong (Paragraph 6.7.4).

Check read/write adjustments (Paragraph 6.5.7).

6.6.7.2 Write Path/Read Preamp Troubleshootmg The following troubleshootmg procedure uses the
PE (1600 BPI) mode. If you are experiencing problems related to the GCR (6250 BPI) mode, simply
place the maintenance switch to 6250 instead of 1600 when directed. The waveforms look similar but
naturally the frequencyis different. A write path one function diagram (Figure 6-32)is prov1ded SO you
may trace the flow of data completely through the transport, from the TU bus to the head, using chan-

nel 7. Figure 6-32 provides pin charts so you may scope other channels as well.
1.

Mount and load a write enabled scratch tape to BOT. Flip the MASSBUS port select switch

to position 3 (maintenance) and place the transport on-line.

Release the service lock, pull out the stabilizer arms and swing open the base assembly.
Make sure all vacuum/pressure hoses and pressure port caps are in place. Check all cables
for proper seating, partlcularly the AMTIE cable from the write to MIA PCBAs.
Set the maintenance switches on the MIA PCBA (Figure 6-14) as followsin the order given.
Pattern select
S1
S2
S3
S4
|

All ones. (all switches forward)
Reverse (left)
Write (right) .
1600 (left)
Manual (right)

The test mode indicator on th MIA PCBA, and the 1600 density indicator on the control
panel should both be lit. The transport should not be moving tape.

Place MIA switch S3 to the right (6250). The 1600 density indicator should go out and the
6250 density indicator should come on.

Change the MIA Switch settings as follows, in the order given.
S4
Sl
S3

Auto (left)
Forward (right)
1600 (left)

The tape should not move. If it does, return it to BOT.
Look at the output of the read preamplifiers. Set the scope as follows.
Vertical
Horizontal
Sync

= CH 1, 0.5 V/div, ac (using 10X probe)
= 2 us/div,
= Norm, ac, Ch 1

Place the channel 1 probe on the upper lead of preamp output resistor R1. This resistor is one

one of a pair for track 1 (channel 5). Refer to Figure 6-9 for location.

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6-60

Figure 6-33 Read Preamplifier Output Wavefo'rm
Place MIA switch S4 to manual (rlght) The transport moves tape and attempts to write an
all ones continuous record down tape. The tape can be started and stopped with the control
| panel QNLINE SW1tch and rewound w1th the REW/ UNL switch when desired.
Look at the waveform on the scope. It should look exactly like the waveform shownin Figure
6-33. The sinusoidal waveshape should have a 5.4 us period and have an amplitude of approx-

1mate1y 1. 2 volts peak-to-peak

Amphtude varies according to the PE gain setting for each track and the type of tape being
used
10.

Monitor each output resistor pair of each channel for a similar signal. Refer to Frgure 6-9 to
locate the resistors. If all signals from all channels are acceptable, assume the following and
~go on to read path troubleshooting (Paragraph 6.6.7.3).
Write path1s ok

Write head is basically working

Read head is working

Preamp PCBAis workmg
11.

1If all channels are not working correctly (the waveshapes are very different from Figure 633), or are missing, the problem could be one of the following things.
Write PCBA
Preamplifier PCBA
- MIA PCBA
Head

Also check signal VWRT, the source for each write head center tap, by placrng the scope
probe on write PCBA TP4. During a write operation, TP4 should be +15 Vdc, +1 Vdc.

12.

Go to step 13.

If most channels are working properly but one or more waveshapes are missing or distorted,

proceed as follows.

6-61

Set the MIA switches as follows.

S1
S2
S3
S4

Off (center)
Read (left)
1600 (left)
Manual (right)

Load a master skew tape (write ring removed) and place the transport on-line.

Set the scope as follows.

Vertical Chl |

5 mV /div, ac (using X1 probe)
5 mV/div, ac, invert (usmg X1 probe)

Vertical Ch2
Vertical Mode

Add

Horizontal

10 us/div

Sync

Normal trigger, HF reJ, normal source

- NOTE
X10 probes do not work for this measurement

Place the Chl and Ch2 probes on each leg of a preamplifier compensation capacitor for

a good track. Refer to Figure 6-9

in this manual, or Figure 23in Vol 1 of the Technical

Manual for capacitor locatlons
Place MIA switch S1 to the forward (right) position. The waveform on the scope should
be sinusoidal, similar to that shown in Figure 6-34.

Now place the scope probes across the compensatlon capacitor for a suspected track. If
the signalis missing or distorted, the headis at fault.
Stop the skew tape and unload it. The resistance of the head w1nd1ng can be measured
across the compensation capacitor.

NOTE
Use a VOM with a 20,000 ohm /volt rating or greater, or

a DVM on low power ohms scale. The read

head windings can be burned out by a high test cur-

rent.

A good head winding measures approximately 8.2 ohms, while an open winding shows
approximately 20,000 ohms (preamp input resistance).

If all read head outputs look okay when using a skew tape, mount ‘t‘he scratch tape
again.
Look at the compensation capacitors again; this time while writing (MIA switch S2
right). You should see a sinusoidal waveform similar to the one shown
in Figure 6-35.

If the waveforms observed at the read head are acceptable while reading a skew tape
and while writing a scratch tape, but not at the preamp output (step 11), possible problem areas are as follows.

6-62

-~
L
L o

MA-7304

Figure 6-34

Normal Read Head Output While Reading

MA-7301

Figure 6-35
e
e

Normal Read Head Output While Writing

Bad GCR/PE preamp 1 PCBA
Bad read PCBA
Bad cable from preamp to read PCBAs
(preamp needs load from read PCBA
to develop an output signal)

Go on to read path troubleshooting (Paragraph 6.6.7.3).

If the waveforms observed at the read head are while reading a skew tape, but not while
writing a scratch tape, possible problem areas are as follows.

‘Bad write PCBA

Bad MIA PCBA

Bad GCR/PE preamp 1 PCBA (write head cable

Bad write head (worn or open/shorted windings)
Go to step 13.

13.

Remove poWer from the transport and place the write PCBA on an extender. Refer to Para-

graph 6.6.2 for instructions on how to use the extender. Remove the write head cable from
the write PCBA (J6).

6-63

Set the MIA switches as follows.

~ Pattern select

S1
S2
S3
S5
15.

All ones (all switches forward)

Off (center)
Write (right)
1600 (left)
Manual (right)

Set the scope controls as follows.
Vertical Chl

= 0.2 V/div,
ac (X10 probe)

Horizontal

= 0.5 us/div

Sync
16.

\‘

14.

= Norm, HF rej, Chl

Flip MIA switch S1 to the right (FWD) and scope each of the write PCBA outputs at J6.
Refer to Figure 6-32 for a pin diagram and signal table for J6. Figure 6-36 shows a write

amplifier output waveshape with no load (P6 unplugged).
17.

If any of the nine channels look s1gn1f1cantly d1fferent trace the signal back to the MIA
PCBA using Figure 6-32 as a guide. Figure 6- 37 shows the waveshape for write data and a

write data strobe entering the write PCBA.
18.

—

If all nine channels areaereeptable, the write head i.s; probably defective. To check, stop the
tape and unload it and remove power from the transport. Measure the resistance of each

write head winding using Figure 6-38 as a guide. Keep in mind that each write head winding
is center tapped. Each half of the winding should measure approximately 3 ohms. If any
winding shows open or shorted replace the head assembly following the procedurein Paragraph 6.7.1.

If the write head continuity checks okay, and the head poles are not worn excessrvely (Para—'
graph 6.7.1), check the erase head continuity. The resistance between P6 pins 11 and 24
should be approximately 75 ohms with the write cable unplugged. In normal operat1on while
writing, the erase head voltage (at the head) should be as follows.
P905 (White wire) = —10 volts

P906 (Black wire) = —15 volts
If the contmulty check fails, the preamp PCBA or the head assembly has to be replaced If
the continuity checkis correct but the voltage checkis incorrect, the write PCBA has to be
replaced. When replacing either of these components, make sure the black and white wires
are put back correctly to observe eorrect erase head polarity.

6.6.7.3

Read Path Troubleshooting — The read path can be divided into the two basic sections; the

data path and the AMTIE path. A read path one function diagram (Figure 6-39) is prov1ded SO you

may trace the data flow completely through the transport, from the head to the TU bus, using channel
5. Figure 6-39 provides pin charts so you may scope other channels as well
In order to check out the preamp PCBA and the read /write head, do check the write path first (Paragraph 6.6.7.2). If the write path checks did not localize a problem, proceed as follows to continue troubleshooting the read path.
|

6-64

e
=
-

)

-t
L

L1l 1L 14
LB

LLLll

TITY

<+ LILAR

TITIgtE

L 1]
T

LLLil

LIRS

(

LiL
L

—

~HHH

MA-7311

Figure 6-36

[

LRI ILE

l.l

BRI

\
—
v

L1l

WDS

i1l

|
|

~ Write Amplifier Output With No Load

Figure 6-37

Write Data at Input to Write PCBA

11
LILILELE

laatlit
L) T

WD (N)

TRIANGLE

PIN 1

PIN 13

;

PIN 14

PIN 26

STRIPE

WRITE HEAD CONTINUITY CHECK

PIN 1 (CENTER TAP) TO PINS 2,3,4,5,14,15,16,17 = 352

PIN 23 (CENTER TAP) TO PINS 6,7,8,9,10,18,19,20,21,22 = 3Q2

Figure 6-38

MA-7303

~ Write/Erase Head Plug (P6) Test Points

6-65

|
To6PF
TC42
|

\ A

POINTS OUT#1 [

°
(CHANT)
]
R2 | ouT#2 |

A A
LA A4

$
10K
5

4
A LA

2%4

~“AUTOMATIC

.//"vwflp

‘

}

epE

PE GAIN

WAVEFORM

GAIN

|P/A

|
18

>
7

19
|

TRACK 8§

>._

' Roo | Rys

Ros
| Rog

PCB

EDGE

' AUTOMATIC

GAIN CONTROL

POINTS

PREAMP| READ

241

|
|

READ PCBA

EDGE CONNECTORE
P5 TO BACKPLAN

RIBBON CABLE

READ

PRE-AMP

WCS TEST DATA

(FROM FORMATTER)

WRITE
PCBA

OUTPUT
| PCBA

TO/FROM PREAMP

READ PREAMP
CABLE

~ P05 (PREANP OUTPUT RD5) | |

BOT AND GCR

PCBA

51 ]

,TP22
ST1
CLOCKS

0S¢

READ HEAD

"Rig | Rog

T
INTERCONNECD1

T 62

READ

COUNTER

TRACK 9% ;

777

Rgq| R
R; | Rg
Rio | R11
Riz | Rig |
Rig | Ry7
|

OloiNjo|u|bd|w|N|-—

TRACK 6§

| Ry| Ry

Olo|N|[ojo|d_]lw|
N

’.5 s

NO.

' OUT

_AGC |PO/RD|

|0¥o!

TRACK 5§

CHAN. | oUT | OUT

g:j*—

TRACK'

|...

GCR.

slojo|=|Nn|D|lw]

rRACK 4§

AGE

TEST

POINT

_ WAVEFORM

(DRIVER)

_GCR

FIGURE 6-40

RESISTOR

FIGURE 6-41

]
- INuros[

ANIP.

___GAIN CONTROL |14 |+

FIGURE

TRACK73 ”ILM | WAVEFORM

——1&4331/1. uuws
w,_,,rafNu_w

32}
I

;

PEAK

(ZERO

CROSS) _DET.

.fl\ s

TRACK 1&

SECOND STAGE

FIRST STAGE

P902

F/F

RDS

.. |BUFFER

5 PIN #

#
| J7PIN

51
52

58|

_66

d — N,

EDGE

_68

69
54
|
~ 55 | 70

57|

71
72

50
| 65

RADIAL

BUS TO FORMATTER

DRIVER

LOOP —=

WRITE ~ READ

;

| (+VAM)

N\ |LEVEL
DET.

125 (ONl P25

ON
~ FRONT|

AMTIE
| TE
OF WRI

DRIVER

| CABLE
pcB)
1

FIGURE 6-43, 44

WAVEFORM
0Oooooooooooo
oo ooooooaoalf
!

[

]

[ 425

| WRITE
GCR

A MTIE |[PIN#

WRITE PCBA
N

AMTIE

CABLE

" 34|

_ 32

MIA

FORMATTER

FROM

.20

MIA

EDGE

|«4—CONNECTOR

READ

_|RADIAL
_ TO

GENABLE|

_—

)

AMTIES

33
0000000006000
O0CO0G6 0060O0CCO0
00006000000

0000000000

- MIA

-39

AMTIE
| .

wes

LooP

TEST WRITE WRITE

DATA

|
PATH

TO
READ
PATH

MA-7320

Figure 6-39 Read Path One Functional Block Diagram
AT

NLTH

AMTIE CABLE

THRESHOLD

e
U

STDTH

J3PIN
#
35

ENABLE

—ti
g b |

1)
TEST (CHAN

Olo|vlololslwNf=

J90t1

(PREAMP QUTPUT)

TITIT

REF.

READ CABLE

PRE-AMP

O v|N|o|
o} sl
rof— o

|
|

6-66

6.6.7.3.1

Read Data Path— When writing or readingin GCR mode, the preamp gain is set automat-

ically. Each trackis set individually according to the playback signal received while reading the ARA
burst. Refer to Paragraph 5.11.5.3 for an explanation of the AGC circuits. Gainin PE modeis a fixed
level set by the read PCBA PE gain POT adJustments
Check the GCR AGC 01rcu1ts as follows
1.

Static tests

Mount and load a write enabled s_cratch tape to BOT but do not place the transport on-line.

Set the MIA PCBA test switches as follows.
Sl
S2
S3
S4.

All ones (all switches forward)

Pattern Select

Forward (right)
Write (right)
6250 (right)
Manual (right)

Set the read PCBA AGC sw1tch to the test AGC posmon (center)
Set the scope controls as follows.

0.5 V/div, ac (X10 probe)
0.5 V/div, dc (X10 probe)
Chop

Vertical Chl
Vertical Ch2
Vertical Mode

= 5 ms/div

Horizontal

= Nor'm,' AC, Chl

Sync

Place the Chl scope probeon read PCBA TP22 (ST1 CLOCKS).

Press the ONLINE button and quickly press it again. This moves tape off the BOT marker
and stops it.

The trace on Chl should have a series of 32 positive going ST1 CLOCK pulses displayed,
each with a period of 850 us +85 us. Refer to Figure 6 40. Pos1t10n the Ch2 trace (straight
|

line) on the bottom graticule of the screen.

Now look at the nine AGC levels at the preamp by placing Ch2 probe on the following IC
pins.

) Track 1

Track2
~Track 3
Track 4
- Track 5

‘Track 6

Track 7

Track 8

~ Track9

U4-1

U4-13
U4-6
U8B-1
US8-13

U8-6

Ul2-1
Ul12-13

Ul2:6

6-67

vvvvvv

ST1 CLOCK

AGC (N)

MA-7300

Figure 6-40

Automatic Gain Control (AGC) Waveform — GCR Mode

Make sure the scope probe is grounded to the preamp to eliminate unwanted noise. Refer to

the lower trace shown on Figure 6-40. The waveform dc level should start at approximately
+1.7 V (PE gain level) and ramp down, in a staircase pattern, to approximately +1.2 V.
i.

If any of the AGC waveforms are incorrect, the likely cause is the read PCBA (AGC
source). Replace it.

Dynamic tests

Use the same scope settings as in step 1d except for the following.
Vertical Ch2 = 0.1 V/div, ac (10X probe)

Reposmon the Ch2 trace and observe the small staircase pattern on the decending ramp.
Increase the time base (Horizontal) for a better view of the steps.

b.
-

While looking at one of the AGC voltages, place the transport on-line. It beglns writing and
moving tape forward.
|

Observe the following thihgs.

‘

The trace on Chl (ST1 CLOCK) shortens to approximately 9 clocks.

The ST1 CLOCKS stop when all read channels lock up (all set).

|
|

Look at the other AGC voltages. Each one locks up
at a different time depending upon that

tracks amplitude. The last channel to lock up reaches a stable level at the last ST1 CLOCK.

To test full count, ground the upper lead of one of the right hand resistors of a resistor pair

If any of the AGC channels in this test remains at the lower voltage (approximately 1.2 Vdc),
which is the maximum gain, it is probably bad and the read PCBA should be replaced.

If the ST1 CLOCKSs fail to shorten up from 32 counts to something less, one or more chan- /
nels are not getting set up. This may be due to a bad read PCBA or a reduced analog signal

for one channel of the preamp. (For example, R2 for Ch5.) The ST1 CLOCKSs go back out to32 because this channel will not lock on.

at its input.

6-68

MA-7312

Figure 6-41

Read Data Output

If any AGC voltage fails to step down evenly, that is if some steps appear larger than others,
part of the AGC DAC circuitry for that channel is not working properly. The transport can
|

still function, but not as reliably as possible. Replace the read PCBA.

Return the read PCBA AGC switch to the nofmal (left) position.

Read data path

Use Figure 6-39 to trace the nine read data channels through the read PCBA and MIA PCBA.
The TU78 does not generate a read data strobe pulse because all nine channels are deskewed in
the formatter. Figure 6-41 shows the waveform for a read data bit at the output of the read PCBA
[IRD (n)]. Read data bits are not latched in the TU78.

6.6.7.3.2

AMTIE Paths Troubleshooting — The TM78 uses AMTIES to detect active/inactive tracks.

They determine the following things.
1.

Which density ID track is written at BOT
(PE = track 4, GCR = track 6)
ARA burst start

Preamble/postamble length and quality

Start/end of data envelopeFilve marks
6.

A low amplitude track

Error correction pointers

Figure 6-42 shows a block diagram of the AMTIE generation circuitry.

6-69

P m\\

NLTH/STDTH

lTHRESHOLD

]

WRITE
(N)
AMTIE PCBA 5 )| AMTIE (N)D> ,I\ANl'JTIEEE;iE
L e AMTIE
TOTM 78

TRACK (N) g figfig

GENERATOR

FORMATTER

IGAIN

| :

NPE

CCRA

(FROM CONTROL M2 PCBA)
MA-7302

Figure 6-42

AMTIE Genéra'tion Circuitry

Troubleshooting +VAM AMTIE threshold voltage without TM78 formatter

Set the scope controls as follows

1.0 V/div, dc (10X probe)
0.1 ms/div
Auto, dc, Chl

Vertical Chl

Horizontal

Sync

Remove power from the tape transport. Place Chl probe on the front lead of write PCBA
R324 (signal 4+ VAM). Refer to Figure 6-43 for locations.
Remove the AMTIE cable from the MIA PCBA. Reapply power to the transport and load a
scratch tape to BOT.

Take AMTIE threshold voltage measurements (+VAM) while grounding the following pins
of the AMTIE cable connector (J25).
Ground Pin

Signal

+ VAM Measurement

5
15

NLTH

+4.8 Vdc, 0.5 Vdc
+10.2 Vdc, =0.5 Vdc

STDTH

If the results differ, replace the write PCBA or the AMTIE cable.

Troubleshooting + VAM AMTIE threshold voltage using TM78 fomatter
d.

Reinsert the AMTIE cable into the MIA PCBA Jack J1. The +VAM voltage should read
+4.5 Vdc, £0.5 Vdc.

Load a scratch tape to BOT and set MIA switch S4 to auto (left).
Set the scope controls as follows.

Vertical Chl

— 2.0 V/div, dc (10X probe)

Sync

= Norm, Chl dc negative scope

Horizontal

= 1.0 ms/div

Place the Port Select switch to position 3 (maintenance), and the transport on-line.

6-70

W
o o
6 L

0[] ¢ ]
7 Uegages001
]

TM oooooo
\

)

PROBE HERE

MA-6853A

Figure 6-43
e.

4+ VAM Test Point on Write PCBA

Enter the following commands into the TM78 maintenance keypad.
e
e
e

ENA (enable)
63 (write GCR)
REP (repeat instruction)

The display should indicate LOOP and the transport should write short records.
f.

The +VAM AMTIE threshold signal shown on the scope should be similar to Figure 6-44.
The voltage goes from +4.5 Vdc, £0.5 Vdc to +10 Vdc, +0.5 Vdc.

Press CLR on the keypad. Enter 7 and press EXE to rewind the tape.

h.
~

does not, the likely cause 1s the MIA PCBA. If neither test works, the likely cause is the

If test “1” (without TM 78 formatter) works properly, but test “2” (with TM 78 formatter)
write PCBA.

AMTIE channel switching

a.
b.

Place the transport off-line and remove the AMTIE cable from the MIA PCBA (J1).
Use the same scope settings as in test 2, step 6, but change the horizontal setting to 1.0
~us/div.
Set the MIA switches as follows.
Pattern select
Sl
S2
S3
S4

= SW1 forward, all others rear (10000000).
= FWD (right)
= WRT (right)
= 1600 (left)
= MAN (right)

Look at each AMTIE output at the cable connector with the scope. Refer to Figure 6-39 for
pin numbers. Each output should be approximately 5.0 Vdc.

Place the transport on-line. The transport drives the tape forward and writes the 10000000

data pattern on each track down the tape. This pattern causes each track to produce an AMTIE. Each output goes to ground and returns to +5 V as shown in Figure 6-45.

6-71

‘ /""\\\
.

Figure 6-44

MA-7308

4+ VAM AMTIE Threshold Voltage

All AMTIE channels should look similar to Figure 6-45. If one or more do not, trace the
signal back using Figure 6-39.

If an AMTIE channelis not acceptable and the preamp tests are all okay, replace the write

PCBA.
h.

If all AMTIE channels are acceptable but TM78 or d1agnostlcs indicate an AMTIE problem, replace the MIA PCBA.

6.7

REMOVAL AND REPLACEMENT PROCEDURES

This section details step-by-step removal and replacement procedures for all field replaceable parts that
require such instructions. Illustrations are referenced as necessary by the procedures. References are

made to any adjustments required due to the replacement of a particular part. (For a cross-reference on
part removal /replacement and associated adjustments, refer to Table 6-13.)
6.7.1

Head Wear Check and Replacement Procedure

The read-write-erase head assembly may require replacement for one of two reasons: internal fault in

the head, or excessive wear. Head wear can be verified by measuring the depth of the wear on the head
crown. In those heads that have guttering (grooves cut on the crown on each side of the tape path), the

head should be replaced when it has worn down to the depth of the gutter. In those heads that do not
have guttering, head wear should be measured with a brass shim that is 0.254 mm (0.010 in) thick. The
shim width should be less than the minimum tape width, 12.598 mm (0.496 in). Place the shim in the
worn portion of the head crown with one side butted against the outer worn edge. The head should be
replaced when the upper surface of the shimis below the unworn surface of the head crown. Thatis the
head has worn to a depth greater than 0.254 mm (0.010 in).

Head replacement is accomplished in the following way (Figure 6-46).

Turn transport power off.

Opén the transport front door and the buffer box door. Swing the base assembly out.

Remove the four hex- head SCrews holdmg the GCR/ PE preamp 1 PCBA bracket to base
assembly

Grasp the head assembly and remove two socket-head screws holding the head against the

head-mounting plate.

6-72

L1011

Trrorrrrrgrernvgy

cETr——

MA-7308

AMTIE Signal Switching

Figure 6-45

Table 6-13 Parts Replacement/ Adjustment Cross Reference
Corequisite

Paragraph

Removal or Replacement Procedure

Check/Adjustment

6.7.1

Head replaeement procedure

6.5.7

6.7.2

Tape cleaner removal, cleaning

6.7.3

- Air guide disassembly

6.7.4

Air bearing removal and cleaning

6.7.5

Capstan motor replacement

and alignment

and cleaning

6.5.7.1,

1 6.5.4.1,
6.5.4.2

6.7.6

Supply reel motor replacement

6.5.6.2,6.5.6.4

6.7.7

Vacuum reel assembly replacement

6.5.6.3,6.5.6.4

and takeup reel motor replacement

Cartridge actuator motor
|
- replacement

| Controls assembly removal

Blower/compressor ac motor

- 6.5.4

6.7.11

Blower removal and replacement

6.5.4

6.7.12

Compressor removal

6.5.4

6.7.8
Lot

6.7.9
6.7.10
o

and replacement

~ replacement

and replacement

6-73

Table 6-13

Parts Replacement/Adjustment Cross Reference (Cont)

Corequisite

Paragraph

Removal or Replacement Procedure

Check/Adjustment

6.7.13

Air valve solenoid replacement

6.7.14

PCBA removal /replacement

6.7.14.1

MIA PCBA

6.7.14.2

Read PCBA

6.5.7.3

6.7.14.3

Write PCBA

6.5.7.2,6.5.7.3

6.7.14.4

Control M2 PCBA

6.7.14.5

Capstan servo PCBA

6.5.1, 6.5.5,

|
6.7.14.6

6.5.7.3

Reel servo PCBA

6.5.1, 6.5.6,

6.6.6.1

6.7.14.7

GCR/PE Preamp 1 PCBA

6.5.7.3

6.7.14.8

Interconnect F1

6.5.2,6.5.3,
6.5.6.4

6.7.14.9

Interconnect D1

Carefully tip the bracket and disconnect the head from the PCBA. Remove the erase head
leads from the PCBA.

Check the head mounting plate and the replacement head for clean mounting surfaces.
NOTE
The mounting surfaces must be free of all foreign
substances, or excessive skew may result.
To install the new head, repeat steps 3 through 5 in reverse order, but do not tighten the

head-mounting screws or the PCBA bracket mounting screws. Note the white lead to the
erase head connects to J905 and the black lead to J905.
7.

Initially align head by visually aligning lower edge of head with inclined edge of base metallic overlay. (Refer to Note 2 of Figure 6-46.) Bias head assembly by pressing it towards the
right, into tape path, with finger pressure. Make sure the erase head contacts a sample section of magnetic tape. Lightly tighten the head-mounting screws. Connect erase head wires to

the PCBA, making sure the white wire is closest to the operator.
8.

Turn transport power on.

6-74

THREAD BLOCK NO. 3

Y
PATH

AIR GUIDE

NOT E1

CIRCULAR CERAMIC

/ LOWER POCKET BAR

GUIDE

CERAMIC GUI

pd
i

RECTANGULAR

DE\

(

/—CAP

TAPE CLEANER\l——
/—CLIP

//ERASE

]

O'—"

GCR/PE PREAMP 1

HEAD

/ WRITE/READ HEAD

PCBA

NOTE 2

l 3
-

)

/—GUIDE BLOCK

RETAINING

SCREWS

CAPSTAN

RECTANGULAR
CERAMIC GUIDE:

NOTES:

1. SURFACES MUST BE PARALLEL
2.

INITIALLY EDGE OF HEAD MUST BE
PARALLEL WITH METALLIC OVERLAY

Figure 6-46

MA-3670A

" Read /Write Head, Tape Cleaner, and Air Guide Removal
and Replacement

Load an all ones PE 64 ¢/mm (1600 cpi) tape on the transport and bring to load point.
10.

11.

12.

Operate the transport in a shuttle mode (that is, forward then reverse) by grounding TP31 on

control M2 PCBA (Figure 6-6).

Using an oscilloscope, observe waveform at the upper lead of R13 (track 5) of the GCR/PE

preamp 1 PCBA (Figure 6-9).

While operating in the shuttle mode, mechanically rotate the GCR/PE preamp 1 PCBA until minimum amplitude difference between forward and reverse operation is achieved. The
forward/reverse amplitudes must be in the 800 mV = 100 mV range, peak-to-peak. The

6-75

lower amplitude must be equal to or greater than 90 percent of the higher amplitude. Grasp
the GCR/PE preamp 1 PCBA on both the front and rear of base assembly to rotate it.
-

13.

Open the buffer box door and make sure the erase head is in contact with tape. Repeat step
12 if necessary.

14,

Tighten head mounting screws and PCBA mounting bracket screws.

15.

Perform the following related adjustments:

Rcad/write adjustments Paragraph 6. 5.7

6.7.2 Tape Cleaner Remova‘l, Cleaning, and Al‘ignment

The tape cleaner may be removed and reinstalled in the following way.
1.

Open transport door and the buffer box door.

Remove two screws attaching the tape cleaner and its cap to the base casting (Figure 6-46).

Clean tape cleaner, cap, clip, and metal 'overlay on the base casting with a lint-free cloth

moistened in 91 percent isopropyl alcohol. Wipe the tape cleaner blades and mounting surfaces carefully to remove all oxide and dirt.

Reinstall tape cleaner and cap with clip on base assembly. Bias the cleaner with finger pressure towards the right (towards the tape). Rotate cap so the formed clip is 1.524 mm (0.06

in) away from tape path. Slide clip against the erase head.
6.7.3

Air Guide Disassembly and Cleaning

The following details the procedure for disassembling and cleaning the air guide.
1.

Open transport door.

Remove seven trim assémbly mdunting screws, and trim assembly froym unit.
Open the buffer box door.

Remove thread block 3 (Figure 6-46), permitting it to hang by its leads.
Remove 'circular ceramic guide from air guide on front of base assembly (Figure 6-46).
NOTE
Do not remove air guide from base assembly.

Carefully insert penhght lens into the front of the air gulde Using a small mirror, make sure
all orifices are open.

Open any closed orifice by inserting a length of 34 AWG wire or one strand of 19 strand 27

AWG wire. Wire diameter should be 0.16002 mm (0.0063 in).

Wipe external bearing surfaces and ceramic guide with a lint-free cloth moistened with 91
percent 1sopropyl alcohol.

6-76

9.
|

10.

Assemble circular ceramic guide to air guide with edge parallel to the edge of lower pocket
bar (refer to Note 1 in Figure 6-46).

Reassemble thread block 3 to base assembly, adjusting
its tip so it is 0.762 mm (0.03 in)

outside of the tape path at the tape cleaner (Figure 6-46). Perform the adjustment by stretch- ing a section of magnetic tape from the lower pocket bar past the head and guide block
around the capstan.

11.

Replace trim assembly

6. 7 4 Air Bearmg Removal and Cleanmg

There are five air bearmgs excluding the air guide (Figure 6-47). The air guide disassembly and clean1ng procedureis given in Paragraph 6.7.3. The air bearing procedure describes removal of the air bearings for cleaning. Since there are three different bearing versions on a transport, they should be disassembled and reassembled one at a time.

Open the transport front door and buffer box door.
2.

Remove air bearing Number 1 (Figure 6-47). Clean parts using 91 percent isopropyl alcohol
and a lint-free cloth. Examine air bearing orifices by inserting a penlight into the bearing.
Open clogged orifices using 30 AWG wire. Clean all surfaces of the air bearing, the circular
ceramic guide (where used) and the bearing mountmg area on metal overlay of the base assembly.

A nonmetallic straight edge is useful to rotationally align the air bearings on the base assembly. A straight edge can be cut from the cardboard on the back of any tablet. Cut the piece
152.4 mm long by 6.35 mm wide (6in by 1/4 in). The stra1ght edge simulates the tape contact tangent line with the first row of holes.

Reassemble air bearing Number 1 to base assernbly. |
-

NOTE

The surface of the air bearing that has been mllled
out must be placed agamst the base plate.

Rest cardboard against adjacent buffer box bar and bearlng until f1rst row of orifices are

tangent to cardboard (Point A), and remaining orifices are in tape path area regions to float
the magnetic tape (Area B). The shiny side of ceramic guideis mounted towards the magnetg

ic tape. Align ceramic guide as shownin Figure 6-47

Follow the same procedure for air bearings Number 2, 4, and 5. This procedureis also used
for bearing Number 3 except that tangent po1nt A 1s ahgned with adJacent bearing Number
2.

6.7.5

Capstan Motor Replacement

The capstan motor and mounting plateis replaced as an assembly The motor and mountmg plate 1s
replaced using the following procedure.
.

Turn transport power off.

Disconnect wires, hose and tube at the motor. Remove tachometer wires from interconnect
F1 PCBA.

6-77

AIR BEARING NO. 3
_

AIR BEARING NO. 1

4+ %/fi

CIRCULAR

CERAMIC GUIDE

AIR BEARING NO. 2

THREAD BLOCK 1

L\/\

CARBOARD

STRAIGHT EDGE

AIR BEARING
NO. 4

|~
S

N
—

SYMMETRICAL WITH VERICAL

AIR BEARING

NO.5

CENTERLINE OF TRANSPORT

CIRCULAR

\-ifi

CERAMIC GUIDE

NOTE:

“A’” IS TANGENT POINT
“B" IS ORIFICE REGION

Figure 6-47

MA-3674

Air Bearing and Ceramic Guide Orientation

Remove the two hex nuts, lock washers, cups, and Belleville washers retaining motor plate to
the base assembly at two locations (Figure 6-48A).
Cradle motor in your hand. At front of base assembly, remove socket-head cap screw (fixed
point) (Figure 6-48B), containing Belleville washers and plain washer, freeing the motor.

Carefully slide motor off two adjusting studs. View the front of base assembly to make sure

the capstan clears metal overlay and base casting.

Install the replacement motor, repeat steps 2 through 5 in reverse order.
NOTE
The following steps provide the procedure to achieve
capstan perpendicularity, a necessary requirement to
ensure

proper tape tracking over the guide
block/head area. Coarse adjustment of tape tracking is performed in steps 7 through 21. A fine tuning
of tape tracking is accomplished in steps 22 through
32.

6-78

INTITAL SETTING
|

070"

HEX NUT

REQURES 7/16"

ADJUSTMENT

WRENCH

STUD

LOCKING SCREW
REQUIRES 1/4”

ALLEN WRENCH

i'\ /
1L

//
Zgi\jvsfifln S$Ew
ENT

]

STUD

FORWARD SKEW

ADJUSTMENT STUD

HEX NUT

"P/“

T—}a—LOCKING SCREW

1‘/

~
CIRCULAR

CERAMIC
GUIDE

]

-a—CAPSTAN

AIR BEARING NO. 5

lfiJ

CAPSTAN

MOTOR

REEL
<

o+ X———m

REVERSE
ADJUSTMENT STUD

A. SIDE VIEW

LOCKING

SCREW

FIXED POINT CAP SCREW

NOTE:

SOCKET HEAD
B. FRONT VIEW

REVERSE ADJUSTMENT DETAILS
ARE THE SAME AS FOR FORWARD
ADJUSTMENT.

Figure 6-48

MA-3689

Capstan Motor Mounting

Turn transport power on.

Mount and load a work tape to BOT.
NOTE

The tape may incur some edge damage in this procedure. When finished, cut off portion of tape used
in the process and install a new BOT tab.
9.

Place control M2 PCBA switch S1 (Figure 6-6) toward the front of the transport and drive

the tape forward for about 15 m (50 ft). Place the switch back in the center position.
10.

Turn transport power off.

6-79

11.

12.

On the rear of the base assembly, at the capstan motor mounting plate, loosen the two hex
nuts 1/4 turn. These hex nuts are the ones referred to in step 3. They are located at the
forward and reverse tracking adjustment points.

On the front of the base assembly, approximately 50.8 mm (2 in) down from the capstan,

loosen the fixed point socket-head cap screw 1/4 turn (Figure 6-48).
13.

14.

Loosen the capstan motor forward and reverse adjustment locking screws one full turn.
Remove the outside rectangular ceramic guide from the gulde block by removing the two
| retammg screws and washers (Figure 6-46).
CAUTION
The thin ceramic guides are easnly bmken Handle

them with extreme care.
15.

Gently retract the spring-loaded ceramic guides at both the guide block and the air guide so
they lock back. Use a nonmetallic instrument, such as the bare end of a cotton-tipped swab,

to retract the guides. Retraction is accomplished by pushing the guide straight back with the
swab positioned in the middle of the guide.
16.

- Close the buffer box door assembly.

17.

- Perform a systems vacuum check (Paragraphs 6.5.4.1 and 6.5.4.2).

18.

Turn transport power on and perform a midreel load.

19.

Run the drive forward using maintenance switch S1 on the control M2 PCBA. Adjust forward adjustment stud from the front of the base assembly (Figure 6-49) so tape edge is
aligned with guide block edge in the area from which the rectangular ceramic guide was removed. Clockwise adjustment shifts tape away from base casting.

20.

Run the drive in reverse using maintenance switch S1 on control M2 PCBA and adjust re-

verse adjustment stud from the front of the base assembly (Figure 6-49) so tape edge is
aligned with the guide block.
21.

Repeat steps 20 and 21 until tape is aligned with the guide block and no front-to-back move-

ment occurs with tape moving in either direction. Shuttle maintenance test point TP31 on
control M2 PCBA can be grounded to TP25 to run the transport in shuttle mode.
22.

Unload work tape and load a master skew tape to fine tune tape tracking.

23.

Connect channel 1 of an oscilloscope to R1 (track 1) of the GCR/PE preamp 1 PCBA (Figure 6-9) and channel 2 to RZS (track 9). Ground oscilloscope probes. Sync internal positive
on channel 1.

24.

Run tape forward and reverse by grofinding shuttle maintenance
test point TP31 on control
M2 PCBA.

25.

Observe the oscilloscope and adjust the capstan tracking adjustment studs (Figure 6-49) for

minimum differential between tracks 1 and 9 (outside two tracks of the read head).

6-80

—
|

TAKE UP

BUFFER BOX

TAPE CLEANER

__—HEAD

FORWARD TRACKING
ADJUSTMENT STUD

VACUUM CAPSTAN

/
TAKE UP REEL

,
FIXED POINT CAP SCREW
REVERSE TRACKING

ADJUSTMENT STUD
MA-3495

Figure 6-49

Capstan Tape Tracking Adjustment Studs

NOTE
Only very slight adjustments are required. Achieving

no differential at this point may not be possible due
to head azimuth plate misalignment.

Tape must be stopped and buffer box door opened each time the forward stud is adjusted.

26.

If coincidence cannot be achleved make sure the differential is minimal and equal but opposite in the forward direction versus reverse direction. This indicates tape trackingis straight
forward and reverse, and the head azimuth plate needs to be ahgned (Paragraph 6.5.7.1).

27.

Tighten locking screws, hex nuts, and socket-head cap screw, observmg osc1lloseope to make

sure adjustments are not disturbed.
28.

Remove jumper from TP31 on control M2 PCBA Remove ose1lloseope connection from
GCR/PE preamp 1 PCBA

29,

Unload the master skew tape.
CAUTION

Do not rewind. A master skew tape should be run
forward and reverse at normal drive speed only to
preserve its integrity.

30.

Return spring-loaded ceramic guides to their operating position by pressing the guide on the
corners with a cotton-tipped swab.

31.

Install fixed ceramic guide. Being careful not to crack it.

32.

Perform the read skew adjustment (Paragraph 6.5.7.1).

6-81

6.7.6

Supply Reel Motor Replacement

The supply reel motor can be replaced as follows.
1.

Turn transport power off.

Open the transport front door and buffer box door.

Remove the supply reel plastic overlay on front of the base casting by removing five small

Phillips screws.

Loosen the two reel hub retaining screws without removing the hex nuts. Use a 5/32 inch
ball-end hex driver inserted through the cutout in the casting behind the hub at the 12 o’clock
position. Normally only finger pressure is required to prevent the nuts for these screws from
turning. A small open-end wrench can be used and can be inserted from the front of the base
assembly through the access cavities in the base casting behind the reel hub.
|
With the straddle plates of the reel hub in a horizontal position, and hex nuts facing down,
remove the hub from motor shaft.

At the rear of base assembly, disconnect motor leads and cooling tubes from motor.
NOTE
|
Note the elbow alignments with respect to the motor
and base assembly so the elbows of the replacement
motor can be properly oriented.

- ‘While supporting the motor, remove four motor-mounting screws on the front of the base
assembly. Remove the motor from the rear.

Install the replacement motor, aligning elbows properly. Center motor in base casting clearance bore using centering tool (DEC P/N 29-23206). Tighten screws.
On the back of base assembly, slip the tubes over the elbows. Tighten hose clamps and attach
motor leads.

10.

On the front of base assembly, slip reel hub over motor shaft seating straddle plate on flat of
shaft. Push hub towards base casting and lightly tighten both clamping screws. Adjust the
hub flange so it measures 11.4 to 11.7 mm (0.451 to 0.461 in) from the machined boss on the
base casting. This machined boss is directly behind the flange at the two o’clock position.

11.

Torque both clamping screws evenly to 2.7 newton meters (24 inch pounds).

12.

Replace the supply reel overlay.

13.

Turn transport power on.

14.

Perform the following related adjustments.

Supply reel load speed (Paragraph 6.5.6.2)
Tape loop position (Paragraph 6.5.6.4)

6-82

6.7.7 .

Vacuum Reel Assembly Replacement and Take-up Reel Motor Replacement

The vacuum reel assembly and the take-up reel motor are replaced using the following procedure. The
vacuum reel assembly must be removed in order to remove the take-up reel motor.
1.

Turn transport power off.
Open transport front door. Remove the seven trim assembly mounting screws and the entire
trim assembly.

Open buffer box door and base assembly.

On.back of base assembly below the take-up reel motor, remove access plug to the vacuum
reel hub.

Through the access hole, loosen both screws retaining hub to shaft.
Remove vacuum reel at front of base assembly.
|

NOTE

If only the vacuum reel assembly is to be replaced,
go to step 10. If the take-up reel motor is to be re-

placed proceed with step 7.

At the rear of base assembly, disconnect motor leads and cooling tubes from motor. Note the
elbow alignments with respect to the motor and base assembly so the replacement motor elbows can be properly placed. While supporting the motor, remove the four mounting screws
on front of base assembly and remove motor from rear.
Install replacement motor, aligning the elbows properly. Center motor in base casting clearance bore using centering tool (DEC P/N 29-23206) and tighten screws.

On back of base assembly, slip tubes over elbows. Tighten hose clamps and attach motor
leads.
10.

11.

Reinstall vacuum reel using buffer box bar (DEC P/N 29-23207) just above the lowest air
bearing. Insert the bar between vacuum reel flanges.

Center reel flanges with respect to the bar and tighten screws on the vacuum reel hub. Rotate
reel and listen for any rubbing with base casting bore. Repeat steps 10 and 11 if necessary.

12.

Reassemble access and trim assembly.

Turn transport power on.

14,

Perform the following related adjustments.

Take-up reel IOad speed (Paragraph 6.5.6.3)

Tape loop position adjustment (Paragraph 6.5.6.4).

6-83

RFI

FILTER

BASE

47.752 + 0.762 mm
(1.88 + 0.03 inch)‘

) — s

\CARWDGE _
1

ACTUATOR ARM
///,//"

CLAMP —]

ACTUATOR MOTOR / |/\
SET SCREW

Cartridge Actuator Motor

)

Figure 6-50

MA-3680 .

6.7.8

Cartridge Actuator Motor Replacement |

The cartridge actuator motor may be replaced as follows.
1.

Turn transport power off

Open transport front door and buffer box door

Remove supply reel plastic overlay on front of the base eastrng by removrng frve small Phill1pS SCrews.

Remove arm from motor shaft by loosening set screw (Figure 6-50). )
NOTE
Note color and location of the two leads with respect
to the motor so they can be properly connected to
replacement motor.

On back of the base assembly, remove clamp from around motor and radro frequeney inter-

~ference (RFI) filter. Remove RFT filter from motor leads by sliding off filter top cover and
lifting wires off the pins. Remove four motor mounting screws, and remove motor.

Install new motor with the four mounting screws. Set arm height shown in Figure 6-50 and
tighten set screw.

Install a new RFI filter (DEC P/N 29- 23279) by laying motor leads into the two filter body
channels and pressing them onto the pins so pins puncture wire insulation. Slide filter top on.
Install clamp around the motor and RFI filter and trghten it so the p1n protrudrng from the
filter bottom makes good contact w1th motor housing.
CAUTION
Do not allow the clamp to touch the motor electrical
terminals.
Turn transport power on.

6-84

Press LOAD/REW control. Arm must rotate clockwise, then stop without bouncing and motor must stop driving. Adjust bottom limit switch if necessary.

10.

Press RESET control. Arm must swing counterclockwise, then stOp without bouncing and

11.

Reassemble supply reel overlay.

6.7.9

motor must stop driving. Adjust top limit switch if necessary.

Control Assembly Removal and Replacement

Turn transport power off at cabinet power control.

Open transport front door. Remove the seven trim assembly mounting screws and entire trim
assembly.

Open the base assembly. Disconnect P10 from control M2 PCBA and free the flat cable

At front of the base assembly, remove the four control assembly mounting screws and slide

from retaining clamps.

the flat cable through base casting.

5.
6.7.10

Install replacement assembly in reverse order.
Blower/Compressor AC Motor Replacement

The following procedure is used to remove and replace the blower/compressor ac motor.
|
WARNING
If the motor has stopped because of overheating, it

restarts when the temperature is normal. Always
turn off or disconnect ac power before working near
motor pulleys and belts.

Turn transport power off at the cabinet power control and disconnect power cord.
CAUTION

Do not attempt this, or amy other removal /replacement procedure within the pneumatic/power supply assembly without first removing the
220 V power cord.

3.
4.

Remove belt guard then remove both belts by manually rotating pulleys clockwise and slip-

ping belts off.
It is not necessary to loosen compressor or blower mounting screws.

Removevpulley set from motor shaft. Do not separate the'pulley set.
Remove transformer mounting screws in front of power pack assembly and lift transformer to
gain access to motor.

CAUTION
The transformer should not be lifted by one person.
An assistant is necessary for this operation.

Remove cover to motor leads and remove leads.

6-85

~ B

COMPRESSOR

—~

BELT TENSION ADJUSTMENT ACCESS
L_.>

PLATE

—— PLATE
MOTOR PULLEY

;

COMPRESSOR

PULLEY

Em—

p—
—
—

—

>{ "—5.080 mm

(0.975 inch)

AC MOTOR

COMPRESSOR

SECTIOM B - B

SECTIOM A - A

Figure 6-51

_—

—’4 ‘4’20.]93 mm

(0.200 inch)

‘

MA-3683

Blower and Compressor Pulley Alignment

Remove four mounting screws at rear of power pack assembly and remove motor from the
front.
|
.

Install replacement motor.

Reassemble
in reverse order aligning pulley on shaft set (Figure 6-51). Manually rotate mo-

tor clockwise and make sure both belts track completely on pulleys. Some slight shift of motor pulley may be necessary.

Reconnect power cord and turn transport power on at the power control.

10.

Perform vacuum and air pressure adjustments (Paragraph 6.5.4).

e /Mm\\

6-86

Blower Removal alid Replacement
‘Turn transport power off at the cabinet power control and disconnect power cord.

Remove belt guard; Remove hoses from top and rear
of blower.
Loosen blower mounting screws. Slide blower left and slip belt off pulley (Figure 6-51).
NOTE
Do not loosen blower pulley from shaft. Replacement blowers have pulley properly located on shaft.

Remove capacitor chassis mounting screws in front of power pack assembly. Position chassis
towards transformer.

.1'/-“\'~

Remove blower mounting screws and remove blower.
Install replacement blower.

Reassemble 1n '_reve-rse order (steps 3 through 6).
Exert approximately 111.2 N (25 1b) of force on blower while tightening the three blower
mounting screws to tension the belt. A slot is provided in the mounting plate to pivot a large
screwdriver against the blower housing for tensioning the belt.
Attach hoses to top and rear of blower and assemble belt guard.
10.

Connect the power cord and turn transport power on at the power control.

11.

Perform vacuum and air pressure adjustments (Paragraph 6.5.4).

6.7.12

Compressor Removal and Replacement

VRN

Turn transport power off at the cabinet power control and disconnect the power cord.
Remove belt guard. Remove tubes from top of compressor.

Loosen compressor mounting screws. Slide compressdr left and slip belt 6ff pulley.
Remove pulley from compressor.

Remove capacitor chassis mounting screws in front
of power pack assembly and position
chassis towards transformer.
Remove compressor mounting screws and remove COmpressor.
Transfer fittings to replacement compressor.
Install replacement compressor.

6-87

Reassemblein reverse order using steps 3 through 6 and setting pulley position according to
Figure 6-51.
10.

Exert approximately 111 N (25 1b) force on compressor while tightening the four compressor
mounting screws to tension the belt. A slotis providedin the mounting plate to pivot a large
screwdrrver against the compressor housing for tensioning.

11.

Attach tubes to the top of compressor. _Manually rotate motor pulley clockwise and make
sure compressor belt does not overhang pulleys; readjust compressor pulley if necessary.

12.

Connect power cord and turn transport power on at the power control.

13.

Perform vacuum and air pressure adjustments (Paragraph 6.5.4).

6.7.13 Air Valve Solenoid Replacement
When replacing the solenoid on either the vacuum or pressure transfer valve assembly, it must be adjusted according to the following procedure.
1.

Loosen the solenoid mounting screws slightly to allow free movement.

Turn transport power off.

Ground the appropriate test point to TP49 to enable solenoid current:

Vacuum transfer valve

Control M2, TP72 (NXFR)

Pressure transfer valve

Control M2, TP51 (NPOL)

Turn transport power on. The solenoid should be energized.

With the solenoid energized and the valve poppet pulled in, grasp the solenoid body and apply pressure away from the valve body until no movement of the actuator rod is detected.
Tighten the mounting screws without relaxing pressure.
|
'
6.

Remove the ground jumper.
Printed Circuit Board Assembly (PCBA) Removal and Replacement

6.7.14

The procedures necessary to remove and replace all PCBAs are listed in the following nine paragraphs.
6.7.14.1

Multiple Interface Adapter PCBA (Slot 1)

Turn transport power off.

Remove the PCBA retainer clip (Figure 3-4).
Remove the three cables from jacks J1 through J3.

Grasp the edges of the PCBA and pull straight out of the interconnect D1 backplane.

Set the transport serial number for the new MIA PCBA by noting the position of the sixteen

DIP switches (U125, U135) on the old MIA PCBA and sliding the new ones so they are
identical (Figure 6-14).

Insert the new PCBA and reconnect the three cables. Make sure maintenance switch S41S tO
the left (auto).

6-88

Install the PCBA retainer clip.
Turn transport power on.

Run the appropriate diagnostics to confirm transport operation.
Read PCBA (Slot 2)
Turn transport power off.

Remove the PCBA retainer clip (Figure 3-4).

Pull the read PCBA straight out of the interconnect D1 backplane.
Remove the read data cable from J4.

Plug the read data cable into J4 of the new read PCBA and insert it into the backplane.
Install the PCBA retainer clip.
Turn transport power on.

Perform the PE gain adjustment (Paragraph 6.5.7.3).

Run the appropriate data reliability diagnostic.
Write PCBA (Slot 3)

Turn transport power off.

Remove thev_PCBA retainer clip (Figure 3-4).
- Remove the write data cable from J6.
Remove the AMTIE cable from J25.

Pull the PCBA str"aight out of the interconnect DI backplane and insert the replacement
PCBA 1n its place.

Reconnect the write and AMTIE cables.

Install the PCBA retainer clip.
Turn transport power on.

Perform the following adjustments.

Write current adjustments (Paragraph 6.5.7.2)
PE gain adjustment (Paragraph 6.5.7.3)
10.

Run the appropriate data reliability diagnostic.

6-89

6.7.14.4

Control M2 PCBA (Slot 4)

Turn transport power off.

Remove the PCBA retainer clip (Figure 3-4).

Rémove the control cable from J10.
Pull the PCBA straight out of the interconnect D1 backplane.

Make sure jumpers W1 through W18, on the new PCBA, are configured according to the

original PCBA. (Refer to Volume 1 of the Technical Manual, Figure 12, sheet 1, Schematic
Number 10687.5,Table IT, Version —12).
Insert the new PCBA and reconnect the control cable.

Install the PCBA retainer clip. |
Switch S1 on the new PCBA should be in the center position.

Turn transport power on.
10.

6.7.14.5

Run the appropriate diagnostics to confirm transport operation.
Capstan Servo PCBA (Slot 5)

Turn transport power off.

Unscrew, but do not remove, the six hex-cap screws holding the PCBA heat sink to the card
‘cage heat sink at the rear. This is accomplished with the 5/32-inch ball-end driver and extension.

Pull the PCBA out of the card cage. Some rocking action may be necessary in order to free
the heat sink due to adhesion of the thermal compound.
|

Spread a thin film of thermal compound on the mating surface of the new PCBA and install

it. Tighten screws securely.
Turn transport power on.

Perform the following checks/adjustment procedures.
Power distribution (Paragraph 6.5.1)
Capstan servo adjustments (Paragraph 6.5.5)
PE gain adjustment (Paragraph 6.5.7.3).

Run appropriate diagndstics to confirm transport operation.
6.7.14.6

Reel Servo PCBA (Slot 6)

Turn transport power off.

Remove the eight connecting wires at the bottom of the PCBA.

6-90

Unscrew, but do not remove, the six hex-cap screws holding the PCBA heat sink to the card
cage heat sink at the rear. This is accomplished with the 5/32-inch ball-end driver and extension.

Pull the PCBA out of the card cage. Some rocking action may be necessary in order to free

the heat sink due to adhesion of the thermal compound.

Spread a thin film of thermal compound on the mating surface of the new PCBA and install

it. Tighten the screws securely.

Replace the eight connecting wires.

Turn transport power on.

Perform the following checks/adjustment ’procedures.

4 Power distribution (Paragraph 6.5.1)

Reel servo adjustments (Paragraph 6.5.6)
Dynamic brake check (Paragraph 6.6.6.1)

9. Run appropriate diagnostics to confirm transport operation.
6.7.14.7 GCR/PE Preamp 1 PCBA ’
1.

Turn transport power off.

Unplug the read data cable from J902 on the preamp PCBA.

Unplug the write data cable from J6 on the write PCBA.

Free the write data cable from all retaining clamps.

2. Open transport front door and buffer box door. Swing base assembly out.

6. Remove the four screws holding the preamp PCBA to its mounting braaket and rotate the
board away from the bracket while releasing the read/write connectors at the rear of the
head assembly. Unplug erase head wires from pins J905 and J906.

Pull PCBA and cable out of base assembly.

Install the new PCBA in reverse order making sure the phenolic insulator is between PCBA
and bracket. Note the white erase head lead connects to J905 and the black lead to J906.

Perform the following adjustment procedure.

PE gain (Paragraph 6.5.7.3).

10.

Run appropriate data reliability diagnostic to confirm transport operation.

6-91

6.7.14.8

Interconnect F1 PCBA

Turn transport power‘off.»

Swing base assembly out.

Disconnect flat cable from J 21 on interconnect F1.

Record wire color and conhection point of all wires making connection at TB1, TB2, TB3,
and TB4. Remove wires.

Remove PCBA from base assembly by alternately unscrewing the four re‘taining SCrews no
more than two turns each, in rotation, around the PCBA until all are free.

CAUTION

The screws are held captive to the PCBA spacers,

and, if each screw is completely removed, independent of the others, the PCBA undergoes a torsional
strain which may fracture etched conductors.
Install new PCBA in reverse order noting the procedure and caution in step 5.

Perform the following adjustment procedures.

EOT/BOT (Paragraph 6.5.2)
Low tape sensor (Paragraph 6.5.3)
Tape loop position and gain (Paragraph 6.5.6.4).
Run appropriate diagnostics to confirm transport operation.
6.7.14.9

Interconnect D1 PCBA

Turn transport power off at the power control.
Remove all card cage

PCBAs according to Paragraphs 6.7.14.1 through 6.7.14.6.

Open cabinet rear access door.
Remove the large metal plate below the exhaust fan assembly.
- Remove plastic shield over terminal strip TB1 at the rear of interconnect D1 PCBA.

Recdrd wire color of wires corinecting to TBI. Remi)vé' wIres.
Remove flat cable from J24 on interconnect DI.

Remove seven cap-head retaining screws and pull PCBA :out-of the front of the cabinet.

The new PCBA has two jumpers (W1 and WZ)»between J20‘1 and J 204‘. Cut jumper W2.
10.

Install new PCBA in reverse order:

6-92

11.

Reinstall all card cage PCBA:s.

12.

Run appropriate diagnostics to confirm transport operation.

6-93

APPENDIX A

GLOSSARY

A.1

GENERAL NOTES

I, prefixed to a mnemonic term, designates an interface 1/0 signal. If the term contains a

suffix R (receiver), the signal is an input (with respect to the tape transport). Similarly, a
suffix D (driver) implies an output signal. Low = true for all 1/O signals.
NOTE

Care should be exercised to avoid confusing specialized uses of I, R, and D, such as I for inverted in
NRZI, R for read, and D for data.

N, prefixed
to a mnemonic term, has a meaning similar to a logic bar or not symbol. N implies that the true signal identified by the remainder of the term is electronically low (low =
true) at the critical point in the circuit identified by the term.

Status signals are true if the condition monitored is true; e.g., LOAD FAULT is true if the

tape is improperly loaded.

’

Mnemonics for signals derived from circuits controlled by switches (automatic as well as
manual) may include N.O. (normally open) or N.C. (normally closed).

D is prefixed to a term to mean the signal has been delayed with reference to the signal iden-

tified by the remainder of the term.

Mnemonic

Definition

ABP

Air bearing pressure

ACRC
AGC

Auxiliary cyclic redundancy check
Automatic gain control

AMTIE

Amplitude track in error

AGCO0—-AGCT
AGCP

Automatic gain control voltage for read Amplifier 0—7
Automatic gain control voltage for the parity channel read amplifier

AMTIEO—-AMTIE7

Amplitude track in error interface signals for read channels 0—7

AMTIE P

Amplitude track in error interface signal for the parity read channel
(low = true)
|

(low = true)

ANSI
BKW
BOT
BPI

American National Standards Institute
Backwrap
Beginning of tape
Bits per inch

C0—-C4
CART MTR =+
CART N.O.
CART PRESS N.O.

CART SOL RET

CC N.O.

CLK
CLKA
CLKB
CLKC
CLKD
CLKE
CLKF
CLKG
CLR
CM +
CO N.O.
CPU
CRC
CRCC

CR N.O.
DDI

DINTLK
DIP

Load/unload sequence count O through 4 (high = true)
Cartridge motor supply voltage
Cartridge normally open
Cartridge pressure
Cartridge solenoid return
Cartridge closed (low = true)
Clock
Clock A (1 MHz)
Clock B (100 KHz)
Clock C (10 KHz)
Clock D (100 Hz) not used
Clock E (10 Hz)

" Clock
F (1 Hz)
Clock G (0.5 Hz)
Clear
Capstan motor voltage
Cartridge open (low = true)

Central processor unit

Cyclic redundancy check

Data density indicator signal
Delayed interlock pulse
~Dual in-line package

DONL

Delayed on-line signal

DRV

Drive

DSE

Data security erase
Drive type
|

DSE

EOT
ERHDLO

Error correcting code
End of tape
Erase head low

ECC

Cyclic redundancy check character
Crippled reel normally open (low = true)

Frequency

FCI

Flux changes per inch

Flip-flop

FPT

File protected (high = true)

FRPI

Flux reversals per inch

F/V
FWD

Frequency-to-voltage converter

GCR

Forward

| Group code recording

HI DEN N.O.

High density normally open (not used)

I/0O (see Note 1)
Beginning of tape interface output (low
= true)

IBOT

ICMD L

Command strobe (low
= true)

ICMD PE L
ID

Command parity error (low = true)
Identification
Data density indicator signal output (low
= PE, high
= GCR)
Data density select input

IDDI

IDDS

IDDSE
IEOT
IFPT
ILDP
INIT
INTLKPI
IONL
IPS
IRDO—IRD7
IRDP

IRDY
IRG
IRTH?2

IRWC
IRWD

IRWU

ISFC
ISLTO

ISLTI
ISLT2

ISLT3
ISRC
ISTATL

ISWS
ITACH
IWCSO0—-IWCS7
IWCSP
IWDO—-IWD7
IWDP
IWDS
IWINH

LATE AGC
LDFO

LDFS

LD/REW
LDS
LED

LO DENSITY
LOAD FAULT
LWR

Data density select enable (always low)
End of tape output signal (low = true)
File protect signal at interface (low
= true)
Load point (low
= true when tape is at load pomt)
Initialize
|
Pulsed interlock (occurs after INTLK before DINTLK)
On-line signal at interface (low
= true)

Inches per second
,
Read data bit O through 7 output, respectlvely Interface signal
(low
= true)
Read data parity output. Interface signal (low
= true)

Tape transport ready output. Interface 51gna1 (low
= true)
Inter-record gap
Read threshold level 2 (not used)
Rewind command input, interface signal (low
= true)
Rewinding signal output, interface signal (low = true)
Rewind and unload command input, interface signal (low
= true)
Synchronous forward command input, commands tape forward motion for
either reading or writing (low = true)
Select port A input, interface signal (low = true)
Select port B input, interface signal (low = true)
Select ports A/B input, interface signal (low = true)
Select maintenance input, interface signal (not used)
Synchronous reverse command 1nput Commands tape motion in reverse at
reading speed.
~
|
Status strobe (low = true)
Set write status, interface signal (low
= true)
Tachometer output, interface signal (low
= true)
Write /command /status bits 0—7
Write /command /status parity bit
Write data bit O through 7, respectively. Interface signal (low = true)
Write data parity, mterfaee signal (low
= true)
Write data strobe, interface signal (low
= true)

- Write inhibit (low
= true)
Late automatic gain control setup (not used)
Load fault zero
Load fault status
- Load/rewind
Load status
Light emitting diode
Low density (for 6250 mdlcator)
Load fault warning signal
Loop write to read

MUX

Multiple interface adapter
Motion
Mid-reel load
Millisecond
Multiplexer

N>80%
NAE

Capstan speed is greater than 80% (low = true)
Reel servo amplifier enable

MIA

MOT
MRL
ms

NAOK

Air okay (low = true)

NARA

Automatic read amplification burst error (low = true)
Beginning of tape (low = true)
Load /unload sequence count O through 4 (low = true)
Cartridge closed command (low = true)
Cartridge open command (low = true)
Delayed interlock signal (low = true)
Capstan/reel servo drive (low = true)

NBOT
NC0—4
NCCC
NCOC
NDINTLK
NDRYV

NEOT
NGOP
NLDC
NLDFS
NLDP
NLDS
NLRSTP
NLTH
NLTP
NMOT
NMRL
NMRSTP
NORMTH
NPE
NPOL
NPORST
NREWP
NRSAE
NRST1
NRTY
NRWC
NRWR
NRWS
NRWT
NRZI
NSFC

End of tape (low = true)
Go pulse (low = true)
Load clock (low = true)
LLoad fault status (low = true)
Load pulse (low = true)
Load status (low = true)
Load reset pulse (low = true)
Low AMTIE threshold
Low tape pulse (low = true)
Motion (low = true)
Mid-reel load (low = true)
Master reset pulse (low = true)
Normal (standard) AMTIE threshold
Phase encoded (low
= true)
Pressure on-low (low
= true)

Power reset, reset signal generated when power is turned on (low
= true)
Rewind pulse (low = true)
Reel servo amplifier enable (low = true)
Reset 1 (low = true)
Retry (repeat load attempt) (low = true)
Rewind command (Jow = true)
Rewind ramp (low = true)
Rewind status (low = true)
Write signal (low = true)
Non-return to zero, inverted

NULC
NUNLC2
'NXFR

Synchronous forward command to move tape in forward direction at reading
and writing speed (low = true)
Small reel sense signal (low = true)
Synchronous reverse command for reverse
motion at reading speed (low
= true)
Tach pulse 2 (squared and set at 20 us pulses) (low
= tach mark sensed
true)
Tach enable (low = true)
Test signal (low = true) (not used)
Thread command
Tape in path (low = true)
Test write strobe (low = true) (not used)
Rewind and unload command (low = true)
Unload command (low = true)
Unload command 2 (low = true)
Transfer, energize vacuum transfer solenoid (low = true)

ONL

On-line

NSMRL
NSRC
NTAP2
NTEN

NTEST(A)
NTHD
NTIP
NTSTR
NULRW

P N.O.
PCB

Pressure normally open
Printed circuit board

PCBA

Printed circuit board assembly

Phase encoded

PKSN

Pack sense
Pulse
|
Pneumatic (blower system on) command

PLS
PNU
PNU RETURN

Pneumatic system return signal

PO0—PO7
POP

Preamplifier output analog data for read channels 0—7
Preamplifier output analog data for the parlty channel

PRES SOL RET

Pressure solenoid return

PRST

PSOL
PWR

Preset
Pressure solenoid command
Power okay

Read data

RDO—RD7

Read data bit O through 7, respectively (high = true)
Read data parity bit
Ready
Record
Reverse or capstan reverse
Rewind
Reset
Rewind
Rewind
Rewind status

RDP
RDY

REC
REV
REW

RST
RWD
RWND

RWS

SEL
SFBRK'
SLIMIT
SLT A
SLT COM
SM +
SN
SPOS
SRBRK
SRF
SRR
STDTH
STL

Select

Supply reel forward brake
Supply tape - loop limit
Transport selected
|
Select common (always low)
Supply reel motor voltage
Serial number
Supply (loop) position
Supply reel reverse brake
Supply reel forward

Supply reel reverse
Standard (normal) threshold
Set loops

TACH

Tachometer

TACHP
TAPEN
TSTDAT

Tachometer output pulse to interface
Tachometer pulse cnable

TFBRK
THDS
TIP
TLIMIT

Test data (not used)
Take-up reel forward brake
Thread status
Tape in path

TM +

Take-up tape - loop limit
Take-up reel motor voltage

TOR

Tape on reel

TPOS
TRBRK
TRF
TRR
TU BUS
TWDS

Take-up (loop) position
Take-up reel reverse brake
Take-up reel forward
Take-up reel reverse
Tape unit bus
Test write data strobe

UNL

Unload

VAC
VAC SOL RET
VPED
VSTEP
VWRT

Vacuum applied

WPINO
WP SOL RET
WRT
WRT BIN
WRT CUR
WRT REG
WRT STAT
9TK

9TK N.O.

Write /command /status
Write data

Write protect solenoid set
Write protect solenoid return
Write or write signal
- Write binary track 4
Write current
Regulated write voltage
Write status (high = true)

Nine track (always high)
9 track normally open (not used)

"h\

WCS
WD

Vacuum solenoid return
Pedestal voltage
Step voltage
Write voltage

APPENDIX B

FLOWCHART GLOSSARY

X - DESCRIPTION OF EVENT OR ACTION (LOWER CASE)

,1’

\‘\

THE SIGNAL LEVEL WRITE IS ASSERTED

THE SIGNAL LEVEL WRITE ISNEGATED

IF CONDITION OR SIGNAL IS TRUE FLOW FOLLOWS
YES BRANCH, OTHERWISE FLOW FOLLOWS NO BRANCH

1—>WRITE

A FLIP-FLOP IS SET ASSERTING WRITE

A FLIP-FLOP IS RESET NEGATING WRITE

|
}
[ | .O—>WRITE

'I
DELAY. IF DELAY IS FIXED
X = AMOUNT OF DELAY OR
DELAY RANGE

ON PAGE CONNECTOR

OFF PAGE CONNECTOR

| coMMENT

BEGINNING OR ENDING POINT OF FLOW
DIAGRAM

ANNOTATION

Figure B-1

ADDITIONAL DESCRIPTIVE CLARIFICATION
OR COMMENT. DOTTED LINE EXTENDS TO
APPROPRIATE POINT FOR COMMENT.

Flowchart Glossary

B-1

MA-3500

APPENDIX C

TAPE UNIT MIA COMMAND/STATUS
REGISTER BIT DESCRIPTIONS

The TM78 formatter controls the tape unit by writing into the TU command locations, and senses tape
unit status by reading TU status locations. The formatter accomplishes this by writing and reading a
unique internal register. This results in an eight bit parallel transfer across the TU bus WCS
(write/command/status) lines.

”

The register address is determined by a special form of command write which has bit 7 = 1. All other
commands have bit 7 = 0, using the other seven bits for command information. Once a command /status address has been specified, it remains in effect until the formatter sends a new address to
the tape unit. Figure C-1 shows the format of the three types of command /status bytes. Figure C-21s a
summary of the tape unit command /status locations. Tables C-1 (Command) and C-2 (Status) provide

{

a detailed description of each command/status register.

PGE |CMD/STA ADDRESS
<3:0>

(A) FORMAT OF COMMAND/STATUS ADDRESS SPECIFIER BYTE

{'f
'

* PATTERN GENERATOR
ENABLE BIT

TU COMMAND
<6:0>

(B) FORMAT OF TAPE UNIT COMMAND BYTE

‘

TU STATUS
<7:0>

]

Figure C-1

Tape Unit Command/Status Byte Format

TU COMMAND
CMD/STA

TU STATUS

TU COMMAND A

TU STATUS

ADR

<3:0>

o [o] |
|

FWD | WRITE
REV

] L7||6| HEE
5

LWR

WRINH

RDY|

AMTIE LOOP

TU
ON LINE

RDYON

PES

REW

EOT
BOT

FPT

DATA <7.P>
TU COMMAND B

MIA STATUS A

TU COMMAND

MANTST|

REV

FWD

AMTIE LOOP

)

|WRINH |

WRITE

moOT

LWR

DSE

MIA STATUS B

O‘I

AMTIE LOOP DATA

<6:0>

|rpORT sELECT

<B,1.0>

CMD PE

|ARA ERR

PEC

SPEED <1:0>

TU78=2

THRESHOLD
7
3

SERIAL NUMBER A

| RD|PORT SELECT

ENA|]

<B10>

‘

SN TH

SN HU

<3:0>

AMTIE THR.
<1:0>

SERIAL NUMBER B
7
4

NOT USED

‘]

L
~

<3:0>

<3:0> 7

AMTIE THR
<1:0>

PATTERN DATA

[o|

EEEN

NOT WR | RD ENA|
TACH
B4
NOTWR EOTDET

PATTERN DATA

SN ONES

TU DIAGNOSTICS

SN TENS

PATTERN GENERATOR
DATA <6:0>

PATTERN GENERATOR-

DATA <7:0>

CMD/STA ADR 6,10<17 NOT USED
MA-7322

Figure C-2

TU Command/Status Summary

Table C-1

TU Command Register Descriptions
Name

Bits

Description

TU CMD/STA ADR = 0 (TU COMMAND A)
7

Forward

Reverse

Write

Zero

" This commands the tape unit (if ready and On-line) to move
tape forward.

This commands tape unit (if Ready and on-line) to move tape
in reverse direction. Tape stops upon detection of BOT.
The tape unit (if on-line and not file protected or

- rewinding) is enabled to erase tape. If not Write Inhibited,
tape may also be written.

Write Inhibit

Prevents tape unit’s write head from being energized, while

allowing erase head to operate normally. This is meaningful
only when write = 1.

LWR

1,0

AMTIE Loop

Loop write-to-read — The tape unit drives nine read data

(RD) lines from corresponding nine WCS lines, and nine
AMTIE lines from corresponding nine AMTIE LOOP bits.

These bits drive AMTIE (amplitude track in error) bus lines
<7,P> respectively when (transport) LWR is set.

TU CMD/STA ADR = 1 (TU COMMAND B)
7:3

2,1,0

TU command |

Zero

Tape unit command function: 2:0
Octal

Value

Function

CLR TU

Clears FWD, REV, WRITE, WR INH,
LWR, DSE, CMD PE, and RDY ON.

Set PE
-

‘Description

Set GCR

Set TU to (PE) phase encoded recording
-

format

Set TU to group code recording (GCR)
format

CLR EOT

Clear EOT status

Rewind

If ready and on-line, tape is rewound to
BOT -~ RDY = 0 until rewind sequence
is completed

Bits

(

TU Command Register Descriptions (Cont)

Table C-1

Name

Description

Octal

Value

Function

Description
A‘?‘,"‘A

Unload
|

CIf ready and on-line, transport switched
off-line, tape rewound and removed
from tape path

DSE

Causes FWD to set until EOT sets or
until a CLR TU command

TEST

Sets RDY ON and CMD PE, causing

CMD PE TU bus line to be asserted

TU CMD/STA ADR =2 (AMTIE LOOP)
7

—

Zero

6:0

AMTIE loop

These bits drive AMTIE bus lines <<6:0> respectively when LWR

6:0

(transport) is set.

TU CMD/STA ADR = 3 (THRESHOLD)

—

Read enable |

5,4,3

Zero

This enables tape unit AMTIE signals to TU bus RD/AMTIE
lines.

Port select

The complement of these bits is logically ORed with tape

<B,1,0>
|

unit’s port select switch. They are normally set to allow
position of the port select switch to be read via status
address 2 MIA STATUS B.

—

1,0

AMTIE threshold
1:0

Not used

A two bit field which establishes threshold of the TU read
electronics for nine AMTIE signals.
Octal
Value

Threshold

Mode

0/1

10%

IBG check

2
3

25%
20%

Write
Read

C-4

(

Table C-1
Bits

TU Command Register Descriptions (Cont)
Name

Description

TU CMD/STA ADR =7 (PATTERN DATA)
Zero

6:0

Table C-2
Bits

Pattern
Generator
Data

Represents data field intended to be written to tape for
maintenance purposes. This register is actually eight bits
wide. On every write to this register, bit 71s set toa 1.
The loaded pattern is generated on all nine channels with bit
0 first, then bit 1, until all have been sent.

TU Status Register Descriptions
Name

Meaning When Set

TU CMD/STA ADR =0 (TU STATUS)
7

Ready

Ready on

The tape unit is on-line, not rewinding, not loading or
unloading, and all pneumatic interlocks are made.

Ready has undergone a transition to set state. This is

cleared by a CLR TU command.

The tape unit has been placed on-line, and if ready, responds
to motion commands issued remotely from formatter.

Rewinding

The tape unit currently rewinding.

PES

The tape unit currently set to phase encoded recbrding

//“"~

On-line

format. If reset, the tape unit is set to group code

recording format.
BOT

The BOT marker on the tape is positioned at the BOT sensor
and ready is set.

EOT

The EOT marker on the tape is, or was, positioned at the EOT
sensor during a forward operation with ready set. EOT status
clears when:

O .

File protect

The EOT marker is positioned at the EOT sensor during a

The tape unit is commanded to rewind tape.

A CLR EOT command is written into the TU CMD B location.

reverse operation with ready set.

The tape reel currently loaded does not have the write
enable ring in place.

C-5

Table C-2
Bits

TU Status Register Descriptions (Cont)

Meaning When Set

Name

TU CMD/STA ADR = 1 (MIA STATUS A)
7

Manual Test

The MIA manual test switch is in the manual test position.

Forward

The forward command bit has been written with a 1, or a DSE

i{\

command has been written into the TU CMD B location.
Reverse

This indicates the state of the reverse command bit.

Write

This indicates the state of the write command bit.

Write Inhibit

This indicates the state of the write inhibit command bit.

This indicates the stéte of the TU loop write to read

LWR

- command bit.

This indicates that the capstan‘ servo motor is turning.

MOT

This indicates that a DSE command has been wfitten into the

DSE

TU CMD B location. It clears when EOT sets, or when a CLR TU
command is written into TU CMD B.
TU CMD/STA ADR =2 (MIA STATUS B)

CMD PE

A command or CMD/STA address has been received by the tape
unit with even parity, or a TEST command has been written
into TU CMD B. This clears when a CLR TU command is received,
whether parity is correct (odd) or not. This bit drives the
TU bus CMD PE L line.
|

PEC

A SET PE command has been sent to TU CMD B. Assuming proper
hardware operation, this bit is the same as PES in TU status.

ARA Error

During a GCR operation, from 24.1 cm (9.5) after BOT, the
read amplifier gains failed to achieve the required value.
This 1s valid only if READY is set.

4,3

Speed

This is a two bit field that indicates tape unit speed.

Port Select

This indicates the position of the multiposition port select
switch on the tape unit operator panel. The bits are

1:0

2,1,0

B,1.,0

TU78 = 2 (125 IPS)

meaningful only when the port select bits in the threshold

command location have been written to ones.

C-6

(

Bits

TU Status Register Descriptions (Cont)

Meaning When Set

Name

1
ko O [E—

Meaning

[S VD WY O

Table C-2

Position 0 (MASSBUS A)
Position 1 (MASSBUS B)
Position 2 or both (MASSBUS A or B)

TU CMD/STA ADR = 3 (SERIAL NUMBER A)
7:4

SN TH
3:0

Most significant (thousands) BCD digit of tape units serial
number

3:0

SN HU

The hundreds BCD digit of tape units serial number

3:0

TU CMD/STA ADR = 4 (SERIAL NUMBER B)
7:4

SN TENS

The tens BCD digit of tape units serial number

3:0

SN ONES
3:0

Least significant (ones) BCD digit of tape units serial
number

TU CMD/STA ADR = 5 (TU DIAGNOSTICS)
7

Not write

This indicates the state (polarity) of the write driver for

Bit 4

physical track four head.

Not write

There 1s no current flowing through the write or erase heads.

(This is the same as MIA status A, bit 7.)

Read enable

This indicates the state of the read enable bit in the

threshold command location.

EOT DET

The tape’s EOT tab is positioned at the EOT sensor. This is
not valid unless ready = 1.

Tach

This indicates the state of the output from the capstan motor
digital tachometer.
|

Any other position (Select neither MASSBUS)

—

Not used

1,0

AMTIE THR

This indicates the value of the AMTIE threshold field in the

1:0

threshold command location.

Table C-2

Bits

TU Status Register Descriptions (Cont)

Name

Meaning When Set

TU CMD/STA ADR =7 (PATTERN DATA)
Pattern

Generator

This indicates the data field currently in the pattern
generator command location.

Data

7:0

APPENDIX D
.

INTERFACE WIRE LIST AND TRANSPORT INTERCONNECTIONS

—— .

Table D-1 Majbr Plug/ Jack Reference Designations
Item

Location

Description/Purpose

MIA J1

On MIA PCBA

Connects to write PCBA J25
via cable
Connector for TU bus A

MIA J2

On MIA PCBA

MIA J3

On MIA PCBA

J1-J3

Interconnect D1 PCBA

Connector for TU bus B
Connectors for P1-P3 on MIA

PCBA

On read PCBA

For ribbon cable to preamp
PCBA on base assembly

On interconnect D1 PCBA

On write PCBA

On interconnect D1 PCBA

Main connector for read PCBA
P5

For ribbon cable to preamp
PCBA
Main connector for write
PCBA P7

On interconnect D1 PCBA

Main connector for control

J10

On control M2 PCBA
|

M2 PCBA
For ribbon cable to manual
controls on transport front

J11

On interconnect D1 PCBA

panel
Main connector for capstan/

J12

|
On interconnect D1 PCBA

regulator PCBA
Main connector for reel

J13

On reel servo PCBA

servo PCBA
For 436 V to unregulated dc

J14

|
On reel servo PCBA

J15

On reel servo PCBA

supply
For supply reel motor drive
power (+)
For supply reel motor drive

J16

On reel servo PCBA

power (—)
For —36 V to unregulated dc

J17

On reel servo PCBA

J18

On reel servo PCBA

J19

On reel servo PCBA

supply

For +36 V from unregulated
~dc supply
For take-up reel drive power

(+)

For take-up reel drive power

(—)

D-1

Table D-1

Major Plug/Jack Reference Designations (Cont)

Item

Location

J20

On reel servo PCBA

J21

Accommodates P21 of
cable from J24 in card
cage to interconnect F1

J22

(

Description/Purpose

For —36 V from unregulated

~dcsupply

For connecting card cage
circuits to base assembly
sensor and control circuits

PCBA on base assembly

On GCR/PE preamp 1 PCBA
attached to rear of

Read head 1nput to preamp

PCBA

base assembly

J23

On GCR/PE preamp 1 PCBA

J24

On interconnect D1 PCBA

J25

On write PCBA

TU Bus Interface Signals

- TU Bus A
MIA J2

GND

WCSO
GND
WCSI1
GND
WCS2
GND
WCS3

AMTIEO
‘GND
AMTIEI
GND
AMTIE2
GND
AMTIE3

WCS4

AMTIEA4

12
13

GND

GND
WCS5

GND

15
16

WCS6
GND

GND

WCS7

GND

<
-

(

~ GND

AMTIEG6
- GND

AMTIE7

GND

WCSP
GND
CMD

AMTIEP
GND
- RDP

23
24
25
26
27

WDS
GND
STAT
GND
CMD PE

RD7
GND
RD6
GND
RD5

GND

GND
AMTIES

19
20
21

PCBA

TU Bus B
MIA J3

3
4
5
6
7
8
9

For cable to interconnect F1

Connects to MIA PCBA

Table D-2

Output from GCR/ PE preamp 1

to write heads

GND

(

TU Bus Interface Signals (Cont)

Table D-2
|

TU Bus A

TU Bus B

MIA J2

MIA J3

28
29

GND
TACH

GND
RD4

GND

RD3

GND

RD?2

34
35

GND

GND
RDI1

GND

37
38

|
GND

RDO
GND

GND

Table D-3

AMTIE Cable Signals

MIA J1/

Write J25
Pin

Signal

PRESENTH

IAMTIE7

IAMTIES

"TAMTIE4

IWINH

NLTH

6
7
8
9
10
11
12
13
14
15
16
17
18
19
20

Ground
Ground
Ground
WRT BIN H

Not used
TARA ERR
IAMTIES3
IAMTIE6
WRT STAT H
STDTH
MOTION H
IAMTIEP
TIAMTIEO
- IAMTIEI
TAMTIE?2

MIA PCBA to Transport Interface

Connector J1/P1

Connector J2 /P2

Connector J3/P3

Signal

1
2
3
4
5

NPORST
IEOT
ILDP
IFPT
IRWD

1
2
3
4
5

IWD7
Ground
Ground
Ground
Ground

1
2
3
4
5

IRD7
Ground
Ground
Ground
Ground

7
8
9
10
11
12
13
14
15
16
17
18
19
20

IRWU
ISWS
ISLTO
IRWC
IDDI
ISRC
IDDS
IFSC
Not used
Not used
Not used
Not used
IRDY
Not used

7
8
9
10
11
12
13
14
15
16
17
18
19
20

Ground
Ground
Ground
Ground
Ground
- Ground
Ground
Ground
Ground
Ground
Ground
IWD6
IWDS5
IWD4

7
8
9
10
11
12
13
14
15
16
17
18
19__
20

Ground
Ground
Ground
Ground
+35
'
+5
+5
Ground
Ground
Ground
Ground
IRD6
NTSTR
IRDS

Not used

IWD3

IRD4

22
23
24
25

‘Not used
Ground
Ground
Ground

22
23
24
25

IWD222
IWDI1
IWDO
IWDP

22
23
24
25

Not used
Not used
Not used Not used

27
28
29
30
31
32

Ground
Ground
Ground
Ground
Ground
Ground
Ground

26
27
28
29
30
31
32

ITACH
Not used
Not used28
Not used
Not used
ISLT2
Not used

26
27
28
29
30
31
32

IRD3
IRD2
+5
+5
+5
IRDI1
IRDO

%Ground

IWDS

IONL

Ground

Table D-5

Ground

ISLTI

Ground

Not used
IRDP

Power Distribution on Interconnect D1 PCBA

Level
Signal

From

Termination
To

+12 Vdc

A2TB1-6

J11-15,55

+24 Vdc
»

A2TB1-7

J11-16,56

- —24Vdec -

A2TBI-8

J11-20,60

- P21-22,
23,24

J24-27,
28,29

Table D-4

Table D-5

Power Distribution on Intercornect D1 PCBA (Cont)

Level

Termination

Signal

From

+36 V(C)

A2TBI-1

J11-1,2,

J7-15,

41,42

DCCOM 2

A2TBil-4

J11-9,10,
11,49,50,51

—36 V(C)

A2TBI-5

J11-12,13,
52,53

DCCOM1

A2TBI1-9

J11-26,27,
66,67

8.5 Vac

A2TBI1-10

CM(+)

- A2TBI1-3

J11-40
J11-6,7,8,
46,47,48

CM(—)

A2TB1-2

J11-3.4,5,
43,4445

0 V(L)

J11-26,

P21-11,

J5-3.,4,

27,66,77

12,14

39,40

16,17

J24-37,39,40

J12-4,5,

51,52,53

J8-22,58

21,22

J1-23 - 34

12217

0 V(1)

J11-26,

27,66,77

J5-26 — 36,

J11-22,23,
.

62,63
»

+5 V(1)

J203-11,

14— 17

J101-2
— 14,
16,17

J102-1 - 18

J201-20 - 34
J204-2 — 17

J202-2 17

J8-38

J103-A,B.C,
DJ-V

J203-2 - 10,
14-17

P21-2,4
- J24-47,49

13210

J7-1-10

+5 V(L)

J3-11,12,13,
J7-18,19,

28,29,30

J5-8,9,44,45

54,55

J8-21,57

J12-1,2,
18,19

J101-S

Wi-1

J201-18

W2-1

J204-1,18

J7-21,57

12,13,28,
29,30
+5 V(T)

W1-2,W2-2

+15V

J11-12,61

—15V

J8-37

J5-5,41

J7-22,58

J8-56

J12-6,23

P21-39

J24-12

J11-14,54

J5-6,42

J7-23,59

J8-55

J12-7,24

P21-33,36

J24-15,18

Table D-6 Deck Interface Ribbon to Interconnect D1 PCBA
Level
Signal

From

Termination
To

TACH
TACH COM
SPARE 2

P21-44
P21-46
P21-49

J24-7
J24-5
J24-2

S.POS
T.POS
0 V(R)

P21-37
P21-21
P21-19

J24-14
- J24-30
J24-32

SPARE

P21-1

S.LIMIT

To
J8-53
J8-54

J24-50

T.LIMIT

P21-10

J24-45

"CR N.O.

P21-8

J24-43
J24-1
J24-6

J8-50
J8-49

NBOT
PKSN
NSMR

P21-42
P21-30
P21-3

J24-9
J24-21
J24-48

J8-52
J8-42
J8-8

CART N.O.

P21-43

P21-41
P21-40

CO
CC

CART M+

SPARE 1
VAC

VAC.SOL.RET.
WP2

Jg-1

J24-8

J8-10
J8-11

J24-10
- J24-11

- J24-20.17

P21-5.7

J24-44,46

P21-48

J24-3

J8-3

P21-15.,18
P21-35,38

J24-33.36
J24-13.16

P21-29.32
P21-27,28

J24-19,22
J24-2324

P.SOL.RET.

P21-13,16

J24-33.38

P21-9
P21-47

J24-42
- J24-4

J11-79

J11-36,76

J11-32.72
|

- J11-69
J11-33,73
J8-4
J8-9

J7-60,24

J11-35,75

‘“\Q

*Also WRT CUR

J11-80

J11-31,71
J11-34,74

J24-25.26
J24-31,34

WP1 N.O.*
W.P.SOL.RET.
ABPNO
TOR

J12-30

J12-31

- J11-30,70

P21-31,34

P21-2526
P21-17,20

CART M —
C.SOLRET

J11-68

Jg8-2

J24-41

P21-50
P21-45

|
To

J12-20
J12-3
J12-34

P21-6

NEOT
TIP

D-6

Internal Control Signals on Interconnect D1 PCBA

Table D-7
Level

Signal

NPE

J8-25

J5-10

J7-61

J103-7

NWRT

J8-26

J5-47

J7-25

18-28

J5-48

17-26

1848

J5-12

MOTION

FPT
T

Termination

From

BOT(INT)

J8-60

NMOT
SRF

J8-51
J8-29

SRR
TRF
TRR

J8-30
J8-31
J8-32

MRL

J8-5

J11-19

‘

J11-24

|
J12-17

J12-16
J12-15
J12-14
J12-28

REWR

J11-78

J12-13

J8-66

J11-18

J12-33

NDRV

J8-65

J11-64

J12-27

N>80%
NTAP2

J8-67
J8-62

J11-25
J11-57

REV

,/_

NINTLK

J8-69

Ji1-65

J12-8,25

NRWR

J8-33

J11-38

NRSAE

J8-34

J11-58

J12-11

NCCC

J8-70

J11-29

NCOC

J8-71

J11-28

NXFR
NPOL

J8-72

J11-39
J11-59

J8-64

(SPARE A)

NPORST

)

J11-37,77

11
S J12-926

PNU RET

J8-68

A2TB1-11

J7-11
J201-1

J8-61

Signal

From

ISFC

J101-C

Termination

-~ To

J1-14

J8-20

J201-14

J201-13
J201-12

Jg-19
J8-18

IDDS
ISRC

J101-D
J101-E

J1-13
J1-12

IDDI
IRWC
ISWS
IRWU
IONL

J101-F
J101-H
J101-K
J101-L
J101-M

J1-11
J1-10
J1-8
J1-7
J1-6

J201-11
J201-10
J201-8
J201-7
J201-6

J8-17
Jg-16
J8-14
J8-13
J8-12

IRWD
IFPT
ILDP

J101-N
J101-P
J101-R

J1-5
J1-4
J1-3

J201-5
J201-4
J201-3

J8-47
J8-46
J8-45

IRDY
IEOT
ISLTO
ISLT1
ISLT2
ITACH

J101-T
J101-U
J101-J
J102-B
J102-D
J102-K

J1-19
J1-2
J1-9
J2-33
J2-31
J2-26

J201-19
J201-2
J201-9
J202-33
J202-31
J202-26

J8-7
J8-44
J8-14
J8-15
J8-16
J8-6

Table D-9

Interface Read Signals on Interconnect D1 PCBA

Level
Signal

From

Termination
To

IRDP
IRDO

J103-1
J103-3

J3-34
J3-32

J5-72
J5-70

J203-34
J203-32

IRD1
IRD2
IRD3
IRD4
IRDS5

J103-4
J103-8
J103-9
J103-14
J103-15

J3-31
J3-27
J3-26
J3-21
J3-20

J5-69
J5-68
J5-67
- J5-62
J5-61

J203-31
J203-27
J203-26
J203-21
J203-20

IRD6

J103-17

J3-18

J5-59

J203-18

J5-58

J203-1

IRD7

-y

Level

D1 PCBA
Interface Control Signals on Interconnect

J103-18

J3-1

Table D-8

Table D-10

Interface Write Signals on Interconnect D1 PCBA

Level

Termination
To

J2-34
J2-25
J2-24

J7-47

J202-34

J7-45
J7-44

J202-25
J202-24

J2-23

J7-43

J202-23

J2-22
J2-21

J7-42

J202-22
J202-21

J2-20

J7-40

IWD6

J102-S
J102-T
J102-U

J2-19
J2-18

J7-39
J7-38

J202-20
J202-19
J202-18

IWD7

J102-V

J2-1

J7-37

J201-1

Signal

From

IWDS

J102-A

- IWDP

J102-L

IWDO

J102-M

IWDI

J102-N
J102-P

IWD?2
IWD4
IWD3
IWD5

J102-R

J7-41

TU78 Magnetic Tape Transport

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