Digital PDFs

EK-0TA78-SV-1

May 1984

285 pages

Original

10MB

Document:	TA78 Magnetic Tape Drive Service Manual
Order Number:	EK-0TA78-SV
Revision:	1
Pages:	285
Original Filename:

OCR Text

EK-OTA78-SV-001

TA78
Magnetic
Tape Drive
Service Manual

EK-OTA78-SV-001

. TA78
Magnetic
Tape Drive
Service Manual

Prepared by Educati<;>nal Services
of
Digital Equipment Corporation

Copyright 0 1984 by Digital Equipment Corporation
All Rights Reserved
The material in this manual is for informational purposes
and is subject to change without notice.
Digital Equipment Corporation assumes no responsibility for
any errors that may appear in this manual.
Printed in U.S.A.

Class A Computing Devices:

Notice: This equipment generates, uses, and may emit radio
frequency energy. The equi puent has been type tested and
fo und to compl y wi th the lim its f or a CI ass A comput ing
device pursuant to Subpart J of Part 15 of FCC Rules, which
are designed to provide reasonable protection against such
radio frequency interference when operated in a commercial
en vir 0 nm en t. Op era t ion 0 E t his e qui pm en t i n are sid en t i a I
area ~ay cause interference in which case the user at his
own expense may be required to take measures to correct the
interference.
The
following
are
trademarks
of
Corporation, Jvla yna rd , Massachusetts.

mD~DDmD

DEC
DECsystem-10
DECSYSTEM-20
DECUS
DEOnate
DECnet

DECwriter
DIBOL
MASSBUS
PDP
p/OS

Professional
Ra inbow

Digital

Equi pment

RSTS
RSX
UNIB US
VAX
VMS
VT
Work Processor

CONTENTS

CHAPTER 1

INTRODUCTION

1.1
1.2
1.3
1.4
1.5
1.6

1-1
Scope •.•.••••••••
Hardware Configuration ••••••••••••••••••••••••••
1-1
Physical Description •.•••••••••••••••••••.••••••
1-3
Maintenance Philosophy •••••••••••••••••••••••••• 1-10
To 01 s ••••••••••••••••••••••••••••••••••••••••••• 1-10
Related Documents ••••••••••••••••••••••••••••.•• 1-12

CHAPTER 2

INSTALLATION

2.1
2.1.1
2.1.2
2.1.3
2.2
2.2.1
2.2.2
2.3
2.3. 1
2.3.2
2.4
2.4.1
2.4.2
2.5
2.5.1
2.5.1.1
2.5.1.2
2.5.1.3
2.5.1.4
2.5.1.5
2.5.1.6
2.5.1.7
2.5.1.8
2.5.2
2.5. 3

Site Planning .•••••.•••••••••••.••••••••••••••••
Space Requirements ••••••••••••••••••••••••••
Power Requirements •••.••••••••••••••••••••••
Environmental Requirements •••••••.••••••••••
Unpacking and Inspection •••••••.••••••••••••••••
Unpacking •••••••••••••••••...•••••••••••••••
Inspection ••••••••••••••.•••••••.•••••••••••
Single Transport Installation ••••••••.••••••••••
Mechanical Installation •••••••••••••••••••••
Power and Cabling •••.•••••••••••••.•••••••••
Multiple Transport Installation .•••••.•••••.••••
Mechanical Installation ••••••••••.••••••••••
Power and Cabling •••••••••••••••••.•••••••••
Ac c e pta n c e Te s tin g •••••••.••••••••••••••••••••••
Turn-On and Loading Checkout •••••••••••.••••
Power On ••••••••••••••••••••••••••••••••
Load Sequence wi thout Tape •••.•••••..•••
Inhi bi ted Autoload Sequence ••••••.••••••
Autoload Sequence ••••••.••••••••••••.•••
Manual Load Sequence •.••••••••••••••••••
Unload Sequence ••••••.••••••••••••••••••
Manual Load Repeatability •.••.••••.•••••
Autoload Repeatability ••••••••••••.••.••
Tape Drive Quick Check •••.•••••••••••••.••..•
Subsystem Level Diagnostics .••••••••••••••..

iii

2-1
2-1
2-2
2-2
2-2
2-2
2-5
2-6
2-6
2-10
2-16
2-16
2-21
2-26
2-26
2-26
2-27
2-28
2-28
2-30
2-30
2-31
2-32
2-33
2-34

CHAPTER 3

CHECKS AND ADJUSTMENTS

3.1
3.2
3.3
3.4
3.5
3.6
3.6.1
3.6.2
3.6.3
3.6.4

3.10.2.2
3.10.3

Preventive Maintenance
Ge n era 1 Ad jus tm E! n t Not e s •••••••••••.•..••••..•.•
TU78 Power Subsystem Adjustments ..••...•••••••••
E0 T/B 0 T Ad jus tm e n t •••••••••••••.•..••••...•••••.
Low-Tape Sensor Adjustment •••••••...••••••.•••••
Vacuum and Air Pressure Adjustments •.•••••.•••.•
System Vacuum Adjustment ••••••••••••••••••••
Take-up Reel Vacuum Adjustment .••••••••••.••
Air Bearing Pressure Adjustment ..••••••.•••.
Thread Block and Cartridge Pressure
Ad jus tm e n t ................................... .
Capstan Servo Adjustments ••••••••••••••••••••.••
Reel Servo Adjustments •••••••.••••••••••••.•••••
Reel Servo Offset Adjustment ••••.•••••••••••
Supply Reel Load Speed Adjustment ••••••.••••
Take-up Reel Load Speed Adjustment " •••••••••
Tape Loop position Adjustment .•.••••••••••••
Tape Path Cleaning .•..••••••••••••••••••••••••••
Read/Write Adjustments .••••••..•.••••• a • • • • • • • • •
Read Skew Adjustment ••••••••••••••••••••••••
Write Current Adjustments ................... .
Phase Encoded write Current
Ad jus tm e n t s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Group Coded write Current Adjustments .••
Phase Encoded Gain Adjustments ••••••.••••••.

CHAPTER 4

TA78 TROUBLESHOOTING AIDS

4.1
4.2
4.3
4.3.1

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Faul t Control and Error Codes .••••••••••••••••••
Microdiagnostics •.•.••••••••••••••••••.•••••••.•
Running Microdiagnostics Via the ASCII
Po r t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Microdiagnostic Response ••••••..••••••••••••
Using STI Loopback Tests ••••••.•..•••••••••.
Subsystem Diagnostics ••••••.••••••••••••.•••.•••
In-Line Tape Diagnostic •••••••••••..•..••••.
In-Line Exerciser .••••••••••••••.•••••••••••
TA78 Diagnostic Mode .••••..•••••••••••••••••
Vi sua 1 Tr 0 ubI e s h 0 0 tin g Ai d s •••••••••••.•••••••••
Error Log . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.7
3.8
3.8.1
3.8.2
3.8.3
3.8.4
3.9
3.10
3.10.1
3.10.2
3.10.2.1

4.3.2
4.3.3
4.4
4.4.1
4.4.2
4.4.3
4.5
4.6
4.7
4.7.1
4.7.1.1
4.7.2
4.7.3
4.7.3.1
4.8
4.8.1

ASC I I

Po r t

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

••••••••••

Buttons and Lights Test •••••••••••••••••••••
Runni~ng B~LT •••••••••••••••••••••••••••••
Checking TS78 Revision Levels ..•••••••••••••
Ke ypa-d Mo-d e ••••••••••••••••••••••••••••••••••
Parameter Area .•.••••••••••••••••••••.••
Prewritten Tape Motion Routines •••••••••••••••••
Running Instructions ...•••.•.....•.•.•..•..•

3-1
3-3
3-4
3-7
3-9
3-10
3-10
3-12
3-14
3-15
3-17
3-25
3-25
3-26
3-28
3-29
3-34
3-36
3-36
3-40
3- 40
3-41
3-43

4-1
4-1
4-5
4-11
4-13
4-14
4-14
4-15
4-16
4-18
4-19
4-23
4-23
4-28
,4-30
4-31
,4-31
4-38
·4-43
·4-43

4.8. 2
4.8.2.1
4.8.2.2
4.8.2.3
4.8.2.4
4.8.2.5
4.8.2.6
4.8.2.7
4.8.2.8
4.8.2.9
4.8.2.10
4.8.2.11

Descriptions and Listings ••.•.••••..•.•.•.•• 4-44
Test 0'
Test 1
Test 2
Test 3
Test 4
Test 5
Test 6
Te s t 7
Test 8
Test 9

••••••••••••••••••••••••••••••••••
..................................
..................................
.•.••.•••••••.•••••••.•.•••...•...
..................................
..................................
.........•.....••..•.•....•......•
.....•....•.....•........•.......•
..................................
..................................

4-45
4-45
4-45
4-45
4-46
4-46
4-47
4- 4 7
4-48
4-48

Test A •.•••.•••••••••••.•••••••••••..•..

4-49

CHAPTER 5

TU78 TROUBLESHOOTING PROCEDURES

5.1
5.2

General

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

PCB A ••••••••••••••••••••••••••••••••••••••••••••

5.2.1
5.2.2
5.3
5.4
5.4.1
5.4. 2
5.4.3
5.5
5.5.1
5.6
5.7
5.7. 1
5.8
5.8. 1
5.8.2
5.8.3
5.8.3.1
5.8.3.2

Pneumatic System Troubleshooting ••.•.••...•••••.
Reel Servo Troubleshooting ••••••••••••.•••••••.•
Dynamic Brake Check .••••.•••••••••••••••••..
Data Paths Troubleshooting •••••••••••••••••••..•
Introduction and Prechecks ..•.••••••••••••••
Write Path/Read Preamp Troubleshooting •.•.•.
Read Path Troubleshooting ••••••••••••••••.••
Read Data Path •••.•...•••••••••••••••..•
AMTIE Paths Troubleshooting

CHAPTER 6

REMOVAL AND REPLACEMENT

6.1
6.1.1
6.1.2
6.1.3
6.1.4
6.1.5
6.1.6
6.2
6.2.1
6.2.2

TS78 Removal/Replacement Procedures ••••••••••••.
TS78 Backplane Assembly •..••••••••••••••••••
TS78 Control Panel Board ••....••••.•.•••••••

6.2.3
6.2.4

5-1

Using the Multiple Interface Adapter (MIA)
Functional Description ..•.••••••.•.•..••••••
Use Procedure •.•••..•.•..••..••••••••••.••••
Using the PCBA Extender •••••••••••••••••••••••••
Power Supply Troubleshooting .•••••••••••••••••••
Troubleshooting Rules •••••••••••••••••••••••
Troubleshooting Hints •..••...•...•••••••••••
Troubleshooting Charts ••••••••.••••••••••.••
Load Cycle Troubleshooting ..•..•..•..••••••.•••.
Load Faul ts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Fa n

•••••••••••••••••••••••••••••••••••••••••

5-1
5-1
5-2
5-3
5-6
5-6
5-6
5-6
5-8
5-10
5-18
5-19
5-22
5-23
5-23
5-24
5-32
5-32
5-36

6-1
6-2
6-3
6-4
6-4
6-5
6-6
6-6
6-8

TS78 Power Supply Chassis ••••.••••••••••••••
Power Supply Regulators ••••••••••••.••••••••
AC/DC LO Boa rd •••••••••••.••••••••••••••••••
TU78 Removal and Replacement Procedures •••••••.•
Head Wear Check and Replacement Procedure ••.
Tape Cleaner Removal, Cleaning,
and Alignment •••••••.•..••••••••••.•.••••••• 6-10
Air Guide Disassembly and Cleaning •.•••.•••• 6-11
Air Bearing Removal and Cleaning .••••••••••• 6-12

6.2. 5
6.2.6
6.2.7
6.2.8
6.2.9
6.2.10
6.2.11
6.2.12
6.2.13
6.2.14
6.2.14.1
6.2.14.2
6.2.14.3
6.2.14.4
6.2.14.5
6.2.14.6
6.2.14.7
6.2.14.8
6.2.14.9
6- 3
6-4
6-5
6-6

B-1

Capstan Motor Replacement ...•.•••••••••••••. 6-14
Supply Reel Motor Replacement •••••••..•••.•• 6-18
Vacuum Reel Assembly and Take-up Reel
Motor Replacement .••••••••••••••••.••••••••• 6-19
Cartridge Actuator l'-1otor Replacement ...••••• 6-20
Control Assembly Removal and Replacement .••• 6-22
Blower/Compressor AC Motor Replacement .••••• 6-22
Blower Removal and Replacement .......•...••• 6-24
Compressor Removal and Replacement •.••..•••. 6-25
Air Valve Solenoid Replacement •.•••••••..••• 6-26
Printed Circuit Board Assembly (PCBA)
Removal and Replacement •..•.•••••••••••••••• 6-26
Multiple Interface Adapter PCBA ....••... 6-26
Read PCE~A •••••••••••.••••.•...••.••••••. 6-27
Wr i t e PCB A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 - 2 7
Control M2 PCBA •.......•...••••••••••••. 6-28
Capstan Servo PCBA •••••••••••••••••••••• 6-28
Reel Servo PCBA ....••....•..•.•••••••••• 6-29
GCR/PE Preamp 1 PCBA ..•••••.•.•••••••••• 6-29
Interconnect F1 PCBA ••••••••••••.••••••• 6-30
Interconnect D1 PCBA ....••.••• ~ ••••••••• 6-31
Capstan Motor Mounting •...•..••.•••••••••••••.•• 6-14
Capstan Tape Tracking Adjustment Studs .••••••••. 6-16
Cartridge Actuator Motor Alignment ...••••••••••• 6-21
Blower and Compressor Pulley Alignment .••••..•.• 6-23
Error Number Bytes ••••••••.••..•..••••
B-37
G

•••••••••

TABLES
2-1
2-2

2-3
2-4
3-1
3-2
3-3
3-4
3-5
4-1
4-2
4-3
4-4
4-5
4-6
4-7
4-8
4-9
4-10
4-11
4-12

Primary Power Connections •..•.••.•••••.•••••••••
High Altitude Kits •••••••.•••••••.••••••••••.•••
Pulley/Belt Part Numbers for Altitude Changes •••
Maximum Error Number •.•••••.•••....•.•.•••••.•••
Preventive Maintenance •.•••••.••••..••.•••••••••
Required Prerequisite/Corequisite Adjustments •..
Power Supply Voltage Readings •••••.•••••••••••••
Vacuum and Pressure Valve Components ••••••••••••
PE Gain Test Points and Adjustments •••..•••••.••
TS78 Control Panel Error Code •..•.••••••.•.•.•••
In-Line Microdiagnostics .••.......••.•.•••••••••
Off-Line Microdiagnostics ••••••••••..••.•••..•..
Microdiagnostic Chains .•.••••.•••••••.••..•.••••
Diagnostic Commands .••••••.•••••.••••.•.•.•••...
Troubleshooting Indicator Functions ...•..•....••
Top Level ASCII Port Commands .•••..••••••••••••.
BLT Devices and Messages .••..••.•.•.....•....•••
Immediate Execution Commands .•.••••••.••••.•.•••
Deferred Execution Commands •••...•.•...•.••.••••
Execution Parameters •••••.••••.•.•.•••••••••••••
Oper at i ona 1 Sta tus Pa r ameter s ••..•••••••••••••••

2-12
2-13
2-13
2-35
3-1
3-3
3-5
3-11
3-44
4-4
4-6
4-6
4-10
4-12
4-21
4-24
4-29
4-32
4-33
4-39
4-41

5-1
5-2
5-3
5-4
5-5
6-1
6-2
6-3
B-1
B-2

MIA LEDs

APPENDIX A

GLOSSARY

APPENDIX B

EXTENDED STATUS BYTES

B.l
B.2
B.3
B.3.1

Introduction .•••••••••••••••••••.••••••••••••••• B-1
Extended Drive Status •••.•.••••••••••.•••••••••. B-1
Extended Formatter Status .•••••••••••••••••••••• B-28
Error Number ••••••••••.•••••••••••••••••...• B-36

••••••••••••••••••••••••••••••••••••••••
5-2
MIA Switch Functions ••••••••••.••••••.•.•••...•.
5-2
Power Supply Troubleshooting Chart ...•..•••••..•
5-7
Load Fault Categories •••.••••••••••••••••••••••• 5-10
Reel Servo PCBA Operating Voltages •••.•..••.•••• 5-20
TS78 Field Replaceable units ••••••••••••••••••••
6-1
Power Supply Regulator Adjustments .•••••••••.•••
6-6
Parts Replaceable/Adjustment Cross Reference ..••
6-7
Operational Error Codes ••••••••••••••••.•••••••. B-37
LASSTA Codes •••••••••••••••••••••••••••••••••••• B-45

FIGURES
1-1
1-2
1-3
1-4
1-5
1-6
1-7
1-8
1-9
2-1
2-2
2-3
2-4
2-5
2-6
2-7
2-8
2-9
2-10
2-11
2-12
2-13
2-14
2-15

Basic Tape Subsystem Configuration ••••••••••...•
Possible TA78 Configurations ••••••••••••••••••••
TA78 Tape Drive •.•..••••.•••••••••.••••••.••.•..
TS78 Formatter Logic Assembly ..••.•••••••.••••••
TS78 Module Layout •••••••••••••••••••••.•.•••.••
TS78 Power Supply •..•.•.••••••••••••••••••••••••
Base Assembly .••....••••••••.••••.••.•••.••••.•••
Card Cage Area ••••••••••.•••••••••••••••••••••••
Power Pack Assembly •••••.•••••••.•••••••••••..••
Space and Service Clearance •••••••••••••••••••••
TA78 Main Power Plug/Receptacle •••••••••••••••••
Unpacking the TA78 •••.•.••••••••••••••••••••.•••
TA78 Mounting for Shipment ••••••••••••••••••••••
Location of Stabilizer Arm and Leveler Feet ..•••
PCB Retainer Bracket ••••••••••••..•••••••••••.••
Releasing the TS78 Logic Gate •••••••••••.•••.••.
Removing the TS78 Logic Cover ••••••••••..•.•••••
TA79/TU78 Power Distribution .•.•••••••••••• " ••.•
874-E/872-E Power Controller •••••••••••••.••••••
Rear of Power Pack with Pulley Cover Removed .•••
STI Bus Cable Connection ••••••••••••••••••••••••
Unit Number Selector Switch •••.••••.•••••••••.•.
Top Cover Fastener ••••••••••••••••••••••••••••••
Cabinet with Side Panels and Top Cover

1-2
1-2
1-3
1-4
1-5
1-6
1-7
1-8
1-9
2-1
2-2
2-3
2-4
2-7
2-8
2-9
2-9
2-10
2-11
2-12
2-15
2-15
2-17

Removed

..•.•.••••••••••••••••••••••.•••••.•.•••.

2-18

2-16

TU Bus Cable Routing for a Multiple Transport
Configuration ••••••••••••••••••••••••••••.••••••
Radial TU Bus Connections •••••.••••••.••••••••••
TU Bus Cable Routing and Hardware •.••••••.••••••
Cable Orientation on TU78 MIA PCB •••••••..••••••

2-19
2-22
2-23
2-24

2-17
2-18
2-19

vii

2-20
2-21
2-22
2-23
2-24
2-25
3-1
3-2
3-3
3-4
3-5
3-6
3-7
3-8
3-9
3-10
3-11
3-12
3-13
3-14
3-15

3-16
3-17
3-18
3-19
4-1
4-2
4-3
4-4
4-5
4-6
4-7
4-8
5-1
5-2
5-3
5-4
5-5
5-6
5-7
5-8
5-9
5-10
5-11
5-12
5-13
5-14

Loading Sequence without Tape •••••••••••••••••••
Inhibited Autoload Sequence •••••••••••••••••••••
Autoload Sequence ••.••..•.•...•...•..•..•...••.•
Manual Load Sequence ••••••••••••••••••••.••.••••
Unload Sequence ••••••••••••••••••••••••••••..•••
TA78 Maintenance Port .••••.•••••••••••••••••••••
Power Supply Fuse Panel . . . . . . . . . . . . . . . . . . . . . . . . •
Capstan/Regulator PCBA Adjustments and Test
Po i n t s ••••••••••••••••••••••••••••••••••••••••••
Interconnect Fl PCBA Adjustments and Test
Po in t s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Base Assembly Front Components ••••••••••••••••••
Vacuum Valve and Pressure Valve Test Points .••••
Control M2 PCBA Adjustments and Test Points .••••
Reel Servo PCBA Adjustments and Test Points •••••
Cartridge Pressure Check Point •••••••••.••••••••
GCR/PE Preamp 1 PCBA Test Points ..••.••••••••...
Forward Start Ramp •••••••••••••••••••••••••••.••
Stop Ra mp •••••••••••••••••••••••••••••••••••••••

Buffer Column Park Zone •••••••••••••••.•.••.••.•
Loop Travel Limits ••••••••••••••••••••.••.•••..•
Transport Items for Cleaning •••••••••••.••••••••
Mu I tip 1 e In t e r fa c e Ad apt e r Co n t r 0 Is, In d i cat 0 r s ,
and Connectors ••.•••••••••••••••.•••••••••••.•• ~
Read PCBA Test Poi nts and Adjustments •••.•••••.•
Read Skew Adjustment Waveforms ••••••••••••••••••
Location of Read Skew Azimuth Adjustment •••••••.
Write PCBA Test Points, Adjustments, and
Connectors ••••••••••••••••••••••••••••.•••••••••
TA78 Troubleshooting Flowchart ••••••••..•••••.••
ILTAPE Example Printout .••••••••••••••••••••••••
ILEXER Example Printout •••••••••••••••••••••••••
TS78 Logic Indicators for Troubleshooting .••••.•
TS78 Power Supply Indicators and Adjustments ••••
TU78 Logic Indicators for Troubleshooting ••••.•.
Tape Motion Returned Status •.••••••••..•••••••••
Keypad Mode Program Example •...••••••••.•••••.••
PCBA Extender

•••••••••••••••••••••••••••••••••••

PCBA in Extended position .•••••••••.•••••.••.••.
Autoload Timing Diagram •••••••••••••••••.••.•..•
Load Fault 0 Flow Diagram ••••••••••••••••••••...
Load Fault 1 Flow Diagram •••••••••••••.•••••••••
Load Fault 2 Flow Diagram •••••••••••••••.....•••
Load Fault 3 Flow Diagram ••••••••••.•.•••..•••••
Load Fault 4 Flow Diagram ••••••••••••••.•.•••••.
Load Fault 5 Flow Diagram •••••••••••••••••••••.•
Load Fault 6 Flow Diagram ••••••••••...••••.••...
Pneumatic Troubleshooting Flow Diagram ••••••••.•
Supply Reel Simplified Schematic Diagram ••••••••
Write Path One Function Block Diagram •••••.•.•••
Read Preamplifier Output Waveform •••.•••••.••.••

viii

2-27
2-2'8
2-29
2-30
2-31
2-33
3-5
3- 6

3-7
3-8
3-10
3-11
3-13
3-16
3-21
3-21
3-23
3-30
3-33
3-35
3-37
3-38
3-38
3-39
3-41
4-2
4-16
4-17
4-19
4-20
4-20
4-36
4-37
5-3
5-5
5-9
5-11
5-12
5-13
5-14
5-15
5-16
5-17
5-18
5-19
5-25
5-26

5 .... 15
5-16
5-17
5-18
5-19
5-20
5-21
5-22
5-23
5-24
5-25
5-26
6-1
6-2

Normal Read Head Output While Reading ••••••.••.•
Normal Read Head Output While Writing .•••••••..•
Write Amplifier Output with No Load ••••••.••.•••
write Data at Input to write PCBA •••••.•.•...••.
Write/Erase Head Plug (P6) Test Points ••••••..••
Read Path One Functional Block Diagram •.••••.••.
Automatic Gain Control (AGC) Waveform - GCR

5-28
5-29
5-30
5-30
5-31
5-33

Mod e

5-34
5-36
5-37
5-37
5-39
5-41

••••••••••••••••••••••••••••••••••••••••••••

Read Data Output •.•••.••••••••.•••••••••••••••.•
AMTIE Generation Circuitry . . . . . . . . . . . . . . . . . . . . . .
+VAM Test Point on Write PCBA ..••••••••••.••..••
+VAM AMTIE Threshold Voltage ••.•••••••••••.••.•.
AMTIE Signal switching ••••••..••••••.••••...•...
Read/Write Head, Tape Cleaner and Air Guide
6-9
Removal and Replacement ••••..•••••••••••••.•••..
Air Bearing and Ceramic Guide Orientation ..••.•. 6-13

CHAPTER 1
INTRODUCTION

1.1
SCOPE
This manual provides information needed by trained, qualified
service personnel to install and maintain TA78 hardware.
Preventive maintenance information in this manual includes a list
of periodic tasks that involve the transport only. Corrective
maintenance information in this manual includes procedures for
adjustments,
troubleshooting,
and
parts
replacement.
Troubleshooting involves the use of certain aids that apply to the
formatter and/or transport, and hands-on procedures that apply to
the transport only.
1.2
HARDWARE CONFIGURATION
The TA78 tape drive includes a TS78 tape formatter and a TU78 tape
transport (Figure 1-1). The TS78 formatter interfaces with up to
four TU78 transports. Therefore, you can add up to three TU78
slave transports to a TA78. Each transport is independently cabled
with a radial bus configuration. This con+igurati~n allows you to
remove one or more transports while the others' s~ay on-line.
The standard tape interface (STl) bus connects the TS78 formatter
to a tape data channel (TDC) module in the hierarchical storage
controller (HSC). A TOC module supports up to 4 TST8 formatters
and therefore supports up to 16 TU78 transports. Separate STl bus
cabling connects each TS78 directly to the TOC module. As with the
transports, you can remove one or more formatters while the others
stay on-line.
The TS78 formatter is avai lable in only one vers ion tha t has
h a r d war e for s tat i c d u a 1- p or tin g wit h . t w·o S T I bus cab 1 e s .
Therefore, a TA78 can be driven by two HSCs (Figure 1-2).
The TA78 is available in two standard versions.
in the input power required by the transport.
TA78-BF
TA78-BJ

208 Vac at 60 Hz
208 Vac at 50 Hz

1-1

They differ only

I"'TA 78TAPE[; RM #-;-

I
I
I

TO
DISK
DRIVES

Vi
W

STI
BUS.

I
HSC
CPU/
STAR
COUPLER

CI
BUS

IDDC
IMODULE

r--

ITDC
IMODULE

(1)

I
I

CONTROLLER:

TS78
FORMATTER

en
:::l
co

(2)

_.J

STI BUS
STI BUS

(3)

TA78#1

....--~-------TA78#2

r:;:-------:-,

TA78 TAPE DRIVE

NOTES
1 THE NUMBER OF TDC AND DOC
MODULES IN THE HSC DEPEND
ON THE EXACT HSC MODEL AND
SUBSYSTEM CONFIGURATION

TS78
FORMATTER 1 4 - - - - 1
STI
BUS

2 NUMBERS IN PARENTHESES REFER
TO POSSIBLE UNIT NUMBERS THAT
ARE ASSIGNED TO EACH TRANSPORT
(PARAGRAPH 2.4.2 STEPS 12-15)

TU78

.----1
TRANSPORT
#0
J(12)1

I
I

(13)

(14)

(15)

L._

MA 0134 83
SHR-0142-84

Figure 1-1

Basic Tape Subsystem Configuration

TS7B FORMATTER
I
I

: (M8955)

r-----

(Ma971) I
I
HSC
CONTROLLER
B

ITU
I PO

I
I
I
I

1<1----'

lp',

I (M8955)

·OPTIONAL
MA 0133-83
SHR-0143-84

Figure 1-2

Possible TA78 Configurations

1-2

1.3
PHYSICAL DESCRIPTION
An H9602-KA cabinet houses the TA78. Figure
subassemblies of the TA78 listed below.

1-3

shows

the major

TS78 tape formatter
TS78 power supply
872-E or 874-E power controller
TU78 transport (base assembly, card cage area, and power pack
assembly)

CABINET
EXHAUST
FANS (2)

TS78 CONTROL
PANEL

TS78

POWER

SU~I"--O_~

HEAT

_ _ _ _ _':lLr--.rl

EXCHANGER~

FRONT VIEW
REAR VIEW

Figure 1-3

LOGIC FAN

TA78 Tape Drive (Front and Rear View)

1-3

The TS78 tape formatter contains the formatter logic assembly,
control panel, and bulkh,~ad connector. The formatter logic
assembly (Figure 1-4) includes the 20 modules in the following
list. Figure 1-5 shows the backplane module layout.

je
FRONT VIEW

REAR VIEW
MA013683
SHR-0144-84

Figure 1-4

TS78 Formatter Logic Assembly
(Front and Rear View)

1-4

M8950 read channel (9)
M895l error correcting code (ECC) controller
M8952 cyclic redundancy checker (CRC)
M8953 read path controller
M8955 tape unit port (2)
M8958 translator
M8959 write microcontroller
M8970 STI protocol microcontroller
M897l STI interface
M8972 microcomputer
M8973 extended memory

COLUMNS

16 15 14 13 12 11 10

87654321

(/)

I-

a: U
0

:2!
~

i='

:2!

X
S

C')

r-..

a: 0)
co

c..

In
In
0)

U U
:2! :2!

::J

t:::

co
:2!

~
0)

In
0)

--J
c:l

<r:
--J

r-..

co co
:2! :2!

.<r:

;;:;:

~
~

~
r-..
0)
0)
co co
:2! :2!

<r:
--J
c:l

MA-6174D

SHR.0145-84

Figure 1-5

TS78 Module Layout (Rear View)

1-5

Figure 1-6 shows the TS78 power supply (70-17121), which includes
the following items.
H7422-AB power supply chassis
H7441 +5 V regulator (2)
H7490 -5 V regulator
H7476 +15 V regulator
54-141~2 AC/DC LO module
Figure 1-7 shows
listed below.

the

components

the base

assembly.

They are

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)
Cartridge motor (PN 29-23280)
Pressure swi tch (pneumatic interlock) (PN 29-23239)
Pressure valve assembly (PN 29-23249)
Interconnect Fl printed circuit board (PCB) (PN 29-23770)
Reel motor assemblies (2) (PN 29-23236)
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
preamplifier PCB (PN 29-23766)
Vacuum transducer assembly (PN 29-23246)
Pressure switch (column limit) (4) (PN 29-23238)

",----

---

-1--

/"
/

-"-

AC ON

·O~
AC OFF

'~5V_~_+5V

ADJ.
I

REGULATOR 2

H7441
L __. ________ _
I

II
I

-5V _~_-5V
ADJ.
ON

REGULATOR 4

H7441
+15V_ /jjJ _
ON

Figure 1-6

REGULATOR 1

REGULATOR 3

H7490

H7476

TS78 Power Supply
1-6

-15V
ON

BUFFER BOX DOOR
ASSEMBLY

HEAD

FRONT VIEW

PRESSURE SWITCH

PRESSURE

PRESSURE SWITCH (2)
(VACUUM)

ASSEMBL Y
VACUUM VALVE
ASSEMBLY
PREAMP PCB

PACK SENSE ASSEMBLY
(NOT SHOWN)

REAR VIEW

MA-01S2-83
SHR-0016-84

Figure 1-7

Base Asssemb1y (Front and Rear View)

1-7

Figure
items.

1-8

shows

the

card

cage,

which

contains

the

following

Multiple interface adapter (MIA) PCB (PN 29-23769)
Read PCB (PN 29-23762)
write PCB (PN 29-23763)
Control M2 PCB (PN 29-23764)
Capstan/regulator PCB (PN 29-23765)
Reel servo PCB (PN 29-23231)
Cabinet exhaust fans (2) (PN 12-17916-02)
Interconnect D1 PCB (not shown in Figure 1-8) (PN 29-23211)

MIA PCB

CABINET
EXHAUST FANS (2)

WRITE PCB

CAPSTAN/REG.
PCB

REEL SERVO PCB
SHR-0147-84

Figure 1-8

Card Cage Area

1-8

Figure 1-9 shows
following items.

the

power

pack

assembly,

which

contains

Rectifiers (3) (PN 29-23311, 29-23312)
Vacuum hose
Fuse panel
Air filter (PN 29-23259)
Blower (PN 29-24013)
pulley cover
Power transformer terminal strip
Compressor (PN 29-23257)
Motor (PN 29-23236)
Transformer (PN 29-23258)
Muffler (PN 29-23220)
Heat exchanger fans (2)

AIR FILTER

RECTIFIERS (3)

MOTOR -----::--~~::::.;...

MUFFLER
COMPRESSOR

POWER
TRANSFORMER
TERMINAL
STRIP
(UNDER COVER)

PULLEY COVER
MA·013783
SHR-0148-84

Figure 1-9

Power Pack Assembly (Rear View)

1-9

the

1.4
MAINTENANCE PHILOSOPHY
TA78 maintenance includes customer care, preventive maintenance,
and corrective maintenance. Customer care involves daily cleaning
of the transport as described in Paragraph 4.3 of the TA78
Magnetic Tape Drive User Guide.
Preventive
and
corrective
mafntenance-tas~should()nJLy-l)e performed by trained, qualified
service personnel.
Preventive maintenance (PM) is necessary only for the transport.
Regular PM includes cleaning certain parts and checking certain
adjustments.
The corrective maintenance philosophy is isolation of a failure to
a single field replaceable unit
(FRU)
such as a module or
mechanical assembly. Some transport fai lures may need only an
adjustment as opposed to FRU replacement.
The TA78 offers several troubleshooting aids which apply to the
formatter and/or transport. The primary t'roubleshooting aids are
formatter-resident microdiagnostics. Other troubleshooting aids
include: subsystem diagnostics, LED indicators, the error log,
prewritten tape motion routines, and the ability for you to write
and run your own tape motion routines.
You may need addi ti ona 1 hands-on troubleshooti ng procedures to
isolate a failure in the transport to a single FRU. In addition,
troubleshooting can also be performed using functional block
diagrams, flow diagrams, timing diagrams, and engineering logic
drawings.
1.5
TOOLS
In addition to the standard Digital tool kit, you need the
following tools to service the TA78. The third column of the list
identifies tools that are in the TS78 control distribution (CD)
kit (PN A2-W0617-10) or the TU78 CD kit (PN A2-W0341-10).
Description

Part Number

Included
in a CD Kit

Dual-trace oscilloscope
with two X10/X1 probes

Digital voltmeter

Two multilayer dual-height
module extenders

W900

Reel motor centering tool

29-23206

Yes

Reel flange locating bar

29-23207

Yes

PCBA extender

29-23218

Yes

1-10

Description

Part Number

Included
in a CD Kit

Lower restraint tube
fitting

29-23228

Yes

Differential pressure
gauge (0--40 inch H2 0)

29-11650

Yes

Differential pressure
gauge (0--5 PSI)

29-11636

Yes

Portable accessory package
for gauges (2 needed)

29-11647

Yes

Tachometer (decimal
readou t)

29-11635

Yes

Tape crimper

47-00038

Yes

Xcelite handle

29-10562

Yes

7-inch extension

29-11625

Yes

5/32 inch X 4 inch
ballpoint hex driver

29-11630

Yes

Number 1 phillips
screwdriver shaft

29-11001

Yes

Master skew tape
(1200 ft)

29-19224

Magna-See tape developer

29-16871

50X microscope with
graticule

29-20273

Heat sink compound

90-08268

Yes

Inspection mirror
(dental type)

29-19663

Cleaning kit

TUC01

(comes with
TA78 )

Standard output tape

29-11691

Handheld terminal kit
(or equivalent)

29-24195

Yes

STI loopback connector (2)

70-19074-01 (2)

Yes

1-11

1.6
RELATED DOCUMENTS
The following list describes documents related to the TA78.

Title

Order Number

Contents

TA78 Magnetic Tape
Drive User Guide

EK-0TA78-UG

Description, operation, and
installation of TA78

TA78 Magnetic Tape
Drive Technical
Description Manual

EK-0TA78-TD

Theory of operation of TU78
transport, TS78 formatter,
and TS78 power supply

TA78 Magnetic Tape
Drive Maintenance
Guide

AA-P673A-TK

Summary of troubleshooting
and maintenance procedures
for TA78

TA78 Magnetic Tape
Drive IPB

EK-0TA78-IP

Exploded views and parts
lists of TU78 transport,
TS78 formatter, and TS78
power supply

874 Power Controller
IPB

EK-00874-IP

Exploded views and parts
lists of 874

872 Power Controller
IPB

EK-00872-IP

Exploded views and parts
lists of 872

TU78 Magnetic Tape
Transport Technical
Manual, Volume 1

EK-1TU78-TM

Schematics and logic prints
of TU78

HSC50 Service Manual

EK-HSC50-SV

Procedures for troubleshooting HSC50

TA78 Field Maintenance
Pr int Set

MP-0l614-00

Engineering drawings and
parts lists for TS78
formatter mechanics and
logic and TS78 power supply
mechanics and circuitry

1-12

CHAPTER 2
INSTALLATION

2.1
SITE PLANNING
Follow the requirements
site for the TA78.

specified

this

section

prepare

2.1.1
Space Requirements
Figure 2-1 shows the space and service clearances required for the
TA78 cabinet. There must be enough space to swing the TS78
formatter out of the cabinet for servicing and open the front and
rear doors on the TU78 tape transport.

-~~2;~N

- r - - - r_ _ \Ie-.- -____

'" \
"

64.1 CM
(251/4 IN.)

REAR DOOR

\
+

144.8 CM
(57 IN.)

+
REMOVABLE SIDE PANEL

76.2 CM
(30 IN.)

LEVELER

L...+_~______+-li,-/ 4 PLACES

/
53.3 CM

(21 IN.)

L
Figure 2-1

BASE ASSEMB L Y

/
/"
SHR-0149-84

Space and Service Clearance (Top View)

2-1

RECEPTACLE

PLUG

------_..

1---

PHASE OR
NEUTRAL
BROWN

BLUE

(~
~

GREEN/YELLOW

GREEN
EARTH
GROUND

~)
~

HUBBEL #2621

HUBBE L #2620

NEMA #L6-30P

NEMA #L6-30R

DEC #12-16886-00

DEC #12-1688700

(NEUTRAL
PREFERRED)

PHASE OR
NEUTRAL

MA 014083
SH n-0150-84

Figure 2-2

TA78 Main Power Plug/Receptacle

2.1.2
Power Requirements
The TA78 tape drive can operate from 188 Vac to 256 Vac at 60 Hz,
or 198 Vac to 256 Vac at 50 Hz, wi th proper connections on the
power pack assembly. Line voltage should be maintained to within
+10 percent of the nominal value. Frequency should not vary more
than +1 Hz. Figure 2-2 shows the compa tible power receptacle for
the TA78.
2.1.3
Environmental Requirements
The TA78 tape drive should be in an area free of excessive dust,
dirt, corrosive fumes, and vapors. 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 coo1
6
0
0
well-;~}ltered, humidified air. A temperature of 15 to 27 C (59
to 80
F) and rela ti ve humidi ty of 40 to 60 percent should be
maintained.
2.2
UNPACKING AND INSPECTION
This section provides procedures for unpacking and inspecting the
TA78.
2.2.1
Unpacking
The TA78 cabinet (H9602-KA) comes mounted to a wooden shipping
skid that absorbs shock. The skid measures about 76 cm (30 in)
wide, 107 cm (42 in) long, and 15 cm (5.75 in) high. The cabinet
is packed in an extra strong corrugated cardboard container. The
container measures about 76 cm (30 in) wide, 89 cm (35 in) long,
and 147 cm (58 in) high. (Uni ts shipped outside the continental
united States have an additional wooden container around the
cardboard carton. The panels of the container are bolted
together.) Also mounted to the skid are two wooden ramps that you
reposition during the unpacking procedure to roll the cabinet off
the skid.

2-2

PLASTIC BANDS,
CONTAINER,
CUT REMOVE AND DISPOSE
REMOVE AND DISPOSE~'
,
PLASTIC BAG,
REMOVE AND DISPOSE

X /.------1---"-----.!" "
// / '",,;
~'"

-/--_. -

"~i ~
~~
"

r~
,,,-~j

-_~I

"j--td I

I
I

.
'-<1<

;

--I

/1';'

I
\/

POLYESTER TAPE,
CUT

RAMPS, ATTACH TO
SKID DECK

MA-7015
S H R -0024-84

Figure 2-3

To unpack the
Figure 2-3.)
1.

TA78,

Unpacking the TA78

perform

the

following

procedure.

Remove banding, angle boards, shipping
plastic bag from unit as shown and dispose.

2-3

(Refer

carton,

to
and

TA78 CABINET
FRAME ~_....._ _......----_ _

TEE NUT

SKIDDECK~

=.~~:
~~
/

HEX BOLT
(NY LOCK)

SQUARE WASHER

MA-7016
SHR-001784

Figure 2--4

TA78 Mounting for Shipment

Remove four hex bolts and square washers which hold unit
to skid
(Figure 2-4). Dispose of skid blocks and
hardware.

From the shipping ki t, remove four thumb screws and two
flat washers. Remove two 1/4-20 X 3/4 hex bolts from the
shipping ki t and secure the orange wheel locks to the
cabinet. Make sure the wheels face from side to side of
the unit and not from front to back.

Remove the two skid ramps from the front of the skid.
Save the two flat washers and dispose of the two hex
bolts and external tooth washers.
You need four
procedure.

NOTE
flat washers

for

this

Attach both skid ramps and secure to the side of the skid
as shown in Figure 2-3.
CAUTION
The following step requires two people
to ro 11 the TA 78 down the ramps. The
majority of the transport's weight is in
the upper-half of the cabinet, making it
top-heavy. Do not try this procedure
alone.

2-4

With one person standing in front and one person standing
in back of uni t, guide uni t down ramps unti I safely on
floor.

Dispose of ramps and hardware.

2.2.2
Inspection
After unpacking the TA78, inspect it, and report any damage to the
responsible shipper and the local Digital sales office. Perform
the inspection as follows.
1.

Inspect all switches, indicators, and panels for damage.

Open the transport front door. Press the upper and lower
release buttons in all the way and open the buffer box
door. Make sure the buffer box door is tightly secured to
the cabinet. Inspect for foreign material, loose or
damaged components, and glass damage.

Check the transport for any foreign material
the take-up reel or other moving parts.

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

Rotate the
damage.

capstan.

Check

for

binding

and

lodged

physical

CAUTION
The capstan is fragile. Do not touch its
rubber surface or apply pressure to it.
Pressure causes it to deform.
6.

Check the tape path for any sharp edges.

Close the buffer box door by pressing the two release
buttons. Use moderate pressure; the buttons will not
catch if pressed too hard.

Close the transport front door.

2-5

2.3
SINGLE TRANSPORT INSTALLATION
This section provides information for
single transport.

installing

TA78

with

2.3.1
Mechanical Installation
After unpacking and inspecting the TA78, roll it into position and
proceed as follows.
NOTE
If the TA78 is placed next to another
system cabinet, do not remove the
adjoining side panels and bolt the
cabinets together. Instead, leave the
panels on and position the TA78 tightly
against the other cabinet. This practice
maintains proper air flow in both
cabinets.
1.

The vent in the cabinet front panel is an array of
vertical slots. A quick-release latch is about 2.54 cm (1
in) behind each end of this array. Insert a thin-bladed
tool ( s uc has a sm all s tee 1 r u 1 e) in too n e 0 f the end
slots and push on the latch while pulling the front panel
forward to release one corner. In the same manner, while
continuing to pull forward, release the latch at the
other end of the array to free the panel. Remove the
panel and set it aside. Do not disconnect the ground
strap from the panel.

Remove the two leveler pads and four leveler feet tha t
are blister-wrapped and taped to the inside of the front
panel.

Ra ise the interlock rods on each side of the cabinet.
Remove the two stabilizer arms from the stabilizer sleeve
assemblies (Figure 2-5).

Screw the leveler pads into the stabilizer arms.

Raise the interlock rods. Reinsert the stabilizer arms in
the stabilizer sleeve assemblies.

Install the levelE~r feet in
cabinet frame (Figure 2-5).

Using a 9/16-inch wrench, lower the leveling feet
they contact the floor and stabilize the cabinet.

Using a
level.

level,

adjust

the

2-6

the

feet

lower

until

corners

the

until

cabinet

INTERLOCK
ROD

STABiliZER
ARM

11-5612
MA-7017
SHR-0022-84

Figure 2-5

Location of Stabilizer Arm and Leveler Feet

Extend the two stabilizer arms and lower the leveler
pads. The pad s should just touch the floor yet easily
sl ide along the floor. Do not place any weight on the
pads.

10.

Insert a 5/32-inch allen wrench in the rear door latch.
Turn the wrench one-quarter turn counterclockwise. Open
the door.

11.

Open the transport front door and the buffer box door.
Us in g a s ere wd r i ve r, reI e as e the s e r vic e 10 c k i n the
lower-right corner of the base assembly. Swing the base
assembly open.
NOTE
The base assembly does not swi ng open
unless the stabilizer arms are extended
(step 9) •

2-7

MIA PCB

READ PCB

WRITE PCB

CONTROL M2PCB

PUSH>

CAPSTAN SERVO PCB
REEL SERVO PCB
MI\ 2645A

SHR-0151-84

Figure 2-6

PCB Retainer Bracket (Side View)

12.

Remove the PCB retaining
lower front and pulling
2-6) .

13.

Check seating of the PCBs in their

14.

Replace the PCB retaining bracket.

15.

Make sure the TS78 is securely mounted to the frame
members inside the cabinet. Check for damage to the
backplane (cracks, bent pins, etc.).

16.

Remove the two 10--32 screws (Figure 2-7) secur i ng the
left side of the ']~S78 gate. Swing the gate out on its
hinge. Loosen the two logic cover retaining screws
(Figure 2-8) and remove the cover.

17.

Make sure all circuit modules are firmly seated in their
correct locations (Figure 1-5).

18.

Replace the logic cover and tighten the retaining screws.
2-8

bracket by pushing in on the
down from underneath (Figure
sockets~

TS78
LOGIC GATE

REMOVE TWO
10-32
SCREWS

MA 0141-83
SH R-0152-84

Figure 2-7

Releasing the TS78 Logic Gate

REMOVE
LOGIC
COVER

RELEASE
CABLES

Figure 2-8

Removing the TS78 Logic Cover

2-9

2.3.2
Power and Cabling
Figure 2-9 shows the TA78 ac power distribution system.
this figure while making the following checks.
1.

Refer to

Check the following internal power cabling connections.
a.

Power cable from 874-E/872-E power
switched outlet to transport power pack

controller

Power cable from power controller switched outlet to
cabinet exhaust blowers

Power cable from power controller switched outlet to
pneumatic system heat exchanger blowers

Power cable from power controller switched outlet to
TS78 power supply

REMOTE SENSE CABLE

c:;==========::::;D (70:08288-8F) OUT

~'---:':1....J1I

TO SLAVE TU78

CABINET EXHAUST
BLOWERS
~--==----"';~===-Tr' LOGIC
o

FAN

n------=;;;;..,., PNEUMATIC
I.I--_ _ _ _-'=I~

SYSTEM HEAT
EXCHANGE R

POWER PACK

POWER
CONTROLLER
(874-E SHOWN)

PLUG [NEMA L6-30P OR
P6-30(IG) FOR ISOLATED
GROUND]

r -

-D~E~B;- -

I
I

I
I
I
I
....J

LOGIC
GATE

'~================~ FAN

L___ . . . . . ~8~Y

MA .. 7018
SH R-Q018-84

Figure 2-9

TA78/TU78 Power Distribution

2-10

Power cable from power controller switched outlet to
TS78 logic cage blower

DC power cable harness from TS78 power supply to TS78
logic gate

Make sure the power on/off circuit breaker on the power
controller is on and the remote/local swi tch is set to
REMOTE ON (Figure 2-10).

POWER ON/OFF
CIRCUIT BREAKER

REMOTE / LOCAL
SWITCH

oeot ",;~,,~,,;:,

iloooll/;looollO

~_o

REMOTE SWITCHING
BUS JACKS

O_O_£D ,--[_----' °

__
o __
0

POWER AVAILABLE
INDICATOR
872-E FRONT PANEL

POWER ON/OFF
CIRCUIT BREAKER

POWER AVAILABLE
INDICATOR

-=I

,/-

,\
O(~~~BO
o 0 0
0
0
0
~REMOTE LOCAL

O___~_O_O_O~~O~

O __

L---l.--_ _ _

REMOTE SWITCHING
BUS JACKS

[

) 0

REMOTE / LOCAL
SWITCH
874-E FRONT PANEL

SWITCHED OUTLETS

UNSWITCHED OUTLETS

/l~

r::A~o ~w
~
w

rw
~o
~

~o
~

,,4

~ 0

REAR PANEL (874-E and 872-E)

MA-0153-83
SHR OQ1!)-B4

Figure 2-10

874-E/872-E Power Controller

2-11

Check

the fuses on the power pack fuse panel (Figure
Swing the TS78 logic gate out on its hinge to see
the fuses from the front of the cabinet.

1-9).

Remove the cover from the power transformer terminal
s t rip ( Fig u r e 2 -11). ( Al so rem 0 vet h e a c in put plug 0 n
power pack.) Make sure the blue, brown, and white/red
wires are connected according to Table 2-1. The terminals
are numbered 1 through 9, from left to right. Replace the
cover and connect the power pack connector.

POWER TRANSFORMER

\)
~

\:'1

CIRCUIT

\) I

BREAKER

COMPRESSOR
PULLEY

Figure 2-11

Table 2-1

BLOWER

MA 026638

PU LLEY

SHR 0020-84

Po we r Pa c k wit h
pulley Cover Removed
Re a r

0 f

primary Power Connections

Input voltage
Taps

Blue Wi re

Brown Wire and
Whi te/Red Wi re

210
220
230

TB1- 3
TBl-4
TBl-3

TBl-7
TBl-8
TBl-8

NOTE: All taps are +10 percent.
2-12

Make sure the circuit breaker on
pack is in the on (up) position.

the rear of the power

NOTE
All TA78s are manufactured to operate at
an elevation of 0 to 610 m (0 to 2000
ft).
If the drive you are installing is
to operate at a higher elevation,
install
one
of
the
optional
high
altitude kits listed in Table 2-2. Table
2-3 lists the parts and their part
numbers for each kit.

Table 2-2

High Al t i tude Kits

Altitude

Frequency

Part Number

610 to 1220 m
(2000 to 4000 f t)

60 Hz
50 Hz

A2W - 0 4 76-- 1 0 or 29-23985
A2W--0476-l1 or 29-23982

1220 to 1830 m
(4000 to 6000 ft)

60 Hz
50 Hz

A2W-0477-10 or 29-23986
A2W-0477-11 or 29-23983

1830 to 2438 m
(6000 to 8000 ft)

60 Hz
50 Hz

A2W-0478-10 or 29-23987
A2W-0478-11 or 29-23984

NOTE: High altitude kits with A2W-class part numbers contain
enough equipment to convert five TA78 tape drives. High altitude
kits with 29-class part numbers contain only enough equipment to
convert one drive.

Table 2-3

Pu 11 e y / Be 1 t Part Numbers for Altitude Changes

Altitude

Freq.

Blower
Belt

Compressor
Belt

AC Motor
pulley

Compressor
pulley

610--1220 m
(2000--4000 f t)

60 Hz
50 Hz

108479-03
108479-05

108479-01
108479-08

108478-- 06
108478-12

102635-03
102635-03

1220---1830 m
(4000--6000 f t)

60 Hz
50 Hz

108479--03
108479-12

108479·--01
108479-08

108478-07
108478-11

102635-03
102635-03

1830--2438 m
(6000--8000 ft)

60 Hz
50 Hz

108479--11
108479-12

108479--01
108479--01

108478--08
108478-13

102635-05
102635-05

--_._.. -- - - - - -

NOTE: Vendor part numbers are shown.

2-13

If you
steps.
a.

need

install

the

kit,

perform

the

following

Disconnect the ac line at the rear of the power pack
by pulling the plug straight out.
CAUTION
Do not try this or any other removal or
replacement procedure in the power pack
assembly without first removing the 230
V power cord.

Remove the belt guard. Remove both belts by manually
rotating the pulleys clockwise and slipping the belts
off the larger pulleys. It is not necessary to loosen
any compressor or blower mounting screws.

Remove the pulley set from the ac motor shaft. Save
the sma 11 e r pull e y (hub) for the ins tall a t i on .
Replace the larger pulley with the appropriate pulley
from the high altitude kit. Reinstall the pulleys on
the motor shaft.

Remove the pulley from the compressor shaft and
replace it with the high altitude compressor pulley.

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

Make sure both belts track completely on the pulleys.
If not, try shifting the motor pulleys.

Replace the belt guard and the power cord.

Pack the old belts and pulleys in a marked container
and leave it in the base of the transport. It is
possible that the transport may be moved to a lower
altitude in the future.

Connect the BC26V flat STI bus cable to the bulkhead
connector (Figure 2-12). The bulkhead connector is a box
at the rear of the cabinet. Cables from the HSC plug into
the bottom of the box. There is one cable for each port.
Secure each required cable with two screws.

2-14

NOTE:
STI CABLE FROM A SECOND HSC FOR
PORT B IS NOT SHOWN

MA·014483
SHR·0021·84

Figure 2-12

STI Bus Cable Connection

OFF

•• ••
- •• ••
•• ••
•• ••
128
64

TOWARD
TOP OF
FORMATTER

BINARY WEIGHTED
SWITCH VALUES

16
8

MA·6101A
SHR·0154-84

Fig ure 2--13
8.

Un it Number Se lector Switch

Assign a unique unit number to the transport in the TA78.
The unit number is a decimal number in the range of 0 to
255. To assign the unit number, use the small DIP switch
on the TS78 backplane (Figure 2-13). The DIP switch
contains eight individual switches with a binary-weighted
value assigned to each switch. To add the binary weight
of a switch to the unit number, place the switch in the
off position (press in on the left side). For example: to
assign
a
unit
number
of
34,
set
the
switches
corresponding to 32 and 2 off. All other switches should
be on.

2-15

Place a decal identifying the unit number in the
bottom-left corner of the glass in the transport door.
The decal has stick-on digits supplied in the ship kit.

100

Connect the remote switching control bus from the HSC to
one of the front
jacks on the 874-E/872-E power
controller. (When both STI ports are used, connect a bus
from both HSCs to the 874-E/872-E.)

11.

Replace the front panel. Close the rear door.

12.

Make sure system power is off at the HSC(s). Connect the
ac power cable from the 874-E/872-E to the power source.

13.

Perform the acceptance testing (Paragraph 2.5).

2.4
MULTIPLE TRANSPORT INSTALLATION
This section provides information for installing a TA78 with more
than one transport.
2.4.1
Mechanical Installation
After removing the shipping containers and skids, inspect the tape
uni ts. Then roll the cabi nets to thei r approx ima te pos i ti ons .
Place the TA78 to the left (facing front) of the slave transports.
NOTE
If the TA78/TU78 on either end is placed
next to another system cabinet, do not
remove the adjoining side panels and
bol t the cabi nets together. Instead,
leave the TA78/TU78 panels on and
posi tion the dl:i ve tightly against the
other cabi net. Thi s practice mai nta i ns
proper air flow in both cabinets.
Only the TA78 cabinet is shipped with side panels. As part of the
following installation procedure, the TA78 and TU78 slave(s) are
bol ted together and the TA78 right side panel becomes the end
slave transport's left side panel.
Unless otherwise specified, install each cabinet as follows.
1.

The vent in the cabinet front panel is an array of
vertical slots. A quick-release latch is about 2.54 cm (1
in) behind each end of this array. Insert a thin-bladed
tool (such as a small steel rule) into one of the end
slots and push on the latch while pulling the front panel
forward to release one corner. In the same manner, while
continuing to pull forward, release the latch at the
other end of the array to free the panel. Remove the
panel and set it aside. Do not di sconnect the ground
strap from the panel.

Remove the

two

leveler pads and
2-16

four

leveler

feet

tha t

Remove the two leveler pads and four leveler feet that
are blister-wrapped and taped to the inside of the front
panel.

Ra i se the inter lock rods on each s ide of the cabi net.
Remove the two stabilizer arms from the stabilizer sleeve
assemblies (Figure 2-5).

Screw the leveler pads into the stabilizer arms.

Raise the interlock rods. Reinsert the stabilizer arms in
the stabilizer sleeve assemblies.

Install the leveler feet in
cabinet frame (Figure 2-5).

Extend the two stabilizer arms from each cabinet. Lower
the leveler pads until they just touch the floor. Do not
place any weight on the pads.

Open the transport front door in the TA78. Using a
screwdriver, release the service lock in the lower-right
corner of the base assembly. Swing the base assembly
open.

the

lower

corners

the

NOTE
The base assembly does not swing open
unless the stabilizer arms are extended
(step 7).
9.

Find the fastener attached to the underside of the TA78
top cover (Figure 2-14). Release the cover by turning the
fastener
one-quarter
turn
counterclockwise.
When
released, the fastener hangs by a wire from the cover.
Pull the cover forward about 1.27 cm (0.5 in) and lift it
off. Rest the cover on top of the cabinet. Leave the
ground wire connected.

Figure 2-14
2-17

Top Cover Fastener

10.

Remove the right side panel from the TA78. Grasp the
panel on both sidE~s and lift it off the four mounting
bolts. If it does not lift off, try loosening the
mounting bolts. In this case, remove the front panel trim
to access the upper-front mounting bol t. To remove the
trim, lift it up ~nd out (Figure 2-15).

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 TA78.

13.

Push the cabinets together so they join with the mounting
bolt plates side by side.

14.

Using the short ground strap included with the slave
transports, ground the TA78 and slave cabinets together.

~MOUNTING BOLTS

FRONTTR~ _ _ _ \i~~
.

_:.

::::::::i
l

MOUNTING BOLTS
MA-2661
SHR-0156·84

Figure 2--15

Cabinet with Side panels
and Top Cover Removed

2-18

15.

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

16.

Using a
level.

17.

Level and adjust the adjoining cabinet (s) so that the
bolting (middle) holes on the four corner bolting plates
align.

level,

adjust

the

feet

until

the

cabinet

NOTE
Before you perform the next step, lay
the TU bus cables for all the slave
transports loosely between the TA78 and
first slave (Figure 2-16). There are two
4.6-m (IS-ft) cables (PN BC06R-IS) for
each slave. Place the cables wi th the
red stripe facing the rear of the
cabinet.
Do
not
tape
the
cables
together. Each cable must be free to
replace in case of failure.

( FRONT VIEW)

TU2(SLAVE)

TU 1 (SLAVE)

NOTE:
ROUTE CAB LES
UP THROUGH SPACE
BETWEEN CABINET
FRAMES.

TU 3 (SLAVE)

MA-7022A

SHR·0157·84

Fig ure 2-16

TU Bus Cable Routing for
a Multiple Transport Configuration

2-19

18.

Insert 1/4-inch bol ts in the holes and secure them wi th
kep nuts. Bol ting the cabinets this way provides good
horizontal alignment.

19.

Readjust the leveler pads on the stabilizer arms until
they touch the foor. Each pad should sl ide easily along
the floor. Do not place any weight on the pads.

20.

Install the four mounting bolts from the TA78 cabinet in
the mounting bolt plates of the end slave transport.
Remove front panel trim if necessary.

21.

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.

22.

Set the side panel from the TA78 next to the slave
transport. Connect the panel ground strap to the cabinet
frame. Mount the panel on the side of the slave
transport.

23.

Replace the top cover and secure the cover fastener.

24.

Insert a 5/32-inch allen wrench in the rear door latch.
Turn it one-quarter turn counterclockwise and open the
door.

25.

Open the base assembly of each transport. Remove the
retaining bracket by pushing in on the lower front
pulling down from underneath (Figure 2-6). Check
sea t ing of the PCBs in thei r sockets. Replace the
shipping bracket.

26.

Make sure the TS78 is securely mounted to the frame
members inside the TA78 cabinet. Check for damage to the
backplane (cracks, bent pins, etc.).

27.

Remove the two 10-32 screws (Figure 2-7) securil'!g the
left side of the TS78 gate. Swing the gate out on its
hinge. Loosen the two logic cover retaining screws
(Figure 2-8) and remove the cover. Make sure all circuit
modules are firmly seated in their correct locations
(Figure 1-5). Replace the logic cover arid tighten the
retaining screws.

2-20

PCB
and
the
PCB

2.4.2
Power and Cabling
Figure 2-9 shows the TA78/TU78 ac power distribution system. Refer
to this figure while making the following checks.
1.

Check the following internal
for all the tape units.

power

cabling

connections

Power cable from 874-E/872-E power controller
switched outlet to transport power pack (Figure 2-9)

Power cable from power controller switched outlet to
cabinet exhaust blowers

Power cable from power controller switched outlet to
pneumatic system heat exchanger blowers

Power cable from power controller switched outlet to
TS78 power supply (TA78 only)

Power cable from power controller switched outlet to
TS78 logic cage blower (TA78 only)

DC power cable harness from TS78 power supply to TS78
logic gat~ (TA78 only)

Make sure the power on/off circuit breaker on the power
controller is on and the remote/local switch is set to
REMOTE ON (Figure 2-10) •

Check the fuses on the power pack fuse panel (Figure
1-9). You can see the fuses from the front of the
cabinet. (In the TA78 cabinet, swing the TS78 logic gate
out on its hinge to see the fuses.)

Remove the cover from the power transformer terminal
s t rip ( Fig u r e 2 -11). ( Al so rem 0 vet h e a c i n put pI u g 0 n
the power pack.) Make sure the blue, brown, and white/red
wires are connected according to Table 2-1. The terminals
are numbered 1 through 9 from left to right. Replace the
cover and connect the power pack connector.

Make sure the ci rcui t breaker on the rear
pack is in the on (up) position.
NOTE
All TU78s are manufactured to operate at
an elevation of 0 to 610 m (0 to 2000
ft). If the transport you are installing
is to operate at a higher elevation,
install a high altitude belt and pulley
ki t. Refer to Paragraph 2.3.2, step 6
for instructions.

2-21

the power

Connect the
BC26V flat STI bus cable to the bulkhead
connector (Figure 2-12). The bulkhead connector is a box
at the rear of the TA78 cabinet only. Cables from the HSC
plug into the bottom of the box. There is one cable for
each port. Secure each required cable with two screws.

Install the TU bus cables between the TS78 in the TA78
cabinet, and the slave transport (s). Figure 2-16 shows
the cable posi tions in relation to the cabinet frames.
The TU bus for the transport in the TA78 is prewired at
the factory. Figure 2-17 shows the electrical connection
for each TU bus cable. Each transport has a unique set of
cab 1 e s. Th e j a c k s to wh i c h the y con n e c t ( 0 nth e T S 7 8 )
determine the cable number and part of the unit number.
For installation, start at the TS78 end of the cable and
work toward the MIA end.

TU BUS OA

TU BUS OB

TU BUS 1A

TU BUS 1B

Ilece

TU BUS 2A

TU BUS 2B

TU BUS 3A

TU BUS 3B

MA-6172A
SHR-0158-84

Figure 2-17

Radial TU Bus Connections

2-22

To route cables from the TS78, first remove the two cable
retainers. Then form and lay the new cable pairs. Figure
2-18 shows the placement of the cables within the TS78.
Install the cable pair for the highest tape unit number
first; install the pair for the lowest tape unit number
last. In other words, work from jack J8 toward jack Jl so
that all cables lie flat. Place the connectors so that
the colored str ipes on the cables are away from the
backplane. Then replace the two cable retainers.

The TU bus cables should exit through the space between
the frame members of the TA78 and the first slave
transport.
(Refer to note after step 17, Paragraph
2.4.1.) Fold all cables over and thread them through the
space between the cabinet frame and the transport card
cage side panels. The cables should lie flat over the MIA
PCBs.

LOGIC GATE
ASCII PORT
CONNECTOR
(CABLE TO TA78
CONTROL PANEL
NOT SHOWN)

FROM
TS78
POWER SUPPLY

CABLE
RETAINER

CABLE
RETAINER
MI\·6161A
SHR·Q023-84

Figure 2--18

TU Bus Cable Routing and Hardware

2-23

~~5~

RED STRIPE ..-----:---£:1

DETAIL

MA 7023A

SHR-0159-84

Figure 2-19

Cable Orientation on TU78 MIA PCB
( S 1 a v e On 1 y)

10.

Dress and bend the cables as shown in Figure 2-19. Note
the orientation of the red stripe. Plug the appropriate
cables into the two MIA jacks (J2 and J3). Take up, fold,
and tie-wrap any slack in the cables.

11.

Repeat this procedure for each set of cables going to
each slave transport. Lay the cables for each succeeding
transport over the preceding transport's MIA card (Figure
2-16) •

12.

Assign a unique uni t number to each transpor-t attached to
the T S 7 8 . Th e un :i t numb e r i s a d e c i:m a 1 numb e r in the
range of 0 to 255ft A transport unit number is equal to a
base unit number plus the transport cable number. Setting
the base number automatically sets all the transport
numbers.

2-24

13.

To assign the base number, use the small DIP swi tch on
the TS78 backplane (Figure 2-13). The DIP switch contains
eight individual switches with a binary-weighted value
assigned to each swi tch. To add the binary weight of a
swi tch to the base number, place the swi tch in the off
posi tion (press in on the left side). For example: to
assign
a
base
number
of
34,
set
the
switches
corresponding to 32 and 2 off. All other switches should
be on.

14.

To determine a transport's uni t number, add its cable
number to the base number. A transport's cable number, in
turn, is determined by the jacks on the TS78 into which
the transpor t' s TU bus cables pI ug (Figure 2-17). For
example: with a base number equal to 34,
the four
transports connected to the TS78 have unit numbers of 34,
35,36, and 37. For the transport in the TA78 cabinet,
note tha t the base number is always equal to the uni t
number because the transport cable is 0.

I 5•

P I ace a dec a l i d e n t i f yin g the t ran s po r tun i t numb e r i n
the bottom-left corner of the glass in the transpor t
door. The decal has stick-on digits supplied in the ship
kit.

16.

Connect the remote switching control bus in a daisy
chain. Connect the bus from the HSC to one of the jacks
on the front of the 874-E/872-E power controller in the
TA78. Using another cable, connect the bus from one of
the other jacks on the power controller to the power
controller in the next tape uni t. Continue the daisy
chain until all the tape units connect to the remote
swi tching control bus. (When both STI ports are used,
connect a bus from both HSCs to the power controller in
the TA78.)

17.

Make sure the system power is off at the HSC(s). Connect
the ac power cable from each 874-E/872-E to a power
source.

18.

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

19.

Perform the acceptance testing

2-25

(Paragraph 2.5).

2.5
ACCEPTANCE TESTING
This section describes all acceptance tests required for the TU78
transport and the TS78 formatter. If the tests are performed
satisfactorily, then thE~ units have been installed and are
operating properly.
There are three categor ies of acceptance testing: turn-on and
loading checkout, tape drive quick check, and subsystem level
diagnostics. The turn-on and loading checkout verifies only basic
functions of the transport and formatter. The tape drive quick
check involves calling certain microcoded test routines via the
ASCII port. The subsystem level diagnostics exercise the formatter
and transport to the fullest extent.
If you are unfamiliar with interlocks and other conditions
affecting autoload/manual load selection, refer to Paragraph 2.2.2
in the TA78 Magnetic Tape Drive User Guide.
2.5.1
Turn-On and Loading Checkout
The turn-on and loading checkout applies power to the tape drive
so you can 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 to check for the proper
responses. The checkout uses flowcharts to show the proper
sequence of events for each loading operation. The flowcharts
include minor troubleshooting aids to help find simple problems
caused by bad tape or improper loading procedures. Perform the
following operations in order.
2.5.1.1 Power On -specified events.

Follow the

instructions and
of

the

check

TA78

for

the

cabinet

Remove the lower front panel
access the TS78 formatter.

'l'urn both TS 78 STI bus ports off-l i ne by placi ng the
PORT SELECT A and B buttons on the TS78 control panel in
the disable (out) position.

Turn on the power. This may be done remotely by turning
on the HSC or locally by flipping the remote/local switch
on the power controller to LOCAL ON. (When both STI ports
are used, use only the HSC connected to port A if remote
turn-on is desired.)

Check for the following conditions.
a.

All fans turn on.

b•

Th e follow i n g i nd i cat 0 r son the TU7 8 con t r 0 1 pan e 1
light:
power,
file
protect,
6250.
All
other
indicators on the TU78 control panel remain unlit.

2-26

Press the MASTER RESET button on the TS78 formatter. All
three control/indicators on the TS78 control panel should
light for about 4 seconds. During this time, the TS78
microcomputer runs the minimum integrity and power-up
microdiagnostics. If the three indicators stay on, the
microcomputer is probably bad. If other hardware has
caused a test to fail, the FAULT indicator lights. Press
and release the FAULT button to obtain the base error
code. Refer to the troubleshooti ng procedures in thi s
manua 1.

2.5.1.2 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 2-20.

PRESS THE RESET
BUTTON ON THE TU78
CONTROL PANEL.

SUPPL Y HUB STOPS.
PRESSURE AND
VACUUM SOLENOIDS
DE ENERGIZE.

PRESS LOAD/REW
BUTTON.

~
SUPPLY HUB
ROTATES CCW.

AC MOTOR STARTS.
TAKE UP REEL TURNS
CWo (NO SUPPLY HUB
MOTION.) CARTRIDGE

1
PRESSURE AND
VACUUM SOLENOIDS
ENERGIZE.

MOTOR OPENS.

PRESSURE AND
VACUUM SOLENOIDS
ENERGIZE.

TA KE UP REEL STOPS.
SUPPLY HUB STOPS.
AC MOTOR STOPS.
PRESSURE AND VACUUM SOLENOIDS DEENERGIZE. LOAD FAULT

SUPPLY HUB
ROTATES CWo

LAMP FLASHES ON
AND OFF.

TAKE UP REEL
COM PLETES ABOUT
TEN REVOLUTIONS.

PRESS THE RESET
BUTTON ON THE TU78
CONTROL PANEL.

l
CARTRIDGE MOTOR
CLOSES. LOAD FAU L T
LAMP GOES OFF.
MA-2639A
SHR-0160-84

Figure 2-20

Lo ad i ng Sequence
Without Tape

2-27

Install a write-enable
2.5.1.3
Inhibited Autoload Sequence
r i n g 0 n a 26 7 - mm ( 1 0 . 5 - in) tape reel. Tape the leader to prevent
magnetic tape from coming off the r eel. Mo un t the r eel 0 nth e
supply hub.
Close
the
transport
front
door.
Follow
the
instructions and check for the events specified in Figure 2-21.

2.5.1.4 Autoload Sequence
Remove the tape from the leader.
Allow the magnetic tape to come off the supply reel. Make sure 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 2-22.

PRESS THE RESET
BUTTON ON THE TU78
CONTROL PANEL.

FILE PROTECTLAMPGOES
OFF. AC MOTOR
STARTS. CARTRIDGE
MOTOR OPENS. TAKE.UP REEL TURNS CWo
(NO SUPPLY REEL
MOTION.)

SUPPLY REEL STOPS.
PRESSURE AND
VACUUM SOLENOIDS
DE- EN ERGIZE.

PRESSURE AND
VACUUM SOLENOIDS
ENERGIZE.

PRESSURE AND VA
CUUM SOLENOIDS DEENERGIZE. SUPPLY
REEL STOPS. TAKE-UP
REEL STOPS. AC MO-

TAKE UP REEL
COMPLETES ABOUT
TEN REVOLUTIONS.

TOR STOPS. LOAD FAULT
LAMP FLASHES ON
AND OFF. FILE PROTECT
LAMP COMES ON.

SUPPLY REEL STOPs.-]
PRESSURE AND
VACUUM SOLENOIDS
DE-ENERGIZE.

LAMP GOES OUT.
MA 2649A
SHR-0161-84

Figure 2·-21

Inhibited Autoload Sequence
2-28

PRESS THE RESET
BUTTON ON THE
TU78 CONTROL
PANEL.

TAKE UP REEL
COMPLETES ABOUT
TAKE UP REEL
COMPLETES ABOUT

PRESSURE AND

TEN REVOLUTIONS.

VACUUM SOLENOIDS

TEN REVOLUTIONS.

DE-EN ERGIZE.
FILE PROTECT LAMP
GOES OFF. AC MOTOR
STARTS. CARTRIDGE
MOTOR OPENS.TAKEUP REEL TURNS CWo

SUPPLY REEL STOPS.

SUPPLY REEL STOPS.
PRESSURE AND
VACUUM SOLENOIDS

INSTALL A BOT

PRESSURE AND

MARKER 4.6M (15 FT.l

VACUUM SOLENOIDS

FROM THE BEGINNING

DE-ENERGIZE.

OF THE TAPE. REPEAT

DE-ENERGIZE.

THE AUTOLOAD PROCEDURE.

(NO SUPPLY REEL
MOTION.)

BOT MARKER IS TOO
FAR FROM BEGINNING

PRESSURE AND

PRESSU RE AND

OF TAPE. MARKER

VACUUM SOLENOI DS

PRESSURE AND
VACUUM SOLENOIDS
ENERGIZE.

SHOULD BE FROM 4.3

ENERGIZE.
REPEAT THE AUTO-

VACUUM SOLENOIDS

LOAD PROCEDURE

ENERGIZE.

WITH ANOTHER REEL

OF TAPE. IF THE LOAD

SEQUENCE IS STILL
DONE

tV
\0

UNSUCCESSFUL, REFER TO TROUBLESHOOTING
PROCEDURES IN THE
TA78 SERVICE
MANUAL.

TO 4.9 M (14 TO 16 FT.)
FROM BEGINNING OF
TAPE. RE POSITION THE
MARKER AND REPEAT
THE AUTOLOAD PROCEDURE. IF THE SAME
PROBLEM OCCURS
AGAIN, REPEAT THE
PROCEDURE WITH AN-

SUPPLY REEL STOPS
PRESSURE AND VA •
CUUM SOLENOIDS DE·
ENERGIZE. AC MOTOR
STOPS. LOAD F AU L T
LAMP F LASHES ON
AND OFF. FI LE PROTECT LAMP COMES ON,

OTHER REEL OF TAPE.
IF THE LOAD SEQUENCE IS STILL UNSUCCESSFUL, REFER
TO TROUBLE-

YES

TAKE UP REEL STOPS.

SHOOTING PROCEDURES IN THE
TA78 SERVICE
MANUAL.

CHECK PARAGRAPH
2.2.5 FOR PROBABLE
CAUSE. ATTEMPT ANOTHER AUTOLOAD. IF
TH E AUTOLOAD PROCEDURE FAILS AGAIN
REFER TO TROUBLE- '
SHOOTING PROCEDURES IN THE
TA78 SERVICE
MANUAL.

MA·26588

SHR·0162·84

Fig ure 2·- 22

Autoload Sequence

2.5.1.5 Manual Load Sequence -- Install a write-enable ring on a
216- or 178-mm (8.5- or 7-in) tape reel. Mount the reel on the
supply hub. Make sure the leader has no creases or rips. If
necessary, crimp the end of the tape with the tape crimper. Insert
8 to 10 cm (3 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 2-23.
2.5.1.6 Unload Sequence -- Follow the instructions and check for
the events specified in Figure 2-24.

PRESS THE RESET
BUTTON ON THE
TU78 CONTROL
PANEL.

TAKE UP REEL
COMPLETES ABOUT
TEN REVOLUTIONS.

SUPPLY REEL STOPS.
PRESSURE AND
VACUUM SOLENOIDS
DE-ENERGIZE.

FILE PROTECT LAMP
GOES OFF. AC
MOTOR STARTS.
CARTRIDGE MOTOR
OPENS. TAKE UP REEL
TURNS CW.(NO
SUPPLY REEL MOTION).

INSTALL A BOT
MARKER 4.6M (15 FT.)
FROM THE BEGINNING
OF THE TAPE. REPEAT
TH E MAN UAL LOAD
PROCEDURE.

PRESSURE AND
VACUUM SOLENOIDS
ENERGIZE.

REPEAT THE MANUAL
LOAD PROCEDURE
WITH ANOTHER REEL
OF TAPE. IF THE LOAD
SEQUENCE IS STILL
UI\ISUCCESSFUL. REFER TO TROUBLESHOOTING
PROCEDURES IN THE
TA78 SERVICE
MANUAL.

PRESSURE AND
VACUUM SOLENOIDS
DE-ENERGIZE.

BOT MARKER IS TOO
FAR FROM BEGINNING
OF TAPE. MARKER
SHOULD BE FROM 4.3
T04.9M(14TO 16FT.)
FROM BEGINNING OF
TAPE. REPOSITION THE
MARKER AND REPEAT
THE MANUAL LOAD
PROCEDURE. IF THE
SAME PROBLEM OCCURS AGAIN. REPEAT
THE PROCEDURE WITH
ANOTHER REEL OF
TAPE.IF THE LOAD SEQUENCE IS STILL UNSUCCESSFUL. REFER
TO TROUBLESHOOTING PRO
CEDURES IN THE
TA78 SERVICE
MANUAL.

PRESSURE AND
VACUUM SOLENOIDS
ENERGIZE.

TAKE-UP REEL STOPS.
SUPPLY REEL STOPS.
PRESSURE AND VACUUM SOLENOIDS DE
ENERGIZE. AC MOTOR
STOPS. FILE PROTECT
LAMP COMES ON.
LOAD FAULT LAMP
FLASHES ON AND OFF.

CHECK PARAGRAPH
2.2.5 FOR PROBABLE
CAUSE. ATTEMPT
ANOTHER MANUAL
LOAD. IF THE MANUAL
LOAD PROCEDURE
FAILS AGAIN. REFER
TO TROUBLESHOOTING PROCEDURES IN THE
TA78 SERVICE
MANUAL.

DONE
MA-2655B
5HR-0163-84

Fig ure 2- 23

Manual Load Sequence

2-30

PRESS THE RESET
BUTTON ON THE TU78
CONTROL PANEL.

l
PRESS UNLOAD
BUTTON.

l
AC MOTOR STOPS.
SU PPL Y REEL TU RN S
CCW. TAKE UP REEL
TURNS CW AND
THEN CCW.

l
TAPE UNLOADS AND
WRAPS ONTO SUPPLY
REEL.

l
SUPPLY REEL
STOPS.

l
CARTRIDGE MOTOR
CLOSES.

l
TAKE UP REEL STOPS.
FILE PROTECT LAMP
COMES ON.
MA-2652A
SHR·0164·84

Figure 2-24

2.5.1.7

Unload sequence

Manual Load Repeatability -- Perform the following steps.

Mount a 216- or 178-mm
supply hub.

Make sure
necessary,
crimper.

Insert 8 to 10 cm
threadblock column.

Close the transport front door.

Initiate

(8.5- or 7-in)

tape reel

the

the leader has no creases or rips.
If
crimp the end of the tape with the tape

manual

load

LOAD/REW button.

2-31

in)

pressing

and

tape

into

the

releasing

the

If the tape loads successfully,
to unload the tape.

Repeat steps 3, 4, 5, and 6 eight times. If a failure
occurs within the eight tests, continue manual loading up
to 20 tests. There should be no more than three failures
in 20 successive tests.

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

2.5.1.8

press the UNLOAD button

Autoload Repeatability -- Perform the following steps.

Mount a 267-mm (10.5-in)

tape reel on the supply hub.

Make sure
necessary,
crimper.

Close the transport door.

Initiate an autoload
LOAD/REW button.

If the tape loads successfully,
to unload the tape.

If autoload fails, the tape automatically tries to load a
second time. If the second try fails, the load fault
indicator flashes. This counts as one failure.

Repeat steps 4, 5, and 6 nine times. If a failure occurs
within the nine tests, continue autoloading up to 20
tests. There should be no more than two failures in the
20 successive tests.

After completing the autoload repeatability test, check
the tape for dama.ge caused by the transport. The tape
should not show enough damage to cause a load failure or
data errors.

the leader has no creases or rips.
If
crimp the end of the tape with the tape

2-32

pressing

and

releasing

the

press the UNLOAD button

2.5.2
Tape Drive Quick Check
This procedure uses TA78-resident test routines to check some
functions of the transport (s). Perform the following operations
starting with transport 0.
1.

Set the transport rotary switch in the number 1,
position (maintenance mode) .

2, or 3

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

desired

Plug an RS232-compatible,
external terminal
a
handheld terminal
(HHT)
for example
into the EIA
connector on the TS78 control panel (Figure 2-25). For
terminals that require +5 V power, +5 V (at 1 A maximum)
is available at a 3-pin Mate-N-Lok connector on the
panel.

the

POWER CONNECTOR

MA 0154-83

SHR-0165_84

Figure 2-25

TA78 Maintenance Port

2-33

Turn the external terminal on. Steps 5 through 11
describe acceptance testing initiated through the
external terminal~

Access the TA78 as follows.
a.

Type CTRL C on the terminal
entry until TA78> appears.

keyboard.

Repeat

the

Type RUN KEYPAD. The acceptable response is KEYPAD>.

To select a transport, type UNIT X where X is the
transport cable number (0, 1, 2, 3) shown in Figure 2-17.
To start testing, set X to 0 selecting the transport in
the TA78 cabinet.

Type WRITE to test the transport's functions. The tape
drive executes a write GCR command on the selected
transport. The drive then displays the results as a
two-digit code on the external terminal and waits for
another command. The only acceptable responses are 00 and
02. Any other response is not acceptable and indicates a
problem somewhere in the tape drive. Refer to the
troubleshooting procedures in this manual.

Repeat steps
present.

Type CTRL Z to ex it from the keypad program. The
drive responds by echoing Z and displays TA78>.

and

for

any

slave

transport
tape

10.

Type CTRL Z to
echoes AZ.

exit

11.

Disconnect
panel.

external

12.

Verify each TU78 vacuum and pressure setting by
performing the adjustment procedures in Paragraph 3.6.
This step is especially important if you have just
installed a high altitude kit. Adjust any setting that is
out of tolerance.

the

from

the

terminal mode.

terminal

from

the

The drive

TS78

control

2.5.3
Subsystem Level Diagnostics
Mount and load a write-enabled 267-mm (10.5-in) tape reel. Place
the transport on-line and make sure the on-line indicator lights.
Depending on the STI port being driven, set the PORT SELECT A or B
button on the TS78 control panel to the enable (in) position. If
exercising a dual port configuration, press the PORT SELEC'r A
button to the in position.
Two subsystem level diagnostics, ILTAPE and ILEXER, verify proper
TA78 operation. The paragraphs that follow briefly describe thesp
two diagnostics.
2-34

In-Line Tape Diagnostic
(ILTAPE)
Forty-seven routines
thoroughly test the TS78 formatter logic. A canned sequence, using
the basic tape commands, tests the TU78 transport functions.
In-Line Exerciser (ILEXER) -- This diagnostic exercises from 1 to
10 units in any combination of disk and tape drives connected to
an HSC. Logic is tested by writing and reading predetermined data
patterns and recording modes.
ILTAPE and ILEXER are run from the HSC ASCII port. Refer
appropriate HSC user documentation for more information.

to the

Perform the following procedure to test the TA78.
1.

Run ILTAPE (47 diagnostics and the canned sequence) for
three passes. No errors are allowed. (When both STI ports
are used, also run ILTAPE through the second port for one
pass. )

Run ILEXER. Use the GCR worst case data pattern (22) for
15 minutes.
Table 2-4 lists the acceptable error
criterion. (When both STI ports are used, also run ILEXER
through the second port for 15 minutes.)

Table 2-4

Maximum Error Number

Error Type
Designation

Description

Hard
Media
Do ub I e Tr ke r r
Do uble Tr krev
Sing 1 e Tr ke r r
Sing Ie Tr krev
Other Er r A
Other Err B
Other Err C

Nonrecoverable
Tape media
Double track correction (read)
Double track correction (read reverse)
Single track correction (read)
Sing·le track correction (read reverse)
Other (read and read reverse)
Status (read and read reverse)
Other (wr i tel

Allowed
Number
'-"
20
1
1
5

NOTES
1.

Other (read and read reverse) -- successful operation without
error correction, but wi th interesting occurrence (AMTIE or
PHTIE flag).
Status (read and read reverse)
retries.

-- successful operation after

Other (write) -- write retry succeeded
location that previous write retry failed.
2.

same

physical

If the TA78 does not meet these specifications, additional run
time is necessary to determine the validity of errors.
2-35

CHAPTER 3
CHECKS AND ADJUSTMENTS

3.1
PREVENTIVE MAINTENANCE
A preventive maintenance (PM) program is necessary for the TU78
transport. The PM tasks should only be performed by trained,
qual ified service personnel. Assuming moderate use, these tasks
should be performed every six months.
If use exceeds 2500
vacuum-on hour s i n six months, the PM frequency should increase
proportionally.
Table
3-1 lists the individual tasks and
references the appropriate paragraph for individual procedures.
Perform 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,
visually inspect the equipment for loose electrical connections,
dirt, cracks, binding, excessive wear, and loose hardware.

Table 3-1

Preventive Maintenance
Paragraph
Number

Procedure
Clean read/write head, erase head, 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.

3.9

CAUTION
Observe warnings and notes in paragraph
3.9

Remove and clean foam cabinet filters
inside front door and rear door. Perform
general cleaning of cabinet area.
Remove and clean air bearings, air guide,
and circular ceramic guide.

3-1

6.2.3,
6.2.4

Table 3-1

Preventive Maintenance (Cont)

Procedure

Paragraph
Number

Remove tape cleaner and clean blades.

6.2.2

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,
replace head.

6.2.1

Check all hoses and tubing for cracks
and tighten all connection clamps if
necessary.
Clean dirt from heat exchanger fins.
Remove pneumatic belt guard and check
belts for wear and proper tracking.

Figure 6-6

Clean compressor intake muffler/filter
element.
REPLACE COMPRESSOR IN-LINE FILTER.
NOTE
If any of the following checks are out
of tolerance, perform the associated
adjustment.
Check vacuums and pressures.

3.6

Check supply reel load speed.

3.8.2

Check take-up reel load speed.

3.8.3

Check loop positions.

3.8.4

Check cartridge limi t switches.

6.2.8
(Steps 8, 9, 10)

Check PE amplitudes.

3.10.3

Check read skew (azimuth) •

3.10.1

3-2

3.2
GENERAL ADJUSTMENT NOTES
This section provides adjustments and alignments relative to the
TU78 transport. Tl)e adj ustments and al ignments are functionally
grouped. Supporting figures are referenced where relative.
Some adjustments may require prerequisite (performed before)
and/or corequisite
(performed with)
adjustments of other
parameters (Table 3-2). 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 designated value as possible.

Table 3-2

Required prerequisite/Corequisite Adjustments

paragraph

Adj ustment

3.3
3.4
3.5
3.6

Power distribution
EOT/BOT adj ustment
pack sense adjustment
Vac u urn and air
pressure adjustments
System vacu urn
adj ustment
Takeup reel vacuum
adj ustment
Air bearing pressure
adj ustment
Thread block and
cartridge pressure
adj ustment
Capstan servo
adj ustments
Reel servo adjustments
Reel servo offset
Supply reel load speed
adj ustment
Takeup reel load speed
adj ustment
Tape loop position
adj ustment
Read/write adjustments

3.6.1
3.6.2
3.6.3
3.6.4
3.7
3.8
3.8.1
3.8.2
3.8.3
3.8.4
3.10

Prerequisites
paragraph

3-3

Corequisites
paragraph

3.3
3.3
3.6.2
3.6.1

3.3
3.3

3.6
3.9, 3.3
3.7

3.10.3

Some adjustments require using the ASCII port with an external
terminal. Procedures for operation via the ASCII port are provided
in each alignment step that requires its use. For more information
on the ASCII port and its functions, refer to Paragraph 4.7.
Some adjustments also require that the front door be open and the
interlock switch be defeabed. To defeat the interlock switch,
first open the front door. Then with a spring hook, or other
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 you have problems dur ing any al ignment procedure, refer to
Chapter 5 (TU78 Troubleshooting) for fault isolation procedures.
3.3
TU78 POWER SUBSYSTEM ADJUSTMENTS
The +5 V log ic supply vol tage is adj ustable • All other power
supplies and regulators are not adjustable. The following
proced ure is given to d i rec t serv ice per sonne I to check, and
adjust if necessary, the +5 V logic supply voltage, and to verify
that all operating dc voltages are present.
WARNING
Dangerous vol tages are present
power supply.

the

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 AI--·TBl). (Refer to Table 2-1 for proper
jumper configuration.)

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 two retaining screws from the left side of the
TS78 logic gate and swing the gate out on its hinge (TA78
only) •

Make sure the power controller circuit breaker (front) is
on as well as the power supply circuit breaker (rear).

3-4

5•

wit h a d i g ita 1 vol tm e t e r ( 0 VM ) c h e c k all the un reg u 1 ate d
dc voltages at fuses Fl through F7 with respect to
chass i s ground. The fuses are on the power supply fuse
panel. Refer to Figure 3-1 for fuse locations and Table
3-3 for proper vol tage read ings. If the read i ng s are
incorrect
go
to
Chapter
5
for
troubleshooting
information.

POWER SUPPLY PANEL

MA-3675
SHR-0166-84

Figure 3·-1

Table 3-3

Power Supply Fuse panel

Power Supply Voltage Readings

Fuse

Circuit
Function

Type

Measured Voltage (dc)
Minimum
Nominal

Maximum

Fl
F2
F3
F4
F5
F6
F7

+12 V
+24 V
-24 V
+36 V
-36 V
+36 V
+36 V

7 A FB
5 A FB
5 A FB
20 A FB
20 A FB
20 A FB
20 A FB

+09.5 V
+22.0 V
-22.0 V
+35.0 V
-35.0 V
+38.0 V
+38.0 V

+11.5
+26.0
-26.0
+40.0
-40.0
+42.0
+42.0

(S)

3-5

+10.5 V
+24.0 V
-24.0 V
+37.5 V
-37.5 V
+40.0 V
+40.0 V

V
V
V
V
V
V
V

With a DVM, check all the regulated voltages b
monitoring TPll, TP15, and TP18 with respect to TPl on
Figure 3-2 shows the
the capstan/regulator PCBA.
locations of test points and adjustments.

TPll

•
•
•

+5.00 Vdc minimum
+5.15 Vdc nominal
+5.30 Vdc maximum

TP15

•
•
•

+14.0 Vdc minimum
+15.0 Vdc nominal
+16.0 Vdc max imum

TP18

•
•
•

-14.0 Vdc minimum
-15.0 Vdc nominal
-16.0 Vdc max imum

If the vol tage measured at TPll is found to be outs ide
specified limits, adjust potentiometer R179 on the
capstan/regulator PCBA (Figure 3-2).
P11 TO INTERCONNECT D1 PCB"

Q----------Q
~EI~---Q

~-------..
- ~.ESTPOINTS"'"
R59 START RAMP ADJUST

R47 SPEED ADJUST

TEST POINTS (4972)

R 179 +5V ADJUST

R78 REVERSE STOP RAMP ADJUST
MA-3679 -.i

- - R66 FORWARD STOP RAMP ADJUST

Figure 3·-2

Capstan/Regulator PCBA Adjustments and Test Points

3-6

3.4
EaT/BOT ADJUSTMENT
The following procedure describes sensitivity adjustment of
EaT/BOT amplifier on the base assembly interconnect Fl PCBA.

the

verify power supply voltages according to Paragraph 3.3.

On the interconnect FI PCBA, connect a DVM wi th its
positive lead to TP6 and its negative lead to TP5 (Figure
3- 3) .

Open the transport front door and the buffer box door.

On a work tape, attach an EaT reflective tab about one
inch in front of the BOT tab.

, - - - - - - R1

SUPPLY POSITION ADJUST

R30

SUPPLY GAIN

TAKE-UP POSTION ADJUST

r----

R31

TAKE-UP GAIN

~--

R17

PACK SENSE (LOW TAPE) ADJUST
EOT/BOT ADJUST

• • • •

TP1 TP2 TP3 TP7 o-c::::::H:>
W1

~~H

____________~101

---- J21
REMOVE PIN 1 BEFORE
INSTALLATION
MA-3681A
SHR-0168- 8 4

Figure 3-- 3

Interconnect FI PCBA Adjustments
and Te st Po ints

3-7

Install the work tape reel on the supply hub. Thread the
tape so the EaT and BOT reflective tabs are not under the
sen s 0 r s ( Fig u r e 3 _. 4). Ma in t a i n ten s ion wit h 0 nee nd 0 f
the tape by holding the tape on the capstan. The tape
must contact the head surface.

Moni tor the DVM. The vol tage displayed should be between
+0.1 Vdc (maximum) and -0.1 Vdc (minimum).

7•

If the vol tage instep 6 is out of tolerance, adj ust
potentiometer R22 on the interconnect Fl PCBA for 0 Vdc
(Figure 3-3).

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 EaT tab under the sensor
and monitor the DVM. The voltage display should be equal
to or more positive than +2.0 Vdc.

LOAD FAULT
INDICATOR
FILE PROTECT
INDICATOR
ON LINE
INDICATOR
BOT
INDICATOR
F'OWER
INDICATOR

MODE SELECT

LOAD REW
ON LINE
UNLOAD

AIR BEARING NO 5
(BEHIND REEL!

Figure 3 4

Mf\ 7.G40D
SllR-0169-84

Base Assembly Front Components

3-8

10.

Remove the work tape and disconnect the DVM.
NOTE
If either voltage is out of tolerance,
the EOT/BOT assembly may have to be
cleaned or replaced.

3.5
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.
1.

Verify power supply voltages according to Paragraph 3.3.

On the interconnect Fl PCBA, connect a DVM with its
positive lead to TP4 and its negative lead to TP7 (Figure
3-3) •

Open the transport front door.

Rotate the take-up reel until the sensor tab (on the
inside of the outer flange of the reel) is in line with
the low tape sensor behind the reel (Figure 3-4).

Monitor the DVM.
Vdc max imum.

If the voltage is out of tolerance, adjust potentiometer
R17 on the interconnect Fl PCBA (Figure 3-3).

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.

The voltage displayed

should

NOTE
If either voltage is out of tolerance,
the pack sense assembly may have to be
cleaned or replaced.

3-9

+0.50

3.6

VACUUM AND AIR PRESSURE ADJUSTMENTS

3.6.1
System Vacuum Adjustment
Refer to Figure 3-5 and Table
adjustment.

3-4

while

performing

this

Turn transport power on.

Mount and load a 267 mm (10-1/2 in)

Open the base assembly to access the rear.

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 SI on the control M2 PCBA
(Figure 3-6) toward the front of the transport to drive
tape forward.

reel of tape.

CRIPPLE
REEL

~5~~UREMENT~O
°OCAPSTAN
MOTOR
(A) VALVE ORIENTATION ON BASE ASSEMBLY
(REAR VIEW)

N
(B) VACUUM VALVE DETAIL

Figure 3-5

MA-3488
SHR-0170-84

Vacuum valve and Pressure Valve
Te st Po ints
3-10

Table 3-4
Figure 3-5
Reference
A
B
C
D
E
F
G
H
I

Vacuum and Pressure Valve Components
Description
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 pneunatic assembl y)
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

K
L
M
N

NOT USED

P8 TO INTERCONNECT D1 PC8A

W13 o-c=J-<>
W14 O-C:J-o
W15 o-c:JO
W16 o-c:::J.<>
W17 o-c:::J.<>
W 18 o-c::J()

oc::::J-O W4

W12

oc=l-O W5

oc::J-O W6
oc=l-O W7
oe::::J-O W8

oc:J.o W9
oc:::ro W10

TEST POINTS (1-24)
J10 TO CONTROLS ASSEMBLY

Figure 3-6

TEST POINTS (25-48)
Sl MAINTENANCE SWITCH

Control M2 PCBA Adjustments and Test points
3-11

TEST POINTS (49-72)

Observe the air gauge while tape is run;~ing 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 adjustment screw (C) for
are a din g 0 f 8 64 mm ( 3 4 in) 0 f wa t e r. Wh i 1 e hoI din g the
screw, tighten the locknut and observe the air gauge to
make sure the adjustment has not changed.

Stop the tape and unload
replace the red cap.

Check the take-up reel vacuum as descr ibed in Pa ragraph
3.6.2.

it.

3.6.2
Takeup Reel Vacuum Adjustment
Refer to Figure 3-5 and Table 3-4
adjustment.

Remove

while

the

air gauge and

performing

this

Before starting this adjustment, make sure system vacuum
is within the specified limits outlined in Paragraph
3.6.1.

Turn transport power off and remove tape from the supply
reel.

Place disable servo swi tch S 1 on the reel servo
(Figure 3-7) toward the rear of the transport.

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 button on the TU78 control
panel.

Immediately rotate the take-up reel three full
deactivate the load fault zero function.

3-12

PCBA

turns to

J12 TO INTERCONNECT 01 PCB A

Q-------~
Q-------~

S1 REEL
SERVO
DISABLE
SWITCH
R52 SUPPLY
REEL
LOAD SPEED
ADJUST

TEST POINTS (1-24)

TEST POINTS (49-72)
R76 REEL SERVO OFFSET ADJUST

R91 TAKE UP REEL LOAD SPEED ADJUST

Fig ure 3·-7

Reel Servo PCBA Adj ustments and Test Po ints

Observe air gauge and check for a reading between 508 mm
( 2 0 in) 0 f wa t e r, ma x i mum, and 45 7 mm ( 18 in) 0 f wa t e r ,
minimum.
CAUTION
The specified duty cycle for vacuum and
air pressure solenoids is intermittent
three minutes on and nine minutes
off. Therefore, the uni t should not be
held in this mode for over three minutes
after which the coil should be allowed
to cool for nine minutes.

10.

If the read ing is out of tolerance, loosen the take-up
reel vacuum adjustment screw (D) and slipe the friction
plate forward or backward to obtain a reading of 483 mm
(19 in) of water.

3-13

11.

Tighten screw while observing
adjustment is not disturbed.

air

gauge

make

sure

12.

Press and release RESET button on the TU78 control panel.

13.

Remove air gauge and replace red cap. Place reel
disable switch Sl forward (servo enable position) •

servo

NOTE
The two vacuum adjustments (Paragraphs
3.6.1 and 3.6.2) are interactive, and
after performing one, the other should
be rechecked.
3.6.3
Air Bearing Pressure Adjustment
Refer to Figure 3-5 and Table 3-4
adjustment.

while

performing

this

Turn transport power on.

Mount and load a 267 mm (10-1/2 in)

Open base assembly to access the rear.

Remove red cap from air bearing pressure port (N) and
connect a differential air gauge with a range of 0 -- 34
kilopascals (0 -- 5 psi). Use the high pressure input of
the air gauge to measure pressure.

Place maintenance swi tch Sl on control M2 PCBA (Figure
3-6) 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
k i 10 pa s cal s ( 4 . 0 psi), ma x i murn , and 2 4 k i 10 pa s cal s ( 3 • 5
psi) , min i mum •

If the read ing is out of tolerance, loosen the locknut
and adjust the air bearing pressure adjustment screw (J)
for a 25.8 kilopascals (3.75 psi) reading.

Tighten the locknut while observing the air gauge to make
sure adjustment is not disturbed.

reel of tape.

CAUTION
Excessive torque on the locknut damages
port threads. Use extreme care.
9.

Stop the tape, remove the air gauge, and replace red cap.

10.

Unload the tape.

3-14

3.6.4
Thread Block and Cartridge Pressure Adjustment
Refer to Figure 3-5 and Table 3-4 while performing
adjustment.

this

NOTE
Both the thread block pressure and
cartridge pressure must be adjusted at
the same time since one ad j us tmen t
directly affects the other.
1.

Turn transport power off.

Place servo disable swi tch Sl on the reel servo PCBA
(Figure 3-7) toward the rear of the transport (servo
disable pos i t ion) .

Remove the red cap from the thread block pressure port
(M) and connect a differential air gauge with a range of
o -- 1016 mm (0 -- 40 in) of water. Use the high input to
the air gauge to measure pressure.

Turn transport power back on.

Press and release LOAD/REW on the TU78 control panel.
Immediately rotate the take-up reel six full turns by
han d . Th i s de act i vat e s loa d fa u I t z e r 0 and c a use s the
pressure solenoid to energize.
CAUTION
The specified duty cycle for vacuum and
air pressure solenoids is intermi ttent
three minutes on and nine minutes
off. Therefore, the uni t should not be
held in this mode for over three
minutes, after which the coil should be
allowed to cool for nine minutes.

Observe air gauge and check for a reading between 660 mm
( 2 6 in) 0 f wa t e r, ma x i mum, and 5 59 mm ( 2 2 in) 0 f wa t e r ,
min imum.

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
locknut while observing air gauge to make sure adjustment
is not disturbed.
CAUTION
Excessive torque on the locknut damages
the port threads. Use extreme care.

Press and release RESET on the TU78 control panel.

3-15

Disconnect air gauge and
block pressure port.

replace red

cap on

the

thread

10.

On the front panel, remove the hex socket head screw from
the cartridge pressure port in the lower cartridge
restraint (Figure 3-8), and install the tube fitting (PN
29-23228) .

11.

Connect the differential air gauge with a range of 0 -1016 mm (0 -- 40 in) of water, to the tube fitting using
the high input to the gauge.

12.

Press and release LOAD/REW on the TU78 control panel.
Immediately rotate the take-up reel six full turns by
han d . Th i s de act i vat e s loa d fa u 1 t z e r 0 and c a use s the
pressure solenoid to energize.
CAUTION
The specified duty cycle for vacuum and
ai r pressure solenoids is intermi ttent
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 for a reading between 76
mm (3 in) of water, maximum, and 50.8 mm (2 in) of water,
min imum.

MA-3484
SH R-0173-84

Fig ure 3 --8

Cartridge Pressure Check Point

3-16

14.

with no cartridge if the reading is out of tolerance,
adjust the cartridge pressure adjustment screw (Figure
3-5) for a reading of 63.5 mm (2.5 in) of water.

15.

Check cartridge pressure with tape and cartridge loaded.
The pressure with a cartridge should be greater than 229
mm (9 in) of water.

16.

Press and release RESET on the TU78 control panel.

17.

Disconnect air gauge,
socket-head screw.

18.

Steps 3 through 16 may have to be repeated several times
to ensure adjustment integration. Observe all cautions.

remove

tube

fitting

and

replace

NOTE
An alternate method to the preceding
steps
would
be
to
acquire
two
differential air gauges. Connect both
gauges to the respective ports, and make
adjustments while observing both gauges.
19.

Place the servo disable swi tch Sl, on the reel servo
PCBA, toward the front of the transport (servo enable
posi tion) .

3.7
CAPSTAN SERVO ADJUSTMENTS
The following are procedures for adjusting the capstan speed,
start ramp, and forward and reverse stop ramps. Capstan speed
adj ustment affects tape speed as it moves past the read/wr i te
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
adj ustments affect the amount of time it takes for the capstan
servo to decelerate the tape from full data handling velocity to
rest posi tion. You must perform the adjustments in the sequence
given.
1.

Verify power supply voltages according to Paragraph 3.3.

Place both STI ports off-line by placing the PORT SELECT
A and B buttons on the TS78 control panel in the disable
(out) position.

Set the transport rotary switch in the number 1, 2, or 3
position (maintenance mode) •

Load any write-enabled 267 mm (10.5 in) tape
desired transport. Place the transport on-line.

3-17

the

Plug an RS232-compatible, external terminal -- a handheld
termi na 1 (HHT) for examp1 e -- into the EI A connector on
the TS78 control panel (Figure 2-25). For terminals that
require +5 V power, +5 V (at lA maximum) is available at
a 3-pin Mate-N-Lok connector on the panel.

Turn the external terminal on.

Type CTRL C on the terminal
until TA78> appears.

To check capstan speed, type RUN VELOCITY/UNIT=X where X
is the desired transport cable number: 0, 1, 2, or 3. (If
X=0, you may omi t "/UNIT=X" from the command.) The tape
drive runs the capstan speed check routine on transport X
and displays a message on the external terminal.

A displayed message of OK indicates the capstan velocity
is within specifications. If this is the case, proceed to
s t e p 1 3 . If cap s t. a n vel 0 cit y r eq u ire sad jus tm e nt, the
tape drive runs the routine repeatedly and the displayed
message is similar to the one shown below.

keyboard.

Velocity test: R47 CAPSTAN SERVO

Repeat the entry

Th e " * " i nd i cat e s t h e ide a 1 val u e. Th e "0" i n d i cat e s t he
actual value and can be on either side of the asterisk.
10.

To adjust capstan velocity, adjust potentiometer R47 on
the capstan/regulator PCBA (Figure 3-2) while observing
the display, until the "a" and "*" merge. If the "0" is
on the left of the "*", the capstan speed is too low and
R47 must be turned clockwise. If the "a" is on the right
of the "*", the capstan speed is too high and R47 must be
turned counterclockwise.
NOTE
If EOT is detected, the tape dr i ve
rewinds the tape and contines to repeat
the test routine. Do not adjust R47
during the rewind operation.

11.

Press and release CTRL C to exit from the test. The tape
drive displays TA78>.

12.

Type RUN VELOCITY/UNIT=X where X is defined as in step 8.
The displayed message should be OK.

3-18

13.

If you suspect an intermittent capstan speed problem,
type RUN VELOCITY/UNIT=X/LOOP where X is defined as in
step 8. The tape drive then runs the capstan speed check
routine repeatedly on transport X. The displayed message
is similar to the error message in step 9. Observe the
display for about 30 seconds noting any irregularities.
Then press and release CTRL C to exit from the test.
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
3-6). The time period from trailing edge
to trailing edge should be 80 +0.8 us.

14.

If it was necessary to adjust capstan speed, then the PE
gains must be adjusted (Paragraph 3.10.3).

15.

To check the start ramp, type RUN RAMP/UNIT=X where X is
defined as in step 8. This tests the start ramp as the
capstan velocity was tested in step 8.

16.

If the displayed message is OK, no adjustment is required
and you can proceed to step 20. Otherwise, the start ramp
requi res adj ustment. The rout ine is run repea tedly and
the displayed message is similar to the one shown below.
start ramp:

R59 CAPSTAN SERVO

The "*" and "a" indicate the ideal and actual values as
described in step 9.
17.

To adjust the start ramp, adjust potentiometer R59 on the
capstan/regula tor PCBA (Figure 3- 2) whi Ie observ ing the
display, until the "a" and "*" merge. If the "a" is on
the left of the "*", the capstan speed is ramping up too
slowly and R59 must be turned clockwise. If the "a" is on
the right of the "*", the capstan speed is ramping up too
quickly and R59 must be turned counterclockwise.

18.

Press and release CTRL C to exit from the test.

19.

Type RUN RAMP/UNIT=X where X is defined as in step 8. The
displayed message should be OK.

20.

If you suspect an intermittent start ramp problem, type
RUN RAMP/UNIT=X/LOOP where X is defined as in step 8. The
start ramp routine is then run repeatedly and the
displayed output is similar to the error message in step
16.
For
30
seconds,
observe
the
display
for
irregularities and then use CTRL C to exit the test.

3-19

NOTE
The following is an alternate procedure
for measuring the start ramp.
•

Rewind
the
tape
transport on-line.

and

place

the

•

Create a 3200 FCI pattern on the tape
by executing a WRTMAI command through
the ASCII port in keypad mode. (Both
STI ports must be off-line.) Rewind
the tape.

•

Connect an oscilloscope to the TU78.
vertical CHI to GCR/PE preamp 1 PCBA
R14 top lead (Figure 3-9)

•

Connect a jumper between the control
M2 PCBA TP30 and TP25.

•

Set control M2 PCBA maintenance
switch Sl to the front (toward you).
The tape alternately starts and
stops.

•

Refer
to
Figure
3-10a
for
a
representative scope waveform and
settings.

The start ramp rise time (0 to 95
• percent)
should be in the 1.1 to 1.3
ms range.
If it is out of adjustment, adjust
• capstan/regulator
PCBA R59 for 1.2
ms.
Return control M2
• center
position.
•

PCBA

the

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 except
there may be a small "forward hitch"
envelope for a 1.7 ms duration
preceding the ramp. This forward
hitch envelope is normal if there has
been no tape motion for about 10 to
20 ms or more before a reverse motion
command. Refer to Figure 3-10b for a
representa t i ve scope waveform and
settings.
3-20

J902 TO
READ PCBA

R13}
R14

TRACK 5
PREAMPLIFIER
OUTPUTS

TRACK
ORIENTATION

{5]6

••••••••••••••••••

P6 TO
WRITE PCBA

R4 R7 Rl0 R13 R16 R19 R22 R25
R2 R5 R8
Rll R14 R17 R20 R23 R26

Ul0

c=J

BLACK - + 0 J906
WHITE --.0 J905

READ HEAD
CONNECTOR

WRITE HEAD
CONNECTOR

Figure 3·-9

MA6806A
SHR-0174-84

GCR/PE preamp 1 PCBA Test Points
0%
95%
!--1.2ms--...:

SLIGHT OVERSHOOT HERE IS DESIRABLE

I
I

PROBE:
HORIZ:
VERT:
CH1:
SYNC:

NOTE:

Xl0
0.2 MSEC/DIV
50mV/DIV
PREAMP R14
AC EXT POSITIVE
TP21 CONTROL
M2 PCBA

II.,

I ,~

PROBE:
HORIZ:
VERT:
CHl
SYNC:

lOX
0.5,sec/DIV
O.1V/DIV
PREAMP R14
AC, EXT, POSITIVE
TP21 CONTROL M2 PCBA

NOTE:

REVERSE START RAMP
IS MEASURED BETWEEN
0% AND 95% OF
STEADY STATE
WAVEFORM AFTER
FORWARD HITCH.

FORWARD START RAMP
IS MEASURED BETWEEN
0% AND 95% OF
STEADY STATE
WAVEFORM

(a) FORWARD START RAMP

FORWARD
HITCH

f4----l.7ms--j

(b) REVERSE START RAMP
(SHOWING FORWARD HITCH)

MI\-7306
SHR-017~}-84

Figure 3-10

Forward Start Ramp

3-21

21.

To check the forward stop ramp,
where X is defined as in step 8.

type RUN FWDSTOP/UNIT=X

22.

If the displayed message is OK, no adjustment is required
and you can proceed to step 26. Otherwi se, the forward
stop ramp requires adjustment. The routine is run
repeatedly and the displayed message is similar to the
one shown below.
Fwd stop ramp: R66 CAPSTAN SERVO

Th e " * " and " 0" i n d i cat e the ide a 1 and act u a 1 val ue s a s
described in step 9.
23.

To adjust the forward stop ramp, adjust potentiometer R66
on the capstan/regulator PCBA
(Figure 3-2)
while
observ ing the display, unt i 1 the "0" and "*" merge. If
the "0" is on the left of the "*", the capstan speed is
ramping down too slowly and R66 must be turned clockwise.
If the "0" is on the right of the "*", the capstan speed
is ramping down too quickly and R66 must be turned
counterclockwise.

24.

Press and release CTRL C to exit the test.

25.

Type RUN FWDSTOP/UNIT=X. The displayed message should be
OK.

26.

If you suspect an intermittent forward stop ramp problem,
type RUN FWDSTOP/UNIT=X/LOOP. The forward stop ramp
routine is then run repeatedly and the displayed output
is similar to the error message in step 22. For 30
seconds, observe the display for irregularities and then
use CTRL C to exit the test.
NOTE
The following is an alternate procedure
for measuring the forward stop ramp.
•

Rewind
the
tape
transport on-line.

•

Create a 3200 FCI pattern on the tape
by executing a WRTMAI command through
the ASCII port in keypad mode. (Both
STI ports must be off-line.) Rewind
the tape.

•

Connect an oscilloscope to the TU78.
Vertical CHI to GCR/PE preamp 1 PCBA
R14 top lead (Figure 3-9), external
sync to control M2 PCBA TP2l (Figure
3-6)

3-22

and

place

the

•

Connect a jumper between the control
M2 PCBA TP3~ and TP25.

Set control
M2
PCBA maintenance
• switch
Sl to the front (toward you).
The
tape
stops.

alternately

starts

and

Refer
to
Figure
3-11
for
a
• representa
t i ve scope waveform and
settings.
•

The forward stop ramp fall time (1~~
to 5 percent) should be in the 1. ~2
to 1.13 ms range.

If it is out of adjustment, adjust
• capstan/regulator
PCBA R66 for 1.
~8

ms.
•

Return control M2
center position.

PCBA

PROBE:
HORIZ:
VERT:
CH1:
SYNC:

NOTES:

X10
0.2 MSEC!DIV
50mV/DIV
PREAMP R14
AC EXT NEGATIVE
TP21 CONTROL M2 PCBA
1.

2.
a. CORRECT WAVEFORM

STOP
RAMP IS MEASURED
BETWEEN 100% AND 5%
ADJUST THE FALL
TIME FOR NO
OVERSHOOT

OVERSHOOT

b. INCORRECT WAVE FORM SHOWING OVERSHOOT
MA·7305
SHR-0176·84

Figure 3 11

stop Ramp

3-23

the

27.

To check the reverse stop ramp,
where X is defined as in step 8.

type RUN REVSTOP/UNIT=X

28.

If the displayed message is OK, no adjustment is required
and you may proceed to step 32. Otherwise, the reverse
stop ramp requires adjustment. The routine is run
repeatedly and the displayed message is similar to the
one shown below.
Rev stop ramp: R78 CAPSTAN SERVO

rrh e " * " and " 0" i n d i cat e the ide a 1 and act u a 1 val ue s a s
described in step 9.
29.

To adjust the reverse stop ramp, adjust potentiometer R78
on the capstan/regulator PCBA
(Figure 3-2)
while
observing the display, until the "0" and "*" merge. If
the "0" is on the left side of the "*", the capstan speed
is ramping down too slowly and R78 must be turned
clockwise. If the "0" is on the right of the "*", the
capstan speed is ramping down too quickly and R78 must be
turned counterclockwise.

30.

Press and release CTRL C to exit from the test.

31.

Type RUN REVSTOP/UNIT=X.
OK.

32.

If you suspect an intermittent reverse stop ramp problem,
type RUN REVSTOP/UNIT=X/LOOP. The reverse stop ramp
routine is then run repeatedly and the display is similar
to the error message in step 28. For 30 seconds, observe
the display for irregularities and then use CTRL C to
exit the test.

The displayed message should be

NOTE
The following is an alternate procedure
for measuring the reverse stop ramp.
•

Rewind
the
tape
transport on-line.

•

Create a 3200 FCI pattern on the tape
by executing a WRTMAI command through
the ASCII port in keypad mode. (Both
STI ports must be off-line.) Rewind
the tape.

•

Connect an oscilloscope to the TU78.
Vertical CHI to GCR/PE preamp 1 PCBA
R14 top lead (Figure 3-9), external
sync to control M2 PCBA TP2l (Figure
3-6)
3-24

and

place

the

•

Connect a jumper between the control
M2 PCBA TP30 and TP25.

•

Set control M2 PCBA maintenance
switch Sl to the rear
(away from
you). The tape alternately starts and
stops.

•

Refer
to
Figure
3-11
for
a
representative scope waveform and
settings.

•

The reverse stop ramp fall time (100
to 5 percent) should be in the 1.02
to 1.13 ms range.

If it is out of adjustment, adjust
• capstan/regulator
PCBA R78 for 1.08
ms.
•

Return control M2
center position.

PCBA

the

33.

Press and release CTRL Z to exit from the terminal mode.
The drive echoes AZ.

34.

Unload the tape.

3.8
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 together (Paragraph 3.8 must be performed in
its entirety). Refer to Figure 3-7 for reel servo adjustment and
test point locations.
3.8.1
Reel Servo Offset Adjustment
Th ere e I s e r v 0 0 f f set ad jus tme n t set s the dc reference level of
the triangle wave generator output. This maintains balanced
currents through the reel motors when they are not commanded to
turn.
1.

verify power supply voltages according to Paragraph 3.3.

Turn transport power off.

Disconnect
motor.

Turn transport power back on.

Open the transport front door, disable the door interlock
switch, and remove the supply reel tape.

the

take-up

reel

3-25

servo

motor

leads

the

Press and release the LOAD/REW button on the TU78 control
panel. Immediately turn the take-up reel three full turns
by hand. This defeats activating load fault zero.
CAUTION
The specified duty cycle fo.r the vacuum
and
air
pressure
seleneids
is
intermittent, three minutes on and nine
minutes eff. Therefere, the unit sheuld
net be held in this mede fer over three
minutes, after which the ceil sheuld be
allowed to. ceol fer 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 net act iva te the backwrap
function.

If motion occurs, adjust potentiometer R76
servo PCBA for no supply reel hub motien.

the

reel

NOTE
If R76 is adjusted, it should be set
first at the peint where the supply reel
hub just starts to. turn in the clockwise
directien, then backed eff until the
reel hub stops turning.
9.

Press and
panel.

10.

Turn transport power off.

11.

Reconnect the take-up reel motor leads.

12.

Turn transport power back on.

3.8.2

release

the

RESET button on

the TU78 control

Supply Reel Load Speed Adjustment

using Handheld Tachemeter
1.

Turn transport power off.

Connect reel servo PCBA test points TP60
(NSRF1) to TP49 (ground).

Turn transport power
rotating cleckwise.

on.

3-26

The

supply

(NAE)
reel

and TP69
should

Measure the supply reel speed directly in rpm with the
handheld tachometer
(PN 29-11635).
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 LEOs. The reading should be in the 50
to 60 rpm range.

If the speed is out of tolerance, adjust
R52 on the reel servo PCBA for 55 rpm.

Turn transport power off and remove the ground jumpers.

potentiometer

without Handheld Tachometer
The followi ng is an al terna te supply reel load speed adj ustment
for instances when a tachometer is not available.
1.

On the supply hub, mount a 267 mm (10-1/2
tape with 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
PCBA to TP49 (ground).

Turn transport power
clockwise.

Observe the masking tape on the supply reel. Using a stop
watch, time ten rotations of the supply reel masking tape
as it passes the tape on the trim.

TP69

on.

The

(NSRF1)

supply reel

in)

the

reel

servo

should

rotate

NOTE
Be sure to start and stop the stop watch
when the two pieces of masking tape are
coincident.
8.

Observe the elapsed time on 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 displayed is 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.

3-27

10.

Turn transport power off.

11.

Remove grounds
masking tape.

3.8.3

from

the

reel

servo

PCBA and

remove the

Take-up Reel Load Speed Adjustment

Using Handheld Tachometer
1.

Turn transport power off.

Connect reel servo PCBA test points TP60
(NTRF) to TP49 (ground).

(NAE)

Turn transport power on.
clockwise.

should rotate

Measure the take-up reel speed directly in rpm wi th the
handheld tachometer
(PN 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 LEOs. The reading should be in the
162 to 198 rpm ran(;Je.

If the speed is out of tolerance, adjust
R91 on the reel servo PCBA for 180 rpm.

Turn transport power off and remove the ground jumpers.

The take-up reel

and TP57

potentiometer

without Handheld Tachometer
The following is an alternate take-up reel load speed adjustment
for instances when a tachometer is not available.
1.

Turn transport power off.

Connect TP60 (NAE) and
the reel servo PCBA.

Turn transport pOvler on.
clockwise.

Connect an oscilloscope input lead to TP43 (low
sensor input) of the control M2 PCBA (Figure 3-6).

Observe the oscilloscope. The time between leading edges
of two consecut i ve pul ses should be between 183. 7 ms
maximum (162 rpm) and 150.3 ms minimum (198 rpm).

TP57

3-28

(NTRF)

TP49

The take-up reel

(ground)

should rotate
tape

If the time displayed is out of tolerance (step 5),
adjust potentiometer R9l on the reel servo PCBA for 167
ms ( 18 0 r pm) .

Turn transport power
leads.

3.8.4

off.

Remove

the

grounds

and

scope

Tape Loop position Adjustment
NOTES
1.

Check, and adjust if necessary, all
vacuum
and
pressure
readings
outl i ned in paragraph 3.6 before
trying to adjust the loop positions.

If the loop positions are so far out
of adjustment that interlock (fai I
safe)
is broken, then proceed to
step I
and execute the entire
procedure. Otherwi se, proceed to
step 23.

Turn transport power off.

Set control M2 PCBA maintenance switch Sl in the center
position (Figure 3-6).

Set reel servo disable switch Sl, located on the
servo PCBA (Figure 3-7) toward the rear (disable).

reel

Connect control M2 PCBA test points
TP7l (PNU return) to TP25 (ground).

and

Disconnect one capstan motor lead.

Mo un t a full 26 7 mm ( 10 -1 /2 in) r eel 0 f tape wi tho u t
cartridge on the supply hub. Open the buffer box door and
hand thread the leader through the tape path. Wind about
9.1 m (30 ft) of tape on the take-up reel. Close the
buffer box door.

Turn transport power back on.
on.

3-29

TP62

(NINTLK)

Vacuum and pressure comes

Manually rotate the supply reel clockwise to put tape
into the supply buffer col umn. Rotate the reel so the
tape forms a loop and the end of the loop is in the
middle of the park zone. The park zone is the series of
thirteen small holes in the center of the buffer column,
shown in Figure 3-12. Hold the reel and apply masking
tape to the outer flange and the transport to prevent the
loop from being pulled down the buffer col umn by the
vacuum.

LIMIT SWITCH
UPPER PORT

:~-

- --T
FORWARD
RUN ZONE

--+
--- -~~f

BUFFER BOX
CENTER BAR ___ ___

REVERSE
RUN ZONE

-~,-:-

TAPE

~ CRIPPLED REEL
SWITCH PORT

LIMIT SWITCH
LOWER PORT
CAPSTAN
TO TAKE UP REEL

MA-3678

SHR-0177-84

Figure 3·-12

Buffer C01unn Park Zone
('ra ke·-up col umn shown)
3-30

9•

Ho 1 d the ta pe a g a ins t air be a r in g n urn b e r 4 ( Fig u r e 3 - 4 )
wi th your finger and manually rotate the take-up reel
counterclockwise to form a loop in the take-up buffer
column. Continue rotating the take-up reel until the loop
is 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 TU78 control panel.

12.

Connect a DVM to the reel servo PCBA as follows: positive
lead to test point TP55 (TPOS) and negative lead to TP49
(ground) .

13.

Observe the DVM. The voltage displayed should be between
+0.2 Vdc maximum and -0.2 Vdc minimum.

14.

If the voltage is out of tolerance, adjust potentiometer
R9 on the interconnect Fl PCBA for 0 Vdc (Figure 3-3).

15.

Connect
(SPaS) .

16.

Observe the DVM. The voltage displayed should be between
+0.2 Vdc maximum and -0.2 Vdc minimum.

17.

If the voltage is out of tolerance, adjust potentiometer
R1 on the interconnect F1 PCBA for 0 Vdc.

the

DVM

positive

lead

reel

servo

PCBA

TP66

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 to Note 1 under Paragraph
3.8.4.)
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
Sl toward the front. Disable the front door interlock
switch.

21.

Reconnect the capstan motor lead.

3-31

22.

Remove the masking tape from both reels and rotate one of
the reels to take up slack.

23.

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 5.7).

24.

Set gain potentiometers R30 and R31 on the interconnect
Fl PCBA (Figure 3-3) fully clockwise. (The potentiometers
have a range of about 28 turns.)

25.

Adjust the position potentiometers Rl and R9 on the
interconnect Fl PCBA so that both tape loops are within
the park zones.

26.

Move the tape about 9 m (30 ft) from BOT by
control M2 PCBA switch 81 toward the front
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
Fl PCBA about ten turns counterclockwise.

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
forward/reverse shuttle.

34.

Fine tune the position (R9) and gain (R31) potentiometers
so the take-up loop matches the boundaries shown in
Figure 3-13. The posi tion potentiometer moves the loop
excursion up and down in the column.

TP31

again

placing
of the

obtain

The gain potentiometer increases and decreases the length
of the excursion. Rotating the gain potentiometer
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

3-32

allow the take-up loop excursion to extend beyond 24 crn
(9-1/2 in).
NOTE
Because
the
gain
and
position
potentiometers are interactive, it is
necessary to alternate adjustments in
the fine tuning process.

SUPPLY
TAKE-UP
a INTERLOCK

a INTERLOCK

o
o
o

o
o

-.---,

~-'

.-----0-9
o

o
MAXIMUM
TAKE-UP
LOOP
TRAVEL

r~-,
PARK
ZONE

MAXIMUM
SUPPLY
LOOP
TRAVEL

•
:

0-1

-, .

0-1

PARK
ZONE

•
•

1 0-'

--0

-'-----0-7
o
o

o
o
o
o

'----0-9

o INTERLOCK

NOTE

o
o

LOOP POSITION MAY BE OFFSET UP OR
DOWN IN COLUMN BY UP TO ONE HOLE
BUT LOOP TRAVEL SHOULD BE NO MORE
THAN SPECI F I ED.

o
a
o

o
o INTERLOCK

MA·7314
SHR·0178·84

Figure 3··13

Loop Travel Limits
3-33

35.

Remove the ground from TP31 on the control M2 PCBA.

36.

Place control M2 PCBA switch 81 toward the front of the
transport and allow the tape to move to the EOT point.
When EOT is reached, move switch 81 to the rear for three
seconds and allow the tape to move 9 m (30 ft) from the
EOT point.

37.

Repeat steps 27 through 35 for the supply reel servo loop
position.
Use position potentiometer Rl and gain
potentiometer R30 on the interconnect Fl 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 inter lock is broken, readj us t the
position and gain potentiometers until an optimum point
is reached.

3.9
TAPE PATH CLEANING
To clean the tape path, you need a
foam-tipped swab and a lint-free wipe.

tape

cleaning

fluid,

CAUTION
Do not use acetone or lacquer thinner,
rUbbing alchohol, or excessive cleaner.
Be extremely careful not to allow the
cleaner to penetrate ball bearings and
motors.
Cleaning fluid, swabs, and wipes are available in the magnetic
tape transport cleaning kit (TUC0l) that comes with the TA78. The
cleaning fluid in the kit is TFl13.
WARNING
TFll3 is a nonrestricted, nonhazardous
substance. However, avoid excessive skin
contacto Do not allow it to contact the
eyes and do not swallow it. Use it only
in a well-ventilated area.
Perform the following steps to clean the TU78 tape transport.
1.

Dismount the tape from the unit.

Lift the plastic cap covering the pour spout of the TFl13
can. Pour a little cleaning fluid into the cap and dip
the swab into the cap. (Never dip a contaminated cleaning
swab or wipe into the cleaning fluid can.)

3-34

With the swab soaked in cleaning fluid, clean the
following components of the transport tape path (Figure
3-14) •

Read/write head
Erase head
Tape cleaner
Air bearings (6)
Spring-loaded ceramic tape guides (2)
Thread blocks (6)
Capstan
Pucker pocket
NOTE
Only use the foam-tipped swabs. Do not
touch any part of the tape path since
oil from fingers attracts dust and dirt.
4.

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

BUFFER

BOXGLASS~

AIR BEARING
NO. 4
I\:-----n--~Q

AIR BEARING
NO.5 AND
SPRING LOADED
TAPE GUIDE

POCKET
GLASS

11lC~~~~=~)
READ/WRITE
HEADS

THREAD
B LOCKS .qr==:;t=--~L-JJJ.

MA-2638
SHR022B-B4

AIR BEARING NO.6

SPRING LOADED
TAPE GUIDE

TAPE PATH ITEMS

Figure 3 . ·14

VACUUM
CAPSTAN
MA-2637
SHR0227-B4

Transport Items for Cleaning
3-35

BUFFER BOX DOOR

Clean the following components of the transport wi th a
lint-free wipe and cleaning fluid (Figure 3-14).
Buffer boxes (2)
Buffer box glass
Pocket glass
Door overlay

When cleaning the inner surface of the door, pass another
lint-free wipe over the head. Use a polishing agent to
remove any remaining deposits.
NOTE
For an unusually stubborn dirt deposi t
that appears to resist TF113, try a mild
soap and water solution to dislodge it.
After using soap, be sure to wash the
area thoroughly with TFl13 to remove
soapy residues.

3.10
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 3.9), the voltages are
correct (paragraph 3.3), and the capstan
servo adjustments are correct (Paragraph
3.7) •

The following functions should now be checked or adjusted in the
following order.
1.

Read skew adjustment (azimuth)

Write current adjustments

PE gain adjustments

3.10.1
Read Skew Adjustment (Azimuth)
To make this adjustment, proceed as follows.
1.

Mount and load a write-protected master skew tape to BOT.
Place the transport on-line. Defeat the front door
interlock switch.

3-36

Set MIA
follows.

PCBA

maintenance

switches

(Figure

3-15)

S2 READ (left)
S3 1600 (left)
S4 MAN (right)

CONNECTORS MATE WITH J2, Jl AND
J3 ON INTERCONNECT Dl PCBA
J3 TO TU BUS
(Nl B CABLE

J2 TO TU BUS
(Nl A CABLE

~ ~ ~~.~ 0,'

CRl

r-----'lJ----_

COMMAND
PARITY LED
INDICATOR

SERIAL NUMBER
ONES/TENS
SELECTOR SWITCH
U125
SERIAL NUMBER
HUNDREDS/THOUSANDS
SELECTOR SWITCH

TEST MODE
LED
INDICATOR

REV OFF FWD READ WRT

TEST PATTERN
SELECTOR SWITCH
U196

16006250

AUTO MAN

MA-7315
SHR-Ol R0-84

Fig u r e 3 . - 1 5

Multiple Interface Adapter Controls,
and Connecto r s

3-37

Indicators,

connect an oscilloscope to read PCBA
point 11. Set the scope as follows.
vertical
Horizontal
Sync

=
=

(Figure 3-16)

test

0.2 V/div
0.5 us/div
+, int, dc

Set MIA PCBA switch Sl to the right (run forward).

Watch the oscilloscope. The overlapping step should not
exceed 1.2 us (corresponding to 150 microinches of skew)
as shown in Figure 3-17.

TRACK CONFIGURATION
REV. U AND BELOW

~ Sl READ AMPLIFIER

EI\JA
_
AGC _
AGC
TEST
(I'JORMAL)

TP1- TP24

GAIN SWITCH

PE
GAIN
MA·7316
SHR·0181·84

TRACK CONFIGURATION
REV. V AND ABOVE

~ Sl READ AMPLIFIER

GAIN SWITCH

ENA _
AGC -PE
AGC
TEST
GAIN
(I\;ORMAL)

TP1- TP24

Figure 3-16

Read PCBA Test Points and Adjustments

-fV
-./

1.2/J SEC MAXIMUM
(CORRESPONDING TO
150 /J INCH OF TAPE)
MA·7317
SHR·0182·B4

Figure 3-17

MA-7316A
SHR0229·84

Read Skew Adjustment
Waveforms

3-38

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 by
inserting a 1/8-inch allen driver through the buffer box
door and into the tape cleaner cap-clip housing (Figure
3 -18) •

7•

Set MIA swi tch S 1 to the left (run rever se). The step
width must not exceed 1.2 us. If it does, the capstan
motor tracking may have to be fine tuned (Paragraph
6.2.5) •

Allow the master skew tape to continue in reverse to BOT,
then remove it.

Set MIA PCBA switch Sl to the center
the left (auto).

(stop),

and

ADJUSTMENT

~ACCESSHOLE

000 0
0

MA-3483
SHR-0183·84

Figure 3-18

Location of Read Skew Azimuth Adjustment

3-39

3.1~.2
write Current Adjustments
To make these adjustments, proceed as follows.

Verify power supply voltages according to Paragraph 3.3.

Load any write enabled 267 mm
Leave the transport off-line.

Set the MIA switches as follows.

(10-1/2 in)

tape to BOT.

Sl = FWD (right)
S2 = WRT (right)
S3 = 1600 (left)
S4 = MAN (r ight)
Data pattern
forward)

(U196)

equals

all

ones

(all

switches

3.1~.2.I
phase Encoded write Current Adjustments -- To make these
adjustments, proceed as follows.

Connect an oscilloscope to write PCBA
point 6. Set the scope as follows.
vertical chI
Horizontal
Sync

(Figure 3-19)

test

1.0 V/div, ac (X10 probe)
0.2 us/div
+, Ch 1, dc

Place transport on-line. The tape starts moving forward.

Adjust write PCBA potentiometer R50 (PE step time)
1.25 us ~.1 us positive pulse width.

Place transport off-line. The tape stops moving.

Move the scope probe to write PCBA
vertical setting to 2.0 V/div, dc.

Change

the

Place transport on-line.

Adjust write PCBA potentiometer RI9 (PE step voltage)
a +8.75 Vdc level.

for

Move the scope probe to write PCBA TP2.

Adjust write PCBA potentiometer R36
+6.2 Vdc level.

10.

Place the transport off-line and rewind the tape to BOT.

3-40

TP3.

for a

(PE pedestal)

for a

CONNECTS TO J7
INTERCONNECT 01 PCBA

J25

CONNECTS TO
GCR/PE PREAMP
1 CABLE

R39
GCR

R48 R50
GCR PE

R36
PE

TEST POINTS
TP1-TP24

AMTIE CABLE
CONNECTS TO MIA Jl

PEDESTAL
ADJUST

STEP
ADJUST

STEP TIME
ADJUST
MA-7318
SHR-018~84

Fig ure 3-19

Write PCBA Test Points, Adjustments,
and Connectors

3.10.2.2 Group Coded write Current Adjustments
These
adjustments involve potentiometers R39, R22, and R48 on the write
PCBA. To make these adjustments, proceed as follows.
NOTE
Use a DVM for all measurements at TP2
and TP3 on the write PCBA.
1.

8et MIA switches 81, 82,83 and 84 to the right. Data
pattern (U196) equals all ones (all switches forward).

Place AGC switch (81)

Adjust R22 to set TP3 to 0 v.

Adjust R39 to set TP2 to 0

Using a l0X probe, set an oscilloscope to 100 mV/div and
0.5 us/dive Place the probe on track 5 (R13) of the
GCR/PE preamp 1 PCBA (Figure 3-9).

on the read module to the right.

3-41

Load a standard output tape (or a good scratch tape) with
the write-protect ring in place. place the transport
on-line to start the tape moving.

Adjust R39 counterclockwise (CCW) for peak amplitude.
(The pedestal write current is now at about the start of
the 100 percent saturation range.)

Measure and record the dc voltage at TP2.

Continue to adjust R39 CCW until the waveform amplitude
beg ins to decrease. (This is about the end of the 100
percent saturation range.)

10.

Measure and record the dc vol tage at
transport off-line to stop tape motion.

11.

Add the two voltages recorded in steps 8 and 10. Divide
this sum by 2. Record the result of the division.

12.

Place the transport on-line and adjust R39 clockwise (CW)
until TP2 is at the voltage calculated in step 11.

13.

Ad jus t
the s cop Ie's v e r tic a 1 sen sit i v i t Y until the
waveform's peak-to-peak amplitude covers the entire
screen (8 cm).

14.

Adjust R39 CCW until the peak-to-peak amplitude covers
7.6 cm (about 105 percent to guarantee media saturation).
Then measure and record the voltage at TP2.

15.

Set TP2 back to the voltage calculated in step 11.

16.

Set the scope to 100 percent amplitude over 8 cm as
step 13.

17.

Adjust R39 CW until the peak-to-peak amplitude covers 7.6
em (about 95 percent saturation).

18.

Adjust R22 until TP3 is at the voltage recorded in step
14. (The pedestal step current is now set to about the
105 percent saturation point.)

19.

Move the scope probe to TP6 on the write PCBA. Using R48
(GCR step time), set TP6 to 350 ns +10 percent at the 50
percent point.

20.

Place the AGC switch back to the left position.

3-42

TP2.

Place

the

3.1g.3
Phase Encoded Gain Adjustments
To make these adjustments, proceed as follows.
NOTE
The capstan servo adjustments (Paragraph
3.7) affect PE gain. Make sure that
these adjustments are wi thin tolerance
before doing the PE gain adjustment.
1.

Mount and load a wr i te-enabled master output
29-11691). Place the transport off-line.

Connect an oscilloscope to GCR/PE preamp 1 PCBA Rl upper
lead (Figure 3-9). 8et the oscilloscope as follows.
vertical Ch 1
Horizontal
8ync

=
=

tape

(PN

0.02 V/div, ac (X10 probe)
1.0 ms/div
auto, + Ch 1, ac

8et the MIA switches as follows.
8 1 = FWD ( rig h t )
82 = WRT (r ight)
83 = 1600 (left)
84 = MAN (r ight)
Data pattern
forward) •

(U196)

equals

all

ones

(all

switches

Place the transport on-line. The tape moves forward.

Adj ust the track 1 read PCBA potentiometer R706 (Figure
3-16)
so the read data envelope measures 1.25 V
peak-to-peak.

Refer to Table 3-5 for test points and adjustments and
adjust the other eight tracks as done in step 5.
NOTE
I f the tape reaches EOT before you
complete
the
adjustments,
the
MIA
rewinds the tape automatically. Upon
reaching
BOT,
the
write
operation
resumes.

7•

Wh e n fin i s he d ad jus tin g a l l n i n e t r a c k s, P 1 ace the
transport off-line, unload, and remove the master output
tape.

Place MIA swi tch 84 to AUTO (left).

Verify proper transport operation by running the In-Line
Exerciser (ILEXER) for 15 minutes.

3-43

Table 3-5

PE Gain Test Points and Adjustments

Physical Track

Preamp Test Po int

Read PCBA Adjustment

RI
R4
R7
R10
RI3
R16
RIg
R22
R25

R706
R906
R506
R106
R406
R306
R206
R806
R606

3
4
5
6
7
8
9

3-44

CHAPTER 4
TA78 TROUBLESHOOTING AIDS

4.1
GENERAL
This chapter describes the aids available for troubleshooting the
TA78. Figure 4-1 is a troubleshooting flowchart which outlines a
general troubleshooting approach.
Refer to the paragraphs
identified
in
the
flowchart
for
further
information
on
troubleshooting steps. In most cases, failures can be isolated to
a single field replaceable unit
(FRU)
such as a module or
mechanical assembly.
4.2
FAULT CONTROL AND ERROR CODES
The FAULT indicator lights to show that a potentially fatal error
has been detected in the formatter. When FAULT stays lit, perform
the following procedure.
1.

Press and release the FAULT button. All three TS78
control panel i nd ica tor sligh t i n a lamp test. These
indicators stay on for as long as you press the FAULT
button, or for at least one second. After you release the
FAULT button, the A, B, and FAULT indicators light to
display a binary error code. The code, defined in Table
4-1, identi f ies one of six areas in the format ter tha t
may have caused the error.

Record the displayed fault number.

Press the FAULT button again for about one second and
then release it. The format ter then tr ies to clear the
error. All three i nd ica tors 1 igh t as long as you press
the FAULT button or until the clear attempt is finished.
If the error is cleared, the FAULT indicator turns off
and PORT SELECT A and PORT SELECT B return to their
normal meaning. If the error remains, FAULT stays on and
PORT SELECT A and PORT SELECT B are off.

4-1

OBTAIN FAULT
NUMBER + ASSOCIATED
MICRODIAGNOSTIC
CHAIN. ATTEMPT
TO CLEAR FAULT.

CONNECT EXTERNAL
TERMINAL TO HSC
ASCII PORT OR
USE PREVIOUSLY
INSTALLED EXTERNAL
TERMINAL

PAR 4.2

PAR. 2.5.3

CONNECT EXT·
ERNAL TERMINAL
TO TA78 ASCII
MAINTENANCE
PORT

FIG 2-25
A

RUN CHAIN
ASSOCIATED
WITH FAULT

PAR 4.3.1

REPLACE PRIMARY
FRU AND RERWN CHAIN.
IF ERROR STILL
PRESENT, REPLACE
SECONDARY FRU AND
RERUN CHAIN AGAIN.

REPLACE PRIMARY FRU
AND RERUN CHAIN O.
IF ERROR STILL
PRESENT,REPLACE
SECONDARY FRU AND
RERUN CHAIN 0 AGAIN

PAR 4.3.2

PAR. 4.3.2

YES

SHR0106B-84

Figure 4-1

TA78 Troubleshooting Flowchart (Sheet 1 of 2)

4-2

NOTES:

PAR 4.6

RUNNING ILTAPETOTEST
FORMATTER RUNS TESTS IN
CHAIN 0

CONNECT EXTERNAL
TERMINAL TO HSC
ASCII PORT OR
USE PREVIOUSLY
INSTALLED EXTERNAL
TERMINAL

USE ILTAPE AND ILEXER
AS DISCUSSED IN PARAGRAPH
2.5.3 TO VERIFY ANY FIXES
EXCEPT FORMATTER ERROR
FIXES
IF PROBLEM STILL EXISTS
WHEN END IS REACHED,
CALL SUPPORT

TEST FORMATTER
SWITCHES WITH
BUTTONS AND
LIGHTS TEST

PAR 4.7.1.1

PAR 4.3.3

TABLE 6·2

PAR 4.7.2

TABLE 6·2
&
PAR 3.3

USE OTHE.R
STANDARt> TU78
TROUBLESHOOTING
PROCEDURES

CH 5

SHR0107B·B4

Figure 4-1

TA78 Troubleshooting Flowchart (Sheet 2 of 2)

4-3

If the FAULT indicator stays on, run the associated
microdiagnostic chain specified in Table 4-1 for the
recorded fault number.
(Refer to Paragraph 4.3.1 for
instructions on running microdiagnostics.)
1.

Table 4-1

NOTES
Pressing the FAULT button cuts off
all communication with the HSC. HSC
communication returns only if the
error is cleared.
In step 1, if the indicators fail
the lamp test, press and release the
MASTER RESET button on the TS78
formatter (Figure 1-4). All three
indicators should then light for
about four seconds. During this

TS78 Control Panel Error Code

Indicator Display
FAULT A
B

Fault
Number

Associated
Microdiagnostic Chain

possible Cause
General Area

Off

401

Miscellaneous

Off

402

Read

M8950 (9)
M8953

Off

403

Write

M8959
M8958

Off

404

TU port

M8955

Off

405

Error correction M895l

Off

406

STI
communication

M8970
M8971

407

Microcomputer

M8972

NOTES
1. On = indicator blinking
Off = indicator always off
2.

Fault number 0 is never used.

4-4

Related
Modules

(2)

time, the microcomputer runs the
minimum
integrity
and
power-up
d i a 9 nos tic s. Wh e n t h e i n d i cat 0 r s
turn off, repeat step 1. However, if
the three indicators stay on, the
microcomputer
is
probably bad.
Replace the M8972 and repeat step 1.
If the error code does not appear
after
releasing
FAULT
[i.e.;
indicator(s)
not flashing],
the
microcomputer
is
probably
bad.
Replace the M8972 and repeat step 1.

4.3
MICRODIAGNOSTICS
The TS78 contains 56 microdiagnostic test routines which are
divided into two categories: in-line and off-line. The 16 in-line
tests reside in read-only-memory (ROM) on the M8972 module. The
microprocessor
(8085)
schedules sequential running of in-line
tests while the formatter is not on-line to verify basic
operation.
In most cases, the 8085 only activates self-test
programs in control ROMs on various modules.
The off-line microdiagnostics thoroughly test the formatter and
any tape transport interface (MIA) module connected to the
formatter. However, these tests cannot be run under normal
operating conditions. Thirty-eight off-line tests reside in ROM on
the M8973 module. On request, the 8085 moves a microdiagnostic
from M8973 ROM to the M8972 random access memory (RAM). The 8085
then runs a checksum test on the transferred microdiagnostic and
ex e cut e s t hem i c rod i a g nos tic. Th e r em a i n i n g two 0 f f ~ 1 i n e t est s
reside in M8972 ROM and are simply executed by the 8085 on
request. These two tests present sample reports of passing and
failing microdiagnostics. Note that three off-line tests in M8973
ROM are STl loopback tests that require installation of a loopback
connector(s) •
Anyone of the 56 microdiagnostics can be run individually through
the ASCII port. Table 4-2 lists the in-line microdiagnostics and
the test numbers used to access them. Table 4-3 lists the off-line
microdiagnostics along with test numbers.

4-5

Table 4-2

In-Line Microdiagnostics

Test
Number

Test
Name

Description

1
2
3
4
5
6
7

C
D
E
F
10

I NWMC
INXMC
INRPM
INRCH0
INRCHl
INRCH2
INRCH3
INRCH4
INRCH5
INRCH6
INRCH7
INRCHP
INECC
INMEM
INCHK0
INCHKl

write microcontroller self-test
Translator self-test
Read path controller self-test
Read channel 0 self-test
Read channel 1 sel f-test
Read channel 2 self-test
Read channel 3 sel f-tes t
Read channel 4 self-test
Read channel 5 self-test
Read channel 6 self-test
Read channel 7 self-test
Read channel P self-test
E'rror correcting code controller self-test
Microcomputer RAM memory test
Micl:ocomputer ROM checksum test
Extended memory ROM checksum test

Table 4-3

Off-line Microdiagnostics

Test
Number

Test
Name

Description

PASS

Prints report for successful test pass

FAIL

Prints error report for test failure

100

WMCITD

Write microcontroller (WMC) microbus
interface test

110

WMC2TD

WMC data format/skip count test

120

WMC3TD

WMC write data byte assembly test

130

WMC4TD

WMC write GCR check character generation
test

140

WMC5TD

WMC write PE ECC character generation test
(note 1)

150

TUP1TD

TU port boards test

160

MTAITD

MIA board(s) test; includes loop command to
status, loop microcomputer to AMTIE lines
and loop microcomputer to RD lines for MIA
board in any transport present

8
9

A
B

4-6

Table 4-3

Off-line Microdiagnostics (Cont)

Test
Number

Test
Name

Description

170

MTA2TD

MIA loop threshold/command function test

180

MTA3TD

MIA tachometer line continuity test

190

XMCITD

Translator

lA0

XMC2TD

XMC PE preamble/postamble test

IB0

XMC3TD

XMC GCR preamble/postamble test; with 1
data group

lC0

XMC4TD

XMC GCR preamble/postamble test; with no
data group

ID0

XMC5TD

XMC GCR 4-to-5 bit data translation test

lE0

XMC6TD

XMC resync burst test

IF0

RPMITD

Read path and channel test; checks TIE bus,
RMC command and status registers, and AMTIE
bus; runs self-test for M8953, M8951 and
M8950s

200

RPM2TD

Read path and channel test; checks read
channel fifos statically, checks read
channel data handling from a~l 4 TU ports,
and tests RMC velocity-check circuit

210

RPM3TD

Read path and channel test; checks ability
to detect valid tape characters (except
mark 2 and end mark) and ability to do GCR
5-to-4 bit translation with valid read
forward data

220

RPM4TD

Read path and channel test; checks ability
to detect illegal 5-to-4 bit translation
patterns in read forward data and ability
to do 5-to-4 bit translation with valid
read reverse data

230

RPM5TD

Read path and channel test; checks ability
to detect mark 2 and end mark and tests
fifo depth

(XMC)

track enable test

NOTES

1.
2.

Run time for this test is between 30 and 60 seconds per pass.
Run time for this test is over 60 seconds per pass.

4-7

Table 4-3

Off-line Microdiagnostics (Cont)

Test
Number

Test
Name

240

ECC1TD

Error correcting code (ECC) module no
correction test; with good data, no TIE
pointers and soft TIE pointers

250

ECC2TD

ECC module single-track error correction
test; with no TIE pointers and correct TIE
pointers

260

ECC3TD

ECC module single-track error correction
test; with incorrect TIE pointers

270

ECC4TD

ECC module test; checks double-track error
correction with correct TIE pointers and
checks no error correction with good data
and 3 hard pointers

280

ECC5TD

ECC module test; checks double-track
correction with 2 hard pointers and 7 soft
pointers and checks error discrimination to
correct errors in outer tracks (1 and 9)
with 9 soft pointers

290

CCM1TD

Cyclic redundancy checker (CRC) module test
(note 2)

2A0

WMC6TD

WMC read data byte assembly test

2B0

WMC7TD

WMC read residual group byte assembly test

2C0

WMC8TD

WMC read byte assembly test; with variable
skip count

200

LWRTD

Loop write path to read path at 4 TU ports
in PE and GCR

2E0

MTA4D

Loop write path to read path at available
MIA boards in PE and GCR

300

PMC1TD

Protocol microcontroller
test:

310

PMC2TD

PM ROM controller/microbus interface test

320

PMC3TD

PM flag EDC and timer test

Description

4-8

(PM) data path

Table 4-3

Off-line Microdiagnostics (Cont)

Test
Number

Test
Name

330

STIlTD

STI interface error detection and reset
test

350

STI2TD

STI interface port A loopback test

360

STI3TD

ST I interface port B loopback test

370

STI4TD

STI interface port A and B loopback test

Description

NOTES
1. Run time for this test is between 30 and 60 seconds per pass.

Run time for this test is over 60 seconds per pass.

The TS78 al so conta ins 10 microd iagnost ic cha i ns tha t res ide in
M8972 ROM.
In most cases, these chains specify sequences of
related microdiagnostics. You request chains through the ASCII
port like the other tests. Table 4-4 defines the chains and the
numbers used to access them. Requesting a chain causes the 8085 to
run the associated microdiagnostic(s) listed in Table 4-4.
Requesting chain 0 (full set) via the ASCII port runs all the
microdiagnostics except the M8970 tests, M897l tests, and sample
report tests (PASS and FAIL). Running the ILTAPE subsystem
diagnostic to test the formatter also runs the tests in chain 0.
Chains 401
407 test various parts of the formatter defined by
the fault numbers in Table 4-1. After a clear attempt with the
FAULT button, the 8085 runs the proper chain to determine if the
error is still there. If the error still exists, run the proper
chain through the ASCII port to determine the field replacement
uni t (FRU).
Ch a i n 4 09 (m i n i murn i n t e g r i t y) qui c k 1 y t est s i f the for mat t e r i s
able to communicate via the STI bus. Running this chain and the
appropr ia te STI loopback prov ides a more complete test of STI
communication. Powering up the TA78 or pressing the MASTER RESET
button causes the 8085 to run chains 408 and 409.

4-9

Table 4-4

Microdiagnostic Chains

Chain
Number

Chain
Name

Full set

1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, 0, E,
F, 10, 100, 110, 120, 130, 140, 150, 160,
170, 180, 190, lA0, IB0, lC0, 100, lE0,
lE'0, 200, 210, 220, 230, 240, 250, 260,
270, 280, 290, 2A0, 2B0, 2C0, 200, 2E0

401

Misc

10, 200, 2E0

402

Read

3, 4, 5, 6, 7, 8, 9, A, B, C

403

Write

1, 2

404

TU port

150

405

Error
correction

406

STI
communication

300, 310, 320, 330

407

Microcomputer

E, F

408

Power-up

1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, 0, E,
F, 10, 300, 310, 320, 330

409

Minimum
integrity

E, F, 300, 310, 320, 330

Associated Test Number

4-10

4.3.1
Running Microdiagnostics Via the ASCII Port
To run a microdiagnostic test or chain, make sure both STI ports
are off-line (i.e.; PORT SELECT A and B are out). Then plug an
RS232-compatible terminal into the EIA connector on the TS78
control panel (Figure 2-25) and proceed as follows.

Press and release CTRL C on the terminal keyboard. Repeat
the entry until TA78> appears.

Type RUN DIAGNOSTIC/TEST=XXX where XXX is the hex number
for the desired test or chain (Tables 4-1 through 4-4).
The tape drive executes the specified test or chain and
issues a pass or fail response (Paragraph 4.3.2). (Note
that the above command may be abbreviated to ROT XXX.)

Press and release CTRL Z to exit from the terminal mode.
The drive echoes AZ.

The command listed in step 2 must be used to run any test
individually or any fault chain (chains 401 -- 407). However, the
remaining chains may be specified by number or with separate RUN
commands. Table 4-5 defines the three additional RUN commands.
Table 4-5 also defines six SET commands that allow you to control
how the diagnostic is run. Accessing the TA78 ASCII port
automatically specifies the default diagnostic control parameters.
To change a parameter, use the appropr iate SET command. Once
specified, a parameter stays in effect until changed with another
command or until an exit from terminal mode.
After doing steps 1 and 2 above, the microprocessor runs the
specified test or chain with no loop on error, no halt on error,
and no repea t. Therefore, a test runs for one pass only. If a
chain is specified, each test in the chain is run once.

~ ,,~. 11<--1

1t r V-'irJ.. jlJ (
'i

uti!

~- ,i}t

~i1.l

4-11

..J!.Af.

, ~.t~

Table 4-5

Diagnostic Commands

Command

Function

Run Diagnostic/Test=XXX

Run test or chain specified by XXX

Run Diagnostic

Run power-up chain (chain number 408 )

Run Diagnostic/Full

Run full set chain (chain number 0)

Run Diagnostic/Qv

R.un minimum integrity chain (chain
number 409)

SEt Diagnostic/Loop

Enable loop on error; no continuation
past failing point unless error clears.
(See note 4.)

SEt Diagnostic/NOLoop

Disable loop on error (default)

SEt Diagnostic/Halt

Enable halt on error; exit is to TA78>
prompt ending test or if chain running
ending entire chain

SEt Diagnostic/NOHalt

Disable halt on error (default)

SEt Diagnostic/Repeat

Enable unconditional loop; repeats
entire test or if chain running repeats
entire chain

SEt Diagnostic/NORepeat

Disable unconditional loop (default)

SHow DIagnostic

Display current diagnostic control
parameters

NOTES
1.
In above commands, lowe:rcase letters may be deleted to
abbreviate a command. In addition, the "/" and "=" characters
may be replaced by blank spaces. For example, SET
DIAGNOSTIC/NOREPEAT may be abbreviated to SE D NOR.
2.

The tape drive presents error reports for every pass while
looping on error and just before exit for halt on error.

Press and release CTRL C to halt test or chain immediately
under any conditions. Tape drive responds by echoing AC and
displaying TA78>. This is the only way to exit an
unconditional loop.

For loop on error, looping ends if error is no longer
continuously present. If you are looking for an intermittent
problem use the REPEAT parameter.

4-12

4.3.2
Microdiagnostic Response
To indicate a successful test pass, the tape drive displays:
TEST XXXX DONE
where XXX X is the number of an in-line or off-line test.
For a chain, the TA78 displays a report for each test as it is run
in the sequence. The TA78 also indicates the beginning and end of
the chain. Listed below is the output for a successful run of the
minimum integrity chain with default parameters.
CHAIN STARTED
TEST 000E DONE
TEST 000F DONE
TEST 0300 DONE
TEST 0310 DONE
TEST 0320 DONE
TEST 0330 DONE
CHAIN DONE
If an error is detected,
shown below.

the TA78 outputs a

TEST:XXXX
SUBTEST:XXXX
ERROR:XXXX
FRU1:M89XXX FRU2:M89XXX
[ASCII text error description]
EXP:XX,XX ••.•• XX (optional)
ACT: XX, XX .•••• XX (opt i ona l)

report in the format

UNIT:TXXX

The headings are defined as follows.
TEST
SUBTEST
ERROR
UNIT
FRU1
FRU2
EXP
ACT

Test number of in-line or off-line microdiagnostic
Subtest number identifying test segment
Error number (Refer to Figure B-1 for a partial
definition)
T=Tape drive
XXX=decimal unit number of transport 0; same as base
number assigned with DIP switch on formatter
Primary field replacement unit (FRU)
Secondary FRU
Expected test results (e.g.; good data bytes)
Actual test results (e.g.; bad data bytes)

For the primary FRU, the error report differentiates between the
two TU port modules and nine read channel modules as follows.
M8955-1
M8955-2
M8950-Y

TU port module for ports 0 and 1
TU port module for ports 2 and 3
read channel module where Y is the channel designation
(0 -- 7, P)

4-13

4.3.3
using STI Loopback Tests
Test numbers 350, 360, and 370 access the STI loopback tests. For
these tests, the TA 78 echoes da ta from its transmi t ter to its
receiver and checks for data integrity at reception. These are the
only tests that check the M8971 serial data path. Test 350 checks
port A only, test 360 checks port B only, and test 370 checks both
ports A and B. To completely test TA78 STI communication, proceed
as follows.
1.

Run the minimum integrity chain. If a test fails, replace
the primary FRU specified in the error report. Then rerun
the chain.

At the TA78 bulkhead connector, remove the BC26V STI bus
cable(s) and plug in two loopback connectors. Each port
requires one loopback connector (PN 70-19074-01).

Run test 370. If the test passes, the TA78 is probably
good. Remove thE~ loopback connectors and refer to the
appropriate HSC service manual. If the test fails, note
which port is reported bad. You must now determine if the
formatter logic is bad or if the cabling is bad between
the bulkhead and TS78 logic gate.

Ga i n access
logic gate.

Loosen the two screws tha t hold the STI cable clamp to
the side of the logic gate. Then pull the clamp straight
out disconnecting the STI cables from the M8971.

Remove the M8971 from the backplane.

PI ug the loopback connectors into the port connectors on
the M8971. Reinstall the M8971 into the backplane.

Run test 370. If the test passes for the suspected port,
replace the associated STI cable (PN 70-20410-4J) between
the bulkhead connector and the logic gate. If the test
fails, replace the primary FRU specified in the error
report. Then rerun the test.

After testing, remove the M8971 from the backplane and
remove the loopback connectors. Then reinstall the M8971
and reassemble the logic gate. Also reconnect the BC26V
STI bus cable(s) to the bulkhead connector.

and

remove

the

back

cover

the

TS 78

SUBSYSTEM DIAGNOSTICS
4.4
Two subsystem level diagnostics, ILTAPE and ILEXER, can be used to
troubleshoot the TA78. These two diagnostics are run from the HSC
ASCII port. ILTAPE and ILEXER make use of a special TA78
diagnostic mode. The paragraphs that follow briefly describe these
two diagnostics and the TA78 diagnostic mode that they use.
4-14

4.4.1
In-Line Tape Diagnostic (ILTAPE)
This diagnostic has two major parts: formatter diagnostic and
transport functionality test. You may run either part separately
but not both pa r ts in the same diagnosti c run. Executi ng the
formatter diagnostic segment runs a selected microdiagnostic test
or chain resident in the formatter. The default is chain 0 which
is the full set (all microdiagnostics except M8970, M8971, and
sample report tests). The error report is similar to the
microdiagnostic error report which includes a suspected failing
FRU (Paragraph 4.3.2).
Executing the transport functionality test runs a selected
functional sequence with a selected data pattern. You may select
one of five functional sequences. The default is the canned
sequence which includes all the basic tape commands (reads, writes
and positions). The other four sequences are user defined. Three
of these are either previously defined and stored on the TU58 or
defined now via the HSC ASCII port. The fourth user sequence must
be defined at run time via the HSC ASCII port and cannot be
stored.
Four data patterns are avai lable for use in the selected
functional sequence. The default pattern is ripple 0s (a rotating
o in a field of Is). You may also specify your own data pattern
via the HSC ASCII port or the host console terminal.
The transport functionality test yields a data transfer error
report every time a hard (nonrecoverable) or soft (recoverable)
error occurs. The error report does not specify a suspected
fa iIi ng FRU. However, the report i ncl udes a secti on of numbers
labeled Drive Error Log. The hex numbers are the bytes transferred
from a TA78 extended drive status area at the request of the HSC
as a result of the error. These bytes are defined in Paragraph
B.2. The output starts with byte number 1 in the upper left. The
first 49 bytes (31 in hex) are valid if byte numbers 1 and 2 are
0s. Only the first 4 bytes a re va lid if byte number I or 2
contains a non-zero value.
At the end of the sequence, ILTAPE yields a summary of soft
errors. These errors are divided into eight categories defined in
Table 2-4.
ILTAPE also has an STI communication test. The test runs
microdiagnostics on the selected TOC port in the HSC, verifies the
state of the STI line, and executes a diagnostic echo to the
formatter.
Figure 4-2 shows a printout of an ILTAPE transport functionality
test run. Defaul t parameters are used. The pr i ntou t i ncl udes a
data transfer error report for a hard error, and a soft error
summary report.
Refer to the appropriate HSC maintenance
documentation for more information on ILTAPE.

4-15

HSC50~

RUN DD1:ILTAPE

ILTAPE:D)14:48 Execution Startin.
DRIVE UNIT NUMBER (UI [J? T5
EXECUTE FORMATTER DIAGNOSTICS (YNI [YJ? N
EXECUTE TEST OF TAPE TRANSPORT(YNI [N]? Y
IS SCRATCH MEDIA MOUNTED (YNI [N]? Y
ARE YOU SURE (YNI [N]? Y
Functional Test SeGuence Number (DI [1]?
ENTER CANNED SEQUENCE RUN TIME IN MINUTES (DI [ll?
SELECT DENSITY (O=ALL, 1=1600, 2=6250) [OJ?
DATA PATTERN NUM8ER (DI [3J?
SELECT RECORD SIZE (.reater than 0) (DI [8192J?
ITERATIONS (DI [1]?
ILTAPE)D>14:50 Tt004 EtOll U-T00005
ILTAPE)D)COMMAND FAILURE
ILTAPE)D)MSCP WRITE MULTIPLE COMMAND
ILTAPE)D)MSCP STATUS: 000010
IL.TAPE)D)POSITION = 000315
ILTAPE)D>CANNED SEQUENCE ABORTED
ERROR-E Tape Drive ReGuested Error Lo. at 7-Jun-1984 14:50:49.90
Command Ref t
000015FE
TA78 unit t
5.
Err Seo.
12.
I:: I' ro r Fla.s
40
FFFC
Event
Position
315.
'1D 02 0005 0000013B
OUIS Te:·:t
Drive Error Lo. 00 00 00 00 4D 38 04 10
46 FF 0'1 FF 00 10 10 10
81 10 10 FA FF 95 00 00
00 00 00 FF 17 [13 00 08
02 02 E2 FF FF 00 00 00
00 4'1 F4 E8 00 56 40 07
A2 '1C 00 FF 17 [13
EF\'ROR-I End of error.

ILTAF'E>D>SOFT ERROR SUMMARY:
IL.TAF'E)D:: Unit Media DOIJb 1 e
ILTAF'E)D> No
Error Trkerr

DOIJbIe
Trkrev

Sin.Ie
Trkerr

Sin.le
Trkrev

Other
Err A

Other
Err 8

Other
Err C

ILTAPE:>D: T005

00000

ILTAPE>D>14:58 Execution Complete
SHFI-02SIJ-S4

ILTAPE Example Printout
4.4.2
In-Line Exerciser (ILEXER)
This diagnostic exercises from 1 to 10 units in any combination of
disk and tape drives connected to the HSC. Logic is tested by
writing and reading a selected data pattern for a selected number
of minutes. You may select 1 of 7 data patterns. The default
pattern is alternating four bytes of 0s with four bytes of 1s.
ILEXER counts operations and errors for statistical reporting in
performance summaries.
Performance summary reports appear
periodically during execution and at the end of execution. The
performance summary includes a breakdown of soft errors into eight
categories defined in Table 2-4.
ILEXER yields a data transfer error report every time a hard
(nonrecoverabl e) or soft (recovera bl e) er ror occurs. The error
report does not speci fy a suspected fa iIi ng FRU. However, the
report includes a section of numbers labeled Drive Error Log. The
hex numbers are the bytes transferred from a TA78 extended drive

4-16

status area at the request of the HSC as a result of the error.
These bytes are defined in Para.graph B.2. The output starts with
byte number 1 in the upper left. The first 49 bytes ( 31 in hex)
are valid if byte numbers 1 and 2 are 0s. Only the first 4 bytes
are valid if byte number 1 or 2 contains a non-zero value.
Figure 4-3 is a printout of an ILEXER run. The default data
pattern is specified to run for three minutes. The printout
includes da ta transfer error report for a media error, and a
performance summary report. Refer to the appropriate maintenance
documentation for more information on ILEXER.
~C

HSC50> RUN DD1:ILEXER
ILEXER>D>14:43 Execution Startins
Do YOU wish to reuse previous parameters (YIN) [NJ ? N
Drive Unit Number (U) []?
T5
Is a Scratch Tape Mounted (YN) [J? Y
Are You Sure (YN) [NJ?
Y
Data Pattern Number (16-22) (D) [21J7
Density (1=800, 2=1600, 3=6250) [3J7
Record Lensth in Bytes (1 to 12288) (D) [8192]7
Data Compare(YN) [NJ?
Another Drive (YN) []?
N
Run Time in Minutes (1 to 32767) [10J? 3
Hard Error Limit (D) [20]?
Narrow Report (YN) [N]?
Enable Soft Error Reports (YN) [N]?
ILEXER>D>T005 RewindinS to Start, Restart, or Exit ILEXER
ERROR-E Tape Drive Reauested Error Los at 7-Jun-1984 14:44:16.50
Command Ref t
00001D30
TA78 unit t
5.
Err Sea t
7.
Error Flass
40
Event
FFFC
Position
49.
GEDS Text
7D 04 0005 00000031
Drive Error Los 00 00 00 00 C5 36 04 71
47 B2 07 FF 00 00 00 00
81 00 00 00 FF 2B 04 00
44 04 44 FF 17 7A 00 08
02 02 62 FF FF FF FF 00
00 47 E6 EO 00 16 40 07
A2 4F 44 FF 17 7A
ERROR-I End of error.
ERROR-W Tape Drive Reauested Error Los at 7-Jun-1984 14:44:16.70
Command Ref t
00001D30
TA78 unit t
J.
Err Sea t
8.
Error FlaSs
40
[vent
FFFC
Positlon
49.
GEDS Te:-:t
7D 04 0005 00000031
Drive Error Los 00 08 00 00 06 00 00 B7
02 00 04 00 FF FF FF FF
FF FF FF FF FF FF FF FF
FF FF FF FF FF FF FF Ff
FF FF FF FF FF FF FF FF
FF FF FF FF FF FF FF FF
FF FF FF FF FF FF
ERROR-I End of error.
Serial
Posi
Kbwte
Kbwte
Hard Soft Software
Number
tion
Read
Written
Error Error Corrected
000000004007 00023 0000000680 0000003952 00000 00001
00000

ILEXER>D>Unit
ILEXER>D> No
ILEXER)D)T005

ILEXER:D>Unit
ILEXER:D) No
ILEXER;D>T005

Media
Error
00001

Double
Trkerr
00000

Double
Trkrev
00000

SinSle
Trkerr
00000

SinSle
Trkrev
00000

Other
Err A
00000

Other
Err B
00000

Other
Err C
00000
SHR·027g..S4

Figure 4-3

ILEXER Example printout

4-17

4.4.3
TA78 Diagnostic Mode
This mode affects four operations: write, write retry, erase gap,
and dumping of extended drive status.
In diagnostic mode, a successful write operation has correct data
on every track. In norma I opera tion, a sing Ie-track error on a
write is acceptable.
In diagnostic mode, write retry operations are modified to
distinguish between media errors and other soft write errors. On
the first write retry after an error, the tape drive does a space
reverse and then a write operation. This is an attempt to write
the data correctly on the same area of tape. If the write retry is
successful, the drive records the error as a miscellaneous soft
wr i te error. For an unsuccessful retry, the dr i ve does a space
reverse, an erase gap and then a write operation. So on the second
retry, data is written on a new area of tape. If the second retry
is successful, the drive assumes the previous tape area is bad and
records the error as a media error.
The drive continues write retry operations in this sequence until
no errors appear or until it reaches the maximum retry count. Only
even numbered attempts include erase gap operations. A successful
wr i te on an odd numbered retry means a miscellaneous soft wr i te
error. Success on an even numbered retry means a media error.
In diagnostic mode, the erasing of tape is modified to detect
incorrect current levels in the write head. The space reverse
preceding an erase stops the tape prematurely. The write head is
now at the start of the record instead of in the gap preceding the
record. Therefore, during the erase operation, the erase head does
not pass over the entire record. Only the energized write head
erases the tape at the start of the record that was initially
between the write head and erase head. Improper erasure in this
area indicates an incorrect step current level in the write head.
In diagnostic mode, the drive stores codes classifying soft errors
in byte numbers I and 2 in the extended drive status areas. While
running diagnostics, the HSC uses the three least significant bits
in these locations as statistical data on soft errors. In normal
operation, bytes 1 and 2 are always 0.
While running diagnostics, the HSC receives 49 bytes from a TA78
extended drive status area for every error-yielding operation
(including retries). In these packets, byte numbers 1 and 2 are 0s
since a soft error can only be classified on a successful
operation. For soft error classification, the HSC receives only
the first 4 bytes of a rrA78 extended drive status area. The
non-zero soft error code is in byte number 1 or 2.
Via its ASCII port, the HSC displays the first information packet
relating to an error and any soft error packet it receives.
Therefore, two packets appear for soft errors involving retries
(e.g.; media errors). Only the soft err6r packet appears for soft

4-18

errors corrected during the original operation (e.g.; single-track
errors). For
ha rd errors, the fi rst recei ved packet appea rs
describing the original operation before retries.
4.5
VISUAL TROUBLESHOOTING AIDS
In addition to control panel indicators, the basic TA78 has 24 LED
indicators for troubleshooting. The TS78 logic gate has 16
indicators, TS78 power supply has 6, and TU78 transport logic has
2. Figures 4-4, 4-5 and 4-6 show the position of the various
indicators. Table 4-6 describes their function and possible causes
of failure.

CD
J..

CHANNELO (TRACK 7) FATAL

TUPORT2
STATUS
PARITY
ERROR

CHANNELl (TRACK6) FATAL

TUPORTO
STATUS
PARITY
ERROR

TRANSLATOR
PROGRAM ROM
PARIT~ ERROR
__~,__~C~O~L~U~M~N~S_~___________~/~

~3l2~\110 9
CHANNEL 2 (TRACK 5) FATAL ~~....,
CHANNEL4 (TRACK 9) FATAL

-p.!-iP. •

CHANNEL 3 (TRACK 31 FATAL -----;

.1'.

'" M N ;=

en en

::2: ::2:

::2:

en en
co

f~V

C")

~ ~

i=
a:

U U
::2:
u

~ ~

=>
C

E
~

Cl...

CHANNEL 7 (TRACK 2) FATAL
CHANNEL6 (TRACK 8) FATAL

C")

::2:

::2: ::2:

LO en en

~ . I;

CHANNEL5(TRACK 1) FATAL ~

::2:

Cl...

RO WS

,,-

/ 6 5 4 3,,}/"l
'/
l
V/
11

1\ ~ f~' ~ v

~~~~~

CHANNEL P (TRACK 4) FATAL

co
::2:

PARITY ERROR

I .......

I'---~

<t:

-'
en

' " WRITE MICROCONTROLLER
PROGRAM ROM PARITY ERROR\:::.)

<t:

-'
en

1\
\

TU PORT 3
STATUS
PARITY
ERROR
\

1'---~::2:

f5\

"'" :::-

~~~en~~

::2: ::2: ::2:
D V l7
/y
ECC PROGRAM ROM
::2:

::2:

~~
~~~
.,"-....- ~ ~ ;::::

en en~ 4' en
0

::2:

co co
::2:::2:

U1 U
u a:
~ ~ ~ a: ~

TU PORT 1
STATUS
PARITY
ERROR
y

MA-fJ174D
SHR-0083-84

Figure 4-4

TS78 Logic Indicators for Troubleshooting

4-19

,r- - -

---------~

/
/

AC ON

+5V _

O~"@
AC OFF

ADJ.

+5Vrf3\:
ON~I

FlEGULATOR 2

I
I

H7441

+5V _1(2) ., -

+5Vt]\'
ON~

ADJ.
REGULATOR4
H7441

L ___ .________ J _ _ _ _ _ _ _ _ _ _ _
I
I
.

-5V _~ __ -5Vf8'{B+15V_lIiJ _-15VtJ()\!
ADJ.
ON "-V I
ON
ON ~
I

HEGULATOR 1
H7490

I
I

REGULATOR 3
H7476

.
MA-7512A
S H R-0065·84

Figure 4,,·5

TS78 Power Supply Indicators and Adjustments

TU BUS
COMMAND
PARITY ERROR

TRANSPORT IS
IN MANUAL
MODE

fi3\

\!.V

MA·26648

SHR·0066-84

Figure 4-6

TU78 Logic Indicators for Troubleshooting

4-20

Table 4-6

Troubleshooting Indicator Functions

Indicator

Normal
state

Function

possible Failing FRU

Figure 4-4
1

Off

Indicates channel
failure. These 9
indicators reflect
the quality of the
data stream for
each channel or
track. They indicate
loss of sync or
track dropout.
(not latched)

TU78 transport
TU bus cable (n)B
M8950
M8955

Off

A parity error
occurred in the
ECC microcontroller.
(la tched)

M895l

Off

Indicates a TU bus
status parity error.
Wrong parity was
received at the TU
port on the WCS lines.
(latched)

TU bus cable (n)A
TU78 MIA
M8955

Off

A parity error occurred
in the translator
microcontroller.
(la tched)

M8958

Off

A parity error occurred
in the write
microcontroller.
(la tched)

M8959

The +5 V regulator
number 2 is OK.
(Supplies TS78
read path.)

H744l
Any module in
slots 10--16

The +5 V regulator
number 4 is OK.
(Supplies TS78
write path, STI
ports, TU ports,
microcomputer.

H744l
Any mod ule in
slots 1--9

Figure 4-5

4-21

Table 4-6

Troubleshooting Indicator Functions (Cont)

Indicator

Normal
State

Function

possible Failing FRU

The -5 V regulator
number 1 is OK.

H7490
M8971

The +15 V regulator
number 3 is OK.

H7476
M8972
Any M8950

The -15 V regulator
number 3 is OK.

H7476
M8972
Any M8950

Power is being
applied to the
H7422 power
supply.

H7422 circuit
breaker tripped
H7422 power cord
H7422 supply

Off

A comma.nd or
command address
on the WC8 lines
was received at
the MIA with
wrong parity.

TU bus cable (n)A
M8955
TU78 MIA

Off

MIA PCBA
maintenance
switch 84 is in
MANUAL position.

Flip switch to
AUTO

Figure 4-6

4-22

4.6
ERROR LOG
All Digital operating systems, under which the TA78 runs, support
an err 0 r log gin g s chern e . Th eTA 7 8 con t a ins f i v e mi c roc 0 de are a s
for storing error log information: one extended formatter status
area and four extended drive status areas
(one for each
transport). When updating a status area, the TA78 alerts the HSC
and upon request transmits the information from the requested
area. If a software switch is enabled, the HSC then transmits the
information to the host.

The extended formatter status area is a 19-byte field that
reflects the contents of important RAM loca ti ons when a fa ta 1
err 0 roc cur red. (An err 0 r i s fat a 1 when the F AU LTin d i cat 0 r t urn s
on.) Each extended drive status area is a 49-byte field that
reflects many 8085 I/O locations in the TS78 and most of the TU78
registers at the time of a failure. In normal operation, the 8085
updates an extended drive status area when one hard error or 100
soft errors is detected during a tape motion operation. A special
zero-threshold mode allows updating of an extended drive status
area after every soft error. Appendix B lists the bytes in the
extended drive and extended formatter status areas.
A Standard Package for Error Analysis and Reporting
(SPEAR)
program for the TA78 may also be available in the operating
system. This program analyzes error log information to aid in
fault isolation to a single FRU. It is especially helpful with
problems that are: subsystem wide, intermittent, media related, or
software related.
4.7
ASCII PORT
The M8972 microcomputer module contains ASCII port firmware that
allows an external terminal to communicate with the TA78. This
firmware includes 32 commands that are listed and defined in Table
4 - 7. E 1 eve n eo mm and s are ass 0 cia ted wit h the T A7 8 - res ide n t
microdiagnostics and are discussed in more detail in Paragraph
4.3.1. Eight commands deal with checking and adjusting the capstan
servo, and are discussed in more detail in Paragraph 3.7.
Additional commands discussed in succeeding paragraphs are used
for: testing switches and indicators, checking revision levels,
and entering the keypad mode.

4-23

Table 4-7

Top Level ASCII Port Commands

Command

Function

Directory

Displays routines accessed with RUN
commands. Output on external terminal
is "KEYPAD DIAGNOSTICS VELOCITY RAMP
FWDSTOP REVSTOP BLT."

Exit

Exits from terminal mode. After exit,
tape drive no longer responds to
external terminal except for CTRL C
input. Tape drive saves contents of
keypad program area and keypad
execution parameters.

HElp <ARG>

Displays all possibilities for next
word in command string specified by
<ARG>. If <ARG> is omitted, output on
external terminal is "SET RUN
DIRECTORY HELP SHOW EXIT" (i.e.; all
possibilities for first word of
command string). If <ARG> specifies
full command string, output on
external terminal is "No further help
available."

Run BIt

Runs buttons and lights test
(Paragraph 4.7.1).

Run Diagnostic

Runs power-up chain (chain number
408) •

Run Diagnostic/Full

Runs full-set chain (chain number 0) •

Run Diagnostic/Qv

Runs minimum integrity chain (chain
n umbe r 409).

Run Diagnostic/Test=XXX

Runs test or chain specified by XXX.

Run Fwdstop/Unit=X

Runs forward stop ramp check routine
on transport X. (See note 4.)

Run Fwdstop/Unit=X/Loop

Runs forward stop ramp check routine
repeatedly on transport X. After
detecting EOT, tape drive rewinds tape
and continues to repeat routine. (See
note 4.)

4-24

Table 4-7

Top Level ASCII Port Commands (Cant)

Command

Function

Run Keypad

Enters keypad mode (Paragraph 4.7.3).

Run RArnp/Unit=X

Runs start ramp check routine on
transport X. (See note 4.)

Run RArnp/Unit=X/Loop

Runs start ramp check routine
repeatedly on transport X. After
detecting EOT, tape drive rewinds tape
and continues to repeat routine. (See
note 4.)

Run REvstop/Unit=X

Runs reverse stop ramp check routine
on transport X. (See note 4.)

Run REvstop/Unit=X/Loop

Runs reverse stop ramp check routine
repeatedly on transport X. After
detecting EOT, tape drive rewinds tape
and continues to repeat routine. (See
note 4.)

Run Velocity/Unit=X

Runs tape speed check routine on
transport X. (See note 4.)

Run Velocity/Unit=X/Loop

Runs tape speed check routine
repeatedly on transport X. After
detecting EOT, tape drive rewinds tape
and continues to repeat routine. (See
note 4.)

SEt Diagnostic/Halt

Enables halt on error; exit is to
TA78> prompt ending test or if chain
is running ending entire chain.

SEt Diagnostic/NOHalt

Disables halt on error (default).

SEt Diagnostic/Loop

Enables loop on error; no continuation
past failing point unless error
clears.

SEt Diagnostic/NOLoop

Disables loop on error (defaul t) .

SEt Diagnostic/Repeat

Enables unconditional loop; repeats
entire test or if chain is running
repeats entire chain.

SEt Diagnostic/NORepeat

Disables unconditional loop (default).

4-25

Table 4-7

Top Level ASCII Port Commands (Cont)

Command
SEt Memory XXXX:YYYY=ZZ

Function
Moves ZZ to formatter storage location
specified by XXXX:YYYY where:
XXXX = memory region number
(defa ul t=FFFF)
YYYY = offset into memory region.
Microprocessor translates XXXX:YYYY
into physical address. (For discussion
of memory mapping in TA78, refer to
Chapter 3 in TA78 Magnetic Tape Drive
Technical Description.) (See note 5.)

SEt Terminal Speed
(XXXX,YYYY)

Sets receive and transmit baud rates
for TA78 ASCII port where:
XXXX = receive (input) baud rate
yyyy = transmit (output) baud rate.
If receive and transmit speeds are the
same, only specify XXXX. Available
speed s are: 300, 600, 1200, 2400,
4800, and 9600 baud. (See note 6.)

SHow DEvice

Displays unit number and serial number
of transport 0 (i.e.; transport in
TA78 cabinet).

SHow DIagnostic

Displays current diagnostic control
parameters.

SHow Memory XXXX:YYYY

Displays contents of formatter storage
location XXXX:YYYY where:
XXXX = memory region number
(default=FFFF)
YYYY = offset into memory region.
Microprocessor translates XXXX:YYYY
into physical address. (For discussion
of memory mapping in TA78, refer to
Chapter 3 in TA78 Tape Drive Technical
Description.)

SHow RAdix

Displays output radix of TA78 ASCII
port. Tape drive displays HEX on
external terminal since all but 4
numerIc outputs are in base 16. (See
note 3.)

4-26

Table 4-7

Top Level ASCII Port Commands (Cont)

Command

Function

SHow ROms

Displays microcode revision level of
every ROM on M8972 and M8973. M8972
ROMs are identified as 0-4 and M8973
ROMs are identified as X0-X6.

SHow TErminal

Displays present receive and transmit
baud rates of TA78 ASCII port. Output
on external terminal is "(XXXX,yyyy)"
where:
XXXX = receive (input) baud rate
YYYY = transmit (output) baud rate.

SHow Versions

Displays TA78 hardware and microcode
revision levels, and STI revision
level that TA78 is compatible with.
Displayed microcode level is highest
revision level of all ROMs on M8972.

NOTES
1.
In above commands, lowercase letters may be deleted to abbreviate
a command. In addition, the "/" and "=" characters may be
replaced by blank spaces, except in SET MEMORY and SHOW MEMORY.
For example, RUN DIAGNOSTIC/TEST=XXX may be abbreviated to R D T

xxx.

Letters X, Y and Z in above commands represent maximum number of
digits that may be needed to complete a command. Leading 0s in a
number are not required.

Radix of numeric input is hex, except for baud rates. Radix for
numeric output is hex except for: unit number, serial number, STI
revision level, and baud rate. These four have decimal radix.

In tape motion commands above, X is transport cable number: 0,
1, 2, or 3. If X = 0, you may omit "/UNIT=X" from command.
with no transport specified, routine assumes the transport
connected to TU port 0 (i.e.; transport in TA78 cabinet).
(Refer to Paragraph 3.7 for discussion of displayed output and
command usage.)
Do not change storage locations in memory region FFFF. To do
so may cause microcode crash since offset translates directly
into memory address space with no restrictions.

The SET TERMINAL SPEED command is only way to introduce split
baud rates (i.e.; different rates for receive and transmit).
with this command, communication must be at new rate(s}
immediately after carriage return. If this does not occur, you
may clear ASCII port with TS78 master reset or TS78 power-up.
Then use CTRL C to access ASCII port again. (Using CTRL C
causes TA78 to autobaud, i.e.; TA78 sets reception rate based
on input speed and assigns same rate to transmit.)
4-27

To access the ASCII port, make sure both STI ports are off-line.
Plug an RS232-compatible t.erminal into the EIA connector on the
TS78 control panel (Figure 2-25). Then press and release CTRL C on
the terminal keyboard. Repeat the entry until TA78> appears.
Anyone of the 32 commands may be entered after the TA78> prompt.
And after entering a command and carriage return, the tape drive
immediately tries to execute the command. However, before one of
the eight tape (capstan) motion commands can be executed: the
desired transport must be in maintenance mode, the transport must
contain a write-enabled tape, and the transport must be on-line.
If these conditions are not met, trying to execute a tape motion
command results in an error message.
NOTE
If you do not respond to a prompt within
five
minutes,
the
TA78
exits
the
terminal mode automatically.
The ASCII port offers two ways to correct input errors. Press and
release the DELETE key to erase the last character entered. Press
and release CTRL U to erase all characters in a line. The TA78
responds by terminating the present line and issuing another TA78>
prompt.
To exit the terminal mode, type EXIT or press and release CTRL Z,
after the TA78> prompt. The tape drive then echoes your input.
Press and :release CTRL C to exit the terminal mode directly while
a command is still executing (e.g.; while a tape motion command is
looping) •
4.7.1
Buttons and Lights Test
The buttons and lights test (BLT) is interactive. It allows you to
verify functionality of certain switches and other assemblies not
tested by resident microdiagnostics.
To start BLT, type RUN BLT on the external terminal after the
TA78> prompt. In response, the TS78 microprocessor (8085) turns on
the TA78 control panel indicators one at a time for about 300 ms
each. The 8085 then determines wha t TU ports have transports
present, and via the ASCII port outputs the results for display on
an external terminal.
For the remainder of the test, you may manipulate switches without
affecting the operational microcode. The 8085, in turn, monitors
several switches and other assemblies via its I/O ports. Any
changes in state are displayed on the external terminal. Table 4-8
shows displayed messages associated with the switches and
assemblies, and the I/O register bits used to monitor these
quantities .. To exit from BLT, press and release CTRL C on the
external terminal.

4-28

Table 4-8

BLT Devices and Messages

switch/Assembly

Corresponding I/O
Register and Bit

FAULT

PSW I

(85), bit 6

Fault switch pressed
Fault switch released

PORT SELECT A

P SW I

(85), bit 5

Port A switch pressed
Port A switch released

PORT SELECT B

PSWI

(85), bit 4

Port B switch pressed
Port B switch released

Unit number
.selector

INDNI

(8A), bits 7-0

unit number changed
to XXX

TU cabling

PSTAT (48), bit 4

Drive X existent
Drive X nonexistent

Mode select

MIA status B (40-2),
bits 2, 1, and 0

Drive X rotary switch
changed to Y

ON LINE

TU status (40-0), bit 5

Drive X online
Drive X offline

BOT

TU status (40-0), bi t

Drive X at BOT
Drive X not at BOT

EOT

TU status (40-0), bit 1

Drive X at EOT
Drive X not at EOT

Write protect

TU status (40-0), bit 0

Drive X write enabled
Drive X write locked

possible Messages

NOTES
1. Numbers in parentheses are I/O port addresses. Addresses for MIA
registers in transport include microprocessor I/O address and MIA
register number.
2.

In unit number selector message, XXX is 3-digit decimal number
between 0 and 255.

Microprocessor checks TU present bit (PSTAT, bit 4)
port to determine if TU78 is cabled to port.

In any displayed message, Drive X identifies a transport with the
TU port number (9, 1, 2, or 3) that it is cabled to. For example,
"Drive 9" refers to the transport in the TA78 cabinet cabled to
port 9.

In mode select message, Y should correspond to rotary switch
position: 9, 1, 2, or 3. Y = ? if microprocessor detects illegal
code in I/O bits for this switch.

4-29

for every TU

Enabling a TS78 control panel switch causes the 8085 to turn on
the corresponding indicato]~ in addition to outputing a message. On
a transport, the wr i te-protect message always agrees wi th the
status shown by the file protect indicator. However, the messages
for ON LINE and BOT do not always agree wi th the corresponding
indicators. Pressing the ON LINE switch may cause the on-line
indicator to light. But the corresponding message does not appear
un til a va c u urn in t e rIo c k i s pre sen t (i. e .; aft e r I o ad in 9 tap e) •
Also, the BOT indicator should light after loading tape. But the
corresponding BOT message does not appear unless the transport is
on-line. These discrepancies occur because in certain cases status
indicator signal lines differ from monitored I/O bit signal lines.
(Refer to Appendix B for definitions of TU Status and MIA Status B
register bits.)
4.7.1.1 Running BLT (Example) -- This example shows how to use
BLT to test the STI port s~7itches and unit number selector switch.
The example assumes only transport 0 is present in a TA78. Proceed
as follows.
1.

Type RUN BLTe
In response, each TS78 control panel
indicator lights for about 300 ms. The displayed message
on the external terminal is Drive 0 existent.

Press PORT SELECT A. The PORT SELECT A indicator turns
on. The displayed message is Port A switch pressed.

Press PORT SELECT A again. The PORT SELECT A indicator
turns off. The displayed message is Port A swi tch
released.

Test the PORT SELECT B switch as PORT SELECT A was tested
in steps 2 and 3.

Change the position of the bottom switch in the unit
number selector switchpack on the TS78 formatter. (The
bottom sw.i tch has a binary value of 1. ) The displayed
message is Unit number changed to xxx. Ignore the value
of xxx.

Move the bottom switch back to its original position. The
displayed message is Unit number changed to xxx where xxx
is the uni t number of transport 0 (identi fied in the
bottom-left corne]: of the transpor t glass in the TA 78
cabinet) •

Press and release CTRL C to exit from the test. The tape
drive responds by displaying TA78>.

4-30

4.7.2
Checking TS78 Revision Levels
To check TS78 revision levels, use the
management document. Proceed as follows.

ASCI I

port and

revision

Type SHOW VERSIONS. The tape drive responds by displaying
the TA78 hardware and microcode revision levels, and the
STI revision level that the TA78 is compatible with.

Look up the displayed hardware level in the revision
management document. Determine the proper revision level
for each TS78 module.

If necessary, remove each TS78 module from the backplane
and check the module's actual revision for proper level.

Type SHOW ROMS. The drive displays the microcode revision
level of every ROM on the M8972 and M8973. The revision
level for every M8972 ROM should match the microcode
revision level displayed by SHOW VERSIONS. If this is not
the case, replace the M8972.

4.7.3
Keypad Mode
The keypad mode allows you to program and run tape motion
routines, and to retrieve and run prewritten tape motion routines.
The keypad firmware provides a 30-location keypad program area, 55
instructions, and a l3l-location parameter area. In addition, a
16-bit address counter and 8-bit accumulator are included. And in
the parameter area, four 16-bit counters are included.
To enter the keypad mode, type RUN KEYPAD on the external terminal
after the TA78> prompt. The tape drive displays KEYPAD> on the
external terminal. Anyone of the 55 commands may be entered after
the KEYPAD> prompt. And after enter ing a command and carr iage
return, the tape drive immediately tries to execute the command.
However, before a tape motion command can be executed: the desired
transport must be in maintenance mode, contain a write-enabled
tape, and be on-line. If these conditions are not met, trying to
execute a tape motion command results in an error message.
The 55 commands are divided into two categories: immediate
execution and deferred execution. The 11 immediate execution
command s ca n be execu ted onl y a fter the KEY PAD> prompt as
prev iously descr ibed. The 44 deferred execution commands may be
executed immediately or placed in the keypad program area for
execution later. Tables 4-9 and 4-10 list and define the immediate
and deferred execution commands. Table 4-10 also includes the
locations of parameters that affect or are affected by execution
of a command in the keypad mode.
Most of the immediate execution commands are used to manage
programming in the keypad mode. Some functions are: entering
deferred execution command (s) into the program area, 1 isting the
contents of the program area, and starting program execution.
4-31

Table 4-9

Immediate Execution Commands

Command

Function

INIt

Clears keypad program area and reset execution
parameters to default values

Get X

Loads tape motion routine X into program area
(Paragraph 4.8)

ENTer XX

Begins input of program command(s) for deferred
execution starting at location XX in program area.
Tape drive displays message on external terminal
asking for user input. (You may omit XX if XX =
00. )

END

Ends input of command(s) to program area. Tape
drive displays KEYPAD> prompt on external
terminal.

LIst XX YY

Displays contents of YY location(s) in program
area starting at location XX. Tape drive displays
"(null)" on external terminal for any location
that contains no command.

STArt XX

Starts program execution at location XX in program
are a. ( Yo u rna y om i t XX i f XX = 0 0 • )

Continue

Continues running previously halted program at one
program location after last executed command.

EXAmine XXXX

Displays contents of location XXXX.

DEPosit XXXX YY

Deposits YY. into location XXXX.

DIRect

Displays listing of all keypad mode commands

EXIt

Exits from keypad mode. Tape drive displays TA78>
prompt on external terminal. Tape drive saves
contents of keypad program area and keypad
execution parameters.

(See note 4.)

NOTES
1. In above commands, lowercase letters may be deleted to
abbreviate a command. F()r example, EXAMINE XXXX may be
abbreviated to
EXA XXXX.
2. Letters X and Y in above commands represent maximum number of
digits that may be neede'd to complete a command .. Leading Is in
a number are not required.
3.
In keypad mode, default radix of numeric input is hex. Radix
is decimal if you follo\t;., numeric input with a period (n .It) •
Radix for numeric output is hex.
4. Before using EXAMINE or DEPOSIT, address mode must be
previously defined with MEM, 10 or PARAM. If memory mode is
used, a region should also be specified. (Refer to Tables 4-l~
and 4-11.)
4-32

Table 4-10

Deferred Execution Commands
Associated
Parameter
Address

Command

Function

Nop

No operation

HAlt

Halts program execution and displays
program location (PC) of last executed
command.

UNIt X

Selects transptirt X for tape motion.
(X is transport cable number: 0, 1, 2,
or 3.)

Fmdump

Updates extended formatter status area.

DUmp

Updates extended drive status area.

ADdress XXX X

Loads XXXX into address counter.

INCR

Increments address counter by 1.

MEmory

Specifies memory address mode; address
counter, EXAMINE command and DEPOSIT
command point within microprocessor
memory address space.

Specifies I/O address mode; address
counter, EXAMINE command and DEPOSIT
command point within microprocessor
input/output address space.

Param

Specifies parameter address mode;
address counter, EXAMINE command and
DEPOSIT command point within keypad
parameter address space.

STOre

Moves contents of accumulator to
location specified by address mode
and address counter.

LOad

Loads accumulator with contents of
location specified by address mode
and address counter.

Mvi XX

Loads XX into accumulator.

ANd XX

Logically ands XX with contents of
accumulator and stores result in
accumulator.

Test XX

Logically ands XX with contents of
accumulator. (Contents of accumulator
are not affected.)

4-33

Table 4-10

Deferred Execution Commands (Cont)
Associated
Parameter
Address

Command

Function

DISplay

Displays contents of accumulator (AC)
on external terminal. In program
deferred mode only, current program
location (PC) also displays.

LD0cntr XXX X

Loads XXXX into counter 0.

LD1cntr XXXX

Loads XXXX into counter 1.

F, 10

LD2cntr XXX X

Loads XXXX into counter 2.

11, 12

LD3cntr XXXX

Loads XXXX into counter 3.

13, 14

INC0

Increments counter 0 by 1.

INC1

Increments counter 1 by 1.

INC2

Increments counter 2 by 1.

11, 12

INC3

Increments counter 3 by 1.

13, 14

DECR0

Decrements counter 0 by 1.

DECR1

Decrements counter 1 by 1.

DECR2

Decrements counter 2 by 1.

11, 12

DECR3

Decrements counter 3 by 1.

13, 14

BZ XX

Branches to program location XX
if last operation produced 0.

BNZ XX

Branches to program location XX
if last operation produced nonzero
result.

BR XX

Branches unconditionally to program
location xx.

WRIte

writes one record.

0, 1, 5, 9,

A, B

WRTmai

writes continuously on all tracks
until EOT.

4-34

5, B

Table 4-10

Deferred Execution Commands (Cont)
Associated
Parameter
Address

Command

Function

RDFwd

Reads forward one record.

0, 1, 6 or
7, C

RDRev

Reads reverse one record.

0, 1, 6 or
7, C

REwind

Rewinds tape.

UNLoad

Rewinds and unloads tape.

ERase

Erases gap.

DSe

Data security erase from current
position to past EOT and rewinds
tape.

WTm

writes one tape mark.

0, 1, 5

xxxx

Spaces forward
end of file.

xxxx records or until

0, 6 or 7

SPRev XXXX

Spaces reverse
end of file.

xxxx records or until

6 or 7
6 or 7

SPFwd

xxxx

Spaces forward XXXX gaps (includes
gaps between records and gaps between
files) •

SERev XXXX

Spaces reverse XXXX gaps (includes
gaps between records and gaps between
files) •

0, 6 or 7

SEFwd

NOTES
1.
In above commands, lowercase letters may be deleted to abbreviate
a command. For example, LD9CNTR XXXX may be abbreviated to LD0
XXXX.
2.

Letter X in above commands represents maximum number of digits
that may be needed to complete a command. Leading 0s in a number
are not required.

In keypad mode, default radix of numeric input is hex. Radix is
decimal if you follow numeric input with a period ( ..... ). Radix
for numeric output is hex.

4-35

The keypad mode offers three address modes: memory address mode,
I/O address mode, and parameter address mode. The memory address
mode allows you to access the entire 64K 8085 address space. This
space contains ROM, RAM, and I/O registers. The I/O address mode
allows you to access only the I/O registers which are in the top
4K of the memory address space. The parameter address mode allows
you to access the parameter address space which is within the RAM.
Executing the INIT command, a TS78 master reset or a TS78 power-up
automatically specifies the parameter address mode as a default.
After execut ing a tape mot ion command, the TS78 microprocessor
(8085) loads a status byte into the keypad accumulator. Figure 4-7
shows the status byte bit assignments. You may wish to test this
byte for any detected tape motion errors.
In a deferred program, only execution of the DISPLAY and HALT
commands results in displayed values on the external terminal.
However, many commands result in displayed values when executed in
immediate mode (i .e.; after the KEYPAD> prompt). Executing the
commands that affect the accumulator cause the display of the new
accumulator value. Executing the TEST command causes a display of
the result. Executing commands that increment or decrement a
general purpose counter cause the display of the logical "or" of
the two counter bytes. Note that in all cases the displayed value
is a two-digit hex code.
In any command input, you may press and release the DELETE key to
erase the last character entered. Press and release CTRL U to
erase all characters in a 1 ine. The TA 78 term ina tes the present
line and issues another prompt.
To end deferred program execution, press and release CTRL G. The
external terminal then identifies the last program location
executed and displays the KEYPAD> prompt. Type EXIT or press and
release CTRL Z after the KEYPAD> prompt to exit the keypad mode.

TAPE
MARK

BEGINNING
OF TAPE

AMTIE

END OF
TAPE

FATAL
ERROR

CORRECTABLE
ERROR
TRANSPORT
IS BUSY
UNCORRECTABLE
ERROR
SHR-0102-84

Fig ure 4-7

Tape Motion Returned Status
(Keypad Mode)

4-36

The external terminal then displays your input and the TA78>
prompt. Press and release CTRL C to exit the keypad mode directly
while a program is still executing.
When entering a command after the KEYPAD> prompt, you may end the
line by pressing and releasing CTRL Z instead of using a carriage
return. Ending a command wi th CTRL Z causes the tape dr ive to
execute the command and then exit from the keypad mode. Because of
their nature, ending a START or CONTINUE command in this manner
causes a keypad mode exit only after a HALT instruction is
executed or after you press and release CTRL G.
Figure 4-8 shows a sample printout that includes: entering an
8-step program, listing the program, executing the program,
modi fyi ng the program, and executi ng the modi fied program. Each
command to be entered is outlined and must be followed by a
carriage return. The remaining printout shows the tape drive's
responses and several commments that have been added for clarity.
The comments are enclosed in parenthesis and do not appear in a
TA78 printout.

Tr178>RUN KEYPAD
KEYPAD> INIT
I~EYF'AD::: UNIT 0
I~E YPAD> ENTER
pc= 00 l' WRITE
pc= 01 l' TEST 4
pc= 02 l' BZ 4
pc= 03 l' HALT
pc= 04 l' TEST 40
pc= 05 l' BZ 0
PC'" 06
l' REWIND
pc= 07 l' BR 0
pc= 08 'r END
KEYPA[ULIST 0 A
00:
WRITE
01:
TEST
0004
02:
BZ
0004
03:
HALT
04:
TEST
0040
05:
BZ
0000
REWIND
BR
0000
( nlJ 11 )

(0 IS TRANSPORT CABLE NUMBER)
(ENTER PROGRAM)

(LIST PROGRAM)

(EXECUTE PROGRAM. PRESS AND RELEASE
CTRL G TO END PROGRAM EXECUTION.)
(MODIFY PROGRAM)

pc= 02 '~END
KEYPAD:::LIST 0 8
00:
WRITE
01:
TEST
0017
02:
BZ
0004
03:
HALT
04:
TEST
0040
05:
BZ
0000
06:
REWIND
07:
BR
0000
KEYPAI:UISTART!
HALT AT pc= 00
KEYF'AD)"Z
Hl'78)"Z

(LIST MODIFIED PROGRAM)

(EXECUTE MODIFIED PROGRAM. PRESS AND
RELEASE CTRL G TO END PROGRAM
EXECUTION.)

SHR0230-84

Figure 4-·8

Keypad Mode program Example

4-37

When executing the program first entered in Figure 4-8, the tape
drive writes records testing for an AMTIE error at the end of
every record. The drive halts at program location 3 if an AMTIE
error has been detected. For error-free operation, the drive
continues to write records until EOT and then rewinds the tape.
The drive then continues writing and testing.
Modifying program location I as shown in Figure 4-8 causes the
tape drive to halt at program location 3 if any error is detected.
Any error includes: a correctable error, uncorrectable data error,
AMTIE error, or fatal error.
4.7.3.1 Parameter Area
The
divided into four areas listed
area, use the PARAM command.

l31-location parameter area is
below. To access the parameter

Parameter
Address
Range

Parameter
Area
Designation

o -- 23

Execution area
Extended drive status area
Extended formatter status area
Operational status area

24
57
6B

56
6A
82

The execution area contains parameters that directly affect how a
command is executed, and parameters that are affected by command
execution. Table 4-11 lists and defines the execution parameters
and their default values. Except for location 0, the execution
parameters are independent of the transport selected.
The three remaining parameter areas reflect various 8085 RAM and
I/O locations. You may wish to analyze these locations after
iunning programs since these locations contain valuable internal
status information. The extended drive and extended formatter
status areas are copies of the areas used for error logging
information. The contents of these two areas are discussed in
Appendix B. The operational status area contains RAM locations
that are periodically updated with formatter and transport status
during normal operation. Table 4-12 lists and defines the
operational status parameters. Note that the contents of the
extended drive status and operational status areas is dependant on
the transport selected in parameter 0.
WARNING
Do not wri te in the operational status
area (addresses 6B--82). To do so, may
cause a microcode crash.

4-38

Table 4-11
Address

Execution Parameters

Name

Default
Value

KEYUNI

Transport cable number (0, 1, 2 or 3).
This number identifies the transport
with the TU port number that it is
cabled to.

Dpv I - "
1

KEYDEN

KP$REG

Description

Recording density.
o = GCR format (9042 fr/in)
Nonzero = PE format (3200 fr/in)
FF
FF

Memory region number (low byte) •
Memory region number (high byte) .
In memory address mode, 8085
translates 16-bit memory region number
and 16-bit offset into physical
address. Offset is in address counter.
(For discussion of memory mapping in
TA78, refer to Chapter 3 in TA78
Magnetic Tape Drive Technica-l--Description.) (See note.)

KP$KDY

Instruction delay. This number affects
elapsed time between execution of
keypad commands. The larger the
number, the longer the elapsed time.

5
6
7

KP$CLK

KP$CLD

10
12
13
10

write function clock control.
Read GCR function clock control.
Read PE function clock control.
Loop write-to-read function clock
control.
8085 loads contents of appropriate
location (5, 6, 7 or 8) into clock
control register before executing
desired function. Bits 7 and 6 are
forced to 0, bits 5-3 specify write
path clock, and bits 2-0 specify read
path clock.
Bit Value Function
-10% clock
5:3 0
+10% clock
5:3 1
Normal clock
5:3 2
-30%
clock
5:3 3
Normal clock (write)
2:0 0
+20% clock
2:0 1
+10% clock (GCR read)
2:0 2
-20% clock (PE read)
2:0 3
Values not listed should not be used.
4-39

Table 4-11

Execution Parameters (Cont)

Address

Name

KP$WSZ,

Default
Value

o
A

Description
Write record size (low byte) .
write record size (high byte) .
8085 uses contents of 9 and A as
16-bit byte count for write record
operations.

KP$WPA

KP$RDA

D
E

KEYCT0

F
10

KEYCTI

KEYCT2

12
13
14

KEYCT3

write data or test pattern. In write
record operations, 8085 loads contents
of B into DDR for use as 8-bit record
data. In write continous operations,
8085 loads contents of B into MIA test
pattern register. This pattern is then
written repeatedly on all tracks until
gOT.
Read data. Contains contents of DDR
after last data byte is read in record
during read forward or read reverse
operation.

o
o
o

General
General
General
General
General
General
General
General

purpose counter
purpose counter
purpose counter
purpose counter
purpose counter
purpose counter
purpose counter
purpose counter

0 (low byte) •
0 (high byte) .
1 (low byte) .
1 (high byte)
2 (low byte) •
2 (high byte) .
3 (low byte) •
3 (high byte) •

These four l6-bit counters can be
loaded, incremented, decremented, and
tested by the 8085 in accordance with
keypad commands.
15--23

Spare locations. These parameter
locations may be used for temporary
data storage (i.e.; as a scratchpad
area) •

NOTE:
Do not change storage locations in memory region FFFF. To
do so may cause microcode crash since offset translates directly
into memory address space, with no rest~ictions.

4-40

Table 4-12

Operational status Parameters

Parameter
Address

Description
Bit

Description

7
6
5

Tape unit was ready and on-line.
Maintenance mode was requested.
Tape unit was on-line but not necessarily
ready.
Last operation was tape rewind.
Last density: l=PE, 0=GCR.
BOT marker on tape was at BOT sensor.
EaT marker on tape was at or past EaT sensor
while tape was mo~ing in forward direction.
Tape unit was write locked.

4
3
2
1

o
6C

Current TU software status byte.
Bit

Description

7
Current density: l=PE, 0=GCR.
6
Tape unit exists and power is on.
S
Tape unit is in maintenance mode.
4
Last operation wrote on tape.
3
Not used.
2
Direction of last motion: 0=Forward, l=Reverse.
l O S E in progress.
o
Rewind in progress.

Pending TU software status byte.
Bit

Description

7
6
5
4
3

Request to unload tape.
Request to erase tape past EaT during DSE.
DSE or rewind in progress.
Clean tape operation in progress.
Update of extended formatter status or extended
drive status is in progress.
Request for diagnostic mode.
Request for zero threshold mode.
Requested density: l=PE, 0=GCR.

2
1

4-41

Table 4-12

Operational Status Parameters (Cont)

Parameter
Address

Description

Drive mode byte.
Bit

Description

7
6

Tape mark is detected.
EOT marker on tape is at or past EOT sensor
while tape m6ving in forward direction.
BOT marker On tape isat BOT sensor.
Tape unit is write l6cked.
Tape unit is on-line and ready.
Tape unit is ready but not on-line.
Maintenance mode request.
Error log information available.

5
4
3
2
1

(/)
6F

Drive error

byte~

Bit

Descrjption

7
6

Drive error occurred (miscellaneous).
Lengthy ope~ation in progress.
Tape position lost.
Exception occurred (bit 7, 6 or 5 of byte 6E is
set) •
Data transfer error occurred (operation
aborted) .
Not used.
Not used.
Not used.

4
3
2
1
(/)
70

write byte count ( low byte) •

Write byte count' (high byte) •

Modulo 7 courit.

Gap count (first byte, least s i g n if i ca n t) •

Gap count (second byte),.

Gap count (third byte) •

Gap count (fourth byte, most signi ficant) •

Soft error count.

4-42

Table 4-12

Operational Status Parameters (Cont)

Parameter
Address

Description

78-7C

Spare locations.

Error number (low byte)

(Paragraph A.2.1).

Error number (high byte)

(Paragraph A. 2.1) •

Low byte for number of gaps (in space operation) or for
byte count (in read operation).

High byte for number of gaps (in space operation) or
for byte count (in read operation).

81-82

Spare locations.

4.8
PREWRITTEN TAPE MOTION ROUTINES
The TA78 contains 11 prewritten test routines (0-A) which involve
tape motion. Most of these routines write and/or read data on
tape. The routines are intended as transport troubleshooting or
adjustment aids. For example, test 2 can be used to test
peakshift.
The routines are in M8972 ROM and are written in keypad code. Any
of these routines can be accessed and run via the ASCII port. A
routine must be moved to the keypad program area in M8972 RAM
before execution. Once in RAM, the routine may also be modified.
4.8.1
Running Instructions
To run a prewritten tape motion routine, make sure: both STI ports
are off-line, the desired transport is in maintenance mode, the
transport contains a write-enabled scratch tape, and the transport
is on-line. Then plug an RS232-compatible terminal into the EIA
connector on the TS78 control panel (Figure 2-25) and proceed as
follows.
1.

Press and release CTRL C on the terminal keyboard. Repeat
the entry until TA78) appears.

Type RUN KEYPAD. The acceptable response is KEYPAD).

Type INIT. This clears the keypad program area and resets
the keypad execution parameters to known default values.

To select a transport, type UNIT X where X is the desired
transport's cable number (0, 1, 2, 3) shown in Figure
2-17. The default number is 0 which selects the transport
in the TA78 cabinet.

4-43

Type GET X where X is the hex test number of the desired
prewritten tape motion routine (Paragraph 4.8.2). The
microprocessor moves the routine from M8972 ROM to the
keypad program area in M8972 RAM.

Type START. The tape drive executes the tape motion
routine in M8972 RAM on the selected transport. In most
cases, the tape drive repeats the routine indefinitely
with no displayed output.

Press and release CTRL G to exit from a tape motion
routine. The tape drive displays HALT AT PC=XX where XX
is a program location. The drive then displays KEYPAD).

Press and release CTRL Z to exi t from the keypad mode.
The tape drive echoes A Z and displays TA78>.

Press and release CTRL Z to exit from the terminal mode.
The drive echoes AZ.

In the above procedure, you may select a transport other than 0.
Otherwise, unless specified in its code, the selected test routine
uses default parameters.
However, you may make additional changes in unspecified parameters
using the PARAM and DEPOSIT commands in the immediate execution
mode, before running the routine in step 6 above. For example, no
test routine specifies density in its code. To change the density
from the default GCR to PE, type the following between steps 4 and
5.
PARAM
DEPOSIT 1 1
Once specified, a parameter remains in effect until changed with
another command. To return all execution parameters to their
default values, use the INIT command. This command also clears the
keypad program area.
Once moved into RAM, a prewritten tape motion routine is like any
other keypad program. To display a routine use the LIST command.
To modify a routine, use ENTER and END. (Refer to Paragraph 4.7.3
for a discussion of keypad mode.)
4.8.2
Descriptions and Listings
This paragraph contains a descriptive summary and code listing for
each prewritten tape motion routine. The code format here is the
same as the format displayed on an external terminal in response
to a LIST command.

4-44

Nondefault write parameters specified in a routine's code are
mentioned in a routine's summary. Writing a record with default
parameters results in a 2.5K-byte GCR record with all 1s data.
writing continuously (in nonrecord format) with default parameters
results in an all 1s test pattern written at 9042 fr/in.
4.8.2.1 Test 0 -- In this test, the tape drive writes an all 1s
test pattern continuously on all tracks until EaT. The drive then
rewinds the tape and the test repeats.
00:
01:
02:
03:
04:
05:
06:
07:

PARAM
ADDRESS 000B
MVI
00FF
STORE
REWIND
WRITE
WRTMAI
BR 0004
Modifying
pattern.

step

NOTE
2 modifies

the

test

This test is the same as test 0 except test
4.8.2.2 Test 1
pattern 10010011 is used here. The program listing is the same as
for test 0 except step 2 is MVI 0093 here.

This test is the same as test 0 except test
4.8.2.3 Test 2
pattern 11100111 is used here. The program listing is the same as
for test 0 except step 2 is MVI 00E7 here.
4.8.2.4 Test 3 -- In this test, the tape drive writes a series of
32-byte records. The drive delays about 4 ms before writing each
new record. After detecting EaT, the drive rewinds the tape and
the test repeats.
00:
01:
02:
03:
04:
05:
06:
07:
08:
09:
0A:
0B:
0C:
00:
0E:

PARAM
ADDRESS 000A
MVI 0000
STORE
ADDRESS 0009
MVI 0020
STORE
REWIND
LD0CNTR 0100
DECR0
BNZ 0009
WRITE
TEST 0040
BNZ 0007
BR 0008

4-45

4.8.2.5 Test 4--In, this, test, the "t;ape drive repeatedly writes
a record and then reads it in the reverse direction. If the EOT
marker is detected, the drive rewinds the tape. This prevents
running off the tape due to tape creep.
00:
01:
02:
03:
04:
05:

REWIND
WRITE
TEST 0040
BNZ!t 0000
RDREV
BR 0001

4.8.2.6 Test 5 -- In this test, the tape drive reads records
testing for errors at the end of every record. The drive displays
a two-digit status word on the external terminal and then halts,
if it detects any error (i.e.; correctable error, uncorrectable
data error, AMTIE error or fatal error). For error-free operation,
the drive continues to read until EOT and then reads reverse until
BOT. The test then repeats.
00:
01:
02:
03:
04:
05:
06:
07:
08:
09:
0A:
0B:
0C:
0D:
0E:
0F:

RDFWD
TEST 0040
BNZ 0008
TEST 0017
BZ 0000
DISPLAY
HALT
BR 0000
RDREV
TEST 0020
BNZ 0000
TEST 001 7
BZ 0008
DISPLAY
HALT
BR 0008

4-46

4.8.2.7 Test 6 -- In thi s test, the tape dr i ve spaces forward
until it detects: one tape mark~ an EDT marker, or a fatal error.
The drive then halts. For a halt on EDT or a halt on error, the
drive displays a two-digitst~tus word on the external terminal.
Therefore, a halt with no status word displayed indicates the end
of one file (i.e.; one t~pe mark detected).
00:
01 :
02:
03:
04:
05:
06:
07:
08:
09:
0A:
0B:
0C:

LD0CNTR 0001
SPFWD FFFF
TEST 0080
BNZ 0008
TEST 0041
BZ 0001
DISPLAY
HALT
DECR0
BNZ 0001
HALT
REWIND
BR 0000
NOTE
Modifying step 0 allows spacing forward
until a specified number of tape marks
have been found as opposed to just one
tape mark.

4.8.2.8 Test 7 -- In'this test, the tape drive writes records
testing for errors at the end of every record. If it detects any
error, the drive displays ~ two-digit status word on the external
terminal and then halts. For error-free operation, the drive
continues to write record"s until EOT, and then rewinds the tape.
The test then repeats~
00:
01:
02:
03:
04:
05:
06:
07:
08:

REWIND
WRITE
TEST 0040
BNZ 0000
TEST 0017
BZ 0001
DISPLAY
HALT
BR 0001

4.8.2.9 Test 8 -- In this test, the tape drive writes records
testing for errors at the end of every record. If it detects any
error, the drive displays a write error count on the external
teminal and then does a write retry operation. The write retries
continue as long as an erl~or remains and the drive updates the
display for every failed retry (i.e.; whenever an error is
encountered). For error-free operation, the tape drive continues
to wr i te record s unti 1 EOT and then rewi nds the tape. The tes t
then repeats.
00 :
01:
02:
03:
04:
0.5 :
06:
07:
08:
09:
0A:
0B:
0C:

00:
0E:

LD0CNTR 0000
PARAM
ADDRESS 0000
REWIND
WRITE
TEST 0040
BNZ 0003
TEST 0017
BZ 0004
INC0
LOAD
DISPLAY
SPREV 0001
ERASE
BR 0004

4.8.2.10 Test 9 -- In this test, the tape drive writes a record
and then reads it in reverse and forward, testing for errors after
every operation. The drive does a write retry operation(s) to
correct any write error detected. However, the tape drive halts if
50 retries fail to yield an error-free record. For a read or read
reverse error, the dr i ve displays a read error coun t on the
external terminal and then delays about 10 seconds. The read error
count is the total number of bad records detected during reads in
forward and reverse since starting the test. with no write or read
reverse errors detected, the drive continues to write, ·read
reverse and read until EOT and then rewinds the tape. The test
then repeats.
00:
01 :
02:
03:
04:
05:
06:
07:
08:
09:
0A:
0B:
0C:

00:
0E:

LD0CNTR 0000
PARAM
ADDRESS 0000
REWIND
LD1CNTR 0032
WRITE
TEST 0040
BNZ 0003
TEST 0017
BNZ 0011
RDREV
TEST 0017
BNZ 0017
RDFWD
TEST 0017
4-48

0F:
10:
11:
12:
13:
14:
15:
16:
17:
18:
19:
lA:
IB:
lC:
10:

BNZ 0017
BR 0005
SPREV 0001
ERASE
DECRI
BNZ 0005
HALT
BR 0004
I NC0
LOAD
DISPLAY
LD2CNTR 2000
DECR2
BNZ 001B
BR 0005

4.8.2.11 Test A -- In this test, the tape drive: writes 100
records, reads reverse 99 records, reads forward 98 records,
wr i tes 97 records, read s reverse 96 records, read s forward 95
records, writes 94 records, and so on. After a write operation
wi th 1 record, the sequence repeats. After detecting EOT, the
drive rewinds the tape and the test repeats.
00:
01 :
02:
03:
04:
05:
06:
07:
08:
09:
0A:
0B:
0C:
00:
0E:
0F:
10:
11 :
12:
13 :
14:
15 :
16:
17:
18:
19:
lA:
IB:
lC:
10:

REWIND
PARAM
LD0CNTR 0065
LDICNTR 0000
LD2CNTR 0003
DECR2
DECR0
BZ 0002
ADDRESS 0000
LOAD
ADDRESS 000F
STORE
ADDRESS 0011
LOAD
BNZ 0011
RDFWO
BR 0018
TEST 0001
BNZ 0017
WRITE
TEST 0040
BNZ 0000
BR 0018
ROREV
DECRI
BNZ 000C
LOAD
TEST 0007
BNZ 0005
BR 0004

4-49

CHAPTER 5
TU78 TROUBLESHOOTING PROCEDURES

5.1

GENERAL

This chapter defines specific procedures for troubleshooting the
TU78 transport only. It is assumed that you have already isolated
a malfunction to the transport, using troubleshooting aids
discussed in Chapter 4 or other methods. It is also assumed that
you understand the normal operation of the TU78 as described in
Chapter 4 of the TA78 Magnetic Tape Drive Technical Description.
This knowledge plus the troubleshooting information in this
chapter should enable you to isola te mal functions to a single
field replaceable unit (FRU) such as a module or mechanical
assembly.

5.2

USING THE MULTIPLE INTERFACE ADAPTER (MIA) PCBA

This section describes how the
performing certain transport
troubleshooting.

MIA PCBA is used as an aid in
adjustments,
alignments,
and

5.2.1
Functional Description
The MIA PCBA is the interface between the TS78 formatter and the
TU78 transport logic. It handles read/write data, command/status
information, and ampl i tude track in error (AMTI E) i nformat ion. It
also provides one of the points where field maintenance personnel
can issue commands to the transport. This is 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 swi tches, eight DIP
switches, and two LEOs for troubleshooting purposes. Figure
3-15 shows where these components are and Tables 5-1 and 5-2 list
their functions. A more detailed description of MIA theory is
found in Paragraph 4.6 of the TA78 Magnetic Tape Drive Technical
Description.

5-1

Table 5-1

MIA LEOs

CR Number

Function

CRl
CR2

Command parity error
Manual mode

Table 5-2
Switch
Number

MIA Switch Functions
Function
Left position

Right position

Forward
Reverse
Sl
S2
Read
Write
1600 mode
6250 mode
S3
Ma n ua 1 ( t est)
Auto (on-line)
S4
--_._------------------------------------

5.2.2
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 swi tches on the MIA now provide command and data
information. The source of this information is transparent to the
transport logic. Therefore, the transport under test must be
placed on-line with the TU78 control panel ON LINE switch in order
to receive the MIA commands. Also, when in manual mode, the
mode select switch on the control panel has no effect and can be
placed in any position.
The eight test pattern DIP switches (Figure 3-15, DIP U196) can be
set to write a repeating eight character pattern to tape. Switch
number 1 of U196 determines whether characters 1, 9, 17, etc., are
all ls or all 0s. Switch number 2 corresponds to characters 2, 10,
18, and so on to switch 8 for characters 8, 16, 24, and so on. For
a detailed description of test write data generation, refer to
Paragraph 4.6.5.8 in the TA78 Magnetic Tape Drive Technical
Description.
The right LED (CR2) is lit when in manual mode. The left LED (CR1)
is lit when the MIA detects a command byte parity error from the
formatter.

NOTES
When in test write mode, a tape must
have a wr i te-enable ring or the
write/erase heads will be disabled.

5-2

All MIA swi tches are dynamic; tha t
is the user may change densi ties,
wr i te/read , whether tape is mov i ng
or not.

When creating a tape in manual mode,
upon reaching EOT, swi tch number 2
should be returned to the read
(left)
position.
If
not,
when
performing
a
reverse/rewind
to
return to BOT, the tape will be
overwritten.

Swi tch number 4 must be placed in
the auto (left) position before
returning the transport to operating
system on-line usage.

5.3
USING THE PCBA EXTENDER (PN 29-23218)
The PCBA extender is used as an aid in troubleshooting the TU78
transport. The read, write, and control M2 PCBAs can be extended
for access one at a time. The MIA cannot be extended, but can be
accessed by removing the cabinet top cover. The capstan/regulator
and reel servo PCBAs cannot be extended due to hea t sinking
requirements. Figure 5-1 shows the PCBA extender.

TO J8

TO J7

TO J5

CONTROL M2

WRITE

READ

EXTENDER PLUG FINGERS

TO PIN 36

TOP~

0-----0
TEST
POINTS

TEST
POINTS

---

DO NOT CROSS
CABLES

PLUG FROM

MA·3498A
SHR·0187-84

Figure 5-1

PCBA Ex tende r

5-3

To extend a PCBA, first remove the PCBA retainer bracket (Figure
2-6), 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 01 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) pointing up. The
extender jack is 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 5-1. The jack must not be rota ted 180 degrees
(indicated by twisted cables). This would not make proper
connections between the extended PCBA and the interconnect Dl
PCBA.
The extended PCBA is supported at an angle wi thin 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 fi t in between the PCBA board and the
support bar runnIng underneath the PCBA's test points. Figure 5-2
shows a PCBA in the extended position.
The 72 test points on the edge of the extender connect to the 72
pins on the interconnect Dl jack. Therefore, serv ice 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 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 5-1) •

5-4

UPPER ANGLE BRACKETS

LOWER ANGLE
BRACKETS

MA-3481A
SHR-0188-84

Figure 5-2

PCBA in Extended position

5-5

5.4
POWER SUPPLY TROUBLESHOOTING
This section contains a failure analysis of the power supply and
power distribution. For theory, refer to Paragraph 4.5 in the TA78
Magnetic Tape Drive Technical Description. For a large functional
block diagram, refer to FigurE~ 2 in Volume 1 of the TU78 Magnetic
Tape Transport Technical Manual. With the exception of +5 V (L)
individual power supply voltages are not adjustable. And, if a
particular vol tage is found to be out of acceptable range, a
subassembly component has to be replaced.
WARNING
Use caution when making measurements and
adjustments wi th power appl ied 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.

5.4.1
Troubleshooting Rules
When troubleshooting power supply problems, follow these rules.
1.

Make sure that pow'er is off and the
unplugged before replacing any defective
the power supply/pneumatic assembly.

transport
components

is
in

The capstan/regulator PCBA cannot be extended from the
card cage for troubleshooting with power applied since it
requires heat sinking. If this PCBA is suspected,
substitute a new PCBA.

5.4.2
Troubleshooting Hints
These hints are helpful when troubleshooting.
1.

Examine the c i rcui try for burn t pr in ted c i rcui t board
etch/components/wiring, oil leakage from capacitors, and
loose connections. A good visual check can quickly
determine the cause of a malfunction.

The +5 V, +15 V, and -15 V regulators contain overvoltage
crowbar 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.

5.4.3
Troubleshooting Charts
In checking the various areas of the power supply/distribution
system, refer to the troubleshooting chart in Table 5-3. Refer to
Figure 3-1 for fuse locations.

5-6

Table 5-3

Power Supply Troubleshooting Chart

Problem

Check

Result

Cause

No TU78
operator
panel
lights/no
functions

Fans and
blower at
rear
operating

Problem is in power
controller or line voltage.

Yes

Breaker CB1 tripped.
Check +5 V (TP11 of
capstan/reg PCBA).
Power jumpers are incorrect
at A1-TB1

No +5 V TP11
of capstan
(regula tor
PCBA)

+12 V at
A2-TBl-6

Troubleshoot +12 V.
Capstan/regulator PCBA is
bad. Etch on interconnect
01 PCBA is burnt.

Yes

+5 V output
too low

No +12 V
(A2-TBl-6)

Capstan/regulator PCBA is
bad or out of adjustment.
Bridge rectifier CR2 is
partially open.
8.5 Vac at
A2-TBl-10

Yes

Fuse F1 is blown.
Bridge rectifier CR2 is
open. Capacitor C3 shorted.
Transformer T1 is defective.

No
No +15 V
(TP15 of
capstan/
regulator
PCBA)

+24 V at
A2-TBl-7

No
Yes

Troubleshoot +24 V.
Capstan/regulator PCBA is
bad. Etch on interconnect
01 PCBA is burnt.

No -15 V
(TP18 of
capstan/
regulator
PCBA)

-24 V at
A2-TBl-8

No
Yes

Troubleshoot -24 V.
Capstan/regulator PCBA is
bad. Etch on interconnect
01 PCBA is burnt.

No +24 V
(A2-TBl-7)

Fuse F2 is blown.
Bridge rectifier CR1 is
open. Capacitor C1 is
shorted. Transformer T1 is
bad.

No -24 V
(A2-TBl-8)

Fuse F3 is blown.
Bridge rectifier CR1 is
open. Capacitor C2 is
shorted. Transformer T1 is
bad.

No +36 V
(A2-TB1-1 )

Fuse F4 is blown.

5-7

Table 5-3
Problem

Power Supply Troubleshooting Chart (Cont)
Check

Uesult

Cause

No +36 V
(Reel servo
PCBA TP12)

Fuse F6 is blown.

No +36 V
(Reel servo
PCBA TP4)

Fuse F7 is blown.

No +36 V
anywhere

Bridge rectifier CR3 is
open. Capacitor C4 is
shorted.

No -36 V
(A2-TBl-5)

-36 V at
reel servo
PCBA
TPl0 and
TP18

Fuse F5 is blown.
Bridge rectifier CR3 is
open. Capacitor C5 is
shorted.

Yes
No

5.5
LOAD CYCLE TROUBLESHOOTING
When a load fault occurs, specific test points can be checked for
clues to the trouble area. Seven test points are specified and
load fault troubleshooting flow diagrams are provided, one
associated with each of the test points. The seven load faults are
numbered 0 through 6 to correspond with the loading flowchart in
the engineering print set (control M2 logic Schematic Number
106875, sheets 1'1 and 12) in Volume 1 of the TU78 Magnetic Tape
Transport Technical Manual.
The autoload cycle requires all vacuums and pressures to be within
specification, and all power supply, control, capstan servo, and
reel servo functional circui try be operating. Before pursuing a
path through these troubleshooting flows, the loading flowcharts
and suggested corrections in Figures 2-22 and 2-23 should be
followed. Also refer to Schematic Number 106875 (control M2 PCBA),
sheets 11 and 12, for a funct ional load ing flowchart and Figure
5-3 for an autoload timing diagram. Figure 4 in volume 1 of the
TU78 Magnetic Tape Transport Technical Manual shows the major
signals necessary to accomplish a load cycle.

5-8

LOAD/REW N. O. (U26-4) ~

I
I
LDS TP 45 .J

NLRSTP (1I24-6)

NLDP TP 18

PNU RET. TP 711
NRSAE TP 70 1
NCOC TP 691
THDS TP 68.J
NXFR TP 721
TRF TP 66~
LOW TAPE TP 43
(LOAD COUNT)

I I I I
0

BKW TP 46

I I

I I I

I I I I I I I I

I I I
6

I I I

I 0

(NO CARTRIDGE)

NPOL TP 51
ASP N.O. TP 48 ~

lTl

I
\.0

THD TP 53
SRF TP 64
RETRY CTR.

o I 1

TIP (U204-3)
(TOR CTR.)
TOR TP 59

BOT GATE (U216-5)

NBOT TP 36

U I

I
I

STL TP 37 _______________________________________________________1_00_M~S__~1
I

TRRTP67 ____________________________________________________________~!
NINTLK TP 62

-1SEC-!L

DINTLK (U184-6)

--Ill-

CAP. REV. TP 22 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -______________________-I---l--_ _ _
ALL TEST POINTS AND SIGNAL NAMES
ARE FOUND ON CONTROL M2PCBA

MA·3491A
SHR-01S9·84

Figure 5-3

Autoload Timing Diagram

5.5.1
Load Faults
When a load faul t occurs (flashing load faul t LED on the TU78
control panel) it can be categorized into one of seven possible
load faul t areas. To determine what area caused the faul t, and
therefore correct the source of this problem, you must scope test
points on the control M2 PCBA. Table 5-4 1 ists the load faul t
n umbers and thei r assoc ia ted test points. Our ing a norma 1 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 faul t area number and the troubleshooti ng flow diagram to be
used. Figures 5-4 through 5-10 are the load fault flow diagrams.

Table 5-4

Load Fault Categories

Load Fault
Number

Control M2 PCBA
Test Point

TP14

No load count sequencing pulses
from take-up reel

TP27

Cartridge fault (not sensed as
being closed or open)

TP32

Cartridge fault (not 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

Category Description

5-10

YES

•

•
FLIP
SWITCH
TO
ENABLE

CHECK FOIL SENSING
MARKERS ON TAKE UP
REEL
CLEAN OR REPLACE
PACK SENSE
ASSEMBL Y

CHECK THE FOLLOWING:
1. BAD INTERCONNECT Fl
2. BAD F1 TO D1 CABLE
3. BAD INTERCONNECT Dl

REPLACE
CONTROL M2 PCBA

REEL SERVO PROBLEM
CHECK THE FOLLOWING:
1. FUSE F6
2. REEL SERVO PCBA
3. TAKE UP REEL MOTOR

REPLACE CONTROL
M2 PCBA

MA-3492A
SH R- QlqQ· 84

Figure 5-4

Load Fault 0 Flow Diagram

5-11

REPLACE
CONTROL M
PCBA

REPLACE
CAPSTAN/
REGULATOR PCBA

•
•

FAULTY CARTRIDGE
MOTOR
FAULTY OR
MISALIGNED
CARTRIDGE MOTOR
SENSING SWITCHES
MA-3489A
SHR-0191-84

Figure 5-5

Lo a d Fa u 1 t

1 Flo w Di ag r am

5-12

YES

FAULTY OR
MISALIGNED
CARTRIDGE
MOTOR SENSING
SWITCHES
PRESS LOADIREW
AND ALLOW FAULT
TO OCCUR. DO NOT
PRESS RESET

REPLACE
CONTROL M2 PCBA

REPLACE
>-----1~ CAPSTAN/REGULATOR

PCBA

- FAULTY CARTRIDGE
MOTOR
-FAULTY OR
MISALIGNED
CARTRIDGE MOTOR
SENSING SWITCHES
MA-3490A
SHR-0192-84

Fig ure 5-6

Load Fault 2 Flow Diagram

5-13

LOADFAUL~

PNEUMATIC FAULT; CHECK:
• BLOWER MOTOR
• BLOWER BELT
• BLOWER
• VACUUM SENSING SWITCH

REPLACE
CONTROL M2
PCBA

PNEUMATIC PROBLEM
CHECK:
• COMPRESSOR BELT
• COMPRESSOR
• AIR BEARING PRESSURE
SENSING SWITCH
MA3486A
SHR~0193-B4

Figure 5-7

Load Fault 3 Flow Diagram

5-14

YES

SUPPLY REEL
SERVO PROBLEM

Ul
I

YES

CHECK:

j-I

•
•
•

FUSE F7
REEL SERVO PCBA
SUPPLY REEL MOTOR

CHECK:
CHECK:
•
•
•

SYSTEM VACUUM
VACUUM TRANSFER
VALVE
CAPSTAN/REGULATOR
PCBA

DEFECTIVE
TAPE ON REEL
SENSING SWITCH

•
•

PRESSURE
VALVE/SOLENOID
CAPSTAN/
REGULATOR
PCBA
NO

MA·3502
SHR_019484

Figure 5-8

Load Fault 4 Flow Diagram

BOT NOT SENSED
IN TIME

FIX
TAPE

CHECK:
• BOT SENSOR
• CONTROL M2 PCB A

TAKE UP REEL
TIMING TOO
FAST. ADJUST
TAKE UP REEL
LOAD SPEED
'15 FT. IS OPTIMUM. TRANSPORT WILL LOAD AT UP TO 30 FT.
IF PROBLEMS ARE EXPERIENCED DUE TO LEADER BEING TOO LONG, CUT IT
DOWN TO 15 FT.
MA-3493A
SHR·0195-84

Figure 5-9

Load Fault 5 Flow Diagram

5-16

LOAD FAULT6

LOOPS FAIL TO FORM IN BUFFER
COLUMNSWITHIN ~ 1.5 SECONDS
AFTER "SET LOOPS" COMMAND

YES

REPLACE
CONTROL M2
PCBA

CHECK SYSTEM
VACUUM ADJUSTMENT.

CHECK:
• BOTH LIMIT
SENSING SWITCHES
• CONTROL M2 PCB A

REEL SERVO FEEDBACK
LOOP NOT FUNCTIONING
PROPER L Y FOR ONE OR
BOTH REELS. CHECK:
• REEL SERVO PCBA
• POSITION TRANSDUCER
ASSEMBL Y
• CAPSTAN SERVO
LOOP

CHECK:
• VACUUM TRANSFER
VALVE
• CAPSTAN/REGULATOR
PCBA
• CONTROL M2 PCBA

CHECK FOR:
•
•
•

HOSE LEAKS
CLEAN CAPSTAN
BUFFER BOX
DOOR CLOSED
PROPERLY
MA-3497A
SHR-0196-84

Figure 5-10

Load Fault 6 Flow Diagram

5-17

PNEUMATIC SYSTEM TROUBLESHOOTING

5.6

WARNING
If
the
ac
motor
=lIin
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 motor pulleys and belts.
The pneumatic system, located in the power supply/pneumatic
assembly and distributed on the base assembly, provides positive
(pressure) and nega t i ve (vacu um) ai r to accompl ish load i ng and
running operations.
The accompanying flowchart (Figure 5-11) is used to troubleshoot a
p n e um a tic s y s t emf ail u r e .
Tot r a c k dow n m01: e sub t 1 e
failures, first inspect the system. Check for holes, cracks, or
pinches in any of the hoses or tubing. Check the condi tion and

ma j 0 r

NO PN'UMATIC SYST')
AIR. MOTOR WON'T
TURN ON

YES

CHECK:
• CONTROL M2 PCBA
• CONTROL PAI'.EL

TURN POWER OFF AT
POWER CONTROL
2. REMOVE PROTECTIVE
COVER FROM POWER
JUMPER PANEL A 1 TB1
3. ATTACH VOLTMETER
(,2300VAC) TO TERMINALS
2 AND 7
4. TURN POWER BACK ON

REPLACE
SOLID
STATE
RELAY
MOTOR CIRCUIT BREAKER
TRIPPED (RED RESET
BUTTON ON REAR
OF MOTOR) OR
DEFECTIVE
MOTOR
MA-3501A
SHR-0197-84

Figure 5-11

Pneumatic Troubleshooting Flow Diagram

5-18

tension of both drive belts. Check all positive and negative air
values as outlined in Paragraph 3.6. Both the muffler filter and
air filter at the input of the positive air system are changed
during semiannual PM. However, a particularly dirty environment
could cause these filters to clog prematurely and should be
suspected. For a schematic of the air system, refer to the
air/load control functional block diagram (Figure 4 in Volume 1 of
the TU78 Magnetic Tape Transport Technical Manual) .
5.7
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) in the card cage
assembly. Inputs to the reel servo PCBA consist of power, control
signal s, and feedback signal s, and are summar i zed in Tables 4-6
and 4-7 of the TA78 Magnetic Tape Drive Technical Description. If
the reel servo PCBA is suspected, it must be replaced since it may
not be extended for
troubleshooting due to heat sinking
requirements. (For a reel servo functional block diagram, refer to
Figure 5 in Volume 1 of the TU78 Magnetic Tape Transport Technical
Manual. Also refer to Figure 5-12 in this manual for a simplified
schematic diagram of the supply reel servo.)
Check all input power sources and voltages developed on the reel
servo PCBA. Table 5-5 lists the test points, voltage names, and
proper readings with allowable tolerances. Check the test points
with a DVM using test point 49 as a ground reference.

+36 V

(SPOS)
TP
SRF

-15 V ----'\)'V'v----,or"""l'o<'"--t
TP71

VACUUM
TRANSDUCER

RUN
OFFSETS
(FWD, REV,
OR REWIND)

INTLK

65
TRIANGLE
WAVE
GENERATOR

-36V
~;H R·O' 98-84

Figure 5-12

Supply Reel Simplified Schematic Diagram

5-19

Reel Servo PCBA Opera ti ng Voltages

Table 5-5
Test Point

Voltage
Name

Voltage
Reading

Voltage
Source

TP62
TP64

+15 V
-15 V

+15 +1
-15 +1

Capstan/regulator PCBA

TPl2
TP18
TP4
TP10

+36 V (s)
-36 V (s)
+36 V (t)
-36 V (t)

+40
-40
+40
-40

Power supply/pneumatic
assembly

TP53

+5 V (s)

5.3 +.3

+2
+2
+2
+2

Reel servo PCBA

A servomechanism is more difficul t to troubleshoot in 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
loop in the buffer column. (For a block diagram, refer to Figure
4-27 in the TA78 Magnetic Tape Drive Technical Description.)
There fore, when-en-co un terTng-aree-r-servo-pr obI em~--wlt1:1I1o
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 element most prone to failure. If this fails to correct the
problem, proceed to check the various feedback elements. Loop
pos i tion feedback elements for each servo cons i st of pos i t ion
transducers, limit sensors, and the crippled reel sensor (take-up
reel only).
Use the following procedure to check reel servo loop feedback
elements. Figure 3-12 shows the take-up buffer column, its zones,
and sen sin g s wit c h e s. Th e s u pp 1 Y b u f fer col urn n i s s i mil a r b u t
without the crippled reel switch port.
1.

Check all system vacuum measurements (Paragraph 3.6).

Turn transport power off.

Set reel servo disable switch Sl, on the reel servo PCBA,
toward the rear (disable).

Ground control M2 PCBA test points TP62 (NINTLK) and TP7l
(PNU RET) .

Disconnect one capstan motor lead.

6•

Mo un t a 10 -1 /2 inc h
(wi thout cartr idge) •

r eel

5-20

0 f

t ape

0 nth e

sup ply

hub

7•

Open the buffer box door and hand thread the leader
through the tape path. Wind about 9 m (30 ft) of tape
onto the take-up reel. Close the buffer box door.

Turn transport power back on. Pn e urn a tic s s h 0 u 1 d be
enabled wi th vacuum appl ied to the buffer col umns and
pressure to the air bearings.
NOTE
If either reel starts rotating at this
point, replace the reel servo PCBA.

9•

Ma n u all y rot ate the sup ply r eel c 1 0 c k wi s e and a 11 ow 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 3-4)
wi th your finger and manually rotate the take-up reel
counterclockwi se to allow a loop to form. Posi tion the
loop in the park zone and release your finger. Tape the
take-up reel to prevent movement.

11.

Press RESET on the TU78 control panel.

12.

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 momentary jumps up to +5 V indicate an
intermittent limit switch or air leak in the associated
tubing.

13.

Connect the scope to reel servo TP66 (SPaS) 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.

14.

Remove the tape from the supply reel and rotate it so the
loop in the supply column extends down to the lower limit
swi tch and observe the vol tage 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
tog e the r. Th e r e suI t s h 0 u 1 d be i nth e 3. 6 V t 0 4. 2 V
range.
NOTE
The 0.6 V tolerance is due to the system
vacuum setting, the position adjustment
setting on the interconnect Fl PCBA, and
individual
position
transducer
characteristics.
5-21

15.

Retape the supply reel and remove the tape from the
take-up reel. Repeat step 14 for the 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 PCBA.

17.

Place the scope on interconnect Fl-TBl-13 wi th ground
probe on TBl-14. With the take-up loop above the crippled
reel port (atmosphere) TBl-13 should be at +5 V. With the
loop below the crippled reel port, TBl-13 should be at or
near ground. Anything else indicates a defective crippled
reel sensor or associated tubing.

18.

Turn transport powE~r 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.)

5.7.1
Dynamic Brake Check:
Th i s proced ure must be accompl i shed when the reel servo PCBA is
replaced, or when tape damage due to power failure is suspected.
1.

Open the transport front door and install a 267
(10-1/2 in) reel of work tape. Load the tape to BOT.

Set control M2 PCBA swi tch Sl towards the front
transport. The tape should be moving forward.

Allow the tape to run to its midposition.

With tape running, turn transport power off.

Open the buffer box door. The tape
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.

5-22

should

of the

not

have

Turn transport power on and perform a midreel load.

with tape rewinding to BOT at high speed turn transport
power off.

10.

Repeat steps 5 through 8.

11.

Unload the tape.

5.8

DATA PATHS TROUBLESHOOTING

5.8.1
Introduction and Prechecks
It is assumed you have localized the fault to the TU78 data paths
be for e en t e r i n g t his sec t ion. Th a t i s , no fat a l e r r 0 reo des are
displayed on the TS78 control panel and the basic integrity of the
HSC and formatter has been established by running the in-line tape
diagnostic (ILTAPE).
If the in-line exerciser (ILEXER) 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 ILEXER 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 (Paragraph 3.9).

Make sure the AGe test switch on the read PCBA is in the
AGC enabled position (left).

Check all
3.3) •

Check all vacuums and pressures (Paragraph 3.6).

Check all capstan servo adjustments (Paragraph 3.7).

Check head wrap angle (forward/reverse differential)
adjustment (Paragraph 6.2.1, steps 6 through 14).

Check
31) •

Check that air bearings
(Paragraph 6.2.4).

Check read/write adjustments (paragraph 3.10).

tape

unregulated and

tracking

regulated voltages

(Paragraph

5-23

are

6.2.5,
not

steps

(Paragraph

installed

through
wrong

5.8.2

Write Path/Read Preamp Troubleshooting

The following troubleshooting 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
frequency is different. A write path one function diagram (Figure
5-13) is provided so you may trace the flow of data completely
through the transport, from the TU bus to the head, using channel
7. Figure 5-13 provides pin charts so you may scope other channels
as well.
1.

Mount and load a write-enabled scratch tape to BOT. Flip
the MODE SELECT switch to position 1,
2,
or 3
(maintenance mode), and place the transport on-line.

Release the service lock, pullout 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, particularly
the AMTIE cable from the write to MIA PCBAs.

Set the maintenance swi tches on the
3-15) as follows in the order given.
Pattern select
Sl
S2
S3
S4

MIA

PCBA

(Figure

All ones (all switches forward)
Reverse (left)
write (right)
1600 (left)
Manual (right)

The test mode indicator on the MIA PCBA, and the 1600
density indicator on the TU78 control panel are both lit.
The transport is not moving tape.
4.

Place MIA switch S3 to the right (6250). The 1600 density
indicator goes out and the 6250 density indicator comes
on ..

Change the MIA swi tch settings as follows,
given.
S4
Sl
S3

in the order

Auto (left)
Forward (right)
1600 (left)

The tape should not move. If it does, return it to BOT.
6.

Look at the output of the read preampliers. Set the scope
as follows.
Ve:rtical
Horizontal
Sync

CH1, 0.5 V/div, ac (using 10X probe)

= 2 uS/div

= Norm, ac, Ch 1
5-24

MIA

WRITE

PCBA
IWD7

PCBA
WRITE AMP

INTERCONNECT Dl
BACKPLANE

37
CLOCK
18
FIGURE 5·17

IWDS

r---------L-------~47~----~)----~

"
TEST WRITE
CLOCK GEN

IWD

1
18
15
20
21
22
23
24
25

TEST DATA PATTERN
SWITCHES

J6
WRITE
AMP
OUTPUT

PIN:

I
N
Ul

WRITE HEAD
CABLE

PREAMP
ETCH

::;;

WRITE
HEAD

g:
z

~
1---------1 a:

HEAD
\
CENTERTAP
COMMON PIN

CENTER TAP
TO ONE LEG
= 3 51 APPROX

11--(r--'--1

1
23
1
23
23
23
23

6
5
4
3
2
1
0
P

15
21
14
22
16
18
19

20
17

3
9
2

10
4
6
7
8
5

HEADER
PCB
J903

WRITE
STACK
J904
CENTER TAP

WD5

WD7

WDP
WD2

23 i---------l
(P904)
CABLE HEADER
WRITE AMPOUTPUT.I
ON PREAMP PCB
TO WRITE HEAD /
IWD
PIN=S
J6.

P6
WRITE
CABLE

WD3

37
38
39
40
41
42
43
44
45

FIGURE
5·16

VWRT
(WRITE
CURRENT)

INTERCONNECT71
' " J7 TO WRITE
P7
IWD PIN:

14
2

WDO
WD6

WD4

}CH5
14

}CH7

}CH3
PINION P6 (COMMON)
CENTERTAP TO PINS
2,3,4,5,14,15,16,17

}CHP
18
6

~5 } CH2

16 }
7
CHI

17 }
8
CHO

WDI

8
21

23.

:p~~~~~PROX.
COMMON
CENTERTAP

PIN 23 (COMMON)
CENTERTAP TO PINS
6,7,8,9,10,18,19,20,21,22

}CH6

}CH4

:1"50

ERASE
HEAD

12
25
13
26

MA-7319
SHR·008&S4

Figure 5-13

Write path One Function Block Diagram

Place the channel I probe on the upper lead of preamp
out put res i s tor RI . Th i s res i s tor i son e 0 f a p air for
track 1 (channelS). Refer to Figure 3-9 for location.

place MIA switch 84 to manual (right). The transport
moves tape and tr ies to wr i te an all ones conti nuous
record down tape. The tape can be started and stopped
wi th the T078 control panel ONLINE swi tch, and rewound
with the LOAD/REW switch when desired.

Look at the waveform on the scope. It should look exactly
like the waveform in Figure 5-14. The sinusoidal
waveshape should have a 5.4 us period and have an
amplitude of about 1.2 volts peak-to-peak.
Amplitude varies according to the PE
each track and the type of tape used.

gain

setting

for

.\ I ~ j' ~, J
, J \ I~ \ I l\
v
."
"
""
I\.

Figure 5-14

10.

Read preamplifier
Output Waveform

Monitor each output resistor pair of each channel for a
similar signal. Refer to Figure 3-9 to locate the
resistors.
If all
signals
from all channels are
acceptable, assume the following and go on to read path
troubleshooting (Paragraph 5.8.3).
•
•
•
•

write path is ok.
write head is basically working.
Read head is working.
Preamp PCBA is working.

5-26

11.

If all channels are not working correctly (the waveshapes
are very different from Figure 5-14), or are missing, the
problem could be one of the following things.

•
•
•
•
•

Write PCBA
preamplifier PCBA
MIA PCBA
Head
Cables to MIA

A1 so check signal VWRT, the source for each wr i te head
center tap, by placing the scope probe on write PCBA TP4.
During a write operation, TP4 should be +15 Vdc, +1 Vdc.
Go to step 13.
12.

If most channels are working properly but one or more
waveshapes are missing or distorted, proceed as follows.
a.

Set the MIA switches as follows.
Sl
S2
S3
S4

Off (center)
Read (left)
1600 (left)
Manual (right)

Load a master skew tape (write
place the transport on-line.

Set the scope as follows.
vertical Ch1
vertical Ch2

=
=

vertical Mode
Horizontal
Sync

=
=
=

X10
probes
measurement.
d.

ring

removed)

and

5 mV/div, ac (using Xl probe)
5 mV/div, ac, invert (using Xl
probe)
Add
10 us/div
Normal trigger, HF rej, normal
source

NOTE
not

work

for

this

Place the Chl and Ch2 probes on each leg of a
preamplifier compensation capacitor for a good track.
For capacitor locations, refer to Figure 3-9 in this
manual or Figure 23 in Volume 1 of the TU78 Magnetic
Tape Transport Technical Manual.

5-27

Place MIA switch 81 to the forward (right) position.
The waveform on the scope should be sinusoidal,
similar to that shown in Figure 5-15 •

•

'\ If\ 1\
, .I , J , J ., J , J
V V V V
~
..
-

MA·7304
SHR0201·84

Figure 5-15

Normal Read Head Output
Wh i 1 e Re ad i n g

Now place the scope probes across the compensation
capacitor for a suspected track. If the signal is
missing or distorted, the head is at fault.

g•

8 top the s ke w tape and un loa d it. Th ere sis t a nc e 0 f
the head winding can be measured across
the
compensation capacitor.
NOTE
Use a VOM wi th a 29, 'HY9 ohm/vol t rating
or greater, or a DVM on low power ohms
scale. The read head windings can be
burned out by a high test current.
A good head winding measures about 8.2 ohms, while an
open winding shows about 20,000 ohms (preamp input
resistance) •

If all read head outputs look okay when using a skew
tape, mount the scratch tape again.

Look at the compensation capacitors again; this time
while writing (MIA switch 82 right). You should see a
sinusoidal waveform similar to the one shown in
Figure 5-16.

5-28

.'\.
"

, I

\ 1 "- I. .\
, 'J
\ II \
'II1II

"""

IW'

MA·7301
SHR0202·84

Figure 5-16

Normal Read Head Output
While Writing

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.
•
•
•

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 5.8.3).
k.

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 Paragraph 5.3 for instructions
on how to use the extender. Remove the write head cable
from the write PCBA (J6).

14.

8et the MIA switches as follows.
Pattern select
81
82
83
85

All ones (all switches forward)
Off (center)
Wr i t e ( rig h t)
1600 (left)
Manua 1 (r igh t)
5-29

15.

Set the scope controls as follows.

= 0.2 V/div, ac (X10 probe)
= 0.5 us/div
= Norm, HF rej, Chi

vertical Chi
Horizontal
Sync
16.

Flip MIA switch Sl to the right (FWD) and scope each of
the write PCBA outputs at J6. Refer to Figure 5-13 for a
pin diagram and signal table for J6. Figure 5-17 shows a
write amplifier output wave shape with no load (P6
unpl ugged) •

~r.
ttl' 11
I

"t~

\.....

Fig u r e 5 -1 7

17.

,r~

~. f

Wr it e Am pI i fie r Ou t pu t
Wi th No Load

If any of the nine channels look significantly different,
trace the signal back to the MIA PCBA using Figure 5-13
as a guide. FigurE~ 5-18 shows the waveshape for wr i te
data and a write data strobe entering the write PCBA.

WDS
1"'1

,~:
(

WD(N )

MA-7313
SHA0204-84

Figure 5-18

Write Data At Input
To Wr i te PCBA

5-30

18.

If all nine channels are acceptable, the wr i te head is
probably defective. To check, stop the tape and unload it
and remove power from the transport. Measure the
res i stance of each wr i te head wi nd i ng us ing Figur e 5-19
as a guide. Keep in mind that each write head winding is
center tapped. Each hal f of the winding should measure
about 3 ohms. If any winding shows open or shorted,
replace the head assembly following the procedure in
Paragraph 6.2.1.

19.

If the write head continuity checks okay, and the head
poles are not worn excessively (Paragraph 6.2.1), check
the erase head continuity. The resistance between P6 pins
11 and 24 should be abou t 75 ohms wi th the wr i te cable
unplugged. In normal operation 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 continuity check fails, the preamp PCBA or the
head assembly has to be replaced. If the continuity check
is correct but the voltage check is 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 correct erase head polarity.

PIN 13

PIN 1

PIN 14

-rmfffm~~~ff::trnmrnmf"

WRITE HEAD CONTINUITY CHECK
PIN 1 (CENTER TAP) TO PINS 2,3,4,5,14,15,16,17 = 3D
PIN 23 (CENTER TAP) TO PINS 6,7,8,9,10,18,19,20,21,22 = 3D
MA·7303
SHR0205·84

Figure 5-19

Write/Erase Head Plug
Test Points

5-31

(P6)

5.8.3
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
5-20) is provided so you may trace the data flow completely
through the transport, from the head to the TU bus, using channel
5. Figure 5-20 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 5.8.2). If the write path
checks did not localize a problem, proceed as follows to continue
troubleshooting the read path.
5.8.3.1 Read Data Path
When writing or reading in GCR mode,
the preamp gain is set automatically. Each track is set
individually according to the playback signal received while
reading the ARA burst. For an explanation of the AGC circuits,
refer to Paragraph 4.l2.~5.3 in the TA78 Magnetic Tape Drive
Technical Description. Gain in PE mode is a fixed level set by the
read PCBA PE gain POT adjustments.
Check the GCR AGC circuits as follows.
1.

Static tests
a..

Mount and load a write-enabled scratch
but do not place the transport on-line.

Set the MIA PCBA test switches as follows.
Pattern Select
Sl
S2
S3
S4

tape

BOT

All ones (all switches forward)
Forward (r ight)
Wr i t e ( rig h t)
6 2 5 0 ( rig ht )
Ma n u a I ( rig h t)

Set the read PCBA AGC switch to the test AGC position
(center) •

Set the scope controls as follows.

Vertical ChI
vertical Ch2
Vertical Mode

= 0.5 V/div, ac
= 0.5 V/div, dc
= Chop

Horizontal

= 5 ms/div

Sync

= Norm, AC, ChI

Place the
CLOCKS) •

ChI

scope

5-32

probe

(XI0 probe)
(XI0 probe)

read

PCBA

TP22

(STI

ON READ PCB
(PREAMP OUTPUTI
P05

READ CABLE
R1

TEST
POINTS

J5
FIGURE 5-22

-----'0

_ _----:-\---'--'-WAVE-'--'-FOR_M

PIN"
P5
69
68
67
62

RESISTOR
TEST
POINT
TRACK
CHAN. OUT
NO.
R1

RlO

R11

R13

R14

R 16

I
W
W

OUT
2

RD
(POI

OUT
AGC PO/RD 1
24
23
9
8
11
12
13
12
14
32
29
21
30
20
27
26

R20

R22

R23

R25

R26

:
I
(

I
I

P05 (PREAMP OUTPUT RD51

~ ~------------~-------[/~::I~

READ
PRE·AMP

PREAMP
OUTPUT
PO
1
2
3
4
5
6
7
P
0

READ
PCBA
J5 PIN #
51
52
53
54
55

66
67
68
69
70
71
72
64
65

56
57
49

. BUS TO FORMATTER

'r [ ]

21
26
21
20
18
1

J3PIN :'

35
33
31
29
27
25
23
21
37

2
PATH
FROM
FORMATTER

MIA
PCBA

MIA
EDGE

3
4
5
'6
7
p

1::::::::::::::::::::1
1

J3
WCS
LOOP
TEST WRITE WRITE
DATA
PATH
TO
READ
PATH

WRITE PCBA

Figure 5-20

AMTIE
CABLE

Read Path One Functional Block Diagram

13
15
17
19

MIA

WRITE
PCBA
J7 PIN #

~RADIAL

GCR PE
(GAINI

:---

READ PREAMP
CABLE
RIBBON CABLE

I
I
READ HEAD:

P/BA

72
70

R17

R19

INTERCONNECT 01

Press the ONLINE button and quickly press it again.
This moves tape off the BOT marker and stops it.

The trace on ChI should have a series of 32 positive
going STI CLOCK pulses displayed, each with a period
of 850 us +85 us. Refer to Figure 5-21. position the
Ch2 trace 1straight line) on the bottom graticule of
the screen.

--+---+--+---+-f----+--+---+----l

STl CLOCK

,. ..

AGC (N)

--+---+--+---+-f----+--+---+----l

MA-7300
~;HR0207~84

Figure 5-21

Automatic Gain Control
(AGC) Waveform - GCR Mode

Now look at the nine AGC levels at the preamp
placing Ch2 probe on the following IC pins.
Track
Track
Track
Track
Track
Track
Track
Track
Track

1
2
3
4
5
6
7
8
9

U4-1
U4-l3
U4-6
U8-1
U8-1.3
U8-6
U12--1
U12-·13
U12--6

Make sure the scope probe is grounded to the preamp
to eliminate unwanted noise. Refer to the lower trace
shown on Figure 5-21. The waveform dc level should
start at about +1.7 V (PE gain level) and ramp down,
in a staircase pattern, to about +1.2 V.
i.

If any of the AGC waveforms are incorrect, the likely
cause is the read PCBA (AGC source). Replace it.

5-34

Dynamic tests
a.

Use the same scope settings as in step ld except for
the following.
vertical Ch2 = 0.1 V/div, ac (10X probe)
Repos i t i on the Ch 2 tr ace and observe the sma 11
staircase pattern on the descending ramp. Increase
the time base (horizontal) for a better view of the
steps.

While looking at one of the AGC voltages, place the
transport on-line. It begins writing and moving tape
forward.

Observe the following.
•

The trace on ChI
clocks.

(STI CLOCK)

shortens to about 9

•

The STI 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 track's
ampl i tude. The last channel to lock up reaches a
stable level at the last STI CLOCK.

To test full count, ground the upper lead of one of
the right resistors of a resistor pair for one
channel of the preamp. (For example, R2 for Ch5.) The
STI CLOCKs go back out to 32 because this channel
will not lock on.

If any of the AGC channels in this test stays at the
lower voltage (about 1.2 Vdc) , which is the maximum
gain, it is probably bad and the read PCBA should be
replaced.

If the STI CLOCKs fail to shorten up from 32 counts
to something less, one or more channels are not
getting set up. This may be due to a bad read PCBA or
a reduced analog signal at its input.

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 transpor t can sti 11 function, but not
as reliably as possible. Replace the read PCBA.

Return the read PCBA AGC switch to the normal
position.

5-35

(left)

Read data path
Use Figure 5-20 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 5-22 shows
the waveform for a read data bi t at the output of the
read PCBA [IRD (n)]. Read data bits are not latched in
the TU78.

-I

!IIIIII ~

MA-7312
SHA020B-84

Fig u [' e 5 - 2 2

Re ad Da t a Ou t put

5.8.3.2 AMTIE Paths Troubleshooting -- The TS78 uses AMTIEs
detect active/inactive tracks. They determine the following.
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 envelope

File marks

A low amplitude track

Error correction pointers

5-36

Figure 5-23
circuitry.

shows

block

diagram

the

AMTIE

generation

NLTH/STDTH
THRESHOLD

PO (N)
TRACK (N)

MULTIPLE
INTERFACE
ADAPTER
PCBA

WRITE PCBA
AMTIE
GENERATOR

AMTIE (N)
TO TS78
FORMATTER

GAIN

NPE - L - - - - - - - ' ' W \ r - _ - - - - I
(FROM CONTROL M2 PCBA)
MA-7302
SHR0209-B4

Figure 5-23

AMTIE Generation Circuitry

Troubleshooting +VAM AMTIE threshold voltage without TS78
formatter
a.

Set the scope controls as follows
vertical ChI
Horizontal
Sync

= 1.0 V/div, dc
= 0.1 ms/div
= Auto, dc, ChI

(10X probe)

Remove power from the tape transport. Place ChI probe
on the front lead of write PCBA R324 (signal +VAM).
Refer to Figure 5-24 for locations.

PLACE CH 1
PROBE HERE

MA-B853A
SHR021 ()'84

Figure 5-24

+VAM Test Point
on Write PCBA

5-37

Remove the AMTI E 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
STDTH

+4.8 Vdc, +0.5 Vdc
+10.2 Vdc,-+0.5 Vdc

If the results differ, replace the write PCBA or the
AMTIE cable.
2.

Troubleshooting +VAM AMTIE threshold vol tage
formatter.

using

TS78

Reinsert the l~MTIE cable into the MIA PCBA Jack Jl.
The +VAM voltage should read +4.5 Vdc, ~0.S Vdc.

Load a scratch tape to BOT and set MIA switch S4 to
auto (left).

Set the scope controls as follows.
vertical ChI
Horizontal
Sync

= 2.0 V/div, de
= 1.0 ms/div
= Norm,

(10X probe)

ChI, de negative scope

Set the MODE SELECT swi tch to posi tion 1, 2 or 3
(maintenance mode), and place the transport on-line.
Then pI ug an RS232-compatible terminal into the EIA
connector on the TS78 control panel (Figure 2-25).

e..

Press and relE~ase CTRL C on the terminal
Repeat the entry until TA78> appears.

5-38

keyboard.

Type the eight commands, shown in the printout below,
on the terminal keyboard. Each command is shown here
in boldface type and should be followed by a carriage
return. The remaining printout shows the tape drive's
responses,
and
a
comment has
been
added
in
parentheses for clarity only.
TA78>RUN KEYPAD
KEYPAO>INIT
KEYPAO>UNIT X (X is transport cable number; e.g., 0)
KEYPAO>ENTER
PC 00 ? WRITE
PC 01 ? BR 0
PC 02 ? END
KEYPAO>START
The tape drive repeatedly
command on transport x.

executes

write

GCR

The +VAM AMTIE threshold signal shown on the scope
should be simi lar to Figur e 5-25. The vol tage goes
from +4.5 Vdc, +0.5 Vdc to +10 Vdc, +0.5 Vdc.

MA-7309
SHR0211-84

Figure 5-25

5-39

+VAM AMTIE Threshold Voltage

Press and release CTRL G to exit from the tape motion
routine. The tape drive displays HALT AT PC=XX where
XXis apr 0 g:r am 10 cat ion. Th e d r i v e t hen dis pIa y s
KEYPAD>.

i .

Type REWIND and a carr iage return. The tape dr i ve
rewinds the 1tape and displays 20 on the external
terminal.

j .

If test 1 (wi thout T87 8 format ter) wo r ks proper ly,
but test 2 (with T878 formatter) does not, the likely
cause is the MIA PCBA. If neither test works, the
likely cause is the write PCBA.

Press and release CTRL Z to ex it from the keypad
mode. The tape drive echoes Z and displays TA78>.
A

1.
3.

Press and release CTRL Z to ex it
mode. The drive echoes AZ.

from

the

terminal

AMTIE channel switching
a.

Place the transport off-line
cable from the MIA PCBA (Jl).

Use the same scope settings as in test 2, step c, but
change the horizontal setting to 1.0 us/dive

8et the MIA switches as follows.
Pattern select =
81
82
83
84

=
=
=
=

and

remove

the

AMTIE

8Wl forward, all others rear
(10000000) •
FWD (right)
WRT (r ight)
1600 (left)
MAN (right)

Look at each AMTIE output at the cable connector with
the scope. Refer to Figure 5-20 for pin numbers. Each
output should be about 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. Th i s pat tern causes each
track to produce an AMTIE. Each output goes to ground
and returns to +5 V as shown in Figure 5-26.

5-40

r--

MA·7308
SHR0212·84

Figure

5~26

AMTIE Signal switching

All AMTIE channels should look similar to Figure
5-26. If one or more do not, trace the signal back
using Figure 5-20.

If an AMTIE channel is not acceptable and the preamp
tests are all okay, replace the write PCBA.

If all AMTIE channels are acceptable but TS78 or
diagnostics indicate an AMTIE problem, replace the
MIA PCBA.

5-41

CHAPTER 6
REMOVAL AND REPLACEMENT

6.1
TS78 REMOVAL/REPLACEMENT PROCEDURES
Table
6-1
lists
all
major
FRUs
and
removal/replacement paragraph (if any) •

Table 6-1

the

associated

TS78 Field Replaceable units
Removal/Replacement
Paragraph

Part Number

Description

70-20415-01

Wire and harness assembly
(backplane assembly)

6.1.1

M8950-M8953
M8958,M8959
M8970-M8973
M8955

Logic modules

None

54-15170-00

TS78 control panel board

6.1.2

12-10930-01

Fa n (230 Va c)

6.1.3

BC26V-25

25 ft STI cable

None

70-17381-08

Flat cable (TS78 control
panel board to backplane
assembly)

None

H7422-AB

TS78 power supply chassis

6.1.4

H7441

+5 V regulator

6.1.5

H7490

-5 V regulator

6.1.5

H7476

+15 V regulator

6.1.5

54-14192

AC/DC LO board

6.1.6

6-1

6.1.1
TS78 Backplane Assembly (70-20415-01)
Use this procedure to remove the TS78 backplane assembly. See step
15 to replace the backplane assembly.
1.

Remove power from the TA78 and all slave TU78s connected
to it, by switching the power controllers (872 or 874)
off.

Swing open the TS78 logic gate.

Disconnect the TS78 control panel cable (PN 70-17381-08),
noting the position of the red stripe.

Disconnect all TU bus cables, noting their position.

Remove the back cover of the TS78 logic gate.

Loosen the two screws that hold the STl cable clamp to
the side of the logic gate. Then pull the clamp straight
out disconnecting the STl cables from the M8971.

Remove all modules from the backplane.

Swing open the TU78 base assembly and unplug the five dc
power connectors from the rear of the TS78 power supply.
Cut tie-wraps to free the wire harness.

Unplug the TS78 cooling fan from the power controller.

10.

Remove the two screws holding the dc power wiring harness
to the top of the card nest.

11.

Remove the backplane assembly from the cabinet by
removing the fivE~ screws at the hinge. The lower two
screws also retain the limit bracket. Support the
backplane assembly from underneath while removing the
screws.

12.

Lay the assembly flat on a work surface with the pin side
of the backplane facing up.

13.

Remove the eight screws that retain the card nest
enclosure to the backplane assembly and Ii ft the
backplane off the enclosure. Notice a plastic spacer with
two holes in it. Thi s belongs on the ca rd side of the
backplane assembly and insulates the backplane from the
card nest enclosure.

14.

Remove the hinge assembly
attach it to the new one.

6-2

from

the

old

backplane

and

15.

Insta 11 the new backplane assembly in reverse order. Be
sure to plug the fan power cord into a switched outlet of
the power controller.
NOTE
Where metal flat washers are used, they
must not contact any etches.

6.1.2
TS78 Control Panel Board (54-15170-00)
Use this procedure to remove the control panel board.
to replace the board.
the

TS78

Remove power from
controller off.

Open the door on the TS78 control panel. Disconnect the
flat cable from the TS78 control panel board (behind the
door), noting the position of the red stripe.

Remove the left side panel from the TA78 cabinet. Grasp
the panel on both sides and lift it off the four mounting
bolts. Disconnect the side panel ground strap from the
cabinet frame and set the panel aside. (You may have to
open the rear door to grasp the panel.)

Remove the four screws that hold the control panel board
and bracket to standoffs. Then remove the board and
bracket as a unit.

Remove the two screws holding the board to the bracket.
Then remove the board.

Reinstall the new control
above procedure.

Check the new control
following steps.

panel

switching

See step 6
the

power

board by reversing

board

performing
in

the

Make sure PORT SELECT A and
disable (out) position.

Reapply power.
All
three
TS78
control
indicators should turn on for about 4 seconds.

Press the FAULT switch for at least 1 second and then
release it. All three TS78 control panel indicators
light in a lamp test for as long as you press the
swi tch.

6-3

B swi tches are

the

panel

Plug an RS232-compatible, external terminal into the
EIA connector on the TS78 control panel board (Figure
2-25) •

Press and release CTRL C on the terminal
Repeat the entry until TA78> appears.

Test the three TS78 control panel switches using the
buttons and lights test (Paragraph 4.7.1).

Press and release CTRL Z to exi t
mode. The drive echoes AZ.

from

keyboard.

the

terminal

Depend ing on the ST I port bei ng dr i ven, set the
SELECT A or B switch to the enable (in) position.

6.1.3
Fan (12-10930-01)
Use this procedure to remove the fan.
fan.
the

TS78

PORT

See step 7 to replace the

Remove power from
controller off.

Swing open the logic gate.

Unplug the fan power cord from the power controller.

Remove the six screws holding the bottom of the enclosure
to the card nest assembly.

Unplug the power cord from the fan.

Remove the fan by removing the four
holding it to the enclosure bottom.

Install the new fan by reversing the above procedure. Fan
air flow should be into the card nest.

Plug the fan power
power controller.

cord

into

switching

the

screws

switched

power

and

nuts

outlet on

the

6.1.4
TS78 Power Supply Chassis (H7422-AB)
Use this procedure to remove and replace the power supply chassis.
1.

Remove power from
controller off.

the

TS78

Swing open the TU78 base assembly and unplug the five dc
power connectors and the ac power cord from the rear of
the power supply.

Remove the four dc
(Paragraph 6.1.5).

power

6-4

switching

regulators

from

the

power

chassis

Remove the
6.1.6) .

ac/dc

Support the power supply chassis from underneath
remove the six screws holding it to the frame.

Install the new power supply chassis in reverse order.

board

from

the

chassis

(Paragraph
and

6.1.5
Power Supply Regulators (H7441, H7476, H7490)
Use this procedure to remove the power supply regulators. See step
9 to replace the regulators.
1.

Remove power from the TS78 by switching the power
controller off. Turn off the power supply circuit
breaker.

Swing open the TU78 base assembly to gain access to the
rear of the power supply.

Loosen but do not remove the two screws holding the top
cover to the rear of the power supply_ Remove the top
cover.

Remove the five screws holding the front cover to the
front of the power supply (rear of the transport). Remove
the front cover to expose the regulators.

Two regulator enclosures are visible now. Each enclosure
contains two regulators. Select the enclosure that
contains the regulator you wish to replace, and slide it
toward you until the two connectors are free of any
interference.

Unplug both connectors by pulling on the plastic
connector housing, not the wires. If the enclosure you
are remov ing is the one wi th a cool ing fan a ttached to
it, unplug the two power leads from the fan.

Slide the regulator enclosure the rest of the way out of
the power supply chassis.

To remove an individual regulator, stand the enclosure on
end, remove the two screws holding the regulator in the
enclosure, and slide it out.

Install the new regulator by reversing the above
procedures. When sliding the enclosure back into the
chassis, note how the enclosure hooks onto a tab
protruding from the chassis sheet metal.

10.

Ad jus t the 0 u t pu t vol tag e 0 f reg u 1 a tor 1 , 2 , 3 , o r 4 ,
using Table 6-2 as a guide. Measure the vol tage wi th a
digital voltmeter and perform the adjustment with a
trimpot alignment tool or an insulated screwdriver.
Figure 1-6 shows the location of the adjustments.

6-5

Table 6-2

Power Supply Regulator Adjustments
Test Point
on Bac)~plane

Voltage
Setting

H7441
(number 2)

A16A2

+5 Vdc, +0.1 Vdc

H7441
(number 4)

A09A2

+5 Vdc, +0.1 Vdc

H7476 +15 V
(number 3)

A16B2 ;~r~-1

+15 Vdc, +0.75 Vdc

H7476 -15 V
(number 3)

A16E2 2~lJ.. -32--

-15 Vdc, +0.75 Vdc

H7490
(number 1)

A01V2

-5 Vdc, +0.16 Vdc

Regulator

NOTE: While the +15 V supplies have a voltage tolerance, their
magnitudes should-measure ~7ithin 0.2 V of each other. That is, if
the +15 V supply measures +15.1 V, the -15 V supply should measure
between -14.9 V and -15.3 V. The +15 V supplies are not
adjustable.
6.1.6
AC/DC LO Board (54-14192)
Use this procedure to remove and replace the AC/DC LO board.
1.

Remove power from the TS78 by switching the power
controller off. Turn off the power supply circuit
breaker.

Remove both regulator enclosures (Paragraph 6.1.5).

The ac/dc 10 board is now exposed at the inside rear of
the power supply chassis. Unplug the two connectors from
the board.

Use a 5/16 inch nutdriver to remove the four nuts holding
the board to the mounting standoffs. Remove the board.

Install the new board by reversing the above procedure.

6.2
TU78 REMOVAL AND REPLACEMENT PROCEDURES
This section details step-by-step removal and replacement
procedures for all field replaceable parts that require such
instructions. Figures are referenced in 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
6-3. )

6-6

Table 6-3

Parts Replacement/Adjustment Cross Reference

Paragraph

Removal or Replacement Procedure

Corequisite
Check/Adjustment

6.2.1

Head replacement procedure

3.10

6.2.2

Tape cleaner removal, cleaning
and alignment

6.2.3

Air guide disassembly
and cleaning

6.2.4

Air bearing removal and cleaning

6.2. 5

Capstan motor replacement

3.10.1, 3.6.1,
3.6.2

6.2.6

Supply reel motor replacement

3.8.2, 3.8.4

6.2.7

Vacuum reel assembly replacement
and takeup reel motor replacement

3.8.3, 3.8.4

6.2.8

Cartridge actuator motor
replacement

6.2.9

Controls assembly removal
and replacement

6.2.10

Blower/compressor ac motor
replacement

3.6

6.2.11

Blower removal and replacement

3.6.1, 3.6.2

6.2.12

Compressor removal
and replacement

3.6.3, 3.6.4

6.2.13

Air valve solenoid replacement

6.2.14

PCBA removal/replacement

6.2.14.1

MIA PCBA

6.2.14.2

Read PCBA

3.10.3

6.2.14.3

Write PCBA

3.10

6.2.14.4

Control M2 PCBA

6.2.14.5

Capstan servo PCBA

3.3, 3.7, 3.10.3

6.2.14.6

Reel servo PCBA

3.8, 5.7.1

6-7

Table 6-3

Parts Replacement/Adjustment Cross Reference (Cont)
Corequisite
Check/Adjustment

Paragraph

Removal or Replacement Procedure

6.2.14.7

GCR/PE Preamp 1 PCBA

6.2.1 (steps
7--14), 3.10

6.2.14.8

Interconnect Fi

3.4, 3.5, 3.8.4

6.2.14.9

Interconnect Dl

6.2.1
Head Wear Check and Replacement Procedure
The read-write-erase head assembly may require replacement for one
of two reasons: internal faul t 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 shim is below the unworn
surface of the head crown. That is the head has worn to a depth
g rea t e r t han 0. 25 4 mm (0. 010 in) .
Use this procedure to replace the head (Figure 6-1) •
1.

Turn transport power off.

Open transport front door and buffer box door.
base assembly out.

Remove the four hex-head screws holding 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.

Carefully tip the bracket and disconnect the head from
the PCBA. Remove the erase head leads from the PCBA.

6-8

Swing the

THREAD BLOCK NO.3
AIR GUIDE

CIRCULAR CERAMIC
GUIDE

~;ATH)/

NOTE 1

~ LOWER POCKET BAR

RECTANGULAR CERAMIC GUIDE

CAP
TAPE CLEANER
-CLIP

ERASE HEAD

GCR/PE PREAMP 1~
PCBA
~~

WRITE/READ HEAD

NOTE 2·

GUIDE BLOCK

RETAIN ING --=:::::::::"'--i~------r.~
SCREWS

RECTANGU LAR
CERAMIC GUIDE

CAPSTAN

NOTES:
1. SURFACES MUST BE PARALLEL
2. INITIALLY EDGE OF HEAD MUST BE
PARALLEL WITH METALLIC OVERLAY
MA·3670A
SHR0213·84

Figure 6-1

Read/Write Head, Tape Cleaner and
Air Guide Removal and Replacement

Check the head mounting plate
for clean mounting surfaces.

and

the

replacement head

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
whi te lead to the erase head connects to J905 and the
black lead to J906.
6-9

Initially align head by visually aligning lower edge of
head with inclined edge of base metallic overlay. (Refer
to Note 2 of Figure 6-1.) Bias head assembly by pressing
it towards the right, into tape path, with finger
pressure. Make SU1~e 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.

Turn transport power on.

Load an all ones PE 64 c/mm (1600
transport and bring to load point.

10.

Operate the transport in a shuttle mode (that is, forward
then reverse) by grounding TP31 on control M2 PCBA
(Figure 3-6).

11.

Using an oscilloscope, observe waveform at the upper lead
of R13 (track 5) of the GCR/PE preamp 1 PCBA (Figure
3-9) •

12.

While operating in the shuttle mode, mechanically rotate
the GCR/PE preamp 1 PCBA until the amplitude difference
between forward and reverse operation is minimal. The
forward/reverse amplitudes must be in the 800 mV +100 mV
range, peak-to-peak. The lower amplitude must be-within
10 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 mount ing
screws.

15.

Perform the read/write adjustments (Paragraph 3.10).

screws

and

cpi)

tape

PCBA mount i ng

Tape Cleaner Removal, Cleaning, and Alignment
6.2.2
Use the following procedure to remove and reinstall
cleaner.

the

bracket

the

tape

Open transport door and buffer box door.

Remove two screws attaching the tape cleaner and its cap
to the base casting (Figure 6-1).

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.
6-10

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.

Air Guide Disassembly and Cleaning
6.2.3
Use the following procedure to disassemble
guide.

and

clean

the

air

Open transport door.

Remove seven trim assembly
assembly from unit.

Open buffer box door.

Remove thread block 3
by its leads.

Remove circular ceramic guide from air guide on front of
base assembly (Figure 6-1) •
Do not remove
assembly.

mounting

screws,

(Figure 6-1), allowing

NOTE
air guide

from

and

trim

it to hang

base

Carefully insert penlight lens into the front of the air
guide. 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 ex ternal bear i ng sur faces and ceramic guide wi th a
lint-free cloth moistened with 91 percent isopropyl
alcohol.

Assemble circular ceramic guide to air guide wi th edge
parallel to the edge of lower pocket bar (refer to Note 1
in Figure 6-1).

10.

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 6-1). Perform the adjustment
by stretching a section of magnetic tape from the lower
pocket bar past the head and guide block around the
capstan.

11.

Replace trim assembly.

6-11

6.2.4
Air Bearing Removal and Cleaning
There are five air bearings, excluding the air guide (Figure 6-2).
The air guide disassembly and cleaning procedure IS given in
Paragraph 6.2.3. 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.
1.

Open transport front door and buffer box door.

Remove air bearing number 1 (Figure 6-2). 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 mounting 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 (6 in
by 1/4 in). The straight edge simulates the tape contact
tangent line with the first row of holes.

Reassemble air bearing number 1 to base assembly.
NOTE
The surface of the air bearing that has
been milled out must be placed against
the base plate.
Rest cardboard against adjacent buffer box bar and
bearing until first 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 guide is mounted towards the
magnetic tape. Ali9n ceramic guide as shown in Figure
6-2.

Follow the same procedure for air bea rings number 2, 4,
and 5. This procedure is also used for bearing number 3
except that tangent point A is aligned with adjacent
bearing number 2.

6-12

AIR BEARING NO.3
AIR BEARING NO.2

THREAD BLOCK 1

AIR BEARING

NO.4

CARDBOARD
STRAIGHT EDGE

r
B

CIRCULAR
CERAMIC GUIDE

NOTE:
"A" IS TANGENT POINT
"B" IS ORIFICE REGION
MA·3674
SHRQ214-84

Figure 6-2

Air Bearing and Ceramic Guide
Orientation

6-13

6.2.5

Capstan Motor Repla'cement

The capstan motor and mounting plate is replaced as an assembly.
Use the following procedur(= to replace the motor and mounting
plate.
1.

Turn transport power off.

Di sconnect wi res, hose, and tube a t the motor.
tachometer wires from interconnect Fl PCBA.

Remove the two hex nuts, lock washers, cups, and
Belleville washers retaining motor plate to the base
assembly at two locations (Figure 6-3A).

HEX NUT
REQURES 7/16"
WRENCH

Remove

LOCKING SCREW
REQUIRES 1/4"
ALLEN WRENCH

I
FORWARD SKEW
ADJUSTMENT STUD

LOCK I NG SC REW --------------I--~9JHr-

CAPSTAN--------,'""c----+-----liOo\
AIFl BEARING NO.5

CAPSTAN
MOTOR

A. SIDE VIEW
B. FRONT VIEW

NOTE:
REVERSE ADJUSTMENT DETAILS
ARE THE SAME ASFOR FORWARD
ADJUSTMENT.

MA·3669
SHR0215·64

Figure 6-3

capstan Motor Mounting

6-14

Cradle motor in your hand. At front of base assembly,
remove socket-head cap screw (fixed point) (Figure 6-3B) ,
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.

Ins tall the rep 1 a c em e n t m0 to r
through 5 in reverse order.

rep eat i n g

s t eps

NOTE
The following steps are the procedure to
achieve
capstan
perpendicularity
necessary to ensure proper tape tracking
over the guide block/head area. Steps 7
through 21 are the coarse adjustment of
tape tracking. Steps 22 through 32 are
the fine tuning of tape tracking.
7.

Turn transport power on.

Mount and load a work tape to BOT.
NOTE
The tape edge may be damaged in th is
procedure.
When
finished,
cut off
portion of tape used in the process and
install a new BOT tab.

Place control M2 PCBA swi tch 81 (Figure 3-6) 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.

11.

On the rear of the base assembly, a t the capstan motor
mounting plate, loosen the two hex nuts 1/4 turn. These
are the hex nuts referred to in step 3. They are at the
forward and reverse tracking adjustment points.

12.

On the front of the base assembly, about 50.8 mm (2 in)
down from the capstan, loosen the fixed point socket-head
cap screw 1/4 turn (Figure 6-3).

13.

Loosen the capstan motor forward and reverse adjustment
locking screws one full turn.

6-15

14.

Remove the outside rectangular ceramic guide from
guide block by re"moving the two retaining screws
washers (Figure 6-1) .

the
and

CAUTION
The th i n cerami c gu ides are eas i 1y
broken. Handle them with extreme care.
15.

Gently retract the spr i ng-loaded ceramic guides a t both
the guide block and the air guide so they lock back. Use
a nonmetallic inst:rument, such as the bare end of a
cotton-tipped swab, to retract the guides. Push the guide
straight back with the swab positioned in the middle of
the guide.

16.

Close the buffer box door assembly.

17.

Perform
3.6.2) •

18.

Turn transport power on and perform a midreel load.

19.

Run the drive forward using maintenance switch 81 on the
control M2 PCBA. Adjust forward adjustment stud from the
front of the base assembly (Figure 6-4) so tape edge is
aligned with guide block edge where the rectangular
ceramic guide was removed. Clockwise adjustment shifts
tape away from base casting.

20.

Run the drive in reverse using maintenance switch 81 on
control M2 PCBA. Adjust reverse adjustment stud from the
front of the base assembly (Figure 6-4) so tape edge is
aligned with the guide block.

system

vacuum

REVERSE TRACKING
ADJUSTMENT STUD

Figure 6-4

check

(Paragraphs

3.6.1

MA-3495
SHR0216-84

capstan Tape Tracking Adjustment Studs

6-16

and

21.

Repeat steps 19 and 20 until tape is aligned with the
guide block and no front-to-back movement occur s wi th
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 3-9) and channe 1 2 to
R25 (track 9). Ground oscilloscope probes. Sync internal
positive on channell.

24.

Run tape forward and reverse by grounding
maintenance test point TP31 on control M2 PCBA.

25.

Observe the oscilloscope and adjust the capstan tracking
adjustment studs (Figure 6-4) for minimum differential
between tracks 1 and 9 (outside two tracks of the read
head) .

shuttle

NOTE
Only
very
slight
adjustments
are
required. It may not be possible to
achieve no differential at this point
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 achieved, make sure the
differential is minimal and equal, but opposite in the
forward
direction versus
reverse direction.
This
indicates tape tracking is straight forward and reverse,
and the head azimuth plate needs to be aligned (Paragraph
3.10.1) •

27.

Tighten locking screws, hex nuts, and socket-head cap
screw, observing oscilloscope to make sure adjustments
are not disturbed.

28.

Remove jumper from TP31 on control M2 PCBA. Remove
oscilloscope 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.

6-17

30.

Return spr ing-Ioad(~d ceramic guides to the i rope rat i n g
posi tion by pressi ng the guide on the corners wi th a
cotton-tipped swab.

31.

Install
it.

32.

Perform the read skew adjustment (Paragraph 3.10.1).

fixed ceramic guide,

being careful not to crack

6.2.6
Supply Reel Motor ~teplacement
Use the following procedure to replace the supply reel motor.
1.

Turn transport power off.

Open transport front door and buffer box door.

Remove the supply reel plastic over lay on fron t 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 needed to prevent the nuts for these screws from
turning. Insert a small open-end wrench 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
posi tion, 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 al ignments wi th respect
to the motor and base assembly so the
elbows of the replacement motor can be
properly oriented.

Whi Ie suppor ting the motor, remove four motor-mounting
screws on the fron t 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 (PN 29-232(6). Tighten screws.

On the back of base assembly, slip the tubes over
elbows. Tighten hose clamps and attach motor leads.

6-18

the

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 3.8.2)
Tape loop position (Paragraph 3.8.4)

6.2.7
Vacuum Reel Assembly and Take-up Reel Motor Replacement
Use the following procedure to replace the vacuum reel assembly
and take-up reel motor. The vacuum reel assembly must be removed
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 19. If the
take-up reel motor is to be replaced
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.

6-19

Install replacement motor, aligning the elbows properly.
Center motor in base casting clearance bore using
centering tool (PN 29-23206) and tighten screws.

On back of base assembly, slip tubes over elbows. Tighten
hose clamps and attach motor leads.

10.

Re install vacu urn rl2el us i ng buffer box bar (PN 29-23207)
just above the lowest air bearing. Insert the bar between
vacuum reel flanges.

11.

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.

13.

Turn transport power on.

14.

Perform the following related adjustments.
Take-up reel load speed (Paragraph 3.8.3)
Tape loop position adjustment (Paragraph 3.8.4).

Cartridge Actuator Motor Replacement
6.2.8
Use the following procedure to replace the
motor.

cartridge

actuator

Turn transport power off.

Open transport front door and buffer box door.

Remove supply reel plastic overlay on front of the base
casting by removing five small phillips screws.

Remove arm from
(Figure 6-5) •

motor

shaft

loosening

set

screw

NOTE
Note color and location of the two leads
with respect to the motor so they can be
properly connected to replacement motor.
5.

On back of the base assembly, remove clamp from around
motor and radio frequency interference
(RFI)
filter.
Remove RFI filter from motor leads by sliding off filter
top cover and lifting wires off the pins. Remove four
motor mounting screws, and remove motor.

6-20

47.752 ± 0.762 mm
1.88 ± 0.03 inch)

RFI
FI LTER

BASE

CASTI~

,.---,r--r---.

CARTRIDGE
ACTUATOR ARM
CLAMP

ACTUATOR MOTOR

SET SCREW
MA·36BO
SHR0217.B4

Figure 6-5

Cartridge Actuator Motor Alignment

Install new motor with the four mounting screws. Set arm
height shown in Figure 6-5 and tighten set screw.

7•

Ins ta 11 a ne w RF I f i 1 t e r ( P N 2 9 - 2 3 2 7 9 ) by 1 a yin g mot 0 r
leads into the two filter body channels and pressing them
onto the pi ns so pi ns puncture wi re insula ti on. Sl ide
f i 1 t e r top 0 n • Ins tall c 1 amp a r 0 un d the mot 0 ran d RF I
fi 1 ter and tighten it so the pi n protrudi ng from the
filter bottom makes good contact with motor housing.
CAUTION
Do not allow the clamp to
motor electrical terminals.

touch

the

Turn transport power on.

Press LOAD/REW button on TU78 control panel. Arm must
rota te clockwi se, then stop wi thout bouncing and motor
must stop driving.
Adjust bottom limit switch if
necessary.

10.

Press RESET button on TU78 control panel. Arm must swing
counterclockwi se, then stop wi thout bounci ng and motor
must stop driving. Adjust top limit switch if necessary.

11.

Reassemble supply reel overlay.

6-21

6.2.9
Control Assembly Removal and Replacement
Use the following procedure to remove and replace
assembly.

the

control

Turn transport power off at cabinet power controller.

Open transport front door. Remove the seven trim assembly
mounting screws and entire trim assembly.

Open the base assE~mbly. Di sconnect Pl0 from control M2
PCBA and free the flat cable from retaining clamps.

At front of base assembly, remove the four
control
assembly mounting screws and slide the flat cable through
base casting.

Install replacement assembly in reverse order.

6.2.1~
Blower/Compressor AC Motor Replacement
Use
the
following
procedure
to
remove and
blower/compressor ac motor.

replace

the

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.
1.

Turn transport power off at the cabinet power controller
and disconnect power cord.
CAUTION
Do
not
try
this,
or
any
other
removal/replacement procedure within the
pneumatic/power supply assembly without
first removing the 22~ V power cord.

Remove bel t guard then remove both bel t s by manually
rotating pulleys clockwise and slipping belts off. It is
not necessary to loosen compressor or blower mounting
sc:rews.

Remove pulley 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.
Two people
transformer.

are

CAUTION
needed

6-22

lift

the

Remove cover to motor leads and remove leads.

Remove four mounting screws at rear of
assembly and remove motor from the front.

Install replacement motor.

Reassemble in reverse order aligning pulley on shaft set
( Fig u r e 6 - 6). Ma n u all y rot ate m0 to r c 1 0 c k wi s e and ma k e
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 controller.

10.

Perform

vacuum

and

air

pressure

power

adjustments

(Paragraph

3.6) •

, /COMPRESSOR

/
/

(

BELT TENSION ADJUSTMENT ACCESS

______- - PLA TE

~PLATE

MOTOR PULLEY

COMPRESSOR
PULLEY

I
.-J ~ 5.080 MM
~ I

-.j f.- 20.193MM

(0.200 INCH)

(0.975 INCH)

COMPRESSOR

AC MOTOR

SECTION B - B

SECTION A - A

Figure 6-6

MA-3683
SHR021B-84

Blower and Compressor Pulley Alignment

6-23

pack

6.2.11
Blower Removal and Replacement
Use the following procedure to remove and replace the blower.
1.

Turn transport power off at the cabinet power controller
and disconnect power cord.

Remove bel t
blower.

Loosen blower mounting screws. Slide blower left and slip
belt off pulley (Figure 6-6) •

guard.

Remove

hoses

from

top

and

rear

NOTE
Do not loosen blower pulley from shaft.
Replacement blowers have pulley properly
located on shaft.
4.

Remove capacitor chassis
power
pack
assembly.
transformer.

Remove blower mounting screws and remove blower.

Install replacement blower.

Reassemble in reverse order

Exert about 111.2 N (25 lb) 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 scre~~river 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 controller.

11.

Perform system vacuum adjustment (Paragraph 3.6.1).

12.

Perform takeup reel vacuum adjustment (Paragraph 3.6.2)

6-24

mounting screws in
position
chassis

front of
towards

(steps 3 through 6).

6.2.12
Compressor Removal and Replacement
Use the following procedure to remove and replace the compressor.
1.

Turn transport power off at the cabinet power controller
and disconnect the power cord.

Remove belt guard. Remove tubes from top of compressor.

Loosen compressor mounting screws.
and slip belt off pulley.

Remove pulley from compressor.

Remove capaci tor 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.

Reassemble in reverse order using steps 3 through 6 and
setting pulley position according to Figure 6-6.

10.

Exert about I I I N (25 lb) force on compressor while
tightening the four compressor mounting screws to tension
the belt. A slot is provided in the mounting plate to
pivot a large screwdriver 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
power controller.

13.

Perform the following related adjustments.

and

turn

Slide compressor left

transport

power

the

Air bearing pressure adjustment (Paragraph 3.6.3)
Thread block and cartridge pressure adjustment (Paragraph
3.6.4) •

6-25

6.2.13
Air Valve Solenoid Replacement
When replacing the solenoid on ei ther the vacuum or pressure
transfer valve assembly, adjust it according to the following
procedure.
1.

Loosen the solenoid
free movement.

mounting

Turn transport power off.

Ground the appropriate
solenoid current.

test

Vacuum transfer valve
Pressure transfer valve
power

screws

slightly

point

TP49

allow

enable

Control M2, TP72 (NXFR)
Control M2, TP5l (NPOL)

Turn transport
energized.

on.

The

solenoid

should

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.

Remove the ground :i umper •

Printed Circuit Board Assembly (PCBA) Removal and
Replacement
The procedures necessary to remove and replace all PCBAs
listed in the following nine paragraphs.

6.2.14

6.2.14.1

are

Multiple Interface Adapter PCBA (Slot 1)

Turn transport power off.

Remove the PCBA retainer clip (Figure 2-6).

Remove the three cables from jacks Jl through J3.

Grasp the edges of the PCBA and pull straight out of the
interconnect Dl backplane.

Set the transport serial number for the new MIA PCBA by
noting the position of the 16 DIP switches (U125, U135)
on the old MIA PCBA and sliding the new ones so they are
identical (Figure 3-15).

Insert the new PCBA and reconnect the three cables. Make
sure maintenance switch S4 is to the left (auto).

6-26

Install the PCBA retainer clip.

Turn transport power on.

Run the appropriate
operation.

diagnostics

confirm

transport

6.2.14.2 Read PCBA (Slot 2)
1.

Turn transport power off.

Remove the PCBA retainer clip (Figure 2-6).

Pull the read
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 3.10.3).

Run the in-line exerciser (ILEXER) for 15 minutes.

PCBA straight out of the

interconnect 01

6.2.14.3 write PCBA (Slot 3)
1.

Turn transport power off.

Remove the PCBA retainer clip (Figure 2-6).

Remove the write data cable from J6.

Remove the AMTIE cable from J25.

Pull the PCBA straight out of the interconnect 01
backplane and insert the replacement PCBA in its place.

Reconnect the write and AMTIE cables.

Install the PCBA retainer clip.

Turn transport power on.

Perform the read/write adjustments (Paragraph 3.10).

10.

Run ILEXER for 15 minutes.

6-27

6.2.14.4 Control M2 PCBA (Slot 4)
1.

Turn transport power off.

Remove the PCBA retainer clip (Figure 2-6).

Remove the control cable from J10.

Pull the PCBA
backplane.

Make sure jumper s Wl through W18, on the new PCBA, are
configured according to the original PCBA.
(Refer to
Volume 1 of the TU78 Magnetic Tape Transport Technical
Manual, Figure 13, sheet 2, Schematic Number 106875,
Table II, Version -- 12).

Insert the new PCBA and reconnect the control cable.

Install the PCBA retainer clip.

Switch Sl
position.

Turn transport power on.

10.

Run the appropriate
operation.

straight

the

new

out

PCBA

the

should

diagnostics

interconnect

confirm

the

center

transport

6.2.14.5 Capstan Servo PCBA (Slot 5)
1.

Turn transport power off.

2•

Use the 5 /3 2 - inc h ball - end d r i v e r and e x ten s i on t 0
unscrew, but not remove, the six hex-cap screws holding
the PCBA hea t sink to the card cage heat sink at the
rear.

Pull the PCBA out of the card cage. Some rocking action
may be needed to free the heat sink due to adhesion of
the thermal compound.

Spread a thin film of thermal compound
surface of the new PCBA and install it.
securely.

Turn transport power on.

6-28

on the mating
Tighten screws

Perform the following checks/adjustment procedures.
TU78 power distribution (Paragraph 3.3)
Capstan servo adjustments (Paragraph 3.7)
PE gain adjustment (Paragraph 3.10.3)

Run
appropriate
operation.

diagnostics

confirm

transport

6.2.14.6 Reel Servo PCBA (Slot 6)
1.

Turn transport power off.

Remove the eight connecting wires at
PCBA.

Use the 5/32-inch ball-end driver and extension to
unscrew, but not remove, the six hex-cap screws holding
the PCBA heat sink to the card cage heat sink at the
rear.

Pull the PCBA out of the card cage. Some rocking action
may be needed 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.

the bottom of the

Reel servo adjustments (paragraph 3.8)
Dynamic brake check (Paragraph 5.7.1)
9.

Run appropriate
operation.

diagnostics

confirm

transport

6.2.14.7 GCR/PE Preamp 1 PCBA
1.

Turn transport power off.

Open transport front door and buffer box door. Swing base
assembly out.

Unplug the read data cable from J902 on the preamp PCBA.

Unplug the write data cable from J6 on the write PCBA.

6-29

Free the write data cable from all retaining clamps.

Remove the four screws holding the preamp PCBA to its
mounting bracket 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 adjustments.
Read/wri te head skew (Paragraph 6.2.1,
14)
Read/write adjustments (Paragraph 3.10)

10.

steps

through

Run ILEXER for 15 minutes to confirm transport operation.

6.2.14.8 Interconnect Fl PCBA
1.

Turn transport power off.

Swing base assembly out.

Disconnect flat cable from J2l on interconnect Fl.

Record
making
wires.

Remove PCBA from base assembly by alternately unscrewing
the four retaining screws no more than two turns each, in
rotation, around the PCBA until all are free.

wire color and connection point of all wires
connection at TBl, TB2, TB3, and TB4. Remove

CAUTION
The screws are held captive to the PCBA
spacers. If each screw is completely
removed, independent of the others, the
PCBA undergoes a torsional strain which
may fracture etched conductors.
6.

Install new PCBA in reverse order noting
and caution in step 5.

6-30

the procedure

Perform the following adjustment procedures.
EaT/BOT (Paragraph 3.4)
Low tape sensor (Paragraph 3.5)
Tape loop position and gain (Paragraph 3.8.4)

Run
appropriate
operation.

diagnostics

confirm

transport

6.2.14.9 Interconnect 01 PCBA
1.

Turn transport power off at the power controller.

Remove all card cage PCBAs
6.2.14.1 through 6.2.14.6.

Open cabi net rear access door.

Remove the
assembly.

Remove plastic shield over terminal strip TBI at the rear
of interconnect Dl PCBA.

Record
wires.

Remove flat cable from J24 on interconnect Dl.

Remove seven cap-head retaining screws and pull PCBA out
of the front of the cabinet.

The new PCBA has two jumpers (WI and W2) between J201 and
J204. Cut jumper W2.

10.

Install new PCBA in reverse order.

11.

Reinstall all card cage PCBAs.

12.

Run
appropriate
operation.

wire

large

color

metal

according

plate

wires

connecting

diagnostics

6-31

below

the

confirm

Paragraphs

exhaust

TBI.

fan

Remove

transport

APPENDIX A
GLOSSARY

Address lines or address on address
lines

ACRC

Auxiliary cyclic redundancy check
character

address

A specific memory or peripheral
register location

AMTIE

Amplitude track in error

ANSI

American National Standards Institute

ARA

Automatic read amplification

architecture

The internal configuration of a
processor, system, or subsystem

ASCII

American Standard Code for
Information Interchange

asynchronous

A mode of operation scheduled by
ready and done signals rather than by
time intervals

ATTN

Attention

BAL

Byte assembly logic (M8959)

BCD

Binary coded decimal

BCTC

Byte count terminal count

bit

A binary number, either 0 or 1

bit/in

Bits per inch
(also known as characters per inch)

block

A record (sometimes considered to be
multiple records within a file)

A-l

BOT

Beginning of tape

buffer

A temporary storage area or an
isolating circuit used to avoid
distortion of the input signal by the
driven circuit or transmission line

bus

A group of signal lines that convey
information from source to
destination. There may be many
destinations, but only one source at
a given time.

byte

A word consisting of eight bits

character

A single letter, numeral, or symbol
used to represent information

char/in

Characters per inch (also known as
bits per inch)

CLK

Clock

CLR

Clear

command

A word, byte, or portion of a byte
that causes a predefined operation to
be performed

CPU

Central processor unit (This is the
8085 microprocessor chip relative to
the TS78 controller.)

CRC

(C)

Cyclic redundancy check (character)

C TO D

Controller To Drive

Data lines or data on data lines

data group

In GCR mode, seven data characters
plus an ECC character combined as a
group prior to translation. Consists
of two data subgroups.

DDR

Diagnostic data register

decoder

A device that detects a certain
specific address and produces a
corresponding single output

DEM

Demand

A-2

density

The nominal distribution per unit
length of recorded information,
usually expressed in bits or
characters per inch

DMA

Direct memory access. A process
whereby data is transferred rapidly
into RAM by the host computer without
microcomputer control.

down-line load

See DMA.

drive

Combination of a formatter and one
transport

Drive select

8MC

8085 microcomputer (M8972)

EBL

End of block

Error correction

ECC

Error correcting code (M895l)

ECC character

A special error correcting code
character on tape, used for error
detection and correction

Ecode

Error code. This code is developed in
the write microcontroller and sent to
the microcomputer on demand.

EOT

End of tape

EXC

Exception

Fc/In

Flux changes per inch

FIFO

See Shift Register.

file

A logical collection of data treated
as a unit. A file may consist of one
or more records or blocks on tape.

file gap

A special extended, erased portion on
tape just prior to the file or tape
mark record

FMK

File mark (also tape mark)

format

The entire set of unique parameters
used to define the recording mode

A-3

fr/in

Flux reversals per inch

FWD

Forward

GCR

Group-coded recording

GCTC

Group count terminal count

group

See Data Group or Storage Group.

group-coded recording

A recoIding technique that collects
groups of characters and translates
or encodes them prior to putting them
on tape

HHT

Handheld terminal

HLD A

Hold acknowledged

hold

A state in which the microcomputer
may be placed during a host-to-RAM
DMA transfer

HSC

Hierarchical storage controller

IBG

Interblock gap (See Interrecord Gap.)

Integrated circuit

lOB

Identification burst

ILR

Illegal register

ILEXER

In-line exerciser

ILTAPE

In-line tape diagnostic

INIT

Initialize

initialize

To set certain logic elements to a
known state, or to set program
variables to their starting values
prior to issuing a subsystem command

in/sec

Inches per second

interrecord gap

A blank space deliberately erased
between data records on tape

interrupt

A hardware signal that causes the
microprocessor to jump to a specific
subroutine

A-4

interrupt service routine

The routine or subroutine executed
when an interrupt occurs.

I/O

Input/output

I/O page

That portion of memory in which
specific locations are associated
directly with subsystem peripheral
device registers

IRG

Interrecord gap

latch

A circuit that, when triggered,
stores whatever appears on its inputs
and holds it. When not triggered, the
output reflects the input.

LSB

Least significant bit or least
significant byte

LSI

Large scale integration

MIA

Magtape interface adaptor

microcomputer

A class of computer having all major
central processor functions, memory,
and control circuitry self-contained
on a single printed circuit board. A
microcomputer usually employs a
mircroprocessor chip.

microcontroller

A semi-intelligent set of logic that
performs simple control functions
directed by a microprogram

microprocessor

A single LSI circuit that performs
the functions of a CPU

microprogram

A program implemented in microcode
for a microprocessor or
microcontrollere A microprogram may
reside in ROM or RAM.

MM I/O

Memory-mapped I/O

modulo

A mathematical operation that yields
the remainder function of a division

monitor

The master control program that
interprets subsystem commands and
schedules internal operations within
the TS78, and external operations
within the tape transport
A-5

MSB

Most significant bit or most
significant byte

NED

Nonexistent drive

NEF

Nonexecutable function

nibble

The low-order or high-order 4-bit
half of one byte

NRZI

Nonreturn to zero indiscrete

pad character

A null or zero character in the
residual data group

page

A set of 32K contiguous byte
locations.

parity bit

A binary digit appended to a group of
bits to make the sum of all the bits
always odd (odd parity) or always
even (even parity). The parity bit is
used to verify data integrity.

PCBA

Printed circuit board assembly

phase encoding

peripheral

In the TS78, any device (register)
responding to an address in the I/O
page

polling

A process in which the microcomputer
interrogates certain command or
status registers one at a time to
determine if service is required

port

A place through which input/output
data is channeled

postamble

Groups of special characters recorded
on tape at the end of a data record
for synchronization

preamble

Groups of special characters recorded
on tape at the beginning of a data
record for synchronization

priority

The order in which the microcomputer
satisfies simultaneous interrupt
requests

A-6

program

A set of sequential instructions that
a microprocessor or microcontroller
follows

program counter

A special register in the
microprocessor or microcontrollers
that points to the location in memory
of an instruction to be executed

PROM

Programmable read only memory

protocol

The set of system or subsystem rules
that define handshaking on a bus

RAM

Random access memory (See Read/Write
Memory. )

Read channel (M89S0)

read/write memory

A RAM in which each cell may be
selected by applying appropriate
electrical input signals. The binary
state of the cell may be either (1)
sensed at appropriate output
terminals, or (2) changed in response
to other similar electrical input
signals.

read-only memory

A memory in which the contents are
not intended to be altered during
normal operation

record

A group of multiple characters on
tape, taken in succession. Records
are separated on tape by interrecord
gaps.

A device that stores data

resident

Present in the subsystem or its
memory

REV

Reverse

RMC

Read (path) microcontroller (M89S3)

ROM

See Read-Only Memory.

Read path

A-7

R/W

Read/write

RWND

Rewind

scratchpad

An area of RAM memory set aside for
short and often-repeated
calculations, or temporary storage

shift register

A memory in which data enters
serially and shifts to successive
storage locations. Data may be read
when it has sequentially shifted to
the output (also known as a FIFO). .

skew

The deviation of bits within a tape
character from the intended or ideal
placement, which is perpendicular to
the reference edge

Serial number

stack

Storage in RAM memory for data during
subroutines or interrupts

storage group

Ten tape characters created from the
8-character data group via the record
code value translation

STI

Standard tape interface

subgroup

One half of a data or storage group

subroutine

A program within a program that
performs a specific, often-used
function

synchronous

Simultaneous performance of a
sequence of operations controlled by
an external clock

system

The TS78 microcomputer and its
peripherals constitute the formatter
control system.

TACH

Tachometer

tape mark

A special control record on tape
which serves to separate files

Terminal count

TCU

Tape control unit

A-8

Tape mark (also known as file mark)

total character skew

The deviation, during reading, from
time coincidence of the bits within a
recorded character; the sum of static
skew and dynamic skew

TRA

Transfer

trap

An urgent microprocessor interrupt
used to flag a power failure or
system monitor parity error

tri-state

The property of a bus signal line to
be placed in a dissociated
(high-impedance) state, as well as
the common HI or LO state

TUP

Tape unit port (M8955)

veo

voltage-controlled oscillator

vector

A specific address loaded into the
microprocessor's program counter to
force it to start processing at that
address

WCS

Writable control store; RAM storage
area that may be overwritten with
microprogram information

Write data

WDS

write data strobe

WMC

write microcontroller (M8959)

Word

Any group of bits indicating a single
number or expression

XMC

Translator microcontroller (M8958)

A-9

APPENDIX B
EXTENDED STATUS BYTES

B.l
INTRODUCTION
This appendix lists the bytes in the extended drive and extended
formatter status areas. These bytes are accessible via the HSC and
the ASCII port. The HSC may request the bytes in any area as a
group. In the listing, the byte number identifies the order in
which the TA78 transmits these bytes to the HSC. Via the ASCII
port, these bytes may be accessed individually with the parameter
addresses listed.
Hardware registers are the source for many extended drive status
bytes. The microbus addresses listed are the 8085 I/O locations of
these registers. Bytes that do not have a microbus address listed
come from RAM locations in the M8972 module. This is the case for
all bytes in the extended formatter status area.
B.2

EXTENDED DRIVE STATUS

Byte number
Parameter address
Name
Microbus address
Register location
Bit

Name

1
24

(Diagnostic mode status byte 1)

Description
With TA78 in diagnostic mode, byte I is one of
two status bytes for classifying soft errors.
One of 6 codes, listed and defined below, may
appear in this byte. In normal operation, byte
1 is a 0 (see note below byte 4).

7:0

Partial Diagnostic Mode Soft Error Status
Code

Meaning

00
07
0E
16
2D

No soft error (see note 2).
Other (write)
Status (read)
Status (read reverse)
Transmission (read)
Transmission (read reverse)

B-1

NOTES:
1. Status (read and read reverse) -- successful operation after
retries.
Other
(write)
write retry succeeded in same physical
location that previous write retry failed.
2. Bytes 1 and 2 must contain 0s to indicate no soft error.

Byte number
Parameter address
Name
Microbus address
Register location
Bit

Name

7:0

(Diagnostic mode status byte 2)

Description
with TA78 in diagnostic mode, byte 2 is 1 of
2 status bytes for classifying soft errors.
One of 8 codes, defined below, may appear in
this byte. In normal operation, byte 2 is a
(see note below byte 4).

Partial Diagnostic Mode Soft Error Status
Code

Meaning

00
01

No soft error
Double track correction
Double track correction
Single track correction
Single track correction
Media
Other (read)
Other (read reverse)

03
04
08

00
15

(read)
(read reverse)
(read)
(read reverse)

NOTES
1. Other (read and read reverse) -- successful operation without
error correction, but with interesting occurrence (AMTIE or
PHTI E flag).
2.

Bytes 1 and 2 must contain 0s to indicate no soft error.

Byte number
Parameter address
Name
Microbus address
Register location
Bit
7:0

Name

3
26

(Diagnostic mode status byte 3)

Description
This byte is reserved for future
use and is always a 0.

B-2

Byte number
Parameter address
Name
Microbus address
Register location
Bit

4
27
(Diagnostic mode status byte 4)

Name

Description

7:0

This byte is reserved for future
use and is always a 0.

NOTE:
When a
non-zero value appears in byte 1 or two, the TA78
does not update bytes
5
and above in an extended drive status
area.
The TA78 then transmits only the first 4 bytes of the
requested extended drive status area to the HSC.
Byte number
Parameter address
Name
Microbus address
Register location
Bit
7:0

Name

5
28
OPSAV

Description
Last STI level 2 command to begin
execution before error detection.
The table below identifies each
available code and its meaning.
Command
Code

41
42
44
47
48

4B
4D
4E
50
53
55
C0
C3
C5

B-3

Meaning
Clear drive errors
Clear formatter errors
Disconnect
Get formatter
characteristics
Get summary status
Initiate rewind
position tape
Set unit execution mode
Set byte count
Write tape mark
Data error recovery
Change controller flags
Diagnose
Get extended drive
status

Command
Code
C6
C9
CA

CC
CF
01
02

D4
Byte number
Parameter address
Name
Microbus address
Register location
Bit

Meaning
Get formatter error log
Get unit characteristics
Erase gap
Online
Read memory
Set unit characteristics
Topology
write memory

6
29
ERF~NUM

(Error number low byte)

Description

Name

Eight least significant bits of
10-bit identification number.
(Refer to Paragraph B.3.l)

7:0

Byte number
Parameter address
Name
Microbus address
Register location

2A
ERRNI (Error number high byte)

Bit

Name

Description

Critical error

True if error is critical;
transport should be removed from
service. This bit is forced to 0
for error that occurs while
operational code is running.

Data available

True if data generated by
diagnostic code is available. This
bit is forced to 0 for error that
occurs while operational code is
running.

5:3

Fault number

Indicates one of six areas in the
formatter that may have caused a
potentially fatal error. (Refer to
Table 4-1)

When 1, indicates operational
error.
When 0, indicates diagnostic
error.

1:0

Two most significant bits of
l0-bit error identification
number. (Refer to Paragraph B. 3.1)
B-4

Byte number
Parameter address
Name
Microbus address
Register location(s)

8
2B
RPFAIL
00-R
M8950s

(RMC write fail bits)
(RC3) via M8953

(RP6)

Bit

Name

Description

7:0

write fail 7:0

These are write fail bits from
read channels 7--0. Write fail
is an OR of certain error
conditions, namely:
Illegal 5-to-4 translation
AMTIE
·PHTIE
Pointer mismatch

Byte number
Parameter address
Name
Microbus address
Register location(s)

9
2C
RPATH
01-R
M8953

(Read path status)
(RP6)

Bit

Name

Description

Velocity ok

True if velocity is within 10% of
125 in/sec or jam velocity ok bit
is set (RPCTL, 09-W bit 2).

Status valid

Indicates M8953 status is valid
(set after 0.1 inch gap found).

Preamble error

True if preamble had AMTIE.

Data ready

Goes false when M8953 asserts
data ready to M8951.

Beginning of
preamble

True when read path senses that
the preamble has just passed the
read head.

Clock stopped

True if read path clock is
stopped.

Statistics select

True if TIE bus statistics are
being sent to TIE bus.

write fail P

Indicates illegal 5 to 4, AMTIE,
PHTIE, or pointer mismatch for
parity bit.

B-5

Byte number
Parameter address
Name
Microbus address
Register location(s)

2D
RSTAT (RMC status byte)
02-·R
M8950s via M8953 (RP4)

Bit

Name

Description

7:0

RMC status 7:0

This byte contains the read path
microcontruller status codes. The
following table identifies each
code and its meaning.

Read Path Microcontroller Status Codes
status

Meaning

Status from ECC self-test command
41
42

ECC controller passed self-test.
ECC controller failed self-test.

Status from an M8953 self-test
43
44

Read path passed self-test.
Read path failed self-test.

Status from an M8950 sel f-tE~st command
46

Read channel tests all passed.

Status from a clear all test command for velocity testing of drive
by microcode
1

First tach pulse
Last tach pulse (eleventh; ten spaces)

Status from a sample density command
88
89
8A

NOT CAPABLE found.
GCR ID found.
PE ID found.

Status from a write test of IBG, PE IO, GCR IO, ARA IO, or ARA
burst
90

Bad status (write test) •

Status from a tape mark test: command
92

Good tape mark found on tape status.

B-6

status resulting from a non-BOT command
GCR or PEl

(read or write FWO or REV,

ARA 10 found (not record or tape mark) •
Tape mark found.
Preamble end not found.
Read path fault 1, too many M8950s have
been fataled to continue record processing.
Read path fault 2, 7 or more M8950 modules
found illegal 5-to-4 translations.
Unexpected 1BG in data; probably creased
tape (seven or more AMT1ES active) •
Postamble long.
Postamble short.
OK

98
99
9C
90
9E
Al
Bl
B2
FF
Byte number
Parameter address
Name
Microbus address
Register location(s)

2E
RCMLP
03-R
M8953

(RMC command loop back)
(RP6)

Bit

Name

Description

7:0

Command 7:0

Contains the last command sent to
the M8953 via RCMO (address 0B-W).
The table below identifies each
code and its meaning.
Command
Code
00
01
02
03
04
05
06
07
08
09
0A
0B
0C
0D
0E
0F

B-7

Task
Nap
1nterblock read
Test PE 1D burst
Test GCR 1D burst
Test ARA 1D burst
Test tape mark
Test ARA burst
Normal non-BOT read
Run RMC self-test
Test unknown 10 burst
Run read channel
micro's test
Diagnostic read
command
Run read channel
self-test
Run clear all RMC
test program
Run ECC self-test
program
Find gap

Byte number
Parameter address
Name
Microbus address
Register location(s)

2F
RAMT (Read channel AMTIE status)
l0-R
Tape transport via M8955, M8950, and
M8953

Bit

Name

Description

7:0

AMTIE 7:0

This byte reflects the state
of the AMTIE lines for channels 7
through 0.

Byte numbe:r
Parameter address
Name
Microbus address
Register location(s)

30
RDON (Read channel done status)
ll-R
M8950s via M8953

Bit

Name

Description

7:0

Done 7:0

A given bit is false if the
associated M8950 has completed
its assigned task.

Byte number
Parameter address
Name
Microbus address
Register location(s)

31
RILL (Read channel illegal status)
l2-R
M8950 via M8953

Bit

Name

Description

7:0

Illegal 7:0

A given bit is true if the
associated M8950 indicates the
following.
GCR

Data contained an illegal 5-bit
code which was either an error or
a tape format control character.
PE
Data error occurred such as no
bit time phase transition.
Byte number
Parameter address
Name
Microbus address
Register location(s)

32
RMK2 (Read channel mark 2 status)
l3-R
M8950s via M8953

B-8

Bit

Name

Description

7:0

7:0 Mark 2

When true, indicates that the
associated M8950 has detected
a Mark 2 tape format control
character. If the corresponding
illegal 5-to-4 bit is set (RILL
7:0), a Mark 2 was detected during
5-to-4 conversion.

Byte number
Parameter address
Name
Microbus address
Register location(s)

10
33
REND (Read channel end status)
14-R
M8950s via M8953

Bit

Name

Description

7:0

END 7:0

End Mark for read channels
o -- 7.

Byte number
Parameter address
Name
Microbus address
Register lpcation(s)

11
34
RPSTA (Read channel parity status)
15-R
M8950 parity module

Bit

Name

Description

Corrected data P

Contains ECC module corrected
output data for parity bit.

Data P

Contains M8950 data output for
parity bit.

Post P

Indicates PE postamble for
parity bit.

End P

Indicates End Mark for parity
bit.

Mark 2 P

Indicates Mark 2 for parity
bit.

Illegal P

Indicates illegal 5-to-4 fer
parity bit.

Not done P

Parity M8950 not done.

AMTIE P

Weak amplitude on parity bit.

B-9

Byte number
Parameter address
Name
Microbus address
Register location(s)

12
35
RPOSTN (Read channel PE postamble detect)
16-R
M8950s via M8953

Bit

Name

Description

7:0

Postamble 7:0

In PE, contains the inverted
data for the byte prior to the
one currently on the data lines
(RC3 D (N) H). Used for PE
POSTAMBLE detection.
Not used in GCR.

Byte number
Parameter address
Name
Microbus address
Register location(s)

13
36
RDATA (Read channel data)
17 --R
M8950s via M8953

Bit

Name

Description

7:0

Data 7:0

Contains data output from read
channels 7--0 to ECC module.

Byte number
Parameter address
Name
Microbus address
Register location(s)

14
37
CRCWRD (CRC byte)
18-·R
M8952 (CRC3)

Bit

Name

Description

7:0

CRC 7:0

These are CRC checker output
bits.

Byte number
Parameter address
Name
Microbus address
Register location(s)

15
38
ECCOR (Corrected data)
19-·R
M8951 (EC5)

Bit

Name

Description

7:0

Corrected
data 7:0

Contains corrected data output
from ECC module to CRC module.

Byte number
Parameter address
Name
Microbus address
Register location(s)

16
39
ECCSTA (ECC status byte)
lA-,R
M8951 (EC5)
B-10

Bit

Name

Description

CRC error

Indicates CRC did not check.

ECC ROM parity
error

Indicates M895l program parity
error.

AMTIE occurred

Indicates AMTIE occurred during
data portion of record.

ACRe error

Indicates ACRC did not check.

pointer mismatch

Indicates the track in error did
not have a pointer.

Uncorrectable

Indicates ECC could not correct
data error.

Two-track error
correction

Indicates two-track error
correction was performed on data.

Single-track
error correction

Indicates single-track error
correction was performed on
data.

Byte number
Parameter address
Name
Microbus address(es)
Register location(s)

17
3A

(Read channels 0 and 1 TIE)
20-R and 2l-R
M8950s channels 0 and 1

Bit

Name

Description

CHI TIE bus 3

Indicates illegal 5-to-4 in GCR,
and dead track in PE. (Bad track
register is ORed into this bit.)

CHI TIE bus 2

AMTIE

CHI TIE bus 1

PHTIE

CHI TI E bus 0

If statistics = 0, indicates
pointer mismatch in GCR and
o in PE.
If statistics = 1, indicates any
pointer occurred (GCR and PE).

CH0 TI E bus 3

Indicates illegal 5-to-4 in GCR,
and dead track in PE. (Bad track
register is ORed into this bit.)

B-ll

Bit

Name

Description

CH0 TIE bus 2

AMTIE

CH0 TIE bus 1

PHTIE

CH0 TI E bus 0

If statistics = 0, indicates
pointer mismatch in GCR and
o in PEe
If statistics = 1, indicates any
pointer occurred (GCR and PE).

Byte number
Parameter address
Name
Microbus address(es)
Register location(s)

IS
3B
(Read channels 2 and 3 TIE)
22-R and 23-R
MS950s channels 2 and 3

Bit

Name

Description

CH3 TIE bus 3

Indicates illegal 5-to-4 in GCR,
and dead track in PEe (Bad track
register is ORed into this bit.)

CH3 TIE bus 2

AMTIE

CH3 TIE bus 1

PHTIE

CH3 TIE bus 0

If statistics = 0, indicates
pointer mismatch in GCR and
o in PEe
If statistics = 1, indicates any
pointer occurred (GCR and PE).

CH2 TIE bus 3

Indicates illegal 5-to-4 in GCR,
and dead track in PEe (Bad track
register is ORed into this bit.)

CH2 TIE bus 2

AMTIE

CH2 TIE bus 1

PHTIE

CH2 TIE bus 0

If statistics = 0, indicates
pointer mismatch in GCR and
o in PE.
If statistics = 1, indicates any
pointer occurred (GCR and PE).

B-12

Byte number
Parameter address
Name
Microbus address(es)
Register location(s)

19
3C
(Read channels 4 and 5 TIE)
24-R and 25-R
M8950s channels 4 and 5

Bit

Name

Description

CH5 TIE bus 3

Indicates illegal 5-to-4 in GCR,
and dead track in PEe (Bad track
register is ORed into this bit.)

CH5 TIE bus 2

AMTIE

CH5 TIE bus 1

PHTIE

CH5 TI E bus 0

If statistics = 0, indicates
pointer mismatch in GCR and
o in PEe
If statistics = 1, indicates any
pointer occurred (GCR and PE).

CH4 TIE bus 3

Indicates illegal 5-to-4 in GCR,
and dead track in PEe (Bad track
register is ORed into this bit.)

CH4 TI E bus 2

AMTIE

CH4 TIE bus 1

PHTIE

CH4 TIE bus 0

If statistics = 0, indicates
pointer mismatch in GCR and
o in PEe
If statistics = 1, indicates any
pointer occurred (GCR and PE).

Byte number
Parameter address
Name
Microbus address(es)
Register location(s)

1A
3D

(Read channels 6 and 7 TIE)
26-R and 27-R
M8950s channels 6 and 7

B-13

Bit

Name

Description

CH7 TIE bus 3

Indicates illegal 5-to-4 in GCR,
and dead track in PEe (Bad track
register is ORed into this bit.)

CH7 TIE bus 2

AMTIE

CH7 TIE bus 1

PHTIE

CH7 TIE bus 0

If statistics = 0, indicates
pointer mismatch in GCR and
o in PEe
If statistics = 1, indicates any
pointer occurred (GCR and PE).

CH6 TIE bus 3

Indicates illegal 5-to-4 in GCR,
and dead track in PEe (Bad track
register is ORed into this bit.)

CH6 TIE bus 2

AMTIE

CH6 TIE bus 1

PHTIE

CH6 TIE bus 0

If statistics = 0, indicates
pointer mismatch in GCR and
o in PEe
If statistics = 1, indicates any
pointer occurred (GCR and PE).

Byte number
Parameter address
Name
Microbus address(es)
Register location(s)

IB
3E
(Read channel P TIE and TIE bus)
28-R and 30-R
M8950 channel P and M8953

Bit

Name

Description

7:4

TIE bus

Reads TIE bus without enabling
any read channel modules. If jam
TIE bus (address 09-W bit 7) is
set, then the value wrixten into
address 0A-W is read.

CHP TI E bus 3

Indicates illegal 5-to-4 in GCR,
and dead track in PEe (Bad track
register is ORed into this bit.)

CHP TI E bus 2

AMTIE

B-14

Bit

Name

Description

CHP TIE bus 1

PHTIE

CHP TIE bus 0

If statistics = 0, indicates
pointer mismatch in GCR and
o in PEe
If statistics = 1, indicates any
pointer occurred (GCR and PE).

Byte number
Parameter address
Name
Microbus address
Register location(s)

IC
3F

TAMT (AMTIE byte)
44-R
M8955 (TUP 2, 4)

Bit

Name

Description

7:0

AMTIE 7:0

This byte reflects
information on TU bus lines
AMTIE 7:0 L.

Byte number
Parameter address
Name
Microbus address
Register location(s)

ID
40

PSTAT (Tape unit port status)
48-R
M8955 (TUP 2, 4)

Bit

Name

Description

Status parity
error

Indicates a parity error has
occurred when reading a TU78
register over the WCS lines.

Write data
strobe

Reflects the state of the TU bus
line WDS.

Command parity
error

Indicates the TU78 has detected
a parity error on the WCS lines
during a TS78 command or command/
status address write.

Tape unit
present

Indicates that a TU78 transport
is physically cabled to this TU
port.

Tachometer

Reflects the state of the TU
bus line TACH.

WCS parity

Reflects the state of the TU
bus line WCS P.

B-15

Bit

Name

Description

Read parity

Reflects the state of the TU
bus line RD P.

AMTIE parity

Reflects the state of the TU
bus line AMTIE P.

Byte number
Parameter address
Name
Microbus address
Register location(s)

IE
41
PRDD (TU port read data)
4C--R
M8955 (TUP 2, 4)

Bit

Name

Description

7:0

Read data 7:0

This byte reflects information
on TU bus lines RD 7:0 L.

Byte number
Parameter address
Name
Microbus address
Register location(s)

IF
42

PERI (STI bus errors)
81
M8971

Bit

Name

Description

Level 1 protocol
error

Indicates that after first frame
of level 2 message, a received
hamming code is not recognized as
valid continue or end code

CRaM parity
error

Indicates M8970 program parity
error

Data late

Indicates one of three
occurrences. An attempt was made
to retrieve data from the PM FIFO
that was not available. An attempt
was made to store data in the PM
FIFO before the input was ready.
Or in autoshift mode, new data
loaded into the hold register
before the PM FIFO could accept
the previous data.

Control parity
error

Indicates parity error or
synchronization error detected on
real-time controller-state line.
A parity error applies to the
status bits. A synchronization
error applies to the pattern of
eight 0s and a 1 before the status
bits.
B-16

Bit

Name

Description

Data pulse
error

Indicates missing pulse on
write/command data line. That is,
two positive pulses appear with no
negative pulse in between, or two
negative pulses appear with no
positive pulse in between.

Control pulse
error

Indicates missing pulse on
real-time controller-state line.
This error is analogous to a data
pulse error.

Cable not
present

Indicates that there is no cable
present between the TS78 logic
gate and the TS78 control panel.
Not used

Byte number
Parameter address
Name
Microbus address
Register location(s)

20
43

WMCSTA (Write microcontroller status)
D0-R
M8 95 9 (WMC 1 )

Bit

Name

Description

XMC not done

If 0, translator microcontroller
is done writing postamble and
waiting to be serviced. If 1,
translator is busy.

WMC not done

If 0, write microcontroller is
done writing PE data or GCR data
groups. (Used in diagnostic
single-step mode; normally
appears for 110 ns.) If 1, write
microcontroller busy or idle.

Transfer

Shifts one nibble on WMC DR bus
into translator.

ECC to WMC DR
bus

Gates HI or LO nibble of ECC
character to WMC DR bus.

CRC to WMC DR
bus

Gates HI or LO nibble of CRC
character to WMC DR bus.

ACRC to WMC DR
bus

Gates HI or LO nibble of ACRC
character to WMC DR bus.

B-17

Bit

Name

Description

Residual to WMC
DR bus

Gates HI or LO nibble of
residual character to WMC DR
bus.

XMC WCLK

Reflects true state of
translator write clock pulse
(110 ns at normal speed).

Byte number
Parameter address
Name
Microbus address
Register location(s)

21
44
TUSEL0 (Tape unit port 0/1 select)
Dl-R
M8955 (port 0/1 slot 08)

Bit

Name

Description

Single tape
unit port

If 0, both TUP modules are
installed in backplane slots
08 and 09.
If 1, only one TUP module is
installed in backplane slot 08.

Byte count
terminal count

If 0, write microcontroller count
terminal count (BCTC) is asserted.
If 1, BCTC is unasserted.

TU port 0
read path enable

When true, indicates that the
read path for tape unit port 0
is enabled.

TU port 1
read path enable

When true, indicates that the
read path for tape unit port 1
is enabled.

TU port 0 write
path enable

When true, indicates that the
write path for tape unit port
o is enabled.

TU port 1 write
path enable

When true, indicates that the
write path for tape unit port
1 is enabled.

1, 0

Tape unit select
1:0

A 2-bit binary field that
reflects the tape unit port
currently selected by the TUSEL
register (E0-W bits 1:0).

B-18

Byte number
Parameter address
Name
Microbus address
Register location(s)
Bit

22
45
TUSELl (Tape unit port 2/3 select)
02-R
M8955 (port 2/3, slot (9)

Name

Description
Not used.

7, 6
5

TU port 2
read path
enable

When true, indicates that the
read path for tape unit port 2
is enabled.

TU port 3
read path
enable

When true, indicates that the
read path for tape unit port 3
is enabled.

TU port 2
write path
enable

When true, indicates that the
write path for tape unit port
2 is enabled.

TU port 3
write path
enable

When true, indicates that the
write path for tape unit port
3 is enabled.

1, 0

Tape unit
select 1:0

A 2-bit binary field that
reflects the tape unit port
currently selected by the TUSEL
register (E0-W bits 1:0).

NOTE
This byte is valid only when two TU port
modules are present in the system (i.e.,
TUSEL9, bit 7 = g.)
Byte number
Parameter address
Name
Microbus address
Register location(s)

23
46

WRTOAT (write data)
03-R
M8959 (WMC 1)

Bit

Name

Description

7:0

DR 07:0 H

Looks at write or read data on
the intermediate ORO bus.

Byte number
Parameter address
Name
Microbus address
Register location(s)

24
47
(Byte counter 10)
04-R (first read)
M8959 (WMC 1)

B-19

Bit

Name

Description

7:0

Byte count
7:0

Low byte of the write micro/byte
assembly byte counter word. The
first read of location D4 yields
this byte.

Byte number
Parameter address
Name
Microbus address
Register location(s)

25
48
(Byte counter hi)
D4-R (second read)
M8959

(WMC 1)

Bit

Name

Description

7:0

Byte count

High byte of the write micro/byte
assembly byte counter word. The
second read of location D4 yields
this byte.

15:8

Byte number
Parameter address
Name
Microbus address
Register location(s)

26
49
(Pad counter 10)
05-R (first read)
M8 9 S 9

(WMC 1 )

Bit

Name

Description

7:0

Pad count
7:0

Low byte of the write micro/byte
assembly pad character counter
word. The first read of location
OS yields this byte.

Byte number
Parameter address
Name
Microbus address
Register location(s)
Bit
7:0

27
4A

(Pad counter hi)
DS-R (second read)
M8 9 5 9 (WMC 1 )

Name

Description

Pad count

High byte of the write micro/byte
assembly pad character counter
word. The second read of location
05 yields this byte.

15:8

Byte number
Parameter address
Name
Microbus address
Register location(s)

28
4B
(Error code counter 10)
06-R (first read)
M8 9 S 9

(WMC 1 )

B-20

Bit

Name

Description

7:0

Error code
7:0

Low byte of write micro/byte
assembly error code count. The
first read of location D6 yields
this byte. (See byte 29 for Ecode
counter values.)

Byte number
Parameter address
Name
Microbus address
Register location(s)

29
4C
(Error code counter hi)
D6-R (second read)
M8 9 5 9 (WMC 1 )

Bit

Name

Description

7:0

Error code
15:8

High byte of write micro/byte
assembly error code count. The
second read of location D6 yields
this byte.
Ecode counter is normally set to
zero at the start of an
operation.
Ecode counter values when read
at the completion of an
operation:
Bit
Value

Error Indication
Operation completed
successfully.

-1

Read skip count >4 in
o core dump, >3 in 10
compatible, or >8 in
10 high-density
compatible.

-2

Read skip count >1 in
11 normal or 15 normal.

-3

Format code >6.

-4

WMC self-test
diagnostic error.

-5

Read overrun or write
fault.

B-21

Byte number
Parameter address
Name
Microbus address
Register location(s)
Bit

Name

Description
Not used

2A
40
WMCERR (Write microcontroller errors)
OA-,R
M89 5 9 ( WMC 2 )

DR MBO

parity error

Bad (even) parity was received
in data at TS78 input port.

Error

Write microcontroller diagnostic
overall error status bit.

WMC ROM parity
error

A write microcontroller ROM
parity error was detected or the
WMC internal microdiagnostic
stopped at an error halt.

DR read
parity error

A parity error was detected on
a read data byte sent from the
eRC/ACRe to WMC module over the
CRe bus.
Not used

2:0
Byte number
Parameter address
Name
Microbus address
Register location(s)

2B
4E
INTSTA (Interrupt status)
E0-R
M8972 (8MC1)

Bit

Name

Description

Interrupt
timer (MCLK)

When clear, indicates the M8970
interrupt timer has timed out.
First interrupt is 600 us after
timer is started and subsequent
interrupts are at 1.2 ms intervals
until timer is reset.

USART receiver
ready (RX)

When clear, indicates ASCII port
USART has received a byte which is
available in the receiver buffer.

Power ok

When set, indicates that the
TS78 power supply has not
signaled an AC LO condition.

B-22

Bit

Name

Description

write data
register parity

Reflects the state of the DR
BYTE PAR H line. Serves as the
parity bit for the WRTDAT
register (03-R), or as a PE
write operation done flag.

KINI

Reflects the state of the KINI bit
on the real-time controller-state
line. When set, indicates
controller request for STI bus
initialization.

USART transmitter
ready (TX)

When clear, indicates the ASCII
port USART is ready to accept a
new character in the transmitter
buffer.

PE write
parity error

When set, indicates that a
vertical parity error has
been detected at the output
of the translator during a
phase-encoded write operation.

Translator
ROM parity
error

When set, indicates that the
translator microcontroller ROM
has experienced a parity error
or has branched to an error
halt during its internal
diagnostic routines.

Byte number
Parameter address
Name
Microbus address
Register location(s)

2C
4F
TADR00 (TU78 status)
40-R (MIA register 0)
M8955/MIA (TU78)

Bit

Name

Description

Ready

The tape unit is on-line, not
rewinding, not loading or
unloading, and all pneumatic
interlocks are made.

Ready on

Ready has undergone a transition
to the set state. Cleared by a CLR
TU command.

On-line

The tape unit has been placed
on-line; if ready, it will respond
to motion commands issued remotely
from the formatter.

B-23

Bit

Name

Description

Rewinding

The tape unit is currently
rewinding.

PES

The tape unit is currently set to
phase-encoded recording format. If
reset, the tape unit is set to
group-coded 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:

File protect

Byte number
Parameter address
Name
Microbus address
Register location(s)

•

The EOT marker is positioned
at the EOT sensor during a
reverse operation with ready
set

•

The tape unit is commanded to
rewind tape

•

A CLR EOT command is written
into the TU CMD B location.

The tape reel currently loaded
does not have the write enable
ring in place.

20
50
TADR01 (MIA status A)
40-R (MIA register 1)
M8955/MIA (TU78)

Bit

Name

Description

Manual test

The manual test switch is in the
MAN TEST position.

Forward

The forward command bit has been
written with a 1, or a DSE command
has been written into the TU CMD B
location.

Reverse

Indicates the state of the reverse
command bit.

B-24

Bit

Name

Description

Write

Indicates the state of the write
command bit.

Write
inhibit

Indicates the state of the write
inhibit command bit.

LWR

Indicates the state of the loop
write-to-read command bit.

MOT

Indicates that the capstan servo
motor is turning.

DSE

Indicates that a DSE command has
been written into the TU CMD B
location. Clears when EOT sets, or
when a CLR TU command is written
into TU CMD B.

Byte number
Parameter address
Name
Microbus address
Register location(s)

2E
51
TADR02 (MIA status B)
40-R (MIA register 2)
M8955/MIA (TU78)

Bit

Name

Description

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. 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
em (9.5 in) after BOT, the read
amplifier gains failed to achieve
the required value. Valid only if
ready is set.

4,3

Speed
1:0

This 2-bit field indicates the
speed of a tape unit; TU78 = 2
(125 in/sec).

B-25

Bit

Name

Description

2,1,0

Mode select
2,1,0

Indicates the position of the
multiposition mode select switch
on the tape unit operator panel.
The bits are meaningful only when
the mode select bits in the
threshold command location have
been written to ones.
Bit
position
210

110
101

Byte number
Parameter address
Name
Microbus address
Register location(s)

Meaning
position
position
position
position

(Normal)
(Maintenance)
2 (Maintenance)
3 (Maintenance)

2F
52
TADR03 (Serial number A)
40-R (MIA register 3)
M8955 /M I A (TU 7 8 )

Bit

Name

Description

7:4

SN TH
3:0

Most significant (thousands) BCD
digit of the tape unit's serial
number

3:0

SN HU
3:0

The hundreds BCD digit of the tape
unit's serial number

Byte number
Parameter address
Name
Microbus address
Register location(s)

30
53
TADR04 (Serial number B)
40-R (MIA register 4)
M8 955/MI A (TU 78)

Bit

Name

Description

7:4

SN tens
3:0

The tens BCD digit of the tape
unit's serial number.

3:0

SN ones
3:0

Least significant (ones) BCD digit
of the tape unit's serial number.

Byte number
Parameter address
Name
Microbus address
Register location(s)

31
54
TADR05 (Tape unit diagnostics)
40-R (MIA register 5)
M8955/MIA (TU78)

B-26

Bit

Name

Description

write
bit 4

Indicates the state (polarity)
the write driver for physical
track 4 head.

Write

There is no current flowing
through the write or erase heads

Read enable

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. Not valid
unless ready = 1.

TACH

The state of the output from the
capstan motor digital tachometer.
Zero

1,0

AMTIE THR
1:0

Byte number
Parameter address
Name
Microbus address
Register location(s)
Bit

Indicates the value of the AMTIE
threshold field in the THRESHOLD
command location.
55

(Spare location)

Name

Description

7:0

This location is valid only for
temporary data storage when using
the ASCII port. Contents of this
location are not returned to the
HSC for error logging.

Byte number
Parameter address
Name
Microbus address
Register location(s)
Bit
7:0

Name

(Spare location)

Description
This location is valid only for
temporary data storage when using
the ASCII port. Contents of this
location are not returned to the
HSC for error logging.

B-27

B.3

EXTENDED FORMATTER STATUS

Byte number
Parameter address
Name

57
ERRNUM (Error number low byte)

Bit

Description

7:0

Eight least significant bits of l0-bit error
identi fica tion number. (Refer to Paragraph B. 3.1)

Byte Number
Parameter address
Name

58
ERRNI

(Error number high byte)

Bit

Description

critical error. When 1, indicates error is critical;
formatter should be removed from service. This bit is
forced to 0 for error that occurs while operational code
is running.

Data available. When 1, indicates data generated by
diagnostic code is available. This bit is forced to 0 for
error that occurs while operational code is running.

5:3

Fault number. Indicates one of six areas in the formatter
that may have caused a potentially fatal error. (Refer to
Table 4-1)

When 1, indicates operational error.
When 0, indicates diagnostic error.

1:0

Two most significant bits of l0-bit error identification
number. (Refer to Paragraph B.3.1)

Byte number
Parameter address
Name

3
59
OPSAV

Bit

Description

7:0

Last received level 2 opcode. Listed below are the
available command codes and their meaning.
Command
Code
41
42

44
47
48

Meaning
Clear drive errors
Clear formatter errors
Disconnect
Get formatter characteristics
Get summary status
Initiate rewind
B-28

Command
Code
4D
4E
50

53
55

C0
C3

C5
C6
C9
CA
CC
CF
01
D2
D4

Byte number
Parameter address
Name

Meaning
position tape
Set unit execution mode
Set byte count
write tape mark
Data error recovery
Change controller flags
Diagnose
Get extended drive status
Get formatter error log
Get unit characteristics
Erase gap
Online
Read memory
Set unit characteristics
Topology
write memory
4

5A
CONNST (Connection state byte)

Bit

Description

7:5

Not used

Broken. When 1, indicates minimum integrity failure.
Formatter cannot communicate via STI bus because of
internal hardware problem.

Off-line. When 1, indicates both formatter ports are
off-line with respect to controller. (No STI communication
since PORT SELECT A and B are in disabled position.)

Topology. When 1, indicates formatter entered topology
mode. With one formatter port on-line, second port
simulates available state for up to 1 second.

Available. When 1, indicates one or both formatter ports
is in available state relative to controller. (PORT SELECT
A and/or B in enabled position but controller has not
placed a port on-line.) Controller can access available
port but access is limited to very few commands such as
retrieving status.
On-line. When 1, indicates a formatter port is on-line
with respect to controller (ready to receive any command
or data). If PORT SELECT A and B are in enabled position,
other port is unavailable except if formatter is in
topology mode.

B-29

Byte number
Parameter address
Name

5
5B

SUMMOD (Summary mode byte 1)

Bit

Description

Formatter attention .. When 1, indicates potentially
significant status change in formatter~ not caused by
reception, validation or execution of controller command.

Transport 3 attention. Analogous to bit 7.

Transport 2 attention. Analogous to bit 7.

Transport 1 attention. Analogous to bit 7.

Transport 0 attention. Analogous to bit 7.

When 1, indicates formatter entered topology mode.
to CONNST bit 2 for further definition.)

When 1, indicates PORT SELECT A and/or B is in enable (in)
position

(Refer

When 1, indicates diagnostic request. Formatter requests
controller to execute diagnostic identified in formatter
memory region FFFD.
Byte number
Parameter address
Name

5B
SUMMOD

(Summary mode byte 1)

Bit

Description

Formatter error. When 1, indicates formatter error
detected while running operational code.

Transmission error. When 1, indicates detection of STI bus
error that falls into one of the following categories.
•

Received hamming code of suspected level 1 message is
not recognized, or received unit number is invalid

•

Received level 1 command is in improper context
(e.g.; formatter is not on-line for write command).

•

Levell protocol error~ received hamming code is not
recognized as continue or end, after first frame of
level 2 message

B-30

Bit

Description
•

Checksum error; calculated checksum does not agree
with received checksum

•

Level 0 error; pulse or parity error on real-time
controller-state line, or pulse error on
write/command data line

Level 2 protocol error. When 1, indicates detection of STl
bus programming error relating to received message byte(s)
in level 2 command. For example, operand has wrong parity
or wrong number of message bytes received for specified
command) .

Diagnostic failed. When 1, indicates formatter error
detected while running in-line, off-line or subsystem
diagnostic. Diagnostic error report is available in
formatter memory region 3432.

3:0

Not used

Byte number
Parameter address
Name

7
5D
SUMMD2

(Summary mode byte 2)

Bit

Description

7:4

Not used

When 1, indicates new error log information is available
in the extended formatter status area

2:0

Retry bits RP, RT and FD. These bits indicate formatter
progress in an error recovery sequence instructing the
controller what recovery step to do next. Retry codes are
listed below.
Bit position

210
RP

Meaning

1
1

No error
Ready for data transfer in same direction
Ready for data transfer in opposite direction
Retried transfer succeeded
Retried transfer failed
Ready to position for retry in same direction
Ready to position for retry in opposite
direction

1
1
1
1

o
o

1
1

o
1

B-3l

Byte number
Parameter address
Name

8
5E

CONBYT (Controller flag byte)

Bit

Description

When 0, indicates normal operation.
When 1, indicates formatter only responds to commands from
controller diagnostic. The controller uses this mode to
execute diagnostics that cannot keep the formatter
on-line.

6:0

Not used

Byte number
Parameter address
Name

5F
PRTOSV (Port control byte)

Bit

Description

7:4

Not used

When 1, indicates formatter transmission enabled on port A
real-time formatter-state line

When 1, indicates formatter transmission enabled on port B
real-time formatter-state line

When 1, indicates formatter reception and transmission
enabled on port A data lines, and formatter reception
enabled on port A real-time controller-state line
When 1, indicates formatter reception and transmission
enabled on port B data lines, and formatter reception
enabled on port B real-time controller-state line

Byte number
Parameter address
Name

60
FSTOSV (Formatter state byte)

Bit

Description

When 0, forces transmission of 0s on enabled port(s)
real-time formatter-state line.
When 1, allows transmission of state bits on enabled
port(s) real-time formatter-state line. Bits 6--1 in
FSTOSV are the state bits.
Bit 7 is a 1 when formatter is on-line or available, and a
o when formatter is off-line. (Refer to CONNST for
definition of formatter connection states.)

B-32

Bit

Description

Formatter receiver ready. When 1, indicates formatter is
ready to receive a new message frame or data. Reception of
a valid sync character causes the formatter to clear this
bit to 0.

Attention. When 1, indicates pohentially significant
status change not caused by reception, validation or
execution of controller command. In most cases, a status
change is caused by user intervention such as opening a
transport door or pressing the LOAD/REW button. Source of
the attention condition is identified in SUMMOD. (See note
below. )

Acknowledge. When 0, indicates data transfer error
occurred (operation aborted) or exception occurred (tape
mark, EaT or BOT detected during data transfer). (See note
below. )

Data ready.
In read operation, leading edge (transition to 1)
indicates tape drive is starting sequence to transmit sync
character and then data. Falling edge (transition to 0)
indicates formatter has transmitted all of the data and
part of the byte count.
In write operation, leading edge (transition to 1)
indicates tape drive is starting write sequence in
autoshift mode. Falling edge (transition to 0) indicates
data received and stored with no error, and EDC received
and verified.
In position tape operation, toggling of data ready bit
indicates progress is being made. Formatter complements
data ready for every gap detected (i.e.; every record or
tape mark passed). Acceptable progress is a toggling rate
of at least twice for every long time-out period. Data
ready is a 0 at beginning and end of operation. (See note
below. )

Not used.

(See note below.)

NOTE
Definitions above for bits 5-2 are valid
only when formatter is on-line. With
formatter in available state, bits 5-2
represent a 4-bit event counter with bit
5 being the most-significant-bit (MSB).
The counter records the number of
changes in connection state of the
transport (s).
(The
three
transport
connection states are on-line, available
and off-line.)
B-33

Bit

Description

Available. When 0, indicates formatter is on-line. When 1,
i nd ica tes forma t ter is ava i lable or of f-l i ne. (Refer to
CONNST for definition of formatter connection states.)
Parity.
When 0, allows normal operation; calculate odd parity
based on bits 6-1 in FSTOSV to yield bit 0 (parity bit) on
enabled real-time formatter-state line(s).
When 1, forces parity error; calculate even parity
yielding a parity bit in bit 0 that is inverted with
respect to its correct value.

Byte number
Parameter address
Name

61
PSWISV (Port switch byte)

Bit

Description

Not used

When 1, indicates FAULT is being pressed

When 1, indicates PORT SELECT A is in enabled (in)
position

When 1, indicates PORT SELECT B is in enabled (in)
position

3:0

Not used

Byte number
Parameter address
Name

62
LASSTA

Bit

Description

7:0

Last checkpoint passed in operational code.
Paragraph B.3.2)

Byte number
Parameter address
Name

63
ERRFLG (Error retry flag byte)

B-34

(Refer to

Bit

Description

7:6

Not used

When 1, indicates initial command was a write

When 1, indicates initial command moved tape in reverse
direction

When 1, indicates initial command moved tape in opposite
direction

Most-significant-bit (MSB) of unit number for transport
that executed initial command

Least-significant-bit (LSB) of unit number for transport
that executed initial command
Not used

Byte number
Parameter address
Name

E
64

RETCNT (Retry counter)

Bit

Description

7:0

Number of retry requests during error recovery sequence

Byte number
Parameter address
Name

65
KICNT (STI bus initialization counter)

Bit

Description

7:0

Number of initializations since TA78 master reset or
power-up

Byte number
Parameter address
Name

10
66

Bit

Description

7:0

Contents of memory location specified in stack pointer
(SP) after underflow error

B-35

Byte number
Parameter address
Name

11
67

Bit

Description

7:0

Contents of next location (SP+l) after underflow error

Byte number
Parameter address
Name

12
68

Bit

Description

7:0

Contents of next location (SP+2) after underflow error

Byte number
Parameter address
Name

13
69

Bit

Description

7:0

Contents of next location (SP+3) after underflow error
NOTE
Bytes 10-13 are only valid
if an
underflow error has occurred. Otherwise,
these four bytes are cleared to 0.

Byte number
Parameter address
Name

6A
(Spare location)

Bit

Description

7:0

This location is valid only for temporary data storage
when using the ASCII port. Contents of this location are
not returned to the HSC for error logging.

B.3.1
Error Number
A 16-bit error number, shown in Figure B-1, reports both
operational and diagnostic errors. Operational errors are errors
that occur while the operational code is running. Diagnostic
errors are errors that occur while an in-line diagnostic is
running (in normal mode)
or while an off-line or subsystem
diagnostic is running.
A hex number of C or 4 in the
least-significant-digit (LSD) of the high byte (ERRNl) indicates
an operational error which is identified in Table B-1. Any other
LSD for ERRNI indicates a diagnostic error which is identified in
a standard error report including FRU and summary description.

B-36

05
: E5

ERROR
IDENTIFICATION
NUMBER

CRITICAL
ERROR
l=OPERATIONAL ERROR
O=DIAGNOSTIC ERROR

DATA
AVAILABLE

LOW BYTE (ERRNUM)

HIGH BYTE (ERRN1)

SHR-0105-84

Fig ure 8,-1

Table B-1

Error Number Bytes

Operational Error Codes

Error Number
Low
High
Byte
Byte

Fault
Number

Error Description

Operation completed with no error
detected.

TV CMO did not load correctly to start
tape motion in Erase Gap routine.

TV velocity never came up to acceptable
speed (i .e.; within 10% of 125 in/s).

write operation successfully completed
beyond EOT marker (exception condition) •

Read path could not verify gap at end of
Erase Gap routine.

TV velocity changed from proper speed to
unacceptable speed during operation.

write attempted on file protected tape
or TV FPT bit set during operation.

TV CMO did not load correctly to start
tape motion to write 10 burst.

TV CMO did not load correctly to set PE
tape density at start of write BOT 10
burst.

Command read from RMC register RCMLP did
not match command loaded into RCMO
register. (This code generated when Find
Gap command loaded during Erase Gap
routine.)

B-37

Table B-1

Operational Error Codes (Cont)

Error Number
High
Low
Byte
Byte

Fault
Number

Failed to write density 10 burst
correctly.

TU CMO did not load correctly to set GCR
tape density after reading a GCR Density
ID burst.

Failed to write ARA 10 correctly.

ARA error bit set in MIA status B
register.

Could not find gap after 10 code was
written correctly.

TU CMO did not load correctly to start
tape motion to write BOT 10 burst.

Error Description
Command read from RMC register RCMLP did
not match command loaded into RCMD
register. (This code generated when
Verify 10 Burst command loaded during
write of BOT area.)

Command read from RMC register RCMLP did
not match command loaded into RCMD
reg i ster. (Thi s code genera ted when
Verify ARA Burst command loaded during
write of BOT area.)
Failed to write ARA burst correctly.

Command read from RMC register RCMLP did
not match command loaded into RCMD
register. (This code generated when
Verify ARA 10 command loaded during
write of BOT area.)

Command read from RMC register RCMLP did
not match command loaded into RCMD
register. (This code generated when
Verify Gap command loaded during write
of BOT area.)
TU CMO did not load correctly to backup
tape to BOT after failing to write BOT
ID.

B-38

Table B-1

Operational Error Codes (Cont)

Er'ror Number
High
Low
Byte
Byte

Fault
Number

Error Description

Time-out looking for BOT after failing
to write BOT 10.

TU CMO did not load correctly to start
tape motion in selected function
routine.

Failed to write tape mark correctly.

Tape never came up to acceptable speed
while trying to reposition for retry of
writing tape mark.

TU CMD did not load correctly to backup
for retry of writing tape mark.

TU velocity changed from proper to
unacceptable speed while trying to
reposition for retry of writing tape
mark.

No record found within 7.6 m (25 ft)
tape.

Time-out looking for BOT after detecting
ARA 10 burst while moving in reverse
direction.

Detected BOT maiker after tape motion
started.

Reverse command issued while tape at
BOT.

ECC ROM parity error.

Command read from RMC register RCMLP did
not match command loaded into RCMO
register. (This code generated when Read
10 Burst command loaded during read of
BOT area.)

Command read from RMC register RCMLP did
not match command loaded into RCMO
register. (This code generated in
selected function routine.)

10 burst neither PE or GCR.

B-39

Table B-1

Operational Error Codes

Error Number
High
Low
Byte
Byte

Fault
Number

(Cont)

Error Description

No Gap found after ID burst
ID burst (GCR).

TU CMD did not load correctly to start
tape motion to read ID burst.

ARA 10 not found.

Command read from RMC register RMCLP did
not match command loaded into RCMD
register. (This code generated when
Verify ARA ID command loaded during read
of BOT a rea. )

Command read from RMC register RCMLP did
not match command loaded into RCMD
register. (This code generated when
Verify Gap command loaded during read of
BOT area.)

TU CMD did not load correctly to set PE
tape density at start of read from BOT.

TU CMD did not load correctly to set GCR
tape density after reading a GCR Density
ID burst.

WMC general error during read operation;
check Ecode register for reason. May be
illegal Format or Skip Count codes.

RD PE set in WMCERR register with no ECC
uncorrectable error in ECCSTA register.
Or during read operation, WMC ROM PE in
WMCERR is set.

XMC ROM parity error.

XMC DONE did not set.

WMC ROM PE set in WMCERR register during
wr.:ite operation.

WMC general error during write
operation; check Ecode register for
reason. May be illegal Format or Skip
Count codes.

B-40

(PE)

or ARA

Table B-1

Operational Error Codes (Cont)

Error Number
High
Low
Byte
Byte

Fault
Number

Error Description

Could not find a gap after writing
record and read path terminated early.

RSTAT contains error code.

AMTIE, pointer mismatch, uncorrectable,
two-track error or single-track error
set in ECCSTA register. (This code
generated by write PE operations.)

At least one write fail bit set in
RPFAIL and RPATH registers.

GCR characters from WMC and RMC do not
match. (This code generated by write PE
operations.)

CRC error, ACRC error, pointer mismatch,
uncorrectable or two-track error set in
ECCSTA register. (This code generated by
write GCR operations.)

More than one write fail bit set in
RPFAIL and RPATH registers. (This code
generated by write GCR operations.)

Could not detect a gap after writing
record.

TU velocity changed while writing PE gap
before starting to write record.

Read path terminated before entire
record was written.

Calculated EDC did not match received
EDC during write operation.

PM DONE did not set at end of port
switch routine.

PM CROM parity error occurred during
port switch routine.

XMC PE mode parity error set in INTSTA
register.

B-4l

Table B-1

Operational Error Codes

Error Number
High
Low
Byte
Byte

Fault
Number

(Cont)

Error Description

Port enable status read after port
switch routine did not match desired
port enable status.

PM CROM parity error occurred while
receiving message in available state.

PM FIFO input not ready at start of send
level 2 message routine.

Data late error caused by attempting to
retrieve message from empty PM FIFO
during level 1 command validation.

PM FIFO output not ready (so message not
available) at start of level 2 command
validation.

PM CROM parity error occurred during
level 1 command validation.

PM FIFO input not ready during
diagnostic echo routine.

PM CROM parity error occurred during
diagnostic echo routine.

PM CROM parity error occurred during
level 2 command validation.

PM CROM parity error occurred during
send level 2 message routine.

TS78 control panel cable is not present.

PM FIFO output ready at start of
diagnostic echo response. This indicates
too many bytes (over two) were in FIFO.

PM CROM parity error occurred while
receiving message in on-line state.

Level 2 message byte-count is too large
(over 63 bytes) to transmit with send
level 2 routine.

B-42

Table B-1

Operational Error Codes (Cont)

Error Number
High
Low
Byte
Byte

Fault
Number

Error Description

Uncorrectable data error detected.

Tape mark detected while reading a
record.

Transmission error detected in PERI
register.

PM clock not enabled at start of write
routine.

PM CRaM parity error occurred during
data operation.

Bad or missing ROM on M8972.

Write current not inhibited during
erase-only portion of write retry
operation.

Illegal microdiagnostic number detected
while running operational code.

Correctable error detected.

Minimum integrity failure.

PM DONE did not set at end of read
routine.

PM FIFO output ready (so FIFO not empty)
at end of read routine.

Stack underflow error.

AC La power interrupt received
indicating impending power failure.

Message retrieved from PM FIFO, during
level 2 command validation, is too large
(over 64 frames).

Data late error detected in PERI
register at end of data operation.

B-43

Table B-1

Operational Error Codes (Cont)

Error Number
High
Low
Byte
Byte

Fault
Number

Error Description

unexpected RST 1 interrupt. (RST 1
interrupt received but RX or TX
interrupt line not asserted in INTSTA
register.)

Unexpected RST 2 interrupt. (RST 2
interrupt received but MCLK or RX
interrupt line not asserted in INTSTA
register.)

unexpected RST 3 interrupt. (RST 3
interrupt received but RX interrupt line
not asserted in INTSTA register.)

unexpected RST 4 interrupt. (RST 4
interrupt received but MCLK or TX
interrupt line not asserted in INTSTA
register.)

Unexpected RST 5 interrupt. (RST 5
interrupt received but TX interrupt line
not asserted in INTSTA register.)

unexpected RST 6 interrupt. (RST 6
interrupt received but MCLK interrupt
line not asserted in INTSTA register.)

Unexpected RST 7 interrupt. (RST 7
interrupt received but TU STAT parity
error not asserted in PSTAT register.)

Unexpected trap interrupt. (Trap
interrupt received but AC LO interrupt
line not asserted in INTSTA register.)

Unexpected RST 5.5 interrupt. (RST 5.5
interrupt received but KINI interrupt
line not asserted in INTSTA register.)

unexpected RST 6.5 interrupt. (8085
received illegal instruction.)

unexpected RST 7.5 interrupt. (RST 7.5
interrupt received but TU CMD parity
error not asserted in PSTAT register.)

B-44

Table B-1

Operational Error Codes (Cont)

Error Number
High
Low
Byte
Byte

Fault
Number

Error Description

Preamble had AMTIE during write
operation.

Follow-up write command not received
within 2.4 ms of finishing last record
in keep going mode.

Forced fatal drive error during data
operation, for testing HSC.

8085 interrupts not enabled in off-line
state.

Forced fatal formatter error during data
operation, for testing HSC.

B.3.2
Last Status (LASSTA) Code
Byte number C in the extended formatter status area contains an
8-bit code that describes the last checkpoint passed in the
operational code before error detection. In effect, the LASSTA
code provides a progress report up to the error detection. Table
B-2 lists and describes the LASSTA codes.
Table B-2

LASSTA Codes

Opcode

Description

Not used.

Level 2 protocol error.

Transmission error.

Diagnostic Echo command executed properly.

Asserted KINI state bit recognized and
STI-bus initialization executed properly.

Change Controller Flags command executed
properly.

B-45

Table B-2

LASSTA Codes (Cont)

Opcode

Description

Clear Drive Errors command executed properly.

Clear Formatter Errors command executed
properly.

Disconnect command executed properly.

Get Extended Drive Status command executed
properly.

Get Formatter Error Log command executed
properly.

Get Formattter Characteristics command
executed properly.

Get Summary Status command executed properly.

Get unit Characteristics command executed
properly.

Erase Gap command executed properly.

Initiate Rewind command executed properly
(rewind, rewind/unload, or DSE/rewind
initiated successfully).

position Tape command executed properly (tape
motion routine initiated successfully and
making progress) •

Read Memory command executed properly.

Set Byt.e Count command executed properly.

Set unit Characteristics command executed
properly.

Topology mode entered successfully.

Successful exit of topology mode.

write Tape Mark command executed properly.

write Memory command executed properly.

On-line state entered successfully.

B-46

Table B-2

LASSTA Codes (Cont)

Opcode

Description

Suspected level 1 frame received and
validation starting.

Suspected level 1 frame failed validation (bad
hamming code or wrong connection state).

Erase Gap subroutine (ERAMOT) entered, and
turn-around delay completed if last operation
was in reverse direction.

TU CMD loaded correctly to start tape motion
in Erase Gap subroutine (ERAMOT).

Tape erasing completed and verification of gap
starting in Erase Gap subroutine (ERAMOT).

Gap verified and TU CMD loaded to stop tape
motion in Erase Gap subroutine (ERAMOT).

TU CMD loaded (but not verified)
motion to write 10 burst.

10 burst written correctly and starting to
verify IBG while writing in BOT area.

TU CMO loaded (but not verified) to start
backup tape motion for retry of 10 burst
write.

TU CMD loaded (but not verified)
motion to write tape mark.

Tape mark written and verified in write Tape
Mark subroutine (WTMMOT).

Successfully moved a record while positioning
tape.

TU CMD loaded (but not verified) to start tape
motion to move forward 1 record.

TU CMD loaded (but not verified) to start tape
motion to move reverse 1 record.

TU CMD loaded (but not verified)
motion during read of BOT area.

Sampled ID burst 255 times and starting valid
determination of density during read of BOT
area.
B-47

to start tape

Table B-2

LASSTA Codes (Cant)

Opcode

Description

10 burst correctly determined and verification
of gap starting during read of BOT area.

TU CMOs loaded (but not verified) to start
tape motion and start erasing before EOT
during OSE operation.

At EOT and starting erase of additional 10 ft
during DSE operation.

Erasure of 5 or 10 ft segment after EOT
completed during OSE operation. (If only 5 ft.
done, erasing of second 5 ft. segment
starting. If 10 ft. done, rewind starting.)

Rewind/Unload motion routine entered
successfully.

Not used.

Read reverse subroutine (DOROR) entered
successfully.

Read or read reverse command recognized
(received, validated and starting execution).

Read subroutine (DOROF) entered successfully.

TU CMD loaded (but not verified) to stop tape
motion during read or read reverse operation.

write command recognized (received, validated
and starting execution).

write command subroutine (OOWRT) entered
successfully.

TU CMD loaded (but not verified) to stop tape
motion during write operation.

Data Error Recovery command executed properly
(does not include error termination).

Set Unit Execution Mode command executed
properly.

B-48