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Document:	TU10 DECmagtape Maintenance Manual
Order Number:	EK-TU10-MM
Revision:	007
Pages:	136
Original Filename:

OCR Text

{

TU10 DECmagtape
main tenance

manual

Ab S T

(

d IgI tal equipment corporatiiIon - maynard, massachusetts

TU10 DECmagtape

maintenance manual

EK-TU10-MM-007

digital equipment corporation - maynard, massachusetts

Preliminary Printing May 1971

st Edition September 1971
2nd Printing January 1972

3rd Printing (Rev) July 1972
4th Printing December 1972
5th Printing April 1973
6th Printing (Rev) October 1973
7th Printing (Rev) December 1974

8th Printing March 1975

9th Printing (Rev) J ahuary 1976
10th Printing (Rev) August 1977

The material in this manual is for informational purposes and is subject to change without

notice.

Printed in U.S.A.

The following are trademarks of Digital Equipment

Corporation, Maynard, Massachusetts:
FLIP CHIP

DECtape

UNIBUS

DECsystem-10

PDP

DECmagtape

CONTENTS
Page

CHAPTER 1

INTRODUCTION

1.1

General Description

1-1

1.2

Magnetic Tape Fundamentals

1-2

1.2.1

Definitions

1.2.2

NRZI (Non-return to Zero — Change on a 1) Recording Technique

1.2.2.1

Definition

1-3

1.2.2.2

Format

1-3

1.3

Technical Characteristics

1.4

Reference Documents

CHAPTER 2

INSTALLATION

1-5

2.1

Site Considerations

2-1

2.2

Unpacking and Inspection

2-2

2.3

Cabinet Installation

2.4

Cable Connections

2-4

2.4.1

Power Cable

2-4

2.4.2

Input/Output Cables

2.4.3

Bus Terminators

2-5

CHAPTER 3 OPERATION
3.1

Controls and Indicators

3-1

3.2

Operating Procedures

3-3

3.2.1

Loading and Threading Tape

3-3

3.2.2

Unloading Tape

3-4

3.2.3

Restart After Power Failure

3-5

3.2.4

Restart After Fail-Safe

3-5

3.2.5

Tape Handling

3-5

CHAPTER 4

THEORY OF OPERATION

4.1

Transport Control

4-1

4.1.1

Capstan Control

4.1.2

Reel and Buffer Controls

4-2

4.1.3

Motion Control Logic

4-6

4.1.3.1

Power Clear

4.1.3.2

Failure Detection

4-6

4.1.3.3

Loading Sequence Logic

4-7

4134

Brake Release

4.1.3.5

Rewind Control

4-7

4.1.3.6

Forward BOT Delay

4-9

4.1.3.7

Ready and Transport Settling Down

4.2

4.2.1

4-10

Tape Unit Status Sensors

4-10

Write Lock

1ii

CONTENTS (Cont)
Page

4.2.2

EOT/BOT Sensor

4-10

4.3

Manual Operation

4-11

4.4

On-Line Operation

4-12

4.4.1

Transport Selection and Status Reporting

4-13

4.4.2

Initiating Operations

4-13

4.4.3

Terminating Operations

4-15

4.4.4

Motion Delay

4-15

Read and Space Operations

4-16

4.4.5
4.4.5.1

TU10 DECmagtape Transports up to No. 10320

4-16

4.4.5.2

TU10 DECmagtape Transports Above No. 10320

4-19

4.4.6

4-21

Write Operation

CHAPTER 5

MAINTENANCE

5.1

Introduction

5-1

5.2

Daily (8-Hour) Preventive Maintenance Procedures

5-4

5.2.1
5.3

General Cleaning and Equipment Care

Monthly (160-Hour) Preventive Maintenance Procedures

5-5

5.3.1

Outer Door and Cabinet Interior

5-5

5.3.2

Cabinet Filter

5-6

5.3.3

Reel Motor Brakes

5-6

5-8

5.3.4

Control Box

5.3.5

Tape Path

5-8

5.3.6

Reel Hubs

5-9

5.4

Quarterly (500-Hour) Preventive Maintenance Procedures

5-11

5.4.1

Vacuum Motor Brushes

5-11

5.4.2

Diagnostic Checks

5-12

5.5

Semiannual (1000-Hour) Preventive Maintenance Procedures

5-13

5.5.1

Capstan Speed and DC Balance

5-13

5.5.2

Capstan Acceleration and Deceleration Times

5-14

5.5.3

Capstan Jitter

5-16

5.5.4

Static and Dynamic Skew

5-17

5.5.4.1

Mechanical Skew Measurement

5.5.4.2

Mechanical Skew Adjustment

5-17

5-20

5.5.5

Electrical Read Skew

5-26

5.5.6

Electrical Write Skew

5-28

5.5.7

Read and Write Slice Levels

5-29

5.5.7.1

Units Up to No. 10320

5-29

5.5.7.2

Units Above No. 10320

5-29

5.5.8

Industry-Compatible Tape Tracking

5-30

5.5.9

Power Supply Voltages

5-32

5.5.10

Read/Write Interlock Assembly

5-33

5.5.11

Tape Guide Rollers

5-33

5.5.12

Delay Diode Check

5-35

CONTENTS (Cont)
Page

Tape Path Alignment

5-36

5.5.13.1

Tools Required

5-36

5.5.13.2

When to Perform

5-36

5.5.13.3

Objectives

5-36

5.5.13.4

Tape Path Alignment Procedure

5.5.13

5.5.14

Vacuum System Adjustments
Changing Operating Frequency

5.5.14.1
5.6

Replacement Procedures

5-37
5-56

5-57

5-58

5.6.1

Reel Motor Filter Elements

5-58

5.6.2

Foam Stripping (Casting Perimeter)

5-59

5.6.3

Vacuum Motor or Vacuum Motor Brushes

5-59

5.6.4

Reel Hubs

5-60

5.6.5

Vacuum Switches and Rubber Sleeves

5-61

5.6.6

Reel Motors and Brushes

5-62

5.6.7

Reel Motor Brakes

5-63

5.6.8

Capstan

5-63

5.6.9

Control Box

5-64

5.6.10

EOT/BOT Assembly

5-65

5.6.11

Head Plate

5-66

5.6.12

Power Supply

5-67

5.6.13

Capstan Motor

5-67

5.6.14

Vacuum System Belt Replacement

5-67

5.7

Brake Adjustment Procedure

5-68

5.8

Capstan Motor Tachometer Checking Procedures

5-69

5.8.1
5.8.2

5.9

Equipment Required

5-69

Checking Tachometer Voltage

5-71

Recommended Test Equipment and Spare Parts

5-71

APPENDIX A VOLTAGE, FREQUENCY, AND 7 TO 9 CHANNEL CONVERSIONS
Al

General

A-1

Applicable Documents

A-1

Voltage Conversion

A3.1
A3.2

A4
A4l
A4.2
A.S

A-2

230 VAC-to-115 VAC Conversion

A-2

Frequence Conversion

60 Hz-to-50 Hz Conversion

A-3

50 Hz-to-60 Hz Conversion

Seven/Nine Channel Conversion

7-Channel-to-9-Channel Conversion

AS5.2

9-Channel-to-7-Channel Conversion

A.6

A-1

115 VAC-t0-230 VAC Conversion

Master/Slave Conversion

A-3

A-4

A-4
A-4

A.6.1

Master-to-Slave Conversion

A.6.2

Slave-to-Master Conversion

A-4

Over/Under-Voltage Range Conversion

A-4

ILLUSTRATIONS
Page

Title

Figure No.

Typical System Using TU10 DECmagtapes

1-1

1-2

Reference Edge of Tape

1-2

1-3

Track-Bit Weight Relationship for Nine-Channel Transport

1-2

1-4

NRZ Format (Nine-Channel)

1-3

2-1

Cabinet Installation Diagram

2-1

2-2

Installation of Filler Strips

2-3

Transport Hold-Down Shipping Bracket

2-3

3-1

Operator Control Box

3-1

3-2

Tape Transport Mechanism

3-4

3-3

Tape Loop Operating Limits

3-6

1-1

4-1

Capstan Servo

4-2

Buffer Column and Vacuum Switches

4-3

Reel Motor Amplifier Equivalent Circuit

4-4

Brake Control

4-5

Brake Current Waveforms

4-6

Rewind Sequence Timing

4-8

4-7

Head and EOT/BOT Sensor Positions

4-9

4-8

Timing of DLY FOR Signal

4.9

4-9

Tape Markers, Recording Area, and Tape Wind

4-11

4-10

Write Operation Timing

4-14

4-11

Equivalent Circuit of Read Timing and Read Circuitry for One Track

4-16

4-12

Read Circuit Waveforms (Units Up to No. 10320)

4-17

4-13

Equivalent Circuit of Read Timing and Read Circuitry for One Track

4-19

4-14

Read Circuit Waveforms (Units Above No. 10320)

4-20

5-1

TU10 Tape Transport Assemblies

5-2

Daily Equipment Care Areas

5-3

Reel Motor Brake Assembly

(Units Up to No. 10320)

(Units Above No. 10320)

5-4

Stator Mounting

5-7

5-5

Examples of Head Assembly Wear Characteristics

5-9

5-6

Hub Composition

5-10

5-7

Compressor Waveform for FWD and REV

5-14

5-8

Compressor Waveform for REW

5-14

5-9

Deleted

5-10

Acceleration and Deceleration Waveforms

5-15

5-11

Deleted

5-12

Deleted

5-13

Capstan Waveform Showing 6-1/2 Pulses

5-18

5-14

Capstan Jitter Waveform Magnified

5-18

5-15

Sync Pattern for Reference Track

5-19

Lead/Lag Patterns

5-19

5-16

ILLUSTRATIONS (Cont)
Figure No.

Title

Page

5-17

9-Channel Skew Plot

5-20

5-18

Head Plate Assembly (Right View)

5-21

5-19

Azimuth Error (0) Static View (Head Assembly, Left View)

5-21

5-20

Mechanical Skew Waveforms

5-21

Mechanical Skew Waveforms

5-21

5-22

Head Plate Assembly Mechanical Alignment

5-24

5-23

Head Plate Assembly (Front View)

5-25

5-24

Example of Peak Deflection

5-26
5-27

5-25

Switch Location Guide

5-26

Examples of Electrical Skew, Read and Write

5-28

5-27

Write Slice Level Measurement

5-29

5-28

Read Slice Level Measurement

5-29

1529

Dipping Tape Section in Magna-see

5-31

5-30

Developed Tape Segment

5-31

Track No. 1 to Reference Edge Measurement

5-32

Read/Write Interlock Assembly

5-34

5-33

Tape Guide Roller Adjustment

5-34

M768 Diode Locations

5-35

Reel Hub Adjustment

5-38

5-36

Location of Upper and Lower Roller Guides

5-39

5-37

Roller Guide Adjustment

5-40

5-38

Machined Reference Surfaces Used to Establish Tape Path Plane

5-41

5-39

Measurement of Head Plate Mounting Surface (HMS)

5-43

5-40

Location of Shims Under Head Plate Assembly

5-44

5-41

Examples of Capstan Non-Perpendicularity

5-44

5-42

Location of Possible Capstan Burrs

5-45

5-43

Measuring Depth of Left Vacuum Column (LVC)

5-46

5-44

Head Plate Assembly Mounted in the Plane of the Tape Path

5-47

5-45

Alignment Glass

5-48

5-46

Using Alignment Glass to Load Tape

5-49

5-47

Capstan Motor Shim Placement

5-50

5-48

Capstan Motor Shim

5-51

5-49

Gap (Y) from Tape to Floor of Left Column

5-51

5-50

Measurement of Tape Gap (Y) with Penlight and Shim

5-52

5-51

Location of Upper Spring-Loaded Guide on Capstan

5-54

5-52

Capstan Wobble Check

5-55

5-53

TUI10 Cover Assembly

5-56

5-54

Motor-Mounting Holes for 50/60 Hz Operation

5-57

5-55

Reel and Motors, Rear View

5-58

5-56

Vacuum Motor, Rear View

5-60

5-57

Reel Hub

5-61

5-58

Vacuum Switches

5-62

5-59

Capstan Adjustment

5-64

vii

ILLUSTRATIONS (Cont)
Title

Figure No.

Page

5-60

EOT/BOT Assembly

5-65

5-61

Belt Tension Gauge

5-68

5-62

Jumper Wires — 2 Required

5-70

5-63

Tachometer Filter Circuit

5-70

TABLES
Title

Table No.
1-1

TU10 DECmagtape Models

Page
1-1

1-2

TU10 DECmagtape Specifications

1-4

2-1

TU10 Input/Output Cable Connections

2-4

TU10 I/O Cable Requirements

2-5

3-1

Control Box Switches

3-2

Status Indicators

5-1

Preventive Maintenance Schedule

5-4

Read Amplifier Pin Numbers

5-20

5.3

Read Buffer Pin Numbers

5-27

5-4

Magtape Tester Connections

5-29

5.5

Recommended Test Equipment and Alignment Tools

5-72

5-6

Control Box Spare Parts

5-72

5.7

Module Spare Parts

5-73

5.8

Power Supply Spare Parts

5-73

A-1

Miscellaneous Spare Parts

5-74

TU10 Configuration Designations

A-1

viii

TU10 DECmagtape Maintenance Vanual

5600-38

TU10 DECmagtape Transport

1.1

GENERAL DESCRIPTION

The TU10 DECmagtape reads and records digital data on magnetic tape in either 7- or 9-track format. Bit packing densities of 200, 556, and 800 bits per inch (bpi) are program selectable. A single capstan drives the tape in
the forward or reverse direction at a speed of 45 inches per second (ips). Tape rewind speed is 150 ips.
The TU10 DECmagtape is available in eight different models (refer to Table 1-1). Each model incorporates a

transport mechanism, head assembly, read/write electronics, motor control circuits, power supply, and cabinet.

Newer TU10 DECmagtapes contain an induction motor vacuum system as well as other modifications. Those
modified models (which bear serial numbers above approximately 10320) are discussed separately wherever
maintenance differs from other TU10 DECmagtapes.

Table 1-1

TU10 DECmagtape Models

Number of

115 Volts

230 Volts

Channels

60 Hz

50 Hz

60 Hz

50 Hz

9-Channel Slave
7-Channel Slave

TUIO-EE
TU10-FE

TU10-EH
TU10-FH

TU10-EF
TU10-FF

TU10-EJ
TU10-FJ

The TU10 is fully compatible with the TC58, TC59, and TM10 controllers manufactured by DEC. Each controller accommodates up to eight TU10 DECmagtapes in any combination of 7- or 9-channel models. The TU10 is
plug-compatible with the TU20 and TU30 transports, thus allowing the TU10 to be added to existing TU20 or
TU30 magnetic tape systems. Figure 1-1 illustrates a typical system employing TU10 DECmagtapes.

L____h\

1/0 BUS

\J—_—L/

TMIO

TU{O

CONTROLLER =" TRANSPORT

(SLAVE)

TU1O

UP TO SIX

ADDITIONAL

» TRANSPORT ke—& TRANSPORTS

(SLAVE)
'

(TU10,TU20,
OR TU30)

CP-0227

Figure 1-1

Typical System Using TU10 DECmagtapes

1-1

1.2
1.2.1

MAGNETIC TAPE FUNDAMENTALS
Definitions

Reference Edge —The edge of the tape as defined by Figure 1-2. For tape loaded on a TU10, the reference edge
is toward the observer.

BOT (Beginning Of Tape) Marker — A reflective strip placed on the nonoxide side of the tape, against the reference edge, 15 feet (£1 ft) from the beginning of the tape.

EOT (End of Tape) Marker — A reflective strip placed on the nonoxide side of the tape, against the nonreference
edge, 25 to 30 feet from the trailing edge of the tape.

Nine-Channel Recording — Eight tracks of data plus one track of vertical parity. Figure 1-3 shows the relationship between track and bit weight for a nine-channel transport.

Tape Character — A bit recorded in each of the nine channels.
Record — A series of consecutive tape characters.

File — An undefined number of records (minimum = zero, no maximum).

Interrecord Gap (IRG) — A length of erased tape used to separate records (0.5 in. minimum for nine-track;
maximum IRG is 25 ft).

Extended IRG — A length of erased tape
(3 in. minimum) optionally used to separate records. It must be used
between BOT and the first record.

Tape Speed — The speed at which tape moves past the read/write heads; normally stated in inches per second.
Tape Density — The density of sequential characters on the tape. It is normally specified in bytes per inch (bpi).
This is equivalent to characters per inch (cpi), since 800 bpi means that there are 800 tape characters per inch
oftape.

REFERENCE

EDGE

TAPE

LEADER

BIT

WT TRACK

—

20 —2

OXIDE
]

SURFACE

‘

REEL

— Db — —
—

,~ EDGE

— — -

— ———

RD
O

RD
1

RD 2

e ]

— 4 —pD—
— — — 4

RD
3

5§ —PD— — —
— 1

RD 4

268

6 —PD— — —
— 1

RD 5

T —7—pDp— — —— -

RD
6

2!l — 8

RD
7

2
SUPPLY

REFERENCE

1 —pD——
—— -

—p— — — —
—

— e

TM~ READ H

e
e

EAD

HEAD

CABLE

RD P

READ AMPS
10-1264

10—~1265

Figure 1-2

Figure 1-3 Track-Bit Weight Relationship
for Nine-Channel Transport

Reference Edge of Tape

1-2

Write Enable Ring — A rubber ring which must be inserted on the supply reel to allow the transport to write on

the particular tape. This safety feature helps prevent accidental destruction of previously recorded data.

Tape Mark (TM) — A record written on the tape to designate the end of a file; sometimes referred to as a file
mark (FMK). In the TU10 , the tape mark is always preceded by an extended IRG.

1.2.2

NRZI (Non-return to Zero — Change on a 1) Recording Technique

1.2.2.1 Definition — NRZI is a recording technique which requires a change of state (flux change) to write a 1,
and no change of state (no flux change) to write a 0.

1.2.2.2

Format

Cyclic Redundancy Check Character (CRCC) — A check character that is written four character spaces after the
last character of a NRZ record (nine-channel only). CRCC is derived by a complex mathematical formula applied
to the characters written in the record. The result of this manipulation (CRCC) can be used to recover a lost bit
in a record read from tape.

Longitudinal Redundancy Check Character (LRCC) — A check character written four character spaces after
CRCC (nine-channel). LRCC consists of one bit of even parity for each track of data. For example, if track 1
had an odd number of 1s written in a record, then a 1 must be written in the LRCC bit associated with track 1.
Tape Mark — A nine-channel NRZ tape mark consists of one tape character (234), followed by seven blank
spaces, and then LRCC (235). (CRCC is not written.) Figure 1-4 illustrates nine-channel NRZ tape format.

OXIDE SURFACE

e I5FT.

RECORD

—_—

)

RECORD

——
4

TAPE MARK
-

REFERENCE
EDGE

BOT MARKER
0N OTHER

SIDE OF >

EXTENDED

~ 25 FT.

l__4__ |

]

////

)

DATA

IRG

EXTENDED

LRCC

IRG

LRCC

TAPE MARK

CRCC

CHARACTER

TAPE

EOT MARKER

ON
OTHER
SIDE OF

TAPE

10-1263

Figure 1-4

NRZ Format (Nine-Channel)

1-3

1.3 TECHNICAL CHARACTERISTICS

Table 1-2 contains operational, environmental, mechanical, and electrical specifications for the TU10
DECmagtape.

Table 1-2

TU10 DECmagtape Specifications

Specification

Characteristic
Packing Density

7-Channel:

200, 556 and 800 bpi; program selectable

9-Channel:

800 bpi

Tape Speed

Forward/Reverse:

45 ips (1.14 m/s)

Rewind:

150 ips (3.8 m/s)

Maximum Transfer Rate

36,000 characters per second

Tape Motion Times

Start:

Normal operating speed is reached within 9 ms after
initiation of forward or reverse command.

Stop:

Motion stops in less than 8 ms after removal of forward
or reverse command.

Electrical Skew

Deskewing effectively eliminates static skew.

Recording Method

NRZI recording; industry-compatible

Transport Mechanism

Single capstan; vacuum columns

R/W Heads

Dual gap, read-after-write

BOT, EOT Detection

Photoelectric sensing of reflective strip

Interrecord Gap

7-Channel:

=0.75 in.

9-Channel:

=0.5 in.

Tape

Width:

0.5 in.

Thickness:

1.5 mil

Tape Reel

Diameter:

10-1/2 in. (0.27m)

Capacity:

2400 ft.

Dimensions

Transport Less Cabinet

With H950 Cabinet

Depth:

25 in. (0.64m)

30 in. (0.76m)

Width:

19 in. (0.48m)

21 in. (0.53m)

Height:

26 in. (0.66m)

72 in. (1.83m)

1-4

Table 1-2 (Cont)

TU10 DECmagtape Specifications

Characteristic

Specification

Weight

Transport Less Cabinet

With H950 Cabinet

150 1b (70 kg)

450 1b (200 kg)

Temperature Limits

45°F (7°C) to 95°F (35°C)*

Relative Humidity

20 to 95%, noncondensing*

Air Volume (Inlet)

400 ft> /min., 190 1/s (top)

Voltage

115 Vac + 10%, 230 Vac = 10%

Frequency

50+ 2 Hz, 60+ 2 Hz

Current @ 115V

6A, Surge 8A

Current @ 230V

3A, Surge 5A

Power/Heat Dissipation

1000W, 3400 Btu/hr

* Magnetic tape operation is more reliable if the temperature is limited to 65 to 75 F (1 8° to 24° C) and the relative humidity to 40 to 60%.

1.4

REFERENCE DOCUMENTS

Refer to the following maintenance manuals for information on the associated magnetic tape controller:
TC58 Tape Controller, DEC-08-14AB-D

TC59 Tape Controller, DEC-9A-I3BB-D
IM10 Tape Controller, A-MN-TM10-0-MAN1

TM11 Controller, EK-TM11-TM-004

TMS8E Controller, DEC-8E-HMM3A-C-D

TMAI11 Controller, DEC-11-HATMA-A-D

This material is available from the nearest DEC Field Office or from:
Digital Equipment Corporation

Communications Services (Direct Mail)
146 Main Street

Maynard, Massachusetts 01754

1-5

CHAPTER 2
INSTALLATION

This chapter outlines TU10 unpacking and inspection procedures, cabinet installation, cable connections, and unit
checkout. A brief discussion of TU10 site considerations is also provided. The DECmagtape is installed at the
customer’s site by DEC Field Service personnel. Customer personnel should not attempt to install the equipment.

2.1 SITE CONSIDERATIONS

The TU10 DECmagtape should be located in an area free of excessive dust and dirt or corrosive fumes and vapors.
To ensure proper cooling, the bottom of the cabinet and the fan inlet at the top of the cabinet must not be ob-

structed. Adequate clearance must be provided for servicing the transport. Refer to Figure 2-1 for applicable
cabinet dimensions. Temperature and humidity specifications are included in Table 1-2.

SWINGING

DOORS
-

MODEL TU-10

TAPE TRANSPORT

>
\

TRANSPORT
EXTENDED

FROM

CABINET

CP-0090

Figure 2-1

Cabinet Installation Diagram

2.2 UNPACKING AND INSPECTION

To unpack and inspect the TU10, proceed as follows:
Procedure

Step
1

Remove the outer shipping container by first removing all metal straps,
fasteners, and cleats securing the transport to the skid.

After removing the outer container, remove the polyethylene cover from the
cabinet.

Inspect external surfaces of the cabinet and related assemblies for possible

shipping damage and report any damage to the local DEC Sales Office.
Remove the tape or plastic shipping pins from the cabinet rear access door.
Inspect the interior of the cabinet for possible damage to cables, loose or
broken modules, or loose mounting rails.

Inspect the wiring side of the logic module mounting panel for bent pins,
cut wires, loose external components, and foreign material. Any defects
found should be corrected by DEC Field Service personnel.

Inspect the power supply for proper seating of fuses and power connecting
plugs.

Remove the bolts securing the cabinet to the shipping skid.
Raise the adjustable leveling feet above the level of the casters. The cabinet
should now be resting on the casters.
10

Use wood blocks and planks to form a ramp from the skid to the floor and
carefully roll the cabinet off the skid.

After the cabinet is moved to the desired location, perform the Cabinet
Installation procedure described in Paragraph 2.3.

2.3 CABINET INSTALLATION

The DECmagtape cabinet is provided with casters and adjustable feet. It is not necessary to bolt the cabinet to

the floor unless conditions dictate otherwise. To install the TU10 cabinet, proceed as follows:
Procedure

Step
1

Lower the adjustable feet so that the cabinet is not resting on the casters.

Ensure that the cabinet is level.

If two or more cabinets are to be bolted together, install filler strips (P/N H952-G)
between the cabinets as shown in Figure 2-2. Tighten the bolts that secure the
cabinet groups together and then recheck that the cabinets are level.
After the TU10 DECmagtape has been positioned per the site plan, loosen

the two shipping brackets that secure the transport to the rear of the cabinet
frame (see Figure 2-3).
NOTE

If the DECmagtape is to be reshipped or installed
in a new location, the shipping brackets should be
repositioned and tightened.
If necessary, clean all outer surfaces.

KX X/ a

71 7/16

NOTE:

ALL DIMENSIONS

FILLER STRIPS

INCHES

I6-00898

Figure 2-2 Installation of Filler Strips

H950 CABINET
<— VERTICAL MOUNTING

MEMBERS

H950 CABINET
VERTICAL MOUNTING —#
MEMBERS

TRANSPORT
CRUCIFORM

SHIPPING BRACKET l

Z-SHIF’PING BRACKET

/\/M

REAR

VIEW
CP-009%

Figure 2-3 Transport Hold-Down Shipping Bracket

2-3

2.4 CABLE CONNECTIONS
2.4.1 Power Cable

The power cable supplied with the TU10 must be plugged into the socket at the rear of the power supply and the
other end in the local power outlet.
CAUTION

Before connecting the TU10 to the local power source, ensure
that the line voltage and frequency are compatible with the
power requirements of the

TU10.

2.4.2 Input/Output Cables
Table 2-1 lists the I/O cable connections for the TU10 DECmagtape.

Fach TU10 is supplied with 15-ft I/O cables. The total cable length between the tape controller and the last
transport on the bus is limited to 80 ft; therefore, 10-ft cables are available for systems employing more than 5
DECmagtape units. Cable part numbers are listed in Table 2-2.
NOTE

The TU10, slave or master, on the end of the bus will have a G741YA
in slot B17 and a G741 in slot B18 and B19.

Table 2-1

TU10 Input/Output Cable Connections

TU10

TCS8

TC59

13?8

TTMTM10

Al17/B17

BO1

C01/D01

Side 1

Al17/B17

B02

C03/DO03

Side 2

A18/B18

AO1

A18/B18

C04/D04
‘

Side 1

AQ02

C02/D02

(not used)

A03

C05/D05

Side 2

- A19/B19
Side 1
(not used)

A19/B19
Side 2

Table 2-2

TU10 I/O Cable Requirements
From

TUI0

Part Number

Qty

TC58/59

BCO08-P-xx

TTM10

BCO08-N-xx

TUI0

TUIO0

BCO08-N-xx

TUIO

TU20

BCO08-P-xx

BCO08-N-xx

BCO8-P-xx

BCO08-N-xx

TU10

TU30

[ 10 (10-ft cable)
xx =

15 (15-ft cable)
25 (25-ft cable)

2.4.3 Bus Terminators
The last (most remote) tape transport on the bus supplies power to the bus terminators. Therefore, ensure that

the PWR ON/PWR OFF switch on the most remote transport is always in the ON position. Terminators are
located in slots 17, 18, and 19 of the last unit. Type G741 modules are used in slots 18 and 19. A type G741YA
module is used in slot 17.
NOTE

If drives are mixed, a TU10 must be the last transport on

the bus.

2-5

CHAPTER 3

OPERATION

This chapter is divided into two major paragraphs. Paragraph 3.1 describes the DECmagtape controls and indicators. Paragraph 3.2 contains operating procedures for loading and threading tape, unloading tape, and restarting

the transport following a power failure or fail-safe condition. Tape handling precautions are also listed in
Paragraph 3.2.

3.1 CONTROLS AND INDICATORS

The operator control box (see Figure 3-1) is mounted to the left of the file reel. The functions of the control box
switches and indicators are listed in Tables 3-1 and 3-2, respectively.

PWR_ON

[ [ewo v | e

PWR OFF

ON-LINE

START

OFF-LINE

STOP

LOAD

FWD

Ii'

BR REL

UNIT
SELECT

REW

REV

CP-0093

Figure 3-1

Operator Control Box

3-1

Table 3-1

Control Box Switches

Function

Switch

PWR ON/PWR OFF

Applies power to entire TU10. Also, supplies power to the

bus terminators if the tape transport is the most remote unit
on the bus.

LOAD/BR REL

LOAD Position

Enables vacuum motor, which draws tape into the buffer
columns.

Center Position

Disables vacuum motor; brakes are full-on.

BR/REL

Releases brakes.

ON-LINE/OFF-LINE

ON-LINE Position

Selects remote operation.

OFF-LINE Position

Selects local operation.

FWD/REW/REV

FWD Position

Selects, but does not initiate, forward tape motion when
transport is off-line.

REW Position

Selects, but does not initiate, tape rewind when transport is
off-line.

REYV Position

Selects, but does not initiate, reverse tape motion when
transport is off-line.

START/STOP

START Position

Initiates tape motion selected by

FWD/REW/REV switch

when transport is off-line.

STOP Position
UNIT SELECT

Clears any motion commands when transport is off-line.
Selects the tape transport unit by number (0—7). This number is used in the program to address the tape transport.

Table 3-2
Status Indicators

Function

Indicator
PWR

Indicates power has been applied to the transport.

LOAD

Indicates that vacuum is on and the tape is loaded into the buffer
columns.

RDY

Indicates that the tape transport is ready (vacuum on and settledown
delay complete); there is no tape motion.

LD PT

Indicates that the tape is at load point (Beginning of Tape)

END PT

Indicates that the tape is at end point (End of Tape).

FILE PROT

Indicates that write operations are inhibited because the write
enable ring is not mounted on the file reel.

3-2

Table 3-2 (Cont)

Status Indicators

Indicator

Function

OFF-LINE

Indicates local operation by the control box.

SEL

Indicates the tape transport is selected by the controller (program).

WRT

Indicates that the program has initiated a write operation in the tape
transport.

FWD

Indicates that a forward command has been issued.

REV

Indicates that a reverse command has been issued.

REW

Indicates that a rewind command has been issued.

3.2 OPERATING PROCEDURES
3.2.1 Loading and Threading Tape

Use the following procedure to mount and thread the tape:
Procedure

Step
1
2

Apply power to the transport by depressing the PWR ON switch.

Ensure the LOAD/BR REL switch is in the center position (this applies the
brakes).
Place a write enable ring in the groove on the file reel if data is to be written
on the tape.

Ensure there is no ring in the groove if data on the tape is not to be erased
or written over.

Mount the file reel onto the lower hub with the groove facing towards the
back. Ensure that the reel is firmly seated against the flange of the hub.
Ensure that the reel hub is securely tightened. Turn it clockwise.
Install the take-up reel (top) as described in Step 4.
Place LOAD/BR REL switch to the BR REL position.

Unwind tape from the file reel and thread the tape over the tape guides and
head assembly as shown in Figure 3-2.

Wind about five turns of tape onto the take-up reel.

Set the LOAD/BR REL switch to the LOAD position to draw tape into the
vacuum columns.
10

Select FWD and press START to advance the tape to Load Point. When the
BOT marker is sensed, tape motion stops, the FWD indicator goes out, and
the LOAD PT indicator comes on.
NOTE

If tape motion continues for more than 10 seconds,
press STOP, select REV (reverse) and press START.
The tape should move to the BOT marker (Load
Point) before stopping.

3-3

GUIDE\

POSITIVE

TAPE

TAPE TENSION
HOLDS TAPE AGAINST

.~ CAPSTAN

TRANSPORT

WILL

HEAD TAPE GUIDES (2)

" SHUT -DowN

COLUMN (TAKE-UP
REEL TURNED OFF)

R/W ERASE HEAD ASSEMBLY

NOTE: TAPE IS AUTOMATICALLY

WILL BE SUPPLIED

TAPE

(FAIL- SAFE CONDITION)

IS SET TO LOAD POSITION
TAPE GUIDE

LEFT VACUUM

COLUMN —_

TAPE WILL BE EXTRACTED

TURNED ON

{\/}

FROM_COLUMN ————

(TAKE-UP REEL TURNED ON)

(FAIL-SAFE CONDITION)

FILE REEL

RIGHT VACUUM

/_ COLUMN
/

}

N @/ /!
|

—\

\\\@///

FILE REEL

TURNED OFF

CP-0107

Figure 3-2 Tape Transport Mechanism

3.2.2 Unloading Tape

To unload the tape proceed as follows:

Step

Procedure

Press OFF-LINE switch if the transport has been operating in the on-line

mode.
2

Press STOP switch and select REW.

Press START switch. The tape should rewind until the BOT marker is reached.

Press the LOAD/BR REL switch to release the brakes.

3-4

Step

Procedure

Gently hand wind the file reel in a counterclockwise direction until all of
the tape is wound onto the reel.

CAUTION

When handwinding the tape, do not jerk the reel.

This can stretch or buckle the tape which could
cause irreparable damage.

Remove the file reel from the hub assembly.

3.2.3 Restart After Power Failure

In the event of a power failure, the DECmagtape automatically shuts down and tape motion stops without damage
to the tape. Return of power is indicated when the PWR indicator lights. To restart the transport proceed as
follows:

Step

Procedure

Press the LOAD/BR REL switch to release the brakes.

Manually wind the reels to take up any slack in the tape.

Set the LOAD/BR REL switch to the LOAD position to draw tape into the
vacuum columns.

Set ON-LINE/OFF-LINE switch to the desired position and continue
operation.

3.2.4 Restart After Fail-Safe

If the tape loop in either buffer column exceeds the limits shown in Figure 3-3, the vacuum system automatically
shuts down and tape motion stops without damage to the tape. When this fail-safe condition occurs, the

DECmagtape does not respond to on-line or off-line commands. To restart the transport, perform Steps 1 through
4 in Paragraph 3.2.3.

3.2.5 Tape Handling
Observe the following precautions when handling magnetic tape:
a.

Always handle a tape reel by the hub hole; squeezing the reel flanges can cause damage to the
tape edges when winding or unwinding tape.

Never touch the portion of tape between the BOT and EOT markers. Oils from fingers attract
dust and dirt. Do not allow the end of the tape to drag on the floor.

c¢.

Never use a contaminated reel of tape. This spreads dirt to clean tape reels and can affect tape
transport operation.

Always store tape reels inside their containers. Keep empty containers closed so dust and dirt
cannot get inside.

Inspect tapes, reels, and containers for dust and dirt. Replace take-up reels that are old or
damaged.

Do not smoke near the transport or tape storage area. Tobacco smoke and ash are especially
damaging to tape.

Do not place the DECmagtape near a line printer or other device that produces paper dust.

Clean the tape path frequently as described in Paragraph 5.2.1.

3-5

SHORT LOOP

VACUUM

—(TRANSPORT

SWITCHES TM\

WILL

SHUTDOWN)

NORMAL
OPERATING
—
LIMITS

| BUFFER
COLUMN

NORMAL
OPERATING
—
LIMITS
LONG LOOP

—(TRANSPORT
WILL

SHUTDOWN

CP-0088

Figure 3-3 Tape Loop Operating Limits

3-6

CHAPTER 4
THEORY OF OPERATION

This chapter provides a detailed description of the TU10 control logic and read/write electronics. The DEC
engineering drawings referenced in this chapter are contained in Volume 2 of the TUI0 Maintenance Manual.

4.1 TRANSPORT CONTROL
The tape transport mechanism consists of the file reel, with its reel motor, brake, and vacuum-buffer column; the

capstan, with its capstan motor and tachometer; the take-up reel with its reel motor, brake, and vacuum-buffer
column; and the drivers and control electronics for the above.

4.1.1 Capstan Control

Figure 4-1 and drawing TU10-0-03. The tachometer produces an output voltage proportional to the velocity of
the capstan. The capstan servo preamplifier compares the tachometer output with a reference voltage that is proportional to the desired capstan velocity, and generates an appropriate error voltage. The error voltage is further
amplified by the capstan power amplifier, the output of which drives the capstan motor. Thus, if the capstan is
running slower than the desired speed, the error voltage, and, consequently, the voltage impressed on the capstan

motor will increase, speeding up the capstan. If the capstan is running too fast, the capstan velocity will similarly

be decreased. Due to the high gain of the error and power amplifiers, the capstan speed will not vary more than

1% from its desired velocity even under varying conditions of mechanical loads, power supply fluctuations, etc.
The power amplifier is designed with a ““dead band”, so that insignificantly small error voltages are ignored. This

design feature prevents capstan “‘creep’ due to slight error voltages produced by offset and drift in the preamplifier when the capstan should be stopped.

The power amplifier operates in push-pull mode from *11V power supplies. One side of the capstan motor is
connected to the amplifier output and the other side is connected (through a small current-sensing resistor) to

PWR COM INT. In normal operation, PWR COM INT is connected to PWR COM (ground) through a relay in the
power supply. However, when tape is not loaded, or the fail-safe circuitry detects a malfunction in the unit that

might cause damage to the tape, the relay opens, interrupting current to the motor and causing the capstan to
come to a stop without damaging the tape. The fail-safe circuitry is explained in Paragraph 4.1.2.

To control the acceleration and deceleration rates of the capstan, the power amplifier contains current-limiting
circuitry.

When the capstan is at rest and the servo receives a Forward command, the difference between the tachometer
output (0V) and the output of the forward reference voltage generator is quite large. This causes the error

4-1

CAPSTAN MOTOR
TACHOMETER

DLY FOR H

]

CAPSTAN

———————————————————

»| FORWARD REFERENCE

VOLTAGE GENERATOR

coms

F UV

=11V

wpoy

ores

Cmmno

GngEn

oERD

0 GENDD GROTD OEED

CAPSTAN

POWER

AMPLIFIER

__._’._

REVERS E() H

REWIND H

REWIND CAP H

VOLTAGE

I
—

REVERSE REFERENCE

GENERATOR

RAMPED REWIND

TM REFERENCE GENERATOR

ERROR
I
ampiiFier ||
VOLTAGE

AMPLIFIER

CURRENT
LIMIT

DETECTOR

LCAPSTAN SERVO PREAMPLIFIER

|
|

>
*‘\

_: :_

'
.
! |
s

PWR

) _j

Ny
cCP-021

Figure 4-1 Capstan Servo

voltage amplifier to saturate, and remain saturated until the capstan velocity closely approaches its final 45 ips
forward velocity. If the power amplifier did not contain current-limiting circuitry, it would also saturate, applying the full power-supply voltage across the capstan motor. The current through the motor, and, consequently,

its acceleration rate, would then be a function of such loosely controlled parameters as power-supply voltage,
motor armature resistance (a function of temperature), and the back-e.m.f. of the motor. By current-limiting the
output of the power amplifier, the acceleration and deceleration rates of the capstan in normal (i.e., forward and

reverse) operation become accurately controlled. This, in turn, maintains accurate control of the amount of tape
traversed while accelerating and decelerating, allowing operation with short, well controlled interrecord gaps.

Due to the danger of “spooking” (slippage between adjacent layers of tape on the reels) which can damage tape

by stretching or buckling it, the tape reels cannot be accelerated as quickly as the capstan for high-Sbeed (rewind)
operation. For normal (45 ips forward and reverse) operation, the vacuum columns buffer enough tape to allow

and from the 150 ips rewind velocity. For this reason, the rewind command logic produces two signals that con-

trol the rewind velocity of the capstan. When the rewind operation bégins, REWIND H is asserted, causing the
capstan to accelerate immediately to 45 ips. REWIND CAP H is then asserted, which causes the ramped rewind
reference voltage generator to gradually increase the rewind speed, exponentially approaching 150 ips, at a rate
at which the reels can be accelerated. When the rewind is completed, REWIND CAP H is first negated, causing

the rewind reference voltage generator to gradually decrease the rewind speed. After the speed has been reduced
to 45 ips, the REWIND. H signal is negated, causing the capstan to rapidly come to a halt.
4.1.2 Reel and Buffer Controls

As explained in Paragraph 4.1.1, it is necessary to buffer a small amount of tape in a low-inertia reservoir to rapidly accelerate and decelerate the tape past the read/write/erase head assembly without “spooking” the tape on the
file and take-up reels. For this purpose vacuum-buffer columns are used. The capstan does not directly move

CHAPTER 4
THEORY OF OPERATION

4.1 TRANSPORT CONTROL

The tape transport mechanism consists of the file reel, with its reel motor, brake, and vacuum-buffer column; the

capstan, with its capstan motor and tachometer; the take-up reel with its reel motor, brake, and vacuum-buffer
column: and the drivers and control electronics for the above.

4.1.1 Capstan Control

The heart of the transport mechanism is the capstan subsystem, which transports the tape across the read/write/
erase head assembly at the proper speed. The capstan is controlled by
a velocity-feedback servo loop, shown in
Figure 4-1 and drawing TU10-0-03. The tachometer produces an output voltage proportional to the velocity of
the capstan. The capstan servo preamplifier compares the tachometer output with a reference voltage that is proportional to the desired capstan velocity, and generates an appropriate error voltage. The error voltage is further
amplified by the capstan power amplifier, the output of which drives the capstan motor. Thus, if the capstan is

running slower than the desired speed, the error voltage, and, consequently, the voltage impressed on the capstan
motor will increase, speeding up the capstan. If the capstan is running too fast, the capstan velocity will similarly

be decreased. Due to the high gain of the error and power amplifiers, the capstan speed will not vary more than
1% from its desired velocity even under varying conditions of mechanical loads, power supply fluctuations, etc.

The power amplifier is designed with a ‘““dead bandTM, so that insignificantly small error voltages are ignored. This

design feature prevents capstan “creep” due to slight error voltages produced by offset and drift in the preamplifier when the capstan should be stopped.

The power amplifier operates in push-pull mode from =11V power supplies. One side of the capstan motor is
connected to the amplifier output and the other side is connected (through a small current-sensing resistor) to
PWR COM INT. In normal operation, PWR COM INT is connected to PWR COM (ground) through a relay in the

power supply. However, when tape is not loaded, or the fail-safe circuitry detects a malfunction in the unit that
might cause damage to the tape, the relay opens, interrupting current to the motor and causing the capstan to

come to a stop without damaging the tape. The fail-safe circuitry is explained in Paragraph 4.1.2.
To control the acceleration and deceleration rates of the capstan, the power amplifier contains current-limiting
circuitry.

When the capstan is at rest and the servo receives a Forward command, the difference between the tachometer
output (OV) and the output of the forward reference voltage generator is quite large. This causes the error

4-1

CAPSTAN MOTOR
TACHOMETER

CAPSTAN

+11V
r

oLy For H

—)

———————————————————

.| Forwaro ReFERENCE

VOLTAGE GENERATOR

=11V

———————————

CAPSTAN

POWER

AMPLIFIER

L]
—

REVERSE(1) H |
FEWIND H

REWIND CAP H

REVERSE REFERENCE
VOLTAGE

[

—

GENERATOR

ERROR

RAMPED REWIND

VOLTAGE

"|REFERENCE GENERATOR

ampLiFier ||

LCAPSTAN SERVO PREAMPLIFIER

_jl :_

>*\

AMPLIFIER

CURRENT
LIMIT

DETECTOR

It '
S

) J

PWR

Ny
CP-0211

Figure 4-1

Capstan Servo

Due to the danger of “spooking” (slippage between adjacent layers of tape on the reels) which can damage tape

by stretching or buckling it, the tape reels cannot be accelerated as quickly as the capstan for high—sbeed (rewind)
operation. For normal (45 ips forward and reverse) operation, the vacuum columns buffer enough tape to allow

time for the reels
to catch up with the rapid accelerations and decelerations of the capstan. However, the buffer
columns cannot contain enough tape to allow the capstan to accelerate and decelerate at its normal high rates to
and from the 150 ips rewind velocity. For this reason, the rewind command logic produces two signals that con-

trol the rewind velocity of the capstan. When the rewind operation begins, REWIND H is asserted, causing the
capstan to accelerate immediately to 45 ips. REWIND CAP H is then asserted, which causes the ramped rewind
reference voltage generator to gradually increase the rewind speed, exponentially approaching 150 ips, at a rate
at which the reels can be accelerated. When the rewind is completed, REWIND CAP H is first negated, causing

the rewind reference voltage generator to gradually decrease the rewind speed. After the speed has been reduced
to 45 ips, the REWIND H signal is negated, causing the capstan to rapidly come to a halt.
4.1.2 Reel and Buffer Controls

As explained in Paragraph 4.1.1, it is necessary to buffer a small amount of tape in a low-inertia reservoir to rapidly accelerate and decelerate the tape past the read/write/erase head assembly without *“‘spooking” the tape on the
file and take-up reels. For this purpose vacuum-buffer columns are used. The capstan does not directly move

4-2

tape from one reel to another; rather, it removes tape from one vacuum column and deposits it in the other.

Fach reel motion servo system endeavors to keep its vacuum-buffer column half filled with tape, ready either to

supply or to take up tape as might be required by a sudden acceleration of the capstan. Figure 4-2 shows a buffer
column and its tape-position-sensing vacuum switches. A vacuum port at the bottom of the buffer column provides vacuum, which draws the tape loop into the column with a constant tension independent of the position or
velocity of the tape loop, thus ensuring good, uniform wrap of the tape on the reel. In normal operation, the

position of the tape loop in the vacuum column is sensed by two vacuum switches, the upper motor switch and

the lower motor switch. These vacuum switches close when subject to a vacuum exceeding 10 inches of water,
and open when exposed to ambient air pressure. Thus, if the tape loop is above the vacuum switch in the buffer
column, the switch is exposed to vacuum, the switch is then closed, and its corresponding signal (UVS for the
upper Motor Switch or LVS for the lower Motor Switch) is then at ground. If, however, the tape loop is below
the vacuum switch in the column, the switch is exposed to ambient pressure, it opens, and its corresponding sig-

nal is high.

RELAY ENABLE L —O
LFS

UPPER

FAIL

ZONE

+&%

_ | __ | YPEER

LI,

F.S.SW.

UPPER

0.S.

450

}—

msec,

Torai-saFE
CIROUITRY

+5V

MOTOR

EUFFER

UPPER

MTR. SW,

UVS

BRAKE ZONE
A

LOWER

-9

MTR. SW.

LOWER MOTOR

ZONE

FS SW.

ZONE

O
O

}_‘BRAKEH
EMPTY

BUFFERH

1
LVS

_ | _ L LOWER
o
LOWER FAIL

‘

+5V

_ TO FAIL-SAFE
CIRCUITRY

VACUUM
PORT

VACUUM BUFFER
COLUMN

CP-0212

Figure 4-2 Buffer Column and Vacuum Switches

The reel servo system endeavors to keep the tape loop in the brake zone between the upper and lower motor

switches. In this position, UVS is high and LVS is low, and braking is applied to the reel. Thus, if the capstan
stops, the reel comes to rest with the tape loop in the brake zone.

If the capstan then begins to put tape into the buffer, the loop moves down until it passes the lower Motor
Switch and enters the lower Motor Zone. At that point, braking is removed and a command is sent to the reel

motor amplifier to accelerate the reel in order to empty tape from the buffer. The tape loop continues to move

down into the lower Motor Zone until the reel is emptying tape out of the buffer as fast as the capstan is putting

it in. As the motor continues to accelerate the reel, the tape loop begins to move up again until it passes the lower
Motor Switch and enters the braking zone. The motor is then turned off and braking is again applied. The tape

loop continues to move up into the braking zone until the rate at which the reel motor is removing tape from the
column is again equal to the rate at which the capstan is putting tape in, and as the reel continues to decelerate,
the cycle repeats. Thus, the tape loop oscillates about the position of the lower Motor Switch. If the capstan,

instead, removes tape from the buffer, the tape loop similarly oscillates about the upper Motor Switch as the

motor and brake aiternately accelerate and decelerate the reel while supplying tape to the buffer column at the
average rate at which the capstan is removing it.

Figure 4-2 shows two additional vacuum switches, one near each end of the buffer column. These fail-safe
switches are used to detect a failure in the tape transport mechanism that threatens to damage the tape. If the
tape loop passes below the lower fail-safe switch or above the upper fail-safe switch, in either buffer column,
power is removed from the capstan and reel motors, braking is applied to the reels, the vacuum motor is shut

down, and all operations of the tape unit are halted. The fail-safe switches are located far enough from the ends
of the buffer columns to guarantee that, in case of failure, tape motion will cease before the tape can be damaged.
Figure 4-3 shows an equivalent circuit of the reel motor driver. The reel motor is connected across a transistor

bridge, which can connect the motor between the -16V and +16V INT power supplies in either direction. Under
normal operating conditions, REEL MTR ENBL L is asserted, and the reel motor responds to control by the
vacuum-switch signals. When UVS is low (upper vacuum switch closed), the reel motor is connected across the
power supnolies in the direction that drives tape into the buffer column. When UVS is high (upper vacuum switch
open) and LVS is low, indicating that the tape is in the braking region, the reel motor is shut off. When both
UVS and LVS are high, the reel motor is connected across the power supply in the direction that removes tape
frrra the buffer.

+16V

INT

EMPTY: A AND B CLOSED
C AND D OPEN

FILL: A AND B OPEN
C AND D CLOSED

NEITHER: ALL OPEN
CP-0213

Figure 4-3 Reel Motor Amplifier Equivalent Circuit

4-4

The reel motor amplifier has an additional input, REEL MTR PULSE H, which is used during the loading
sequence to start tape into the vacuum column. REEL MTR PULSE is asserted during the tape loading sequence

to cause the reel motor to feed a few inches of slack tape into the buffer column, sealing the buffer column and
allowing vacuum to build up in the column. The loading sequence is explained in more detail later.
When tape is not loaded, or when a failure is detected by the fail-safe switches, REEL MTR ENBL L is negated,

disabling FILL BUFFER and EMPTY BUFFER signals from the vacuum switches (see Figure 4-2), and +16V INT
is interrupted, removing power from the reel motors.

Figure 4-4 shows the brake control circuitry. The brakes used on the TU10 are electromagnetically-operated
friction brakes. In normal 45 ips operation, when UVS is high and LVS is low (i.e., when the tape loop is in the
braking zone), approximately 310 mA of current is driven through the brake winding. This produces enough
torque to rapidly bring the reel to a stop. When the tape loop moves out of the braking zone, the current is shut

off. Because the braking current tends to produce a significant residual magnetism in the brakes, a short (15 ms)
pulse of about 150 mA current is applied in the reverse direction when the brakes are released to ensure complete
demagnetization and release of braking.

BRAKE

‘

UVS —

LVS —O

HI BRK H

FORCE BRK ON L

CURRENT

SWITCH

310ma

%08

6—

REWIND

CAP H

+16V

| ] 2208

|
i

]

SWITCH

BRAKE

~60ma

:3—4 LO BRK—H o CETD R CT G D J

— O

CURRENT
L

Ll{PPER(TAKE-UP)REEL ONLY
* UPPER (TAKE-UP) REEL IS

1?25

o—|

CURRENT
SwITCH |—

—
—

150ms
l

DEMAG

-18V

ADJUSTABLE : 15-40 ms.

LOWER (FILE) REEL IS 12ms.

CP-0214

Figure 4-4 Brake Control

During high-speed rewind, the operation of the braking circuitry must be modified somewhat to avoid stopping

the reel whenever the tape loop enters the braking zone. Without this modification, the reel motor could not
accelerate the reel to 150 ips rapidly enough to prevent failure. For this reason, when REWIND CAP H is

asserted and the tape loop enters the braking zone, only a short pulse of braking is applied to the reel to slow it
down, but not to bring it to a halt. In the case of the upper (take-up) reel servo, if the tape loop remains in the
braking zone longer than about 50 ms, a low current of about 60 mA is applied to the brake, further decelerating
the reel. In the case of the lower (file) reel, this is not necessary.

4-5

The difference in braking of the two reel systems occurs because the upper reel is dumping tape into the buffer
during rewind and is, therefore, accelerated by torque resulting from the tape tension produced by the vacuum

column; whereas the lower reel is removing tape from its buffer, and, therefore, the tape tension tends to decelerate the lower reel, making low drag braking unnecessary.

Figure 4-5 shows the brake current waveforms of each reel system during both 45 ips and rewind operations.

310 mA
HIGH

UPPER-REEL BRAKE

CURRENT WITH
REWIND CAP ASSERTED

BRAKE

<22 ms+

<—15-40ms —>{(See

((
ow

60mA

~{50mA
310m

HIGH

Ole

REWIND CAP ASSERTED

ol(See

12 ms

note)l

((

~150mA

3{0OmA
|

EITHER BRAKE CURRENT
WITH REWIND CAP

NEGATED

HIGH BRAKE

(See

note) l———

-150mA
1

((

BRAKE H ¢
:
NOTE

15ms DEGAUSSING
cP-0215

Figure 4-5

Brake Current Waveforms

Whenever tape is not loaded or the fail-safe switches detect a failure, and the LOAD/OFF/BRK RLS switch is not
in the brake release position,

FORCE BRK ON L is asserted. This signal causes high (310 mA) braking to be

applied to both reels, regardless of the signals from the vacuum switches.

4.1.3 Motion Control Logic

The motion control logic, shown in drawing TU10-0-06, provides the necessary sequencing and control for load-

ing tape, rewinding, brake release, and shutting the unit down if power or the tape unit itself should fail. Its main
sections are listed and explained below.

4.1.3.1 Power Clear — The power clear circuitry consists of a power transient detector and one-shot. When the

+5V power supply is turned on, the circuit produces a 400 ms PCLR pulse that resets all of the various status

flip-flops of DECmagtape to the idle, unloaded, off-line condition, keeps all motors turned off, and asserts braking on the reels. Similarly, when the +5V power supply drops to approximately 4.4V, a PCLR pulse is produced
that lasts for 400 ms or until the power supply drops too low to operate the power clear circuitry (approximately
3V).

4.1.3.2 Failure Detection — As explained in previous sections, there are two fail-safe switches in each buffer
column that define the permissible limits of excursion of the tape loop in the column. If the tape loop in either

4-6

buffer column goes below its lower fail-safe switch, the switch opens and LFS H is asserted. If either tape loop
is above its upper fail-safe switch, then UFS L is asserted. When VACUUM ON L is asserted, indicating that tape

is loaded, and either LFS H goes to 1 or UFS L goes to 0, then the FAIL flip-flop is set (drawing TU10-0-06).
The effect of FAIL(1) is essentially the same as that of the PCLR pulse, except that FAIL(1) is a level and remains asserted, preventing tape unit operation until manually reset by moving the LOAD/BRK RLS switch to its
center or OFF position.

4.1.3.3 Loading Sequence Logic — Initiation and shutting down of the reel motors, brakes and function control
logic is controlled by the loading sequence logic. The loading sequence logic consists of the RELAY ENBL flipflop, the REEL MTR ENBL L and VACUUM ON L integrating one-shots, and their associated gating. The

RELAY ENBL flip-flop is reset by the assertion of CLR RLY ENBL L, a signal made up of the OR of PCLR,

FAIL(1), or the LOAD/OFF/BRK RLS switch being in the OFF position. When RELAY ENBL is reset the
RELAY ENBL H signal itself is negated, turning off the vacuum motor; MTR PWR RELAY COIL is turned off,
causing the power supply to interrupt PWR COM INT and +16V INT which turns off power to the reel and
capstan motors; the REEL MTR ENBL L integrating one-shot is held to its 1 state, negating REEL MTR ENBL L;

and the VACUUM ON L integrating one-shot is held to its 1 state, negating VACUUM ON L, and preventing the
function control logic from responding to any command.
The RELAY ENBL flip-flop is set by LOAD PULSE L, a pulse produced when the LOAD/OFF/BRK RLS switch

is brought to the LOAD position. When the RELAY ENBL flip-flop is set, RELAY ENBL H is asserted, turning
on the vacuum motor; RELAY ENBL L is asserted clearing FORCE BRK on and causing the generation of

REEL MTR PULSE; and MTR PWR RELAY coil is turned on, causing the power supply to turn on
PWR COM INT and +16V INT.

REEL MTR PULSE causes each reel motor to dump a small amount of tape into

the top of its buffer column, sealing it and allowing vacuum to build up in the column. When the lower fail-safe
switches in both vacuum columns sense vacuum, causing LFS to be negated, the overriding set inputs to the

REEL MTR ENBL L and VACUUM ON L integrating one-shots are negated, allowing the one-shots to begin to
time out. Approximately 300 ms is allowed for the vacuum to build up and stabilize before the

REEL MTR ENBL L one-shot times out, asserting REEL MTR ENBL.
When REEL MTR ENBL is asserted, the reel servos can then function normally, bringing the tape loops to the
middle of the buffer column. Approximately 260 ms thereafter, the VACUUM ON L one-shot times out, asserting VACUUM ON. This allows the function control logic to accept commands and also enables failure detection.
The tape loading sequence is then complete, and the transport remains loaded until the RELAY ENBL flip-flop
1S reset.

4.1.3.4 Brake Release — When the FORCE BRK ON flip-flop is set, full braking is applied to both reels. It is
set by CLR RLY ENBL L whenever the RELAY ENBL flip-flop is reset and is cleared whenever RELAY ENBL
is set.

FORCE BRK on can also be cleared by BRK REL L, the signal which is asserted when the

LOAD/OFF/BRK RLS switch is in the BRK RLS position, provided that LFS H is asserted. Thus, the lower
vacuum switches prevent brake release until the vacuum has drained out of the buffer columns. Moving the

LOAD/OFF/BRK RLS switch from BRK RLS to the center OFF position causes CLR RLY ENBL L to be asserted, again setting the FORCE BRK ON flip-flop.

4.1.3.5 Rewind Control — Due to the limited rate at which the reels can be accelerated and decelerated, a special
sequence of control signals must be generated to perform a high-speed rewind operation.

in Figure 4-6.

4-7

The sequence is shown

REWIND H

REWIND CAP

BOT

O_A.

REWIND BRK (1) H

O—~O_s

TD
H

©c

TA
H

-—

TS
H

O.‘.O—L

REWIND STATUS (1) H

FORWARD
(1) H

FOR H

+45ips

CAPSTAN

VELOCITY

-45ips
-150ips
HIGH

BRAKING

PULSED

———=——=~=~—

fr, il
CP-0216

Figure 4-6 Rewind Sequence Timing

When the function control logic accepts a rewind command, it asserts REWIND STATUS(1) H, triggering the TS
one-shot (drawing TU10-0-06). The TS one-shot times out for 300 ms, allowing the reels to come to a stop if
they were still moving due to a previous operation. When TS‘times out, it triggers the TA one-shot, setting the
REWIND BRK flip-flop and asserting REWIND H. The REWIND H signal causes the capstan servo to accelerate
to 45 ips in the reverse direction.

After approximately 380 ms, TA times out and REWIND CAP H is asserted, causing the capstan servo
to gradually
increase speed to 150 ips, and causing the brake controls to operate in the pulsed rewind mode. Normally, re-

winding continues until the function control logic detects the Beginning of Tape (BOT) marker. When BOT is

detected, the function control logic asserts FORWARD(1) and removes REWIND STATUS(1). The assertion of
FORWARD(1) L with REWIND BRK(1) asserted triggers the TD one-shot (drawing TU10-0-06, coordinates A7).
The REWIND BRK flip-flop is cleared, negating REWIND CAP H and causing normal braking to be restored and
the capstan servo to gradually decelerate to 45 ips, still travelling in the reverse direction past BOT.

After approximately 120 ms, TD times out, negating REWIND H and allowing the forward command to be passed
to the capstan servo. The capstan then accelerates from 45 ips in the reverse direction to 45 ips forward. The

tape then moves forward until the BOT marker is again detected. At this point, the function control logic clears
both FORWARD(1) and REWIND STATUS(1), and the capstan comes to a stop, terminating the rewind.

The rewind control logic is designed so that if the rewind is terminated at any point in the sequence the operation
will stop without failure and without danger of “spooking’ the tape.

4-8

4.1.3.6 Forward BOT Delay — As shown in Figure 4-7, the EOT/BOT sensor is located some distance ahead of

the read/write head on the tape path. Thus, when the tape is stopped with the BOT marker at the EOT/BOT
sensor, the BOT marker is still some distance before the read and write heads. Because the industry-standard tape
format requires that the first record be written at least 3 in. past the trailing edge of the BOT markers, all DEC

magnetic iape controls must wait a specified length of time between initiating forward motion in the tape unit
and commencing data transfers when starting an operation from BOT. This time period must be long enough to

move the BOT marker past the write head and 3 in. beyond it.

READ

HEAD,>

Ll llllld il il

WRITE

ERASE

HE AD

il el

\HELAD/

il il

&bl il ld & Ll il

L Ll

Ll Ll

FORWARD DIRECTION
OF TAPE MOTION

EOT/BOT
SENSOR
cP-0217

Figure 4-7 Head and EOT/BOT Sensor Positions

The TU10 EOT/BOT sensor is located about 1 in. closer to the write head than the sensors in some older Digital
tape units.

Consequently, to be compatible with other Digital tape units and controls, the TU10 must wait about

23 ms before starting forward from BOT. If BOT is asserted when FOR H is asserted, the rise of DLY FOR H
will be delayed 23 ms.

If BOT is not asserted, DLY FOR H will rise immediately upon the rise of FOR H.

The

relationship among FOR H, DLY FOR H, and BOT H is shown in Figure 4-8.

FORHO1__|

[

i‘——23ms—+{
1

DLY FOR H o
1

BOTHOI

I
]

cCp-0218

Figure 4-8 Timing of DLY FOR Signal

4.1.3.7 Ready and Transport Settling Down — The READY L and TRANSPORT SETTLING DOWN L signals

indicate whether the transport is idle (ready to begin an operation) or settling down (coming to a halt after performing an operation). When the DECmagtape is on-line and selected by its controller, it transmits the signals to
the controller to notify the controller when it is able to accept another command.

Whenever an operation is being performed, the function control logic asserts MOTION H. The OR of MOTION H
(operation in progress) or LOCAL(1) H (unit off-line) sets the RUNNING H integrating one-shot (drawing
TU10-0-06, coordinates C2), thereby negating READY L, and also inhibiting TRANSPORT SETTLING DOWN L.

When both MOTION H and LOCAL(1) H are negated, the RUNNING H one-shot begins to time out and

TRANSPORT SETTLING DOWN L is asserted, indicating that the transport is ready to accept a command to
move tape in the same direction as the previous command. After approximately 10 ms, when the capstan has had
time to come to a complete stop following any previous operation, the RUNNING H one-shot times out, negating

TRANSPORT SETTLING DOWN L and, provided that VACUUM ON H is asserted, asserting READY L, thereby
indicating that the unit is ready to accept any command.

4.2 TAPE UNIT STATUS SENSORS
4.2.1 Write Lock

To protect tapes from inadvertent erasure, tape reels are provided with a write-enable ring. If a reel of tape is
mounted on the DECmagtape with its write-enabled ring removed, this condition is sensed and the DECmagtape
will refuse to honor write commands. Further, if the transport is on-line and selected by its controller, it will
assert transport bus signal BWRI H, indicating to the controller that it is write-locked.

The write lock assembly is shown schematically on drawing TU10-0-04, Sheet 1. The physical assembly is shown
in Figure 5-17. The assembly consists principally of the write-lock solenoid and the write-lock switch. When no

write-enable ring is inserted in the file reel, a feeler attached to the end of the solenoid shaft extends into the
write-lock slot on the back of the reel. This feeler puts the write-lock switch in its normally closed position,
asserting WRITE LOCK L. When a write-enable ring is inserted in the file reel, the ring pushes back the solenoid
shaft, actuating the write-lock switch and negating WRITE LOCK L. If the write-enable switch is actuated when
+12V INT is turned on, i.e., when tape is loaded in the buffer columns, the write-lock solenoid is engaged to

withdraw the write-lock feeler from contact with the ring. This keeps the write-lock switch actuated until the
tape is unloaded and reduces wear of the write-lock assembly and write-enable ring during tape unit operation.

4.2.2 EOT/BOT Sensor

To locate the beginning and end of the fecording area on the tape, the load and end points are marked by reflective strips mounted on the non-oxide side of the tape. The dimensions and placement of these strips are shown

in Figure 4-9. They are detected by the phototransistors of the EOT/BOT sensor assembly, shown schematically
in drawing TU10-0-04, Sheet 2. The assembly is illustrated in Figure 5-24. The EOT/BOT assembly is located on
the head mounting plate opposite to the tape cleaner. It consists of an EOT sensor phototransistor, located to
detect light reflected from the EOT strip; a BOT sensor phototransistor, located to detect light reflected from the
BOT strip; and a light-emitting diode (LED), located opposite the center of the tape, which illuminates both the
EOT and BOT strips. The LED operates in the infrared region and produces no visible light. The outputs of the

EOT and BOT signals are amplified, filtered, and converted to logic levels as shown on drawing TU10-0-05, to
produce the logic signals EOT L, EOT H, BOT L, and BOT H.
The assertion of EOT H sets the END POINT flip-flop, which remains set until the tape is rewound or EOT is
negated while the tape is travelling in the reverse direction. Thus, if the tape is moved forward past the EOT

marker, END POINT remains set even after the marker is passed and is cleared only by rewinding or reversing the

tape back past the EOT marker. Setting END POINT has the following effects:

If the DECmagtape is off-line (LOCAL(1) H asserted), forward tape motion stops and the transport will not accept manual forward commands until the tape is rewound or reversed off of the
EOT marker.

4-10

PHOTO REFLECTIVE MARKERS
SEE NOTE 1

RECORDING AREA
SEE NOTE 2

REFERENCE /
EDGE

{ +0.002 IN.

0.03-IN. MAX

0.498

EOT

T——— 0.03-IN. MAX

10 FT.

I5FT.H{FT,

o5t" TOFT
-0OFT.

BACK SIDE
|

0.0019

—

t0.0003|N.

MAGNETIC SIDE

HUB END

¥—— RIM END

MAGNETIC SIDE

BACK SIDE

FRONT VIEW

NOTES:

(1) Photo reflective markers shall not protrude beyond

edge of tape and shall-be free of wrinkles and excessive adhesive. Marker dimensions: length, 1.2 + 0.2 inch: width,
0.19 + 0.02 inch: thickness, 0.0005 * 0.0001 inch.

SCHEMATIC OF TAPE WINDING

(2) Minimum for test area: maximum for recording.

(3) Tape shall not be attached to the hub,

cpP-0223

Figure 4-9 Tape Markers, Recording Area, and Tape Wind

The End Point indicator lamp is lit.

If the DECmagtape is on-line and selected by its controller, the transport bus signal BEOT H is

asserted (drawing TU10-0-07), indicating to the controller that it has passed the End Point.
Note that if the DECmagtape is on-line, it will not automatically stop on detecting EOT. It is permissible to write
data up to 10 ft past the End Point, and it is up to the programmer to ensure that he does not run past this point.
The assertion of BOT has the following effects:
a.

The DECmagtape accepts no new rewind commands,

When the transport rewinds into BOT (REWIND STATUS(1) and FORWARD(O) and the rise of
BOT H), the FORWARD flip-flop is set (drawing TU10-0-05); (see the description of rewind

operation in Paragraph 4.1.3.5);

When the transport moves forward into BOT, the

FORWARD flip-flop is cleared. (If the

REWIND STATUS flip-flop is set at this time, clearing FORWARD also clears REWIND STATUS,
terminating the rewind sequence);

The Load Point indicator lamp is lit;

If the DECmagtape is on-line (LOCAL(O) asserted) and selected by its controller, it will assert
the transport BUS signal BBOT H (drawing TU10-0-07), indicating to the controller that it is
at BOT.

4.3 MANUAL OPERATION

Manual operation of the transport is effected by the operator control box switches (refer to Paragraph 3.1). The
detailed operation of each of the switches is explained in this section (drawing TU10-0-04).

4-11

PWR ON/PWR OFF — When this switch is in the PWR ON position, POWER ON L is at ground. This signal
operates a relay in the power supply to apply the line voltage to the power transformer.

LOAD/BR REL — This switch has three positions. In its center, or “off” position, OFF L is asserted to clear the
FAIL and RELAY ENBL flip-flops. When the switch is brought to the LOAD position, OFF L is negated and
LOAD PULSE L is asserted for a few microseconds, setting RELAY ENBL and initiating the tape loading sequence.

When the switch is brought to the BR REL position, OFF L is asserted and BRK REL L is asserted for brake
release. For a more detailed explanation of these operations, see the relevant paragraphs of the section on
Motion Logic.

ON-LINE/OFF-LINE — When this switch is quiescent in either position, no output occurs to change the state of
the transport. When it is moved from its ON-LINE to its OFF-LINE position, OFF-LINE L is momentarily

asserted, setting the LOCAL flip-flop (drawing TU10-0-05, coordinates D6/7). When the ON-LINE/OFF-LINE
switch is moved from its OFF-LINE to its ON-LINE position, ON-LINE L is asserted for a few microseconds,
clearing the LOCAL {lip-flop.

Unless a rewind operation is in progress, the assertion of either OFF-LINE L or ON-LINE L causes the assertion of

LINE SW CL L (drawing TU10-0-05, coordinates A2/3), which, in turn, causes the assertion of INIT L, clearing

the FORWARD, REVERSE, and REWIND STATUS flip-flops and bringing tape motion to a halt.
The LOCAL flip-flop controls the operating mode of the transport. When LOCAL is cleared, the transport is
on-line and all operations of the transport are directed by the tape control via the Transport Bus. When LOCAL
is set, the transport is off-line and is effectively isolated from the Transport Bus. In this mode, tape motion is con-

trolled by the FWD/REW/REV and START/STOP switches, as discussed below.
FWD/REW/REYV — This three-position switch selects the direction of tape motion for off-line operations. When
it is in the FWD position,

position,

M FWD L is asserted; in the REW position,

M REW L is asserted; and in the REV

M REV L is asserted. These signals do not initiate tape motion, but are strobed by the START L pulse

as explained below.

START/STOP — When this switch is moved from its START position to the STOP position, STOP L is asserted
for a few microseconds. If the transport is off-line (LOCAL(1) asserted) this causes a corresponding pulse at

INIT L, clearing the FORWARD, REVERSE, and REWIND STATUS flip-flops (drawing TU10-0-05) and bringing

tape motion to a halt. When the START/STOP switch is moved to the START position, START L is asserted,
causing a short, HIGH-going pulse at START PULSE H (drawing TU10-0-05, coordinates D2). This pulse is

ANDed with LOCAL (transport off-line) and MOTION (no operation in progress) to produce a pulse that strobes

the M FWDL, M REW L, and M REV L lines. The assertion of one of these lines causes the FORWARD,
REWIND STATUS, or REVERSE flip-flop, respectively, to be set, initiating tape motion in the indicated direction.

Note, however, that if BOT L is asserted, the signal that sets the REWIND STATUS flip-flop is gated off, because

the tape is already at BOT. Note also that if END POINT(1) H is asserted and
asserted to clear the

FORWARD is set, INIT L is

FORWARD f{lip-flop and prevent running off the end of the tape.

4.4 ON-LINE OPERATION

When the LOCAL flip-flop is in its O state, the DECmagtape is on-line. In this state, all operations of the transport
are directed by the tape control unit via the Transport Bus. The Transport Bus consists of 40 wires that connect
the tape control unit to up to 8 transports. Unlike the TTL signal levels of the logic within the DECmagtape
itself which are nominally +3V at high and OV at low, logic levels on the Transport Bus are OV at their high levels

and -3V at low to allow compatibility with existing tape systems. Therefore, all Transport Bus signals are transmitted and received via level converters as shown on drawings TU10-0-07, TU10-0-08, and TU10-0-09.

4-12

To reduce the number of bus connections, certain Transport Bus wires (BBOT, BEOT, BWRL, and BRWS) are bi-

directional: transmitting command signals from the controller to the transport during one phase of operation,
and transmitting other signals from the transport to the controller at other times. Another set of wires (BRDP,

and BRD (0:7)) transmit timing information to the controller when the transport is beginning and ending operations, but transmits to the controller data read from the tape during the operations themselves.

4.4.1 Transport Selection and Status Reporting
All of the transports in a system are wired to the same Transport Bus wires, but only one transport can be logically
connected to the bus at one time;i.e., only one transport can transmit its status to the tape control and respond

to commands, and only one transport can be reading or writing data at a given time.

To select the particular transport to converse with the tape control, the control transmits a binary code on Transport Bus lines BSELO, BSEL1, and BSEL2. Each transport on the bus compares this code to the transport num-

ber, determined by the position of its unit select switch (drawing TU10-0-07). If the selection code transmitted
by the tape control matches the transport number, and if the transport is on-line, SELECT REMOTE is asserted
and the transport logically connects itself to the Transport Bus. All other transports remain logically disconnected

and neither transmit nor respond to bus signals.
When a transport is logically connected to the Transport Bus, it transmits status information to the tape control
as follows:
B7CH H

— Asserted if a 7-track, rather than 9-track head is installed on the transport;

BBOTH

— Asserted when the tape is positioned at Load Point;

BEOTH

— Asserted when the END POINT flip-flop is set;

BWRLH

— Asserted when the tape unit is write-locked;

BRWS H

— Asserted when the REWIND STATUS flip-flop is set;

BSDWN H

— Asserted when the tape unit is settling down following an operation, i.e., asserted
for about 10 ms following the command to terminate an operation while the capstan
1s coming to a halt.

BTUR H

— Asserted when the tape unit is ready to receive any command, i.e., when the transport is neither performing an operation nor settling down following an operation.

As shown in drawings TU10-0-08 and TU10-0-07, the transport also generates two clock signals that are transmit-

ted to the tape control when the transport is connected to the bus;
BC800

Consists of a constant stream of clock pulses, present at all times, at the rate at

which data is transferred at 45 ips and 800 bpi, i.e., at 36 kHz;
BC556

Consists of a stream of clock pulses, valid whenever the transport is selected for
operation at 556 bpi recording density, at the rate at which data is transferred at

45 ips and 556 bpi, i.e., at 25.02 kHz.
These clock signals are used by the tape control in timing functions and in interpreting record formats.

4.4.2 Initiating Operations

The sequence of bus signéds during execution of read space and write commands is shown in Figure 4-10. The
various on-line operations of the DECmagtape are controlled in a similar manner:

The tape control sends the

specified function and the transport responds by moving tape in the specified direction until the tape control
sends a stop signal.

The rewind and unload operations are an exception to this, in that they continue to

4-13

completion even after the control unit has sent a stop signal to the transport. These operations are explained in
more detail later.

IS()

() (T

{() T

{(
)T

g)T

£) (T

|___§()

BALFA %__]

(

BSTOP %__I

ssown ZA

(s(

(
e

*BREC

J,F_rLH.%HJ—U-Lfl.g

* BLRCC

fl()

{(
)

()

4 CHARACTERS
MISSING

(fl_
)
10Oms

{(

(

BEMD

(

{

\flfi

S—

BSET%

—

SELECTED _J

LT
|
'
4 CHARACTERS

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< MISSING
*WRITE OPERATION ONLY

cpP-0219

Figure 4-10 Write Operation Timing

On receipt of computer instructions, the tape control initiates operation by sending a negative pulse on the BSET
line. Simultaneously, the particular tape function command is specified on the appropriate bus line(s). The command lines are listed and explained below (drawings TU10-0-05, TU10-0-07, and TU10-0-08).
BBOT H — When this line is HIGH (0V) at the HIGH-going (trailing) edge of BSET, (RFWD H and SET PULSE H),
the FORWARD flip-flop is set, causing tape to move in the forward direction.
BREV H — When this line is asserted at the HIGH-going edge of BSET, the REVERSE flip-flop is set, causing tape
to move in the reverse direction.

BEOT H — When this line is asserted at the HIGH-going ~edge of BSET, the REWIND STATUS flip-flop is set,
initiating the rewind sequence and causing BRWS H to be asserted thereafter.

BRWS H — When this line is asserted at the HIGH-going edge of BSET and the tape unit is not write-locked, then
the WRITE ENABLE flip-flop is set, turning on the write head drivers and beginning a Write operation. If, however, either BREV H (Reverse command) or BEOT H (Rewind command) is asserted at the trailing (HIGH-going)

edge of BSET, then WRITE ENABLE will be cleared, because writing in the reverse direction is not allowed.

BWRL H — When this line is asserted at the HIGH-going edge of BSET, and BEOT H (Rewind command) is also

asserted, then in addition to set‘ting the REWIND STATUS flip-flop to initiate a rewind operation, the LOCAL
tflip-flop is set taking the unit off-line. This prevents a response to further commands from the tape control until
the operator manually returns the transport to its on-line condition by moving the ON-LINE/OFF-LINE panel
switch to its OFF-LINE position and then back to its ON-LINE position, clearing the LOCAL flip-flop.

4-14

Note that the function commands are sampled at the trailing (HIGH-going) edge of the BSET pulse. Several of

the wires used to transmit function commands from the tape control to the transport are used at other times to
transmit status information from the transport to the control. To prevent interference with the incoming function command signals, the transport removes its status from the BBOT, BEOT, BWRL, and BRWS lines when

BSET goes low.

4.4.3 Terminating Operations
At the leading (LOW-going) edge of the BSET pulse, the tape control brings BSTOP to a HIGH (0V) level. For
all operations except Rewind and Unload, BSTOP remains HIGH throughout the operation. When the tape control determines that tape motion should be stopped, it brings BSTOP to a LOW level (-3V). This generates
CLEAR FUNCTION in the DECmagtape which clears the

FORWARD and REVERSE flip-flops and brings tape

motion to a halt (drawings TU10-0-07 and TU10-0-05).

For the Rewind and Unload operations, the tape control asserts BSTOP LOW soon after the trailing edge of BSET,

but the function continues to completion;i.e., the fall of BSET has no effect, and the Rewind sequence continues
until the transport stops at BOT.

4.4.4 Motion Delay
Records on tape are separated by blank areas, called interrecord gaps, of specified minimum length. The interrecord gaps allow the transport to accelerate the tape to operating speed before reading or writing. The transport
must stop in approximately the middle of the interrecord gap after an operation in order to be able to accelerate
to operating speed in either direction before beginning the next operation.

Similarly, the transport must traverse

a measured amount of tape before writing a record in order to leave a gap of the proper length between the record

being written and the preceding record.
To control the length of tape traversed between initiating a command and beginning the record, the tape control
unit times out an interrecord delay between sending the command and initiating data transfers. Similarly, to con-

trol the point in the interrecord gap at which the transport stops, the tape control times out an interrecord delay
between reading the end of the record and sending BSTOP L to terminate tape motion.
The interrecord delays are implemented by a count-down counter in the tape control, which is preset to a certain
number and then counted down to zero by BC800 pulses received from the transport. Because the time to
traverse a given length of tape while starting or stopping depends on the acceleration characteristics of the trans-

port, and because several types of transports can be used with standard DEC tape controls, the tape control must

interrogate the transport in order to determine the number of BC800 pulses required for the proper interrecord

delay.

On transmitting a command to the transport prior to beginning the acceleration interrecord delay, and again on
reading the end of the record prior to beginning the deceleration interrecord delay, the controller asserts BEMD H

for a few microseconds, requesting the proper interrecord delay time. The DECmagtape responds by sending a
code to the control that is a function of the command (Forward, Reverse, or Write) and the state of the BALFA

Transport Bus line, a signal transmitted by the tape control which is HIGH for the acceleration delay and LOW
otherwise. As shown on drawing TU10-0-08, the transport transmits the interrecord delay via the nine

BRD (P, 0:7) lines, which are normally used to transmit read data from the transport to the control. When the
tape control asserts BEMD H, the bus receiver generates DELAY OUT L (drawing TU10-0-07), which disables

read data from the BRD lines and enables output of the appropriate interrecord delay code via these lines. The
tape control then samples the code, negates BEMD H, and times out the appropriate delay before initiating data
transfers or bringing BSTOP to a LOW state to stop tape motion.

4-15

4.4.5 Read and Space Operations

For the DECmagtape transport, there is no difference between a Read operation and a Space Forward operation;
both are initiated by the tape control simply by commanding the transport to move tape in the forward direction.

The Space Reverse operation differs from the Read/Space Forward operation only in the direction in which the
transport is commanded to move tape. For all tape functions except Rewind and Unload (Read, Space, Forward,

Space Reverse, and Write), the read circuits operate in essentially the same manner, and the transport transmits
all data read to the tape control.

4.4.5.1

TU10 DECmagtape Transports up to No. 10320 — An equivalent circuit of one of the 9 (or 7) read

channels is shown in Figure 4-11. Figure 4-12 shows possible read signal waveforms at the indicated points. For
more complete and accurate representations, see drawings TU10-0-10 and TU10-0-08. Although for simplicity
this discussion considers only one read channel, the user should remember that the read electronics includes
either 9 or 7 identical, parallel read channels.

E(fig. 4-12)

'-SLICER

REFER TO FIGURE 4 - 12

—

i
READ

| GO64
|

+3V —{D

| 5.3y

|
!

G060

—1\

COMPRESSOR

l/
.

AMP GO50

HEAD

PEAK
|

<— D(fig.4-12)

DETECTOR
G062

T
T T =TT ===== I

!
!

+3v —|0

RDn H

RDn L

|
L

DEN8

START
SKEW | oens o
DELAY H |

(1.7ps ||

|
BUFFER

—(

READ BUFFER M765

_.I

e D 1

|
DELAY

|
I
l

‘

CLEAR L

]
I

|
I

|
|

STROBE L

7
|

SKEW DELAY M767

I
|

CP-0220

Figure 4-11

Equivalent Circuit of Read Timing and Read Circuitry
for One Track (Units up to No. 10320)

of the direction of magnetism of the tape. As the tape passes the read head, each flux reversal produces an output
pulse of approximately 13 mV amplitude. Because alternate flux reversals in a given channel are of alternate

4-16

IIAN

READ
HEAD

NBN

READ
AMPLIFIER
OUTPUT

IICII

COMPRESSOR

OUTPUT

IIDN

PEAK

DETECTOR

OUTPUT
"E“

SLICER
OUTPUT
CrP-0221

Figure 4-12

Read Circuit Waveforms (Units up to No. 10320)

polarity, the read head output pulses are of alternating polarity. The Read Amplifier (G050) amplifies and rectifies the read head output pulses, producing a positive-going pulse of approximately 1.5V amplitude peak-to-peak
as each ONE bit passes the read head.
The Read Amplifier output is fed into the Compressor (G060) which inverts and amplifies the signal and logarithmicly compresses the waveform. The Compressor also shifts the voltage level of the signal to an adjustable predetermined level to establish the Slice Voltage, discussed later in this section.
The output of the Compressor is routed to two circuits, the Peak Detector (G062) and the Slicer (G064). The
Peak Detector is somewhat misnamed in that it does not actually detect the peak of the Compressor output waveform, but rather generates a positive-going logic level transition when the Compressor output swings approximately
1.4V more positive than its negative peak, on the trailing side of the Compressor output pulse (see Figure 4-12).
This signal does, however, have a fixed phase relationship to the peak of the Compressor output independent of

the magnitude of the Compressor output pulse due to the logarithmic transfer function of the Compressor.
The outputs of both the Compressor and Peak Detector are fed to the Slicer. The Slicer output normally goes

HIGH at the HIGH-going edge of the Peak Detector output and remains HIGH until the Compressor output goes

more positive than -3.3V. If, however, the Compressor output is more positivé than -3.3V at the time of a HIGHgoing transition of the Peak Detector output, the Slicer output will not go HIGH at all. The Peak Detector must

be sensitive to low-level signal transitions in order that its output be accurately referenced to the signal peak, so

as to avoid phase shift or skew between channels. This makes it very sensitive to low-level noise pulses. The
Slicer eliminates this low-level noise by requiring that the Compressor output pulse exceed a certain voltage, called

the Slice Voltage, in order to recognize a pulse as a valid ONE bit.

4-17

As mentioned earlier, the effective Slice Voltage is adjusted by the Compressor by means of shifting its quiescent
output voltage up or down as desired. The Slice Voltage is adjusted to give maximum noise rejection while retaining the ability to read weak data from badly worn tapes. The Slicer output is a HIGH-going logic signal of a few
microseconds duration each time a ONE bit is read. Due to both electrical and mechanical delays, the Slicer out-

put pulses for the several read channels may be “‘skewed”, or displaced in time, relative to each other. This skew

consists of two components. Static skew is caused by errors in head alignment (azimuth error), tolerance in the
location of read gaps relative to each other in the read head (gap scatter), and differing signal propagation delays
through the read electronics, all of which result in a fixed time displacement of one channel relative to another.
Dynamic skew is caused by variations in tape speed and position during both reading and writing (mechanical dynamic skew), magnetic effects during both writing and reading (write crosstalk, pulse crowding, etc.), and variable
skew introduced in the read electronics, such as shift in the peak detection caused by superimposed noise, all of

which produce skew between channels which varies with time.
The Read Buffer (M765), in conjunction with the skew delay section of the Clock and Skew Delay (M767), eliminates both static and dynamic skew so that all channels are aligned and the bits of a character can be read out in

parallel. The Read Buffer receives and holds data from the Slicer. It consists primarily of nine data-holding flipflops with delayed inputs. Each delay is implemented as an eight-bit shift register clocked at a shift rate of

576 kHz. Each shift register has an associated eight-position switch that selects the output from one of the eight
stages of the shift register. Thus, according to the switch setting, the Slicer output pulse is delayed from one to
eight stages, at approximately 1.7 us per stage.

By adjusting the switch setting of each channel, static skew

between channels can be “tuned out’ and, reduced to less than 1/2 stage delay, or about 870 ns, maximum.
‘The output of each shift register delay line is fed to the clock input of the corresponding holding flig flop

(RD (P, 0:7)). The leading (HIGH-going) edge of each delayed Slicer pulse sets the flip-flop for that channel. The
flip-flop outputs are transmitted to the tape control on Transport Bus lines BRD (P, 0:7) H (drawing TU10-0-08).
The outputs of all Read Buffer channels are ORed to produce START SKEW DELAY H. Thus, when the first

bit is set, START SKEW DELAY H is asserted. This signal goes to the Skew Delay and enables the Skew Delay
counter. The Skew Delay compensates for dynamic skew by providing a delay time in which all bits can be read

for the particular character that is passing under the read head. When the Skew Delay times out, it asserts
DELAY STROBE L. This causes the Transport Bus line BSKEW H to be asserted, informing the tape control that
a character has been read and can be strobed from the BRD (P, 0:7) lines. After one period of the CLOCK L signal, approximately 1.7 us, the Read Buffer is cleared, negating START SKEW DELAY H. This causes the Skew
Delay counter to be reset, and DELAY STROBE L is negated. The Read Buffer and Skew Delay are then ready
for the next character.
To provide maximum immunity to skew, the Skew Delay should be equal to 1/2 the period between characters.

The period varies according to the recording density of the tape being read; thus, the Skew Delay counter is
initialized to a number that varies with the recording density. The tape control indicates the recording density by
transmitting a code on Transport Bus lines

B DEN5 H and B DENS8 H, as in the table below:

B DENS5 H

B DENS H

Density

-3V

200 bpi

56 us

-3V

556 bpi

20 us

any

800 bpi

14 us

In concluding this discussion of the read electronics, two facts should be noted:

Skew Delay

First, the DECmagtape transport

does not perform format recognition operations, such as parity checking and recognizing the end of the record;
these functions are performed by the tape control. Second, for a character to be recognized and read from tape,
it must contain at least one ONE bit; thus, tapes must be written with ODD parity if the data contains any allzeros characters.

(The BCD code, which is normally written with even parity, does not use the all-zeros

character.)

4-18

4.4.5.2

TU10 DECmagtape Transports Above No. 10320 — An equivalent circuit of one of the 9 (or 7) read

channels is shown in Figure 4-13. Figure 4-14 shows possible read signal waveforms at the indicated points. For
more complete and accurate representations, see drawings D-BS-TU10-0-10 and D-BS-TU10-0-08. Although for
simplicity this discussion considers only one read channel, the user should remember that the read electronics

includes either 9 or 7 identical, parallel read channels.

E(Fig 4-14)

[THRESHOLD AND

|BUFFER
|

REFER TO FIGURE 4-14
p

| -5V(WRITE)

-4V (READ)

CEED

PEAK

CEmD

Cnmm

+3v —D

|
|

|
1

coRn

Grmm

COREd

RDn H

RDn L

(L7es D
BUFFER

CLEAR L

—1C_ ©

L e = ————

AMP GO50

|
|

HEAD

COMPRESSOR

READ

GO60- YA

2 CRrmn

0 oonmmn @mmwy

<+—D(Fig 4-14)

DETECTOR
G093

}—

————————————

I
|

|
]

DENS8 L

START
SKEW | oens 1
DELAY H |
|

=P
‘

|
]

|
|

L L_READ BUFFER M765-YA

i|
DELAY

r———lv—L_l_D——— cC

STROBE L

_l SKEW DELAY M767

]

|
I

cp-2122

Figure 4-13

Equivalent Circuit of Read Timing and Read Circuitry
for One Track (Units Above No. 10320)

The DECmagtape records and reads data in the NRZI (Non-Return-to-Zero Inverted) format, which means that
each character written on tape contains at least one ONE bit. A ONE bit consists of a flux reversal, i.e., a reversal
of the direction of magnetism of the tape. As the tape passes the read head, each flux reversal produces an output

pulse of approximately 13 mV amplitude. Because alternate flux reversals in a given channel are Qf alternate

4-19

IIA”

READ
HEAD

NBII

READ
AMPLIFIER
OUTPUT

[t}

-4V (READ)
-5V (WRITE)

COMPRESSOR

OUTPUT

Dll

PEAK
DETECTOR
OUTPUT
llEll

SLICER
OUTPUT

NOTE

Peak detector oscillates when
no signal exists.
cpP-2120

Figure 4-14

Read Circuit Waveforms (Units Above No. 10320)

polarity, the read head output pulses are of alternating polarity. The Read Amplifier (GO50) amplifies and rectifies the read head output pulses, producing a positive-going pulse of approximately 1.5V amplitude peak-to-peak
as each ONE bit passes the read head.

The Read Amplifier output is fed into the Compressor (GO60-Y
A), which amplifies the signal in a logarithmic

fashion. This logarithmic amplification tends to minimize variations in head output caused by differences in
heads, tapes, or tape defects.

Unlike the G060 used in prior units, the GO60-Y
A does not induce a variable dc offset in its output signal.
Rather, its output always maintains a null signal level slightly (approximately 0.3V) below ground (Figure 4-14).

The Compressor output is routed to two circuits, the G093 Peak Detector and the G094 Threshold and Buffer.
The G093 is a true peak detéector, differentiating the input signal to produce a transition about one microsecond
after the input peak occurs, regardless of the amplitude or shape of the peak. As Figure 4-14 indicates, the
output of the G093 oscillates when no signal is fed to it.

The G094 compares the Compressor output to a reference voltage. That voltage should be between -3.5V and
-4.0V when reading, and between -4.5V and -5.0V when writing. Whenever the G094 input from the Compressor exceeds (becomes more negative than) the reference voltage, the output of the G093 is enabled to clock a ONE

into the corresponding position of the buffered output of the G094. That bit is automatically reset to a ZERO
when the Compressor output climbs back above the G094 reference voltage.

4-20

The G094 output is next fed into the M765-YA Read Buffer, which differs from the M765 used in prior units
only in that the shift register formerly used for deskewing pnrposes has been deleted. As a result, the 1.8 micro-

second maximum latency between detection of a ONE at the G094 and detection of a ONE at the M765 has been

eliminated.
4.4.6 Write Operation
The write circuitry is shown in drawing TU10-0-09. To initiate a Write operation, the tape control sends to the
transport both the Forward and Write Enable commands (BBOT H and BRWS H with BSET). This causes tape to

move forward and sets the WRITE ENABLE flip-flop, as previously discussed. The Write operation proceeds as
follows: Prior to receiving the command, the head drivers are turned off so that no current flows through the
write and erase heads, and all of the flip-flops in the write circuitry are reset. When the WRITE ENABLE flip-flop
is set, the head drivers are turned on, putting current through the erase and write heads in the ‘“‘erase’ direction.
and the tape begins to move forward. After the interrecord delay, the tape control begins sending characters of
data to the transport. To do this, the tape control puts each character onto the BWD (P, 0:7) H Transport Bus

lines, and when the character is to be written, it puts a positive pulse on the BREC H line. The assertion of

BREC H produces two corresponding signals from the DECmagtape bus receivers: C STROBE L, which goes from
OV to -3V and WRITE STROBE H, which goes from OV to +3V. The BWD (P, 0:7) H write data lines are connected to the resistor inputs of nine level-shifting, resistor-capacitor-diode gates. The diode (strobe) inputs of the

gates are all driven by C STROBE L; at the falling edge of C STROBE L, negative-going pulses of about 100 ns
duration appear at the outputs of those resistor-capacitor-diode gates whose resistor input has been enabled by a

ONE (0V) input from its corresponding BWD line. The output pulses set corresponding flip-flops in the Write

Skew Buffer. At the same time, WRITE STROBE H sets a flip-flop that causes a single ONE bit to be shifted
into an eight-bit shift register called the Write Strobe Delay, which is shifted by the CLOCK L signal every 1.7 us.
As the pulse is shifted through the Write Strobe Delay, it produces a HIGH-going pulse on each of the Write

Strobe Delay outputs in turn. The reset input of each flip-flop in the Write Skew Buffer is connected through an
eight-position switch to one of the Write Strobe Delay outputs. As the delayed WRITE STROBE pulse is shifted
into the selected stage of the Write Strobe Delay shift register, the Write Skew Buffer flip-flop is cleared, producing a negative-going transition on its output if the flip-flop was previously set by a BWD input.

The outputs of the Write Skew Buffer are connected to the clock inputs of corresponding flip-flops in the Write
Data Buffer. When a flip-flop in the Write Skew Buffer is set by its corresponding BWD line and is then cleared,
it causes the corresponding bit of the Write Data Buffer to be complemented. The outputs of the Write Data

Buffer determine the polarity of the current produced by the head driver for the corresponding channel. Thus,
each time a bit of the Write Data Buffer is complemented, a flux-reversal (ONE bit) is written on tape.
To summarize, when the tape control asserts BREC H, the write data on BWD (P, 0:7) H is strobed into corresponding bits on the Write Skew Buffer. After a delay that is determined by a separate switch for each channel,
each bit of the Write Skew Buffer that was set is cleared, causing corresponding bits of the Write Data Buffer to

complement. This, in turn, reverses the direction of magnetization of the tape, writing a ONE. By adjusting the

Write Strobe Delay switches for each channel, the writing of each channel can be delayed relative to the others so

as to “‘tune out” write skew caused by head misalignment, gap scatter, etc.

4-21

After all the data characters of the record (including the CRC character, if any) have been written (as determined
by the tape control), the tape control sends a positive-going pulse on the BLRCC H line to cause the LRCC
(Longitudinal Redundancy Check Character) to be written. The BLRCC H pulse is received by a DECmagtape

bus receiver that produces a corresponding pulse on LRCC STROBE H. Assertion of LRCC STROBE H causes
every bit of the Write Skew Buffer to be set and initiates a pulse in the Write Strobe Delay. The effect is as though
the tape control had sent a BREC H pulse with data of all ONES, with one exception: In the absence of a
BREC H pulse, the J inputs of the J-K flip-flops that compose the Write Data Buffer are disabled; the K inputs are
always enabled; thus, when the LRCC is written, the Write Data Buffer is set to ZERO, instead of being comple-

mented. ONEs (flux reversals) are written on tape in only those channels for which the Write Data Buffer was
ONE prior to writing the LRCC. Because all bits of the Write Data Buffer were ZERO when the record began,

were complemented each time a ONE was written in that channel, and are ZERO after the LRCC, it can be seen
that the LRCC consists of even-forcing parity bits for each channel on the tape.
The read, write, and erase heads are arranged so that tape passes first over the erase head, then over the write head,
and finally over the read head. During a Write operation, the read circuits are also active, reading the record after
it is written and returning it to the tape control for verification of character parity and LRCC in order to ensure

that the record was written correctly. During a Write operation, the read electronics perform exactly as during
a Read operation, with one exception: The assertion of WRITE ENABLE(1) L causes the Compressor to shift

the Slice Level, so as to require a stronger output pulse in order to recognize a ONE bit. This is done so that if
the tape is nicked or badly worn, errors will result in the data read back, and the marginal quality of the record

will be detected during the Write operation, when the record can easily be rewritten.

After writing LRCC, the transport continues to move tape, réading and verifying the record. When the tape control reads the end of the record, it begins the interrecord delay, after which it asserts BSTOP L, clearing the
FORWARD f{lip-flop and bring tape motion to a halt. To ensure complete erasure of the interrecord gap, the

WRITE ENABLE flip-flop remains set; therefore, the head drivers continue to put current through the erase and
write heads in the erase direction (Write Data Buffer ZERO) until tape motion has come to a complete stop, as
determined by the time-out of the RUNNING one-shot (drawing TU10-0-06 and TU10-0-05). The

WRITE ENABLE flip-flop is then cleared, turning off current to the write and erase heads and completing the
Write operation, simultaneously with the assertion of READY L.
In concluding this discussion of the Write operation, note that while the DECmagtape transport does generate the

LRCC, character parity (vertical parity) is generated by the tape control, and data from the BWDP H line is written exactly like data from the BWD (0:7) H lines. Further, all checking of read data, including the LRCC, is performed by the tape control.

4-22

CHAPTER 5

MAINTENANCE

5.1

INTRODUCTION

This chapter contains preventive and corrective maintenance procedures for the TU10 DECmagtape. Table 5-5
lists the recommended test equipment. A list of spare parts for the TU10 is provided in Tables 5-6 through 5-9.

Appendix A contains both voltage and frequency conversion information and 7- to 9-track conversion information. The major TU10 assemblies referenced throughout this chapter are shown in Figure 5-1. Access to the interior components of the TU10 is gained by rotating the service locks in the upper left-hand side and the lower

right-hand side of the TU10 to release the unit from the ¢abinet (see Figure 5-2a).

NOTE
The recommended frequencies for performing the PM steps in

these procedures are based on moderate usage of the equipment.
In cases where usage is heavy, certain steps should be performed
more frequently.
For example, steps 1 and 9 through 16 of the quarterly pro-

cedure assume that tape motion will not exceed 150 hours/
quarter; if tape motion exceeds that figure, the steps should be
performed more often. (Tape motion = Time spent actually

moving tape; this must be decreased by 1/2 if software is not
double-buffered, or if two drives exist on the same controller.)

Step 2 of the quarterly procedure assumes that vacuum on-

time will not exceed 1000 hours/quarter; if vacuum on-time
exceeds that figure, this step should be performed more
frequently. (Vacuum on-time = Time that tape is loaded on

a drive with vacuum on, whether or not the tape is actually
moving.)

Steps 1 through 8 of the semiannual procedure assume that
tape motion will not exceed 300 hours during a 6-month
period; if tape motion exceeds that figure, these steps should
be performed more frequently.

5-1

CAPSTAN
MOTOR

SHIPPING
BRACKETS

N\ VACUUM

SWITCHES

%%%%ffé%%;4
POWER

SUPPLY

,j %?"%%%W
:_

_;%%%%%5/

5480-5

LOGIC ASSEMBLY

H603

POWER AMPLIFIER

|
/

BRAKE
ASSEMBLY

TAKE-UP REEL
MOTOR
AIR FILTER

22544457044

ASSEMBLY

MOTOR

A
7

L
L
7

BRAKE
ASSEMBLY

READ /WRITE

INTERLOCK
ASSEMBLY

Figure 5-1

TUI10 Tape Transport Assemblies

TAPE GUIDE
ADJUSTMENT
PLUGS

SERVICE

?x\

LOCK

UPPER

LOWER

N
N

\\\

N
N

..........

Transport Service Locks
D

[

—

b.
Figure 5-2

Cleaning Areas
Daily Equipment Care Areas

5-3

11 - 3357

5.2

DAILY (8-HOUR) PREVENTIVE MAINTENANCE PROCEDURES

The inspection and cleaning procedures described in this section should be performed daily to ensure optimum
operation of the TU10 DECmagtape. A summary of these preventive maintenance procedures is listed in

Table 5-1.
NOTE
Remove tape or wind all tape onto file reel prior to performing
any of the cleaning procedures.

Table 5-1
Preventive Maintenance Schedule

Daily (8-Hour) (Paragraph 5.2)

Clean Read/Write Head
Clean Erase Head
Clean Tape Cleaner

Clean Roller Guide
Clean Vacuum Pockets

Clean Vacuum Door Glass
Monthly (160-Hour) (Paragraph 5.3)

Clean Outer Door
Clean Cabinet Interior
Clean Cabinet Filter

Disassemble and Clean Reel Motor Brakes

Check Operator Panel Switches and Indicators
Clean and Inspect Tape Path
Inspect Reel Hubs
Quarterly (500-Hour) (Paragraph 5.4)

Replace Vacuum Motor Brushes

Perform Diagnostic Checks

Semiannual (1000-Hour) (Paragraph 5.5)
Check Capstan Speed and DC Balance
Check Capstan Acceleration and Deceleration Times

Check Capstan Jitter
Check Static and Dynamic Mechanical Skew
Check Flectrical Read Skew
Check Electrical Write Skew
Check Read and Write Slice Levels
Check Industry-Compatible Tape Tracking

Check Power Supply Voltages

Check Read/Write Interlock Assembly
Check Tape Guide Rollers

Check Delay Diodes
Align Tape Path
Adjust Vacuum System

5-4

CAUTION

Two types of DECmagtape cleaning fluid exist. One typé is
clearly labeled Freon TF113; the other is labeled only with a

DIGITAL label. Freon TF113 is a mild solvent that will not
harm capstans, painted surfaces, or plexiglass, and can be used
to clean all parts of the tape drive. The other cleaning fluid
contains a mixture of Freon and alcohol. It will attack painted

surfaces and some plastics, particularly the plastic used on the
capstan. When cleaning a tape drive with this type of fluid,
use only water to clean the capstan, painted surfaces, and the

plexiglass insert in the tape drive door. In all cases, whether
using pure Freon or a Freon-alcohol mixture, care must be

taken to ensure that no fluid comes in contact with magnetic
tape.

5.2.1

General Cleaning and Equipment Care
1.

Clean following with swab and DECmagtape Cleaning Fluid (DEC part no. TUC-01).
a.

Read/Write Head (A in Figure 5-2b)
Erase Head (B)
Tape Cleaner (C)
Upper Roller Guide (D)

Lower Roller Guide (E) (Check carefully for freedom of lower spring-loaded washer guide)

Clean following with lint free cloth and DECmagtape Cleaning Fluid.
a.

Vacuum Pockets (F)

Vacuum Door Glass (G)

NOTE
Certain conditions may cause the unit to require more frequent

cleaning; e.g., high temperatures in excess of 80° F, high humidity in excess of 80 percent, new tape, dust environment, etc.

Most errors are caused by dirt or oxide buildup.

5.3

MONTHLY (160-HOUR) PREVENTIVE MAINTENANCE PROCEDURES

The following procedures should be performed monthly, in addition to the daily (8-hour) procedures.
A summary appears in Table 5-1.

5.3.1

Outer Door and Cabinet Interior

Use a moistened or lint-free cloth to wipe off all material buildup on the reel hub surfaces, especially around the
rubber ring. Dust and clean the outer door. Clean all dust from the interior surfaces of the cabinet using a
vacuum cleaner with a brush attachment.

5-5

5.3.2

Cabinet Filter

Remove the cabinet filter and vacuum and wash it with water. Allow the filter to dry completely before reinstalling it in the cabinet.

5.3.3 Reel Motor Brakes
Disassemble, clean, and reassemble the reel motor brakes according to the following procedure:
With power OFF, pull the transport out on its slides. (Access brakes from the right side of the transport; operation is identical for both reel motors.)

Loosen the Allen-head screw located on the clamp. (See Figure 5-3)

SPRING

F____

\— MOTOR SHAFT

—~§
1

REEL MOTOR

AT
1]

AAAAAARAAARAARAANALAAAAAAN
AAh
AAAAAAAAAAAAAAAAAAALAAALA

3e
——Ik————.om"
CLEARANCE
o

-7

CLAMP

3/I6" GAP

ROTOR

‘

ROTOR DISC
STATOR SLOT
STATOR

CP-1539

Figure 5-3

Reel Motor Brake Assembly

Remove the spring and brake assembly. Push a cotton swab through each of the inserts (locating holes)
that hold the rotor disk and rotor to ensure that they are securely held in the rotor and that they do

not protrude in such a way as to interfere with operation of the rotor disk. If inserts are loose,
replace the brake assembly.

Using a clean, dry, lint-free cloth or wipe, clean the following:

The brake surface of the stator (Figure 5-4). (Stator is still on motor.)

Both sides of the rotor disk, including location pins.

The face of the rotor next to the rotor disk.

5-6

NOTE

Avoid skin contact with brake surfaces; body oils
are detrimental to brake function.

Install the rotor disk into the rotor; select the mating combination that allows for smoothest insertion
and retraction of rotor disk pins into the rotor locating holes. Try each of the 120-degree intervals
for best fit.

NOTE
New brake assemblies have been burnished at the
factory. Do not disassemble new assemblies.

Replace the brake, leaving a clearance of 0.010 inch between the rotor disk and the stator and a 3/16
inch clearance between the rotor and the clamp. In this position, the clamp should be clamping on
the splits cut into the sleeve of the rotor, ensuring that the rotor is fastened securely to the reel
motor shaft. When clearances are correct, tighten the Allen screw.

With the 0.010-inch feeler gauge inserted between the stator and the rotor, rotate the reel motor
manually from the front of the unit to see that the brake is spaced uniformly all around. If necessary,

rotate the brake at 120-degree intervals to determine the best position for uniform separation. (An
excessively high or low spot is cause for replacing brake assembly.)

Remount the rotor spring between the rotor disk and the rotor.

When the above steps have been completed for both reels, rotate both reels, feeling for free rotation

and listening to ensure that there is no squealing from stator/rotor disk contact.

MOTOR

CONNECTOR

BRAKE CONNECTOR —-—b[
N

CONNECTOR

STATOR MUST

MOUNTING

BRACKET

MOUNTED

WITH SLOT IN
DOWNWARD
POSITION

REAR VIEW

Figure 5-4

Stator Mounting

5-7

5.3.4

Control Box

Check the operator panel switches and indicators as follows. (Replace switches and/or indicators as required.)
1.

Apply power to the TU10; ensure that the OFF-LINE and PWR indicators on the control panel are ON.

Place a scratch tape (with write ring) on the lower hub and secure the hub lock. Set the LOAD/BR
REL switch to LOAD and then back to BR REL. Ensure that both reels turn freely and that the
FILE PROT light does not light as the supply reel is rotated.

Thread the scratch tape through the tape path and take two wraps around the take-up reel. Set the

LOAD/BR REL switch to LOAD; ensure that the LOAD indicator on the control panel comes ON.
Place the FWD/REW/REYV switch to FWD; place the START/STOP switch to STOP and then back to
START. Ensure that the FWD indicator is lit while the drive is moving the tape toward BOT, and that
the LD PT indicator lights when the drive stops at BOT.

Run the tape forward for approximately 30 seconds; set the START/STOP switch to STOP.
Set the FWD/REW/REYV switch to REV; press START. Allow the tape to run in reverse for approxi-

mately 10 seconds and ensure that the REV indicator is ON. Place the START/STOP switch in the
STOP position.

Set the FWD/REW/REYV switch to REW; press START. Ensure that the REW indicator is ON.
Set the ON LINE/OFF LINE switch to ON LINE. When the drive has completed the rewind operation
in step 7, above, check that the RDY indicator comes ON. Check that the SEL indicator also comes
ON if the controller is currently selecting this TU10.

Set the ON LINE/OFF LINE switch to OFF LINE and the LOAD/BR REL switch to BR REL. Dismount the tape and remove the write enable ring. Mount the tape and ensure that the FILE PROT
indicator is ON. Rotate the reel; ensure that the FILE PROT indicator remains ON.

5.3.5

Tape Path

Clean the tape path and inspect it for wear as follows:

Turn power OFF. Remove and clean the take-up reel, using a Kimwipe dampened with water or

Freon; inspect the take-up reel for cracks or loose center ring (hub interface). Replace if defective.
Remove supply reel (if installed). Using water- (or Freon-) dampened Kimwipes, clean the deckplate

surfaces and front door.

CAUTION
Be careful not to saturate the Scotch-Lite lining on the vacuum

column walls with fluid; this could cause damage to the lining.

Remove the head cover and open the vacuum door.

Using a penlight flashlight, inspect the read/write head and erase head for oxide accumulation. A
worn head will normally show oxide accumulation on the worn spot. If the read/write head is unevenly
worn or if the erase head shows any wear, replace the head plate assembly. (Refer to Figure 5-5; shiny
spots indicate uneven wear.)
WEAR SPOT ON

N HIIHHIIQHH

READ/WRITE
HEAD

/ ONE SIDE

HEAD

CP-1997

\— w‘éi\{fN

\ EVEN

cP- 1998

Figure 5-5

WEAR
CP-1999

Examples of Head Assembly Wear Characteristics

NOTE
Wear spots of any kind on erase head are bad.

Using DECmagtape cleaning fluid and cotton-tipped wooden swabs, clean any accumulated oxide

from the read/write head, erase head, tape cleaner, and fixed guides. (Pay particular attention to
removing oxide buildup from ceramic surfaces of fixed guides.)

NOTE
Ensure that the inner (spring-loaded) guides move freely after
cleaning and that they are not jammed under the fixed guides.

Clean vacuum columns and vacuum column doors with DECmagtape cleaning fluid and Kimwipes.
Clean roller guides with cotton swabs and DECmagtape cleaning fluid.

5.3.6

Reel Hubs

Inspect reel hubs as follows. (Refer to Figure 5-6.)

Place the take-up reel on the lower hub. Turn the hub lock until it hits the stop pin. Hold the hub
with one hand and attempt to turn the reel counterclockwise with the other hand.

PRESSURE PLATE
ROLL

PLASTIC DISK

STOP PINS

KNOB

TEFLON

WASHER

COMPRESSION RING
o

Figure 5-6

10-1303

Hub Composition

If the hub lock does not hit the stop when tightened or if the reel turns while the hub is being held
stationary, readjust the hub pin and replace the compression ring according to the following procedure.
a.

Remove power from the TU10 and remove the tape reel.

Carefully snap out the plastic disk from the reel hub.

Mark the position of the center roll pin in the hub guide.

Using a pair of heavy duty diagonal pliers, carefully remove the center roll pin.

Grasp the reel hub and unscrew the knob from the hub.

Remove (in order) the Teflon washer, pressure plate, and rubber compression ring.

Install (in order) the new compression ring, (P/N 12-10021) pressure plate, and Teflon washer.

Lightly tighten the knob on the hub until the compression ring is compressed and fully seated.

Loosen the knob until it is free of the Teflon washer. Then gently screw it in until it just touches
the washer.

Reinstall the roll pin in the same hole from which it was removed (step d, above).

5-10

Turn the knob counterclockwise until the roll pin makes contact with one of the two hub stop
pins.

Try to install a tape reel on the hub. If the tape reel does not easily slip on the hub, move the
stop pin back one hole at a time until the knob can be released far enough to permit the tape reel
to slip on the hub.

With a tape reel installed, tighten the knob (clockwise) until the roll pin contacts the other hub
stop pin. If the tape reel is not secure, move the stop pin ahead until the knob can be tightened
correctly.

Place the take-up reel on the upper hub. Repeat the procedure followed for the lower hub take-up
reel in step 2, above.

5.4

QUARTERLY (500-HOUR) PREVENTIVE MAINTENANCE PROCEDURES

The following procedures should be performed quarterly, in addition to the daily (8-hour) and monthly
(160-hour) procedures. A summary appears in Table 5-1.

5.4.1

Vacuum Motor Brushes
NOTE

This procedure should be followed only for TU10s with serial
numbers up to 10320, which use vacuum systems that are DEC
P/N 12-05944. For later models, which use vacuum systems that

are P/N 7012052, skip this procedure, as these TU10s do not use
brushes. Because of the long running-time interval required to seat

brushes properly, it is not regarded as advisable. If one of these

motors needs brushes, the motor should be replaced.

5-11

With power OFF, replace the vacuum motor brushes as follows:
1.

Disconnect the vacuum motor electrical connector by unplugging P9 from J9 (wires from plenum
cover on vacuum motor).

Loosen three large Phillips head screws that fasten plenum chamber cover to the casting and remove
plenum chamber cover.

Remove the brush assembly by removing the screws that hold the U-shaped bracket over the brush
assembly, then pull out the connector that holds the coil wire of the brush assembly.

Using a cotton-tipped wooden swab, carefully clean the commutator. Apply a drop of light oil at the
rear sleeve bearing, taking care not to get any oil on the commutator.

Install and connect the new brush assembly.

Reinstall cover and reconnect P9 to J9.

NOTE
If a semiannual PM procedure is scheduled, proceed to

the first step of that procedure; if not, continue with
the procedure described in Section 5.4.3, below.

5.4.2

Diagnostic Checks

Perform the appropriate diagnostic check as follows:

Position the tape at BOT; place the TU10 on-line.

Run the appropriate data re‘liability diagnostic for 10 minutes.
NOTE

If possible, the recently-released Multidrive Random
Data Exerciser Programs should be used to make this
check. (MAINDEC-11-DZTMH is the PDP-11 diagnostic;
MAINDEC-08-DHTSD is designed for use with the TS03
tape drive, but can be used with the TU10.) These

diagnostics are extremely sophisticated and versatile
tools for checking TU10 performance. They feature:

Switch-selectable option for automatic retries,
allowing the user to differentiate between driveinduced and tape-induced Read Errors.

Switch-selectable randomization of data, record
size, and block size.

Switch-selectable choice of write-only, read-only,
or write-backspace-read modes.

Switch-selectable ‘‘rock-back-and-forth-on-a-singlerecord” option to aid in debugging operations.

5-12

If any read errors occur, it will be necessary to run a complete pass to determine whether the
frequency of soft errors is within specifications. Acceptable soft error rates for one 2400-ft reel of
tape are:

5.5

Two Forward Read Errors that are not accompanied by Write Errors.

Two Write Errors.

SEMIANNUAL (1000-HOUR) PREVENTIVE MAINTENANCE PROCEDURES

The following procedures should be performed semiannually, in addition to the daily (8-hour), monthly (160hour), and quarterly (500-hour) procedures. They are summarized in Table 5-1.
5.5.1

Capstan Speed and DC Balance

The potentiometers on the G932 Module (slot A/B04) are used for adjusting dc balance and the FWD, REV, and
REW speeds. Each potentiometer is identified on side 2 of the module.

CAUTION
The master skew tape must not be rewound at 150 ips; doing
so may result in microstretching of the tape.

NOTE
The REW potentiometer is not provided on early versions of

the TU10.

To check capstan speed and dc balance, proceed as follows:
1.

Load Master Skew Tape (800 bpi).

Connect scope to pin B31D2 (G060 compressor output).

Initiate FWD tape motion and measure the compressor waveform for a double-period of 55—57 us
(Figure 5-7).

If necessary, adjust FWD (middle) potentiometer on G932 module for 56 us.

Imitiate REV tape motion and measure the compressor waveform for a double-period of 55—57 us

(Figure 5-7).

If necessary, adjust REV (top) potentiometer on G932 module for 56 us.

Remove the Master Skew Tape (800 bpi); mount a good tape with write ring in place.

Write all 1s for at least 400 feet of tape.

Initiate rewind tape motion and measure the compressor waveform for a double-period of 16—18 us
(Figure 5-8).

10.

If necessary, adjust REW (bottom) potentiometer on G932 module for 16 us.

5-13

le—————
55 -57)5 ———
|

-V

Figure 5-7

o,
R

cP-0127

Compressor Waveform for FWD and REV

le———1618 us ———»
|

Figure 5-8

‘

Do,
i

CP-0128

Compressor Waveform for REW

11.

Stop tape.

12.

Measure voltage at pin AO4P2 for £20 mV. If necessary, adjust dc balance potentiometer on G932
module to obtain minimum of test voltage.

5.5.2

Capstan Acceleration and Deceleration Times

To check capstan acceleration and deceleration, perform the following steps:

Connect the sco’;')e probe to A04J2.

Connect SYNC + to AC4E2.

Set scope to 5 ms/cm horizontal and 0.2 V/cm vertical.

5-14

Load the Data Reliability Diagnostic and answer the questions as follows:

TMA-11 tape drive test (DZTMH-C)
Enter conditions in octal

Vector address = 224

Unit number = 0 9 CHAN
Density = 3

Parity = 1
Unit number =
Record count = 1

Character count = 10

Pattern number = 6
Tape mark =0

Single pass = 0

Enter stalls

Read =1

Write = 1
Turn around =1

Place switch 5 to the up position. This causes the program to yozzel on one record, thereby creating
the forward and reverse motion required to generate forward and reverse acceleration ramps.
Check the forward and reverse acceleration and deceleration times on the scope. The waveforms should

be as shown in Figure 5-10.

Figure 5-9 Deleted

5-15

R 05==——7

8ms |

MAX

(ACCEL),

[

iaflms i
I'MAX |

A 0.5-~|-——~=- '

-V

MAX

(ACCEL)!

-V

a.FWD TAPE

8ms :

‘

(DECEL), T

MOTION

Iszs :

MAX

kDECEL)!

V¥

b.REV TAPE MOTION
cP-0124

Figure 5-10

Acceleration and Deceleration Waveforms

If necessary, adjust the forward and reverse acceleration times with the two potentiometers on the

H603 module. The potentiometer nearest the casting adjusts the forward acceleration (negative
waveform), while the other adjusts the reverse acceleration (positive waveform).

NOTE
The deceleration times are not adjustable.

Figure 5-11

Deleted

Figure 5-12 Deleted

5.5.3

Capstan Jitter

To check capstan jitter, proceed as follows:
1.

Set oscilloscope sweep rate to 20 ;u_s/ cm.

Set oscilloscope gain to 0.5V/cm.

Connect channel A probe to pin A32L1.

Mount a skew tape and initiate FWD tape motion. Check that about 6-1/2 pulses appear on the
screen. (See Figure 5-13.)

5-16

Position the fourth leading edge of this waveform in the center of the screen. Use the horizontal 10X

magnifier to increase the horizontal display rate to 2 us/cm.
Raise the vertical gain to 50 or 100 mV/cm, so that a trace similar to that shown in Figure 5-14 is
obtained.

Check that the waveform jitter is less than 3 cm wide (6 us). If jitter exceeds 6 us, replace or clean
the capstan motor. (Refer to Section 5 of this manual.)

NOTE

If it is necessary to replace the capstan motor, tape path

alignment must be performed at the same time.

Remove the 10X horizontal magnification on the oscilloscope.

Initiate REV tape motion and repeat steps 1 through 8, above.

5.5.4

Static and Dynamic Skew

Mechanical skew is checked by measuring the lead or lag time of each track relative to a reference track. In

9-channel units, track 5 is used as the reference track; in 7-channel units, track 1 is used as the reference track.
The lead or lag times are then plotted to determine the mechanical skew. If the skew exceeds 2.0 us, the tape
attitude with respect to the head assembly can be changed by rotating the upper and lower tape guides in opposite directions.

CAUTION
Mechanical deskewing on a head assembly should not be attempted
again once it has been mechanically deskewed at the time of

installation. If the mechanical skew is out of specification, a new
head assembly should be installed and then electrically deskewed
following the mechanical deskewing procedures. It should be
understood that there is a physical limit to the amount of mechan-

ical skew that can be removed (see text) and this limit must not be
violated or tape damage and instability will result.

5.5.4.1
1.

Mechanical Skew Measurement — Proceed as follows to measure mechanical skew:
Load Master Skew Tape (800 bpi) and initiate FWD tape motion.

Set time base on scope to 5 us/div and connect channel 1 to pin B32L1 (read amplifier output,
track 5).

Invert channel 2 and sync on B32L1. Waveforms should appear as shown in Figure 5-15.

NOTE
For 7-channel units, connect scope to track 1 (pin B32R1).

5-17

-~ —r——T—0VOLTS

—— T

L U

LN I LI

HORIZONTAL=20mS/Cm

VERTICAL =0.5V/cm

\
\

19 I

[

- — -

\FOURTH LEADING

CP- 2147

EDGE

Figure 5-13 Capstan Waveform Showing 6-1/2 Pulses

/ /,‘

]

// f /

,/ ”‘/‘

/‘ 1/
/

e
/
j// /

‘

"’/’l’)’/"’/
‘/’

/ /”,

PIN A32L1
FOURTH LEADING EDGE,

i
i
.

. L L

USING X10 HORIZONTAL

IER
AND INVERTING
MAGNIF

VERTICAL GAIN TO 100 mv/cm

NOTE

Use AC coupler if necessary.

)

’/ '/' / i; / |

dcm

)
(6 ms

)

ACCEPTABLE
RANGE

OF JITTER

Figure 5-14 Capstan Jitter Waveform Magnified

CP-2148

Leave channel 1 connected to the reference track and connect channel 2 to track 7 (pin B32R1).

Measure lead or lag time between track 7 and reference track (see Figure 5-16). Plot lead/lag time
on graph paper as shown in Figure 5-17.

Compare each of the remaining tracks to the reference track and plot the corresponding lead or lag
time (see Figure 5-17). Refer to Table 5-2 for read amplifier pins.

Examine the graph and draw a straight line as shown in Figure 5-17. The line should originate at the
reference track and should be equally spaced between the points farthest to the left and right.

The intersection of the “mean line” drawn in Step 7 with the horizontal line for track 4 represents
the mechanical skew (for example, in Figure 5-17 this skew value is —4.4 us). If the measured skew
exceeds 2 us, refer to the deskewing procedure that follows. (The tape guide system allows
approximately 3 us of mechanical deskewing.)

Figure 5-15

REF. TRACK NO.5
(CHANNEL 1)

REF. TRACK NO.5
(CHANNEL 2, INVERTED)

Sync Pattern for Reference Track

|
|

—

REF. TRACK

—

LEADING

CONDITION

COMPARED
TRACK

REF. TRACK

LAG TIME IN ps—»|

le—

LAGGING CONDITION

|
|
/\/\
/\ COMPARED TRACK

cpP-0129

Figure 5-16

Lead/Lag Patterns

5-19

A.S.A,
TRACK

I1BM
TRAC
NO.

GAP SCATTER BAND

7
3

—\//

/()

/ / /
P

<i /

REFERENCE TRACK

2
3

ESTIMATED"MEAN |LINE"

/
/ 1/
—pD
#

fl/\‘

/ / /
a

VA
/
/
() #

/ / /
N
Cf

-5

. L

T -4
-44

-3

-2

-1

LAG

(SKEW VALUE)

TIME IN ps

Figure 5-17

LEAD

CP-0126

9-Channel Skew Plot

Table 5-2
Read Amplifier Pin Numbers

Track

9 Ch

No-

Vzen|

B32
L1

B32
R1

B32
Fi1

A32
L1

Slot
Pin No.

| B | =

| =

B32
D1

| 2|8

A32 | A32
R1
N1

B32
N1

* Not used in 7-track.

5.5.4.2

Mechanical Skew Adjustment
NOTE

There are three different versions of the head plate assembly.
The early version had no jacking screws, and used movable tape

guides to adjust skew. The second version has jacking screws

incorporated into the front plate (Figure 5-18) and a stepped

machined relief in the rear surface (Figure 5-19). The most
recent version has a spring-loaded, cantilevered head-mounting

surface, a single Phillips head skew adjustment screw, and fixed
guides.

5-20

B32
J1

TAPE

le/“vfld”

SKEW TAPE
FORWARD
DIRECTION

—

COLUMN

GUIDE
LOCATED

SET SCREWS
ON OPPOSITE

GUIDE

PLATE

MAGNETIC
HEAD

MEAN

JACKING

<—QS———HEAD

Vo
b

ON HEAD

SCREW

CENTERLINE

SCREW CENTERLINE

PLATE

N
§

]

BRONZE

MOUNTING —#

PLATE

le—

nin

REFERENCE
EDGE OF

TAPE

TRACKA TRACKS T\ TRACK
.

N\
T4

\\\

ASSEMBLY

N\
N
| __

HEAD GAPS

_——’————

SHOULDER

—-

LINE OF

GAPS

RELIEF

UPPER GUIDE ——v[

LOWER

UPPER

SIDE OF MOUNTING——"""'"—’GD

BUFFER

/c/>cr96/5 2>}:%1/i/7 /L‘:t]////W/

LEFT

LN NN

GLASS

TAPE

No.
5

Px—— TAPE DECK CASTING

GUIDE

LOWER

GUIDE

“

ii?

‘GLASS —}]

RIGHT BUFFER COLUMN

NOTE:

CP-0638

Figure 5-18

Head Plate Assembly

fe—560s —f

this

Azimuth Error (0) Static View

SCOPE | TRACK 5 (9 CHANNEL)

CHAN 1 J TRACK 1 (7 CHANNEL)

|
|

[e—560s —f

cow

is exaggerated for

illustration.

(Head Assembly, Left View)

error (@)
of

Figure 5-19

(Right View)

CWe—i—

cP-0123

Azimuth
purpose

scoPE [ TRACK 4 (9 CHANNEL)

[

CW =

CHAN 2 | TRACK C (7 CHANNEL)

SCOPE {

TRACK 5 (9 CHANNEL)
TRACK t (7 CHANNEL)

[+—

56ps —f

SCOPE [TRACK 4 (9 CHANNEL)
CHAN 2TRACK C (7 CHANNEL)

CP-1350

CP-1354

Figure 5-20 Mechanical Skew Waveforms

Figure 5-21

5-21

Mechanical Skew Waveforms

Early TU10 Head Plates

To reduce mechanical skew on the earliest version of the head plate, proceed as follows:
1.

Remove the two plugs from the buffer column door to expose the tape guide adjustment slots
(Figure 5-2).

CAUTION

Do nor attempt to force the guides. Loosen the set screw

slightly to relieve the binding. If the guide is too loose, tighten
the set screw slightly or the adjustments become unstable.

Load Master Skew Tape (800 bpi) and initiate FWD tape motion.

Carefully rotate the upper and lower tape guides in opposite directions to reduce skew. For example,
in Figure 5-19, the skew can be reduced by tightening the upper guide (CW rotation) and loosening the
lower guide (CCW rotation).

Set time base on scope to 5 us/div and connect channel 1 probe to the Read Amplifier output at pin
B32L1 (track 5 of 9 channel unit) or B32R1 (track 1 of 7 channel unit).

Connect channel 2 probe to pin B32J1 (track 4 of 9 channel unit) or pin A32L1 (outside track of 7
channel unit); observe two waveforms (Figure 5-20). If the waveforms are incorrect, mechanical skew
must be adjusted as described in the following steps.

Mechanical skew can be adjusted and reduced by turning the upper tape guide (CW or CCW) and
turning the lower tape guide (CCW or CW).

NOTE

When one tape guide is rotated CW, the other must be rotated
CCW an equal amount. Turn the tape guides only a very small
amount at any one time.

CW rotation of the upper tape guide and CCW rotation of the lower tape guide will move the waveforms as shown in Figure 5-20.

CCW rotation of the upper tape guide and CW rotation of the lower tape guide will move the waveforms as shown in Figure 5-21.

If mechanical skew is correct, the waveforms should overlay and appear as one waveform. Another
check would be to invert and algebraically add both channels; a straight line (minute ripples only)
should appear if mechanical skew has been adjusted correctly.

10.

Retighten the two guide set screws; replace the head cover and install the guide plug in the buffer
column door.

5-22

NOTE

The capstan should be checked and, if necessary, replaced if
one or more of the following conditions occur:

The waveforms display a left-to-right jitter that exceeds
5 us.

The static skew in the reverse direction is not within 2 us
of the value measured in the forward direction.

The track patterns become totally unstable in the reverse
direction with erratic jumps (sideways).

Second Version Head Plates

To reduce mechanical skew on the second version head plate assembly, proceed as follows:
1.

Load a scratch tape and initiate FWD tape motion. Wind about half the tape onto the take-up reel
then initiate REV tape motion. Use a flashlight to check for gross mechanical misalignment as follows:
a.

Shine the flashlight to create a reflection off the tape at the upper tape guide (Figure 5-22).

Check to see if the tape is puckering against the outer fixed edge of the upper guide, or depressing
the spring loaded inner edge of the upper guide.

If either condition exists, adjust the head plate mechanical alignment as described in Step 2,
below.

If the tape is puckering against the outer fixed edge of the upper guide (head plate assembly in too
far in the casting) continue REV tape motion and adjust the head plate assembly as follows.

Slightly loosen the upper shoulder screw (Figure 5-23) and slowly turn in the upper jacking

screw until the pucker is eliminated.
b.

Lightly retighten the upper shoulder screw.

Operate the tape in both the FWD and REV direction and ensure that the tape travels smoothly,
without damage, through both tape guides.

If the tape is depressing the spring loaded inner edge of the upper guide (head plate assembly out too
far from the casting) continue REV tape motion and adjust the head plate assembly as follows.
a.

Back off the upper jacking screw (Figure 5-23) about one-half turn then slowly tighten the upper
shoulder screw until the tape no longer depresses the inner tape guide edge.

Operate the tape in both the FWD and REYV direction and ensure that the tape travels smoothly,
without damage, through both tape guides.

Set the scope time base to 5 us/div and connect the channel 1 probe to pin B32L1 (track 5 read
amplifier output). Synchronize the scope on channel 1 and connect the channel 2 probe to B32J1
(track 4 read amplifier output).

5-23

NOTE

For 7-track units, connect the scope probes to pins B32R1
(track 1) and A32L1 (track c).

Load a Master Skew Tape (800 bpi). |
Check for minor mechanical misalignment by initiating FWD then REV tape motion while checking

that the forward and reverse skews are approximately equal (within about 2 us of each other). If not,

further adjust the upper jacking screws as described in Step 2 until both skews are approximately equal.

Gently snug down the upper jacking and shoulder screws.

With the skew tape running in REV, monitor the outside tape channels as described in Step 3 and
tighten the ‘head plate assembly in the following sequence.

Gently turn in the middle left jacking screw until it touches the tape deck casting.
FIXED EDGE

SPRING LOADED EDGE —\ A~
\

UPPER GUIDE

HEAD-MOUNTING

—

PLATE

—]
TRACK #4

||||||||¥l

READ GAP

«— CENTERLINE

SKEW ANGLE

TRACK #5 (REF)

REFERENCE EDGE OF TAPE

DATA ON TAPE

LOWER GUIDE

A o
REVERSE

TAPE MOTION
CP-0639

Figure 5-22

Head Plate Assembly Mechanical Alignment

5-24

Lightly tighten the middle left shoulder screw with just enough force to keep the head plate
assembly from twisting when the upper shoulder and jacking screws are tightened.

Ensure that the upper jacking screw is in contact with the casting then, starting with the upper
shoulder screw, alternately tighten both the upper shoulder and upper jacking screws, being
careful not to disturb the displayed skew pattem during the tightening sequence.

Starting with the middle left shoulder screw, alternately tighten the middle left shoulder and
middle left jacking screws, again being careful not to disturb the displayed skew pattern during
the tightening sequence.

Snug down the reference hole shoulder screw.

Replace the head cover.

MIDDLE LEFT

JACKING SCREW \

REV the skew tape, remove the upper reel and tighten the tape guide set screws with an Allen wrench.

/_(©) o

_‘r*“’"“"‘““""""""[

UPPER

SHOULDER

SCREW

3\\\\\ X

- iy

UPPER
JACKING SCREW

MIDDLE LEFT
SHOULDER SCREW

REFERENCE HOLE

SHOULDER SCREW

(
CP-~-0837

Figure 5-23

Head Plate Assembly (Front View)

5-25

Recent Version Head Plate Assemblies

For TU10s with the most recent version of the head plate, proceed as follows:
1.

Remove the head plate cover by removing the 2 Allen head screws.

Load a skew tape.

Place probe 1 at B32L1 (7-channel B32R1). Sync the scope with this input.

Place probe 2 on B32R1. (7-channel B32N1).

Run skew tape forward. Adjust the azimuth screw for minimum peak deflection (Figure 5-24).

Place probe 2 on B32J1 (7-channel A32L1).

Adjust the azimuth screw for minimum peak deflection.

NOT THIS

THIS

(Channel 2 lag)

NOT THIS

(Channel 2 lead)

cp-2123

Figure 5-24

Example of Peak Deflection

NOTE

This version is factory-aligned; the single skew adjustment
described above is the only adjustment necessary.

5.5.5

Electrical Read Skew

Proceed as follows to check and adjust electrical read skew:

Mount M765 Read Buffer Module (slot A/B 28) on a double-height extender board. Set all module
switches two positions clockwise from Stop.

5-26

Set the scope to 2 VOLTS/CM, 10 uSEC/CM, and sync to channel 1 only-pesitive slope. Invert
channel 2 and add the two channels together.

Connect channel 1 of the scope to pin B2812 (track 5) for 9-track; connect to pin B28S2 (track 1)
for 7-track.

Connect channel 2 to the remaining tracks and check the read skew with respect to track 5 (refer to
Table 5-3 for pin numbers). When necessary, adjust the switches on the Read Buffer Module (Figure
5-25) so the scope shows minimum skew in the positive and negative direction of the waveform.
Maximum allowable skew in either direction is 1.8 us. Figure 5-26 illustrates the acceptable

waveforms. If it is not possible to achieve skew less than 1.8 us, it will be necessary to perform a
tape path alignment (Section 5.5.13).

After read skew is set up, remove the Master Skew Tape from the transport. The Read Head can now
be used as a standard to set the Electrical Write Skew.

Table 5-3
Read Buffer Pin Numbers

IBM

9 Ch

TrackNo. | -

4 | 1

A | C

2 | 8

Slot

B2§

B28

B28 | A28

B28

A28

B28

Pin No.

SLOT 28

P @ AK2
SO

AP2

AR2

BB1

BK2

BL2 {SET TWO POSITIONS CLOCKWISE FROM STOP, AND

BR2

BS2

REFERENCE TRACK:CHANNELS

FOR 9-TRACK; CHANNEL{ FOR 7-TRACK.

LEAVE IN THIS POSITION TO BEGIN READ/WRITE DESKEWING.

NOTE
Switches on M765 in slot 28 for read deskew.
Switches on M763 in slot 26 for write deskew.
Most recent M785 revision has no swiiches.

No electrical read deskew can be performed,
CP-0291

Figure 5-25

Switch Location Guide

5-277

WAVEFORM AT CH. 1 ____[

l l

WAVEFORM AT CH. 2 ____[

I I

_*jg$fi;;_

TIME
LAGus
—sf "}e—1.8
CHANNEL 2
OF SCOPE

e [

ZERO STATIC

SKEW

ACCEPTABLE
SKEW

LEAD TIME

—sl

Je— 3.6ps

EXCESSIVE

SKEW

LEAD TIME

je— 3.6us LAG TIME o\ hrosivE

SKEW

CP-0224

Figure 5-26
5.5.6

Examples of Electrical Skew, Read and Write

FElectrical Write Skew

Proceed as follows to check the electrical write skew:
1.

Mount a good quality scratch tape with write ring.

Mount the M763 Write Buffer Module (slot A/B 26) on the extender boards.
Put the TU10 online.
Write an all-1 data pattern. (Table 5-4 shows cable connections when using a magtape tester.)

Set all of the switches on the Write Buffer Module to the center position.

Set scope to 2 VOLTS/CM, 10 uSEC/CM, and sync to channel 1 only-positive slope. Invert channel 2
and add the two channels together.

Connect channel 1 of scope to pin B28L2 (track 5); for 7-track connect to pin B28S2 (track 1).
Select the transport by means of the UNIT SELECT switches on the tester and initiate a write FWD
command.

Connect channel 2 of scope to the remaining tracks and check the write skew with respect to track 5
(refer to Table 5-3 for pin numbers). When necessary, adjust the switches on the M763 Write Buffer
Module for minimum skew. (Each turn of a Write Buffer switch produces a time change of 1.8 us.)
Refer to Figure 5-26 for examples of electrical skew.

5-28

Table 54
Magtape Tester Connecticns

5.5.7

Tester

TU10

AAO01
AAQ02
AAO03

A17/B17, Side 1
A18/B18, Side 2
A17/B17, Side 2

AA04

A18/B18, Side 1

ABO1

A19/B19, Side 2

Read and Write Slice Levels

5.5.7.1

Units Up to No. 10320 — Proceed as follows to check and adjust the slice levels:

Put the TU1O online.

Setscopeto 1 VOLT/CM, 10 uSEC/CM, and sync to channel 1 only-negative slope.

Connect channel 1 to pin B31L2 (track 5).

Initiate a series of WRITE FORWARD commands.

Measure the compressor waveform as shown in Figure 5-27 and, if necessary, adjust the upper
potentiometer on the G060 Module.

Initiate READ FWD commands.

Measure the compressor waveform as shown in Figure 5-28 and, if necessary, adjust the lower
potentiometer on the G060 Module.

READ

WRITE SLICE LEVEL
ov—

o — |[—
-1/2V —

—

T
T_____

-1V

|—

—

.__...__T_____

-8y —

-8V —
7

Figure 5-27

SLICE LEVEL

CP-0I30

Write Slice Level Measurement

Figure 5-28

CP-013!

Read Slice Level Measurement

5.5.7.2 Units Above No. 10320 — Proceed as follows to check and adjust the slice levels for those TU10s with
a G093 (slot 30), G094 (slot 29), GO60-YA (slot 31), and M765-YA (slot 28).

Ensure that the poteritiometers on the GO60-Y
A are fully clockwise. Verify that test points AE1 and
AB1 are at minimum levels (i.e., as close to OV as possible).

5-29

Power down the drive, and mount the G094 on a double extender. (G094s at Rev B and subsequent
need not be put out on an extender.)

Power up the drive.

To adjust write threshold:

Ground A29E1, using a jumper wire. (It is possible to ground this point without causing damage
to the circuit generating the WRITE L signal.)

Place scope probe on the junction between L15, R23, and R22 pins.. (For G094s at Rev B and
subsequent, place scope probe on BV2.)

Adjust the bottom potentiometer (R22) for -5.0V.

To adjust read threshold:

Remove ground from A29E]1.

Leave probe in place. Adjust the top potentiometer (R23) for 4.0V.

Stop the tape and remove the jumper from A29E]1.

Run the Data Reliability diagnostic (MAINDEC-11-DZTMB for 9-track; MAINDEC-11-DZTMC for
7-track) to verify correct read/write operation.
Return the transport to operational status.
5.5.8

Industry-Compatible Tape Tracking

Check industry-compatible tape tracking as follows:
1.

Position a scratch tape at BOT; using the appropriate diagnostic, write about 10 feet of tape with an
all-1s pattern. Make records as long as possible.
Stop the diagnostic, and rewind the tape.

Remove the tape from the drive, take it to a work area, and proceed as follows:
a.

Unwind tape until you reach the BOT marker; cut the tape with scissors.

Unwind 3 feet of tape beyond the BOT marker; cut the tape again.

Shake Magna-see solution vigorously.

Dip the 3-foot section of tape in Magna-see solution. (Refer to Figure 5-29.) Try to keep a loop
of tape at the bottom of the can.

5-30

Work the tape back and forth until the entire 3-foot section (except for the ends being held) has
been dipped into the solution.

Allow the tape to dry. Data written on the tape should appear as the solution dries. (See Figure

5-30.) If necessary, dip the tape again.

When the tape has been developed, proceed as follows:

Place the developed tape flat on a white background (e.g., white sheet of paper).

Make sure that the tape is flat, then place a weight on each end.

Check four points along the reference edge (edge with BOT marker) 1-1/2 inches apart. (See
Figure 5-30.)

Set up microscope according to Figure 5-31; lay the penlight flat on the table, positioned so that

it shines on the reflector.

7660-24

Figure 5-29

Dipping Tape Section in Magna-see

N *

N %
7660-27

‘

TU45A/TMO3

Figure 5-30

Developed Tape Segment

5-31

RECORDED

REFERENCE

MICROSCOPE

EDGE

TRACK

TRANSPARENT

REFLECTOR

TAPE

PENLIGHT

CASE

Figure 5-31

7660-28

Track No. 1 to Reference Edge Measurement

Ensure a distance of 0.007 £ 0.003 inch for 9-track operation and 0.016 £ 0.006 inch for 7-track

operation from the reference edge to track 1 at each of the four points mentioned in Step c, above.
NOTE

If the tracking check described above fails, tape path
alignment must be performed at this time.

Install a new BOT marker 15 feet from the front of the tape on the non-oxide side, against the reference
edge. (The reference edge faces the operator when the tape is installed on the transport.)

5.5.9

Power Supply Voltages (does not apply to early master units)

Proceed as follows to check the power supply voltages:

Connect voltmeter to +5V and GND terminals at the side of the logic rack facing the casting.

Voltage should measure +5V £ 0.25V.

Connect voltmeter to =15V and GND terminals.

Voltage should measure =15V £ 0.5V.

5-32

If necessary, adjust potentiometer on voltage regulator board.

CAUTION
Be sure to slide the regulator board partially out so that

there are no wires in the way that could be shorted.

5.5.10

Read/Write Interlock Assembly

To perform the following adjustment, refer to Figure 5-32:

Loosen the two screws securing the switch to the bracket just enough to allow the switch to be moved.

Loosen the locknut and adjusting screw several turns (see detail B, Figure 5-32).

Insert the small end of the setting gauge (No. 29-18610) in front of the roll pin through the bottom of
the bracket so that it fits between pin and bracket body edge. Tighten the adjusting screw until the
switch just actuates.

Tighten the two screws securing the switch to the bracket and lock adjusting screw using the locknut.

Loosen the two solenoid mounting screws on the left of the interlock assembly (see detail A, Figure

5-32).

Insert the large end of the setting gauge in front of the roll pin as described in Step 3. Push soleinoid
body forward until plunger bottoms out, then tighten the solenoid mounting screws, keeping solenoid

body parallel to upper edge of bracket.

Loosen bottom screws securing the interlock assembly to mounting bracket (see detail C, Figure 5-32).

Insert ring gauge (No. 29-18608) on reel, lock it, and spin reel to check for even rotation.

Push interlock assembly forward until the shaft bottoms in the solenoid and the small spring is fully

depressed.

10.

Tighten screws securing assembly to bracket, remove ring gauge, and check for free movement of
solenoid shaft in casting.

5.5.11

Tape Guide Rollers

Proceed as follows to adjust the tape guide rollers:

Release service locks and pull transport forward approximately 8 to 10 inches.

Loosen the clamp lock screw (see Figure 5-33).

Use gauge No. 29-18607 to adjust the tape guide roller as shown in Figure 5-33.

Tighten the clamp lock screw.

Repeat the same procedure for the second tape guide roller.

5-33

SOLENOID WIRES

SOLENOID (ADJUSTABLE)———=

SOLENOID SHAFT

SWITCH (ADJUSTABLE)

SWITCH

Nz czo

INTERLOCK ASSEMBLY
ADJUSTMENT
SCREWS

(UNDERSIDE OF
MOUNTING BRACKET)

SOLENOID
ADJUSTMENT
SCREWS (LEFT OF
INTERLOCK ASSEMBLY

SWITCH

ADJUSTMENT
SCREW

CP-0096

AS VIEWED FROM

FRONT OF TU10)

Figure 5-32

Read/Write Interlock Assembly

FRONT OF

/‘ TRANSPORT

TAPE ROLLER
GUIDE ALIGNMENT

/ GAUGE # 29-18607
ROLLER SHAFT
LOCK CLAM P

TAPE GUIDE ROLLER |

# 6 X 32 X 1/2" ALLEN
CLAMP

LOCK

SCREW ‘\

TAPE GUIDE /

ROLLER

R
.

-==l----

|__ —=|-==-

EXERT PRESSURE

AT THIS POINT

DURING

ALIGNMENT

SHAFT

CP-0105

CLAMP

MOUNTING

SCREW

Figure 5-33

Tape Guide Roller Adjustment

5-34

Delay Diode Check

5.5.12

Set the magtape tester to EMD. Check the status of each of the delay diodes (M768 Module, Figure 5-34) by

setting the following commands and pushing CLEAR and SET: (If no magtape tester is available, use the
appropriate DRIVE FUNCTION TIMER diagnostic to make this check.)

Alpha

Write

Forward

Octal Reading

1
0

0
1

0
1
1

0
0
0

1
0
1

1
1
0

0
0
1

0
:

Channel Lights

Reverse

9-Track

7-Track

200
240

700
340

200 (600)* | 200 (600)*

400
200
400

* Later units have an additional write shutdown count, hence the octal code 600.

VIEW OF MODULE
*

I
T

|
I
;

D29

REV STOP
2

l,_

b1z

===\FORRD STOP|===
N

DR -J.-_'l— _____ 1’-——

- '{WDSTART 8}'

D19

WR STOP

__I
T

FOR RD START

-:_ ______ _:-

D27
START

-’

REV

Jd L.IJ

TOP

1__
e

——— ;7

-L

- = .J—-—'r______:-——

b———

==
e _— -

TOP VIEW

9 TRACK

_____ _“IREV START1 I‘—

—‘IFORRDSTARTl_"
WR STOP |

—bt-:v
STOP J——

FOR RD STOP

D38

FTTTT=

WD START
4

D20
WR STOP 2

D29
REV STOP 2

D39

————— A

D37
WD START 2

—

D19

"'"L

—————

I REV STOP4 I

_____

—_

WD START
8

= —"""'L

——-1

ees

7 TRACK

Figure 5-34

CP-0290

M768 Diode Locations

5-35

5.5.13

Tape Path Alignment

5.5.13.1 Tools Required — The following tools are required to perform a tape path alignment:
Tool

DEC Part No.

Skew Tape (800 bpi)

29-19224

1200 ft

600 ft

29-22020

Reel Hub Tool

29-18611

Roller Guide Tool

29-18607

Microscope

29-20273

Magna-see

29-16871

Penlight

Alignment Doors

74-13969

Depth Micrometer
Shim Stock

29-22039
|

0.001 inch

48-50023-01

0.002 inch (red)

48-50023-03

0.003 inch (green)

48-50023-04

0.004 inch (tan)

48-50023-05

0.005 inch (blue)

48-50023-06

0.0075 inch (transparent)

48-50023-07

0.010 inch (brown)

48-50023-08

5.5.13.2 When to Perform - A tape path alignment should be performed:

When a capstan, capstan motor, roller guide, or head plate is replaced.

When forward and/or reverse skew is found to exceed specifications.

When an amplitude difference of more than 10 percent is seen between forward and reverse read amp
output.

When a visible change in the tape’s path across the capstan is apparent when changing from forward to
reverse tape motion.

When measurement of reference edge to Track 1 of the developed (with Magna-see solution) tape shows
a result different from 0.007 inch (£0.003).

When, after tape speed adjustment, mechanical skew adjustment, capstan ramp adjustment, and read
amplitude adjustment have all been performed, and all of the applicable diagnostics have been run,
the unit is still incompatible with other tape transports.

5.5.13.3

Objectives — The objectives of tape path alignment are:

To establish a single plane for tape to travel from supply reel to take-up reel, independent of the
capstan and fixed guides (part of the head plate assembly). This is accomplished by aligning reel hubs
and roller guides.

5-36

To mount the head plate in the plane established in 1, above. This is accomplished by establishing the

relationship between the reference surfaces used in 1, above, and the surface onto which the head plate
is to be mounted. - If this relationship is not nominal, appropriate shims are placed underneath the
head plate so as to bring the reference edges of the fixed guides into the proper plane.

To minimize the amount of distortion to the tape as it travels through the plane established in 1 and 2,
above. This is accomplished by shimming the capstan motor in such a way that the capstan motor

shaft becomes perpendicular to the tape path.
NOTE

The effect of accomplishing 1, 2, and 3, above, is to minimize

static skew, dynamic skew, and tracking error in both forward

and reverse directions. Skew is the total amount of non-perpendicularity of characters written on tape. Tracking is
defined by ANSI standard as the measurements from the

reference edge to each track center line. Improper tracking
takes two forms:
@

Read — A tape transport that is tracking incorrectly will

not have its read head elements centered over tracks
correctly written by another tape transport.

Write — A tape transport tracking incorrectly will

write tracks of data that are not correctly spaced from
the reference edge of the tape. Therefore, a transport

with proper tracking alignment would not have its
read head elements centered on the incorrectly
written tracks.

5.5.13.4

Tape Path Alignment Procedure — To establish a basic plane for the tape path, proceed as follows:

Remove supply reel and take-up reel.

Use reel hub alignment tool to check alignment of both reel hubs. A small amount of friction should
be felt when sliding the tool in and out between alignment boss and reel hub. It should not be possible
to move the tool back and forth between the hub and the alignment boss; if it is possible, loosen the
Allen screws and adjust the hub as necessary (Figure 5-35).

Rotate hub, checking fit of alignment tool at several intervals. Some high and low spots will probably

be found, but tool should not bind hard or become loose when moving toward and away from the

casting. Replace hub and/or motor if either of these conditions exist.

Remove upper roller guide ramp. (See Figure 5-36.)

Slide roller guide alignment tool underneath upper roller guide. A small amount of friction should be
felt as the tool is slid back and forth under roller guide. Loosen clamp on back side of casting and
adjust roller guide if necessary. (See Figure 5-37.)

5-37

7660-3

Front View

REEL

HUB

TOP

ALIGNMENT

GAUGE #29-18611

TRANSPORT

(Should feel friction
in vertical ($) axis.
Gauge should not move
in horizontal (=) axis.)

HUB

LOCKING SCREW
ACCESS OPENING

MACHINED
ALIGNMENT

BOSS

REEL HUB ALLEN
LOCKING

(

SCREWS (2)

TEFLON

WASHER

3/16 INCH KEY —
'

REEL

HUB

REEL

MOTOR

DRIVE

SHAFT

ASSEMBLY

FRONT OF

-LQ~g

TRANSPORT

CP-01049

Figure 5-35

Side View

Reel Hub Adjustment

5-38

UPPER
ROLLER

LOWER

ROLLER

GUIDE

7660-12

Figure 5-36

Location of Upper and Lower Roller Guides

Slide one side of roller guide alignment tool under lower roller guide. You should feel slight amount
of friction as you move tool back and forth. Adjust if necessary. (See Figure 5-37.)
Load a scratch tape. Run tape forward for 5 seconds.

Ensure that tape is not touching either side of supply or take-up reel while tape is moving.

Look for tape puckering against either column floor or door glass at both upper and lower roller
guides.

If either of these conditions exist, recheck the associated roller guide and reel hub adjustments.

Dismount tape. Reinstall upper roller guide ramp.
CAUTION

When installing ramp, it is necessary to push down on right side of

ramp while tightening screw. Otherwise, it is possible that the ramp
will be touching tape.

5-39

;

Figure 5-37

Lower Roller Guide Adjustment

Roller Guide Adjustment (Sheet 1 of 2)

5-40

The reel hubs and roller guides are now set in the same plane as the vacuum columns. (See Figure

5-38.)

To mount the head plate in the plane of the tape path, proceed as follows:
1.

Remove head plate cover.

Disconnect Write, Read, and Erase head cables from head.

Loosen the three shoulder screws and remove head assembly.

M\
FRONT OF

/ TRANSPORT

TAPE R OLLER
GUIDE ALIGNMENT

/ GAUGE # 29-18607
ROLLER SHAFT
LOCK CLAMP

TAPE GUIDE

ROLLER

# 6 X 32X 1/2" ALLEN
CLAMP

LOCK

SCREW —\

o |

@®

-===----Hl|------

EXERT PRESSURE

it iniaid o [| S

DURING

TAPE GUIDE

ROLLER

AT THIS POINT

ALIGNMENT

V\fi\

SHAFT

CLAMP
MOUNTING
SCREW

CP-0105

Side View of Roller Guide Tool Insertion

Figure 5-37

SUPPLY
REEL

LOWER
ROLLER
GUIDE

Roller Guide Adjustments (Sheet 2 of 2)

RIGHT
VACUUM

LEFT
VACUUM

COLUMN

UPPER
ROLLER
GUIDE

TAKE -UP
REEL

MACHINED

B0OSS

MACH INED
BOSS
MACHINED

REFERENCE

SURFACES
CP-1993

Figure 5-38

Machined Reference Surfaces Used to Establish Tape Path Plane

5-41

Measure depth from outer surface of left vacuum column to surface onto which head plate was
mounted. Nominal value is 1.120 inches. Call this value “HMS”’. (See Figure 5-39.)
NOTE

This measurement may prove difficult to make since only
one side of the micrometer can be seated on the vacuum
column surface. Therefore, proceed as follows:

Place the micrometer base at 45-degree angle with

the vacuum column surface (to give greater seating area).

Make the measurement with the micrometer shaft as
close as possible to vacuum column wall. (Permits more
leverage to keep the micrometer base seated and less
distance to project error.)

Repeat the measurement several times to verify results.

Subtract 1.120 from HMS (HMS-1.120).

6.*

If result obtained in Step 5 is zero or negative, mount head plate without shims.

If result obtained in Step 5 is positive, cut three.horseshoe-sfiaped shims of the value obtained in

Step 5 and place one under each of the three shoulder screws when mounting head plate. (Shims go
between head plate and mounting surface.) See Paragraph 3 for shim color codes. Also cut shim of

same value to surround vacuum port which goes to tape cleaner (prevents air leakage). (See Figure
5-40.)

Making Capstan Motor Shaft Perpendicular to Tape Path

Steps 1 through 21 below, will ensure that the capstan motor shaft is perpendicular to the tape path. There are
two conditions that can cause non-perpendicularity of the motor shaft to the tape path. One is the capstan

motor shaft not being perpendicular to the mounting face of the motor. Figures 5-41a and 5-41c are examples
of this condition. (Specifications allow 0.005 inch of non-perpendicularity of the motor shaft.) The other
condition is non-parallelism between the motor mounting surface on the back of the casting and the front
surface of the casting. Figure 5-41b illustrates this situation. (Specifications allow 0.004 inch of non-parallelism
between the machined surfaces on the front and back of the casting.)

The effect of the capstan motor shaft not being perpendicular to the tape path will depend on the direction of
the non-perpendicularity (i.e., whether the motor shaft is pointing up, down, toward the left, or toward the

right). When the shaft is pointing down (Figure 5-41a), the top of the capstan is away from the casting, causing
the tape to track away from the casting. Hard guiding will occur on the vacuum door glass and the fixed guides
in both forward and reverse directions. When the shaft is pointing up (Figure 5-41b), the bottom of the capstan
is away from the casting, causing the tape to track toward the casting. Hard guiding will occur on the vacuum

column floor and the spring-loaded guides in both forward and reverse directions. When the shaft is pointing
toward the left (Figure 5-41¢), the tape will track away from the casting in the forward direction and toward the
casting in the reverse direction. If the shaft were pointing toward the right, the opposit‘e would be true (i.e., the
tape would track toward the casting in the forward direction and away from the casting in the reverse direction).
*If a new head assembly is mounted, electrical write deskew will have to be performed. This should be done after the read mechanical skew adjustment.

5-42

GSRRS
4.

DEPTH

HEAD PLATE

MICROMETER

MOUNTING

SURFACE

LEFT VACUUM
COLUMN

7660-18

DEPTH
MICROMETER

LEFT
VACUUM

COLUMN

HEAD PLATE
MOUNTING
SURFACE
cP-1991

Figure 5-39

Bottom View of HMS Measurement

Measurement of Head Plate Mounting Surface (HMS)

5-43

HOLES FOR MOUNTING

SCREWS (3)

VACUUM PORT

7660-20

Figure 5-40

Location of Shims under Head Plate Assembly

CP-1996
CP-1994

CP-1995

Side View — Capstan Motor

c. Top View — Capstan Tipped

Shaft Pointed Down due to

Shaft Pointing Up due to

Toward Casting on Left Side

Non-Perpendicularity of

Non-Parallelism of Machined

and Away from Casting on

Shaft

Motor Mounting Surfaces

Right Side due to Non-Perpendicularity of Motor Shaft

Figure 5-41

Examples of Capstan Non-Perpendicularity

5-44

Remove the capstan by loosening the capstan locking clamp with an Allen wrench and remove the

capstan and clamp.
NOTE

If the capstan is hard to remove, it may be bent, and should
be replaced. The inside of the capstan should be checked for
burrs in the area of the slots. The end of the capstan motor

shaft should be checked for burrs also. (See Figure 5-42.)

CAPSTAN MOTOR
SHAFT

{
.

BURRS TO BE
REMOVED

CP-1987

Figure 5-42

Location of Possible Capstan Burrs

Remove the capstan motor by unplugging P1 from the H606 Power Board and removing the four
bolts holding the capstan motor on the casting.

CAUTION
Because the bolt heads are in front of the casting and the
motor is on the rear, caution should be used that the motor
does not fall when the screws are removed.

DO NOT ATTEMPT to remove the tachometer portion of
the motor; the two are replaced as an assembly.

Check the capstan motor and casting for the following:
a.

The capstan motor specification template does not interfere with the motor mounting on the

casting. If there is interference, remove the template.
b.

The motor does not have any burrs on the mounting surface that would prevent it from mounting
squarely on the casting.

Ensure the mounting surface of both the motor and casting are free of dirt, gummy substances,

and burrs pushed up by machining operations.

Lift up and remove the vacuum column door.

Measure depth from the outer surface of left vacuum column to floor of left vacuum column.

Nominal depth = 0.502. Call this value LVC. (See Figure 5-43.)

5-45

7660-11
a.

Placement of Depth M 1crome ter

DEPTH

MICROMETER

LEFT
VACUUM
COLUMN
CP-1990

b. Top V iew of LVC Measurement

Figure 5-43

Measuring Depth of Left Vacuum Column (LVC)

5-4€

Subtract 0.500 from LVC; call the resulting value X (LVC-0.500 = X). Record value X as it will be
used in Step 16.

NOTE
X is the distance that the inside edge of the tape should be
from the floor of the left vacuum column when the outside
edge is 0.002 inch from the outer surface of left vacuum

column. If our capstan motor shaft is perpendicular to the
tape path and the operations described above have been
performed correctly, X will be equal to this distance.

Remount the capstan motor on the casting (four bolts). Tighten the mounting bolts.

Clean the capstan with a water-dampened Kimwipe or lint-free cloth. Do not use any cleaner other
than water on capstan.

Reposition the capstan on the capstan motor shaft. Tighten the clamp.

10.

The reference edge of the fixed guides is now set into the plane of the tape coming out of the vacuum
columns. (See Figure 5-44.)

11.

Load a good quality tape using the alignment glass (Figure 5-45). It will be necessary to hold glass

doors with one hand while pressing ‘‘load’ with other. (See Figure 5-46.)

12.

Ensure that the tape rides in the center of the capstan. This can be done by running the tape forward
several feet and eyeballing the tape position on the capstan. The capstan can be moved in or out to
ensure that the tape is in the middle of the capstan. The capstan alignment tool (29-18609) can be

used for coarse adjustment. Ensure that the capstan is clamped securely to the capstan motor shaft.

READ/WRITE
HEAD

zHEAD

MOUNTING

FIXED GUIDE ON

/" REFERENCE EDGE

\DOTTED LINE

SURFACE

GUIDE

SPRING LOADED

INDICATES

TAPE PATH

¥*Dimension from reference edge of fixed guide to

**Nominal vacuum column depth is 0.502; nominal

mounting surface set up by head plate jigging in

tape width is 0.498; one edge of tape should be

factory.

0.002 from floor of vacuum column; other edge
should be 0.002 from glass.
cP-1983

Figure 5-44

Head Plate Assembly Mounted in the Plane
of the Tape Path

5-47

IF THERE IS MASKING TAPE ON
ALIGNMENT GLASS, REMOVE IT
TAPE IS DETRIMENTAL TO
PROPER

ALIGNMENT

v
!

|
y

|‘

I|'

14"

)
|1

[

14"

MATERIAL IS

0.12" THICK

LEXAN

]
]

!
__JL_

LL::".'."'_.‘__ ____

a. LEFT COLUMN GLASS

b. RIGHT COLUMN GLASS
CP-1989

Figure 5-45

You are now ready to begin aligning the capstan motor shaft (making it perpendicular to tape path).
This will be done by placing shims between the capstan motor mounting face and the casting surface
onto which the capstan motor is mounted. Shims will be placed in the vertical axis to correct for
capstan steering when both forward and reverse tape motion produces the same steering characteristic

(i.e., tape steers toward the deck plate or toward the vacuum column glass in both directions). Shims
will be placed in the horizontal axis if forward and reverse tape motion show opposite steering
characteristics. (See Figure 5-47.)

NOTE
To facilitate this step, note the following:

The sequence of tightening the bolts on the capstan motor

is important. Each time the bolts are tightened in a
particular procedure, they must be tightened in the same
order. This allows the procedure to be repeated while
keeping the motor in the exact same position.

The use of sharp scissors on the plastic shim stock is
necessary to keep the edges from curling up. The

plastic shim stock sizes are identifiable by the color
coding as follows:
Amber

0.001 inch

Red

0.002 inch

Green

0.003 inch

Tan

0.004 inch

Blue

0.005 inch

Transparent

0.0075 inch

Brown

0.010 inch

5-48

13.

Alignment Glass

LEFT COLUMN

GLASS

R
S

SR SR

RS S

R
*

RN
W
&

7660-17

Figure 5-46

Us ing A lignment Glass to Load Tape

5-49

The use of a good quality tape is necessary for correct
capstan alignment. A used or abused tape will not run
true over the capstan, causing false readings during the
capstan alignment procedure.

14.

Cut one piece of each type of shim stock as indicated in Figure 5-48. Exact dimensions of shim stock
are not critical; main thing is to have a manageable size to use as a feeler gauge. The blunt point shown

in Figure 5-48 also minimizes curling of the end which will be used.

Run tape forward from BOT for 5 seconds.

MOUNTING
SCREWS
_

N
DECK
PLATE

SHIM

CAPSTAN

MOTOR

CAPSTAN
a. SIDE

\QD —

VIEW

FRONT VIEW
Shim placed in horizontal
axis

when forward ond
reverse steering are
opposite.
PP

_—

c. FRONT VIEW

Shims placedin vertical
axis when forward and
reverse steering are

similar,

[o2)

15.

cpP-2121

Figure 5-47

Capstan Motor Shim Placement

5-50

>'/BLUNT
<

2“

POINT

CpP-1988

Figure 5-48

l6.

Capstan Motor Shim

Using shim stock and penlight determine the spacing (Y) between the inside edge of the tapé and the
floor of the left vacuum column. (See Figure 5-49.) The method of measuring space Y is shown in

Figure 5-50 and is as follows:
d.

Slide shim stock underneath inside edge of tape at slot between top of left column and capstan.

Shine light onto full width of tape while moving shim stock back and forth; look for puckering.
Measurement has been obtained when you select a piece of shim stock which causes small

amount of friction when sliding back and forth, yet no visible pucker.

NOTE

Value Y (obtained in Step' 16) must be equal to value X (obtained
in Step 6). The tolerance for value Y is £0.002 inch. In no case
shall value Y be less than 0.001 inch. Continue with procedure to
determine corrective action.

17.

Run tape reverse for 5 seconds. Measure tape to column spacing to obtain value Y.

Value Y obtained in Step 16 must equal value Y obtained in Step 17, £0.001 inch.

17A.

In other words, it will be necessary to continue shimming the capstan motor as described in Step 13
until value Y is:
No greater than value X plus 0.002 inch in forward or reverse.
No less than value X minus 0.002 inch in forward or reverse (no less than 0.001 inch in any case).
The difference between forward and reverse does not exceed 0.001 inch.

FLOOR OF LEFT
VACUUM COLUMN
/ CAPSTAN

—

IIY

|7 J*_ MAGNETIC
TAPE
CP-1985

Figure 5-49

Gap (Y) from Tape to Floor of Left Column

5-51

7660-15

Figure 5-50

Measurement of Tape Gap (Y) with Penlight and Shim

5-52

17B.

Shimming will be accomplished as follows:

If tape is too close to casting in forward and reverse: loosen motor mounting bolts, place a shim
under the motor adjacent to the bolt at 6 o’clock, tighten bolts, and repeat Steps 15, 16 and 17.

If tape is too far away from casting in both forward and reverse: loosen motor mounting bolts,
place a shim under the motor adjacent to the bolt at 12 o’clock, tighten bolts, and repeat Steps
15,16 and 17.

If tape is too close to casting in forward and too far away from casting in reverse: loosen motor

mounting bolts, place a shim under the motor adjacent to the bolt at 3 o’clock, tighten bolts, and
repeat Steps 15, 16 and 17.

If tape is too far away from casting in forward and too close to casting in reverse: loosen motor
mounting bolts, place a shim under the motor adjacent to the bolt at 9 o’clock, tighten bolts,
and repeat Steps 15, 16 and 17.

17C.

If measurements meet the criteria stated in Step 17A, go to Step 18.

Following guidelines should be adhered to:

A 0.005 inch shim is usually a good starting point, but almost any size shim (up to 0.010 inch)
may be necessary to accomplish the criteria stated in 17A.

If a shim size greater than 0.010 inch is called for, it is advisable to rotate the motor mounting
90 degrees and try again; or change the motor.

Inno case should there be a shim at the two ends of the same axis (e.g., 3 and 9 o’clock, or 6 and
12 o’clock). In other words, if the formula in Step 17B says to place a shim at 6 o’clock and
there is already a shim at 12 o’clock, decrease the shim size at 12 o’clock instead.

It is quite normal to have one shim in each of the two axes. In fact, it is desirable, as this will
make the procedure less subject to irregularities due to variations in bolt tightening sequences.

(A shim in the vertical axis will allow the motor to rock in the horizontal axis.) For this reason,

at the start of a shimming session, place a shim of half the value in the horizontal axis, if a shim
is placed in the vertical axis due to the formula in Step 17A (or vice versa). This is only a time-

saving starting point; both shims may need adjustment on re-runs through Steps 16 and 17.

Itisacceptable to use multiple shims under a given bolt to obtain the desired value (e.g., placing

a 0.005 inch and 0.004 inch together to obtain 0.009 inch).

If Steps 16 and 17 seem impossible to accomplish, or if measurements taken in these steps are

inconsistent, see Step 20 for explanation of capstan and tape phenomena.

It should be noted that, while a guiding surface exists on the right side of the capstan (the head
plate guides), none exists on the left side (left vacuum column). This will tend to make forward

capstan steering look less severe than reverse. Therefore, small differences between forward and
reverse are sometimes better corrected by shims in the vertical axis.

5-53

18.

Mount a skew tape; adjust mechanical skew per quarterly P.M. schedule.

19.

With skew tape mounted, scoping tracks 1 and 9 (9-track) or O and 6 (7-track), evaluate capstan
alignment as follows:
a.

Run tape forward looking at skew signal on scope. Skew jitter must be less than 2 us.

While tape is running forward, move upper spring-loaded guide (Figuré 5-51) away from tape.
Skew jitter must not increase more than 2 us (take care not to touch tape).

While tape is running forward, look at tape interface to upper fixed guide (use a penlight to
reflect light off the tape surface); ensure that no puckering exists.

Run tape reverse, looking at skew signal on scope. Basic skew must not change more than 0.5 us,
and jitter must remain less than 2 us.

While tape is running reverse, move upper spring-loaded guide away from the tape. Skew must
not increase more than 2 us.

While tape is running reverse, look at tape interface to upper fixed guide; ensure that no
puckering exists.

Corrective Action:

If skew increases by more than 2 us in either forward or reverse when the spring guide is depressed,
it should be assumed that the tape is running too close to the casting in that direction of tape

travel.
b.

If tape is puckering on the guide in either forward or reverse, or if the skew or jitter is excessive
in forward or reverse yet does not increase when the upper spring guide is depressed, it should be
assumed that the tape is running too far away from the casting in that direction of tape motion.

UPPER
SRING-LOADED

]
,

GUIDE

7, m

READ/WRITE

HEAD

/
/

CpP-213)

Figure 5-51

Location of Upper Spring-Loaded Guide on Capstan

5-54

If neither condition exists, go to Step 20.

If a or b exists, make final shimming corrections according to procedure in Step 17B.

NOTE
After all shimming is done in this step, it will be necessary
to verify that the criteria in Step 17A (tape to column
spacing) are still met.

20.

Run tape forward. Look in the slot between the inside tape edge and the left vacuum column floor
while the tape is moving forward. If room light is not adequate, shine penlight through from inside
of vacuum column. (See Figure 5-52.)

A constant space (width of light) should be seen in this slot as the tape moves forward. Periodic width

change at a very low frequency (less than one per second) is probably due to tape defects; these
changes may be disregarded unless they are very repetitive and cause wide excursions. Higher frequency

width changes (5 to 10 times per second) are usually caused by a bent capstan. If this occurs, it will
be necessary to replace the capstan and recheck tape-to-column spacing with shim stock feeler gauges.

21.

22.

Run tape in reverse. Check slot width to same criteria as Step 20.

Replace vacuum column door. Run skew tape forward; ensure that skew does not exceed 2 us. Run
tape reverse; ensure that packet width does not exceed 2.5 us. If either criteria fails, suspect roller

guide adjustment problem.

SHINE

LIGHT
HERE IF

NECESSARY
1.

LoOK

CAPSTAN~__

TM~ THROUGH
SLOT HERE

TAPE

B” ”

RIGHT WALL OF

LEFT

VACUUM
-

COLUMN
CP-1984

CP-1986

a. Front View

Figure 5-52

b. Right Side View

Capstan Wobble Check

5-55

5.5.14

Vacuum System Adjustments (Units above No. 10320)

TU10s above approximately no. 10320 contain a vacuum blower driven by an induction motor through a pulley
and belt. This system may require adjustment either to change the operating frequency, which necessitates a
pulley readjustment as described below, or to change the belt. (Refer to Section 5.6.14.)

To make any adjustments on this assembly, proceed as follo'wsf
1.

Remove the four Phillips head screws holding the cover in place, and remove the cover (Figure 5-53).

TENSION
ADJUSTMENT
SCREW

CP-2126

| Figure 5-53 TU10 Cover Assembly

5-56

Remove the long 10/32-inch Phillips head screw that passes through the left member of the TU10
cruciform to secure the left side of the vacuum assembly.

Loosen, but do not remove, the Phillips head screws that hold the right side of the assembly to the
casting.

Loosen all of the nuts (four) that secure the motor mounting plate to the vacuum system chassis.

Lift the left (motor) side of the vacuum assembly high enough to expose the belt tension adjusting
screw (Figure 5-53). If possible, place a small block between the protruding tab of the vacuum
assembly and the TU10 cruciform so that the adjusting screw remains exposed.

Back off on the tension adjusting screw until the belt is loose enough to be removed easily. Remove

belt.

Changing Operating Frequency — To change operating frequency, proceed as follows:

Remove the black anodized pulley from the motor shaft by removing the set screw holding it in place.

(This set screw will be either a 10/32-inch or a 1/4-20 screw; DEC part numbers 9009174-10 or

9007722-10, respectively).

Inspect the set screw for stripped threads or a damaged tip; replace it, if it appears damaged.

Inspect the motor mounting plate, which should have an open set of four motor-mount holes. Remove
the four socket-head screws holding the motor in place and remount them in the open set of holes, as

shown in Figure 5-54.

Replace the pulley; use the pulley height gauge (DEC part number 7416187) to set the pulley height

(0.820 inch for 50 Hz; 0.520 inch for 60 Hz).

Ensure that the set screw rests on the flat part of the motor shaft. Retighten the set screw.

MOUNT MOTOR IN THIS
HOLE PATTERN FOR 60Hz

el
-

AR
NI
MOUNT MOTOR IN THIS

HOLE PATTERN FOR SOHz
CP-2130

Figure 5-54

Motor-Mounting Holes for 50/60 Hz Operation

5-57

5.6 REPLACEMENT PROCEDURES
5.6.1

Reel Motor Filter Elements

Proceed as follows to replace the reel motor filter elements (see Figure 5-55):
1.

Remove the filters from reel motors

Unscrew the two 4/40 Kep-nuts that secure the filter body together.

Remove the old filter element and replace with a new one.

Reassemble filter body.

Wrap Teflon tape (90-093583) on threads of filter body and hand tighten onto reel motor.

BRAKE MOUNTING SCREWS (4)
REEL MOTOR—
-

S
'

MOTOR DRIVE SHAFT

TAKEUP REEL

MOTOR AIR
TRANSPORT
—

FILTER

(DEC Part Number 12-09956)

FEED REEL
CP-0097

Figure 5-55 Reel and Motors, Rear View

5-58

5.6.2

Foam Stripping (Casting Perimeter)

Proceed as follows to replace the foam stripping along the perimeter of the casting:

Remove defective stripping from casting.

Cut new stripping to proper length before removing the protective backing.

Carefully install foam stripping on casting.

5.6.3

Vacuum Motor or Vacuum Motor Brushes

Proceed as follows to replace vacuum motor brushes:

Disconnect vacuum motor electrfcal connector.
Remove the three 4-40 X 1/4 screws from plenum cover and then remove cover.
Disconnect brushes, then remove brush retainers and brushes.
Carefully clean commutator with a small brush.

Apply a drop or two of light oil at rear ‘sleeve bearing taking care not to get any oil on the commutator.

Install and connect new brushes.

Re-install plenum cover and reconnect vacuum motor electrical connector.

Proceed as follows to replace the vacuum motor (see Figure 5-56):
1.

Remove both reel motor air filters.

Disconnect vacuum motor electrical connector.

Remove the two 10-32 screws located on the filter side of the plenum chamber.
Remove the third 10-32 screw while supporting the chamber with your free hand; move the chamber
to a work area.
Remove the two 6-32 screws from the cleat; remove cleat, motor, and rubber ring after removing
connector from wires.

Clean and inspect the rubber ring and replace if necessary.
Drop rubber ring into casting (concave side up); insert motor feeding wires through grommet and

secure motor cleat to casting with the two 6-32 screws.

Connect new sockets to wires of new motor and insert them into holes 1 and 3 of the connector

housing.
Re-install the plenum assembly by starting the first screw in the position adjacent to the vacuum

channel cover and continuing with the two remaining screws near the filters. Insert a new piece of
foam tape, then align housing and tighten all three screws.

5-59

WIRES

UPPER REEL MOTOR

GROMMET

123

ELECTRICAL
CONNECTOR

DEFLECTOR

(NEW)

AIR FILTERS

4-40x1/4 SHCS
3

PLACES

®
-

PLENUM COVER (NEW)

TAPE SEAL

TEFLON TAPE
ON THREADS

TUBE

«— LOWER REEL MOTOR

TO CLEANER.

®
®

VACUUM

CHANNEL COVER

CP-0101

Figure 5-56

10.

Vacuum Motor, Rear View

Wrap Teflon tape around filter threads and re-install filters. Reconnect the vacuum motor electrical
connector.

5.6.4

Reel Hubs

Proceed as follows to inspect the reel hub knob threads or to replace the compression ring and Teflon washer:
1.

Snap out plastic disk from reel hub.

Use a pair of heavy-duty diagonal pliers to carefully remove the center roll pin from the hub guide,
noting its position for reassembly purposes.

Unscrew knob and remove Teflon washer, pressure plate, and rubber compression ring. Apply a small
amount of silicon grease to finger tips, rub finger tips together, and lightly lubricate the surfaces of a
new compression ring. Use a lint-free cloth to wipe all excess grease from the ring.

Install the compression rihg, pressure plate, and afzew Teflon washer. Apply a very light coat of
silicon grease to hub guide threads and wipe off any excess grease.

Screw on knob and tighten to conipress rubber ring. This ensures proper seating of the assembly.
Loosen the knob so that it is free from the Teflon washer, then gently retighten the knob to meet the
washer.

Reinstall the roll pin in the same hole from which it was removed.

5-60

The following checks must be performed to ensure proper alignment of the hub guide pins:
1.

With the knob turned fully CCW (released position), the knob should have about 8 to 15 degrees of
freedom in the CW direction before it begins to compress the assembly. If necessary, shift the

positions of the two pins in the hub to obtain the required clearance and hub tightness.

If the hub pins have been shifted and the reel hubs are still loose, install a new compression ring and
washer (Paragraph 5.6.4).
Load a tape reel on the hub and check for proper engagement and release or possible binding.

Proceed as follows to replace the reel hub assembly:

Loosen the two Allen locking screws that secure the reel hub to the shaft and remove hub (access
holes for the screws are located on the side of the hub). Remove any burrs on the shaft.
Install a new reel hub on the shaft. Use a 0.125 inch gauge to achieve the necessary clearance

- between the back surface of the reel hub and the machined boss on the casting (see Figure 5-57).
5.6.5

Vacuum Switches and Rubber Sleeves

Proceed as follows to replace the vacuum switches or the rubber sleeves on the switches (see Figure 5-58):

Remove the two 8-32 screws securing the switch brackets to the casting. Pull the brackets rearward
to disengage the assembly.
Carefully detach the pair of fast-on connectors from each switch and note their positions for reassembly
purposes.

TOP

REEL

HUB

ALIGNMENT

GAUGE #29-18611

TRANSPORT

(Should feel friction
in vertical ($) axis.
Gauge should not move
in horizontql («=) axis.)

HUB

LOCKING SCREW
ACCESS OPENING

MACHINED
ALIGNMENT

BOSS
REEL HUB
LOCKING

ALLEN

SCREWS (2)

TEFLON

WASHER

3716 INCH KEY —]

REEL MOTOR
DRIVE SHAFT

REEL HUB ASSEMBLY—/\%
FRONT OF

TRANSPORT

/m
CP-0104

Figure 5-57

Reel Hub

5-61

MOUNTING SCREW
8 NUT —>

(2 PER SWITCH)

LOW OUTLET —

RUBBER SLEEVE _»%% | l \V
(HOSE)

TRANSPORT
MOUNTING —
BRACKET

LOW OUTLET
CP-0103

Figure 5-58

Vacuum Switches

Remove the switch from the bracket by removing the two 2-56 screws.

Replace the rubber sleeve on each switch with a 7/8-inch length of tubing. Replace the switch, when
necessary.

If a switch is replaced, it should be left slightly loose until the bracket is secured to the casting. This
allows for any misalignment present in the mechanics.

CAUTION
Never overtighten the screws securing the vacuum

switches to the bracket. This can damage the switches.

Reconnect the fast-on connectors to all switches.

Guide the switch assemblies so that each switch sleeve fits snugly into its respective hole in the casting
without any lateral strain.

5.6.6

Insert and tighten bracket screws.-

Operate transport off-line to check switch functions.

Reel Motors and Brushes

Recent investigations indicate that reel motor brushes have a normal operating life of 10,000 hours. Brushes are
matched to the motor’s commutator by a burnishing process, new unburnished brushes may generate unacceptable
levels of electrical noise.

5-62

If a motor exhibits symptoms indicating a need for brush replacement, the motor should be changed as a unit,
as follows:

Remove the reel hub assembly by loosening the two Allen locking screws that secure the reel hub to

the shaft.

Remove the air filter.

Remove the brake assembly (refer to Paragraph 5.6.7).

Remove the four captivating screws that secure the motor to the deck casting.

Replace the reel motor and tighten the four captivating screws to a torque value of 19 inch-pounds.

Install the brake assembly (Paragraph 5.6.7), air filter, and reel hub assembly. Use a 0.125-inch reel
hub gauge (part number 29-18611) to achieve the necessary clearance between the back surface of the
reel hub and the machined boss on the casting.

5.6.7

Reel Motor Brakes

If the stator slot is worn away, proceed as outlined in 5.3.3 to remove and replace the reel motor brakes.

5.6.8

Capstan

Proceed as follows to remove and replace the capstan:

Use a pair of tru-arc pliers* to loosen the capstan lock-ring and slide the capstan from the motor shaft.

Check that there are no burrs on the end of the shaft or in the slots cut in the shaft of the capstan

(Figure 5-59).

*0ld style only (see Figure 5-59).

5-63

CAPSTAN

EXERT

PRESSURE

‘

CAPSTAN LOCK-RING

HERE FOR
INSTALLATION

%
4

|
CAPSTAN MOTOR

SHAFT

r1----

TMN

(/77—

CAPSTAN /

GAUGE TOUCHES

ALIGNMENT
GAUGE 29-18609

THIS SURFACE

CAPSTAN LOCK-RING
EXPANSION POINT

SEB g%lflf‘g ONLY

ONLY

MILLED FRONT
OF TRANSPORT

NEW STYLE CAPSTAN CLAMP

|
|

CP- 0108

Figure 5-59

Capstan Adjustment

Place a new capstan on the motor shaft and lise the tfu—arc_ pliers* to carefully install the lock-ring

flush with the end of the capstan. Ensure that the lock-ring slot is in the center of a section of the
capstan.

Mount the capstan to the motor shaft, using the capstan gauge to push the capstan on the capstan
motor shaft. (If new style clamp is used, tighten it.)

Power up the drive. Mount a good-quality tape.

Run the tape forward and reverse to ensure that the tape is centered on the capstan.

Align tape path. (Refer to Paragraph 5.5.14.)
Control Box

5.6.9

Proceed as follows to replace the bulbs in the control box:

Loosen the screw at the bottom-center of the control box and remove panel.

Use a bulb extracting tool to remove and replace defective bulbs.

Mount panel on control box and tighten screw.

*Qld style only (see Figure 5-59).

5-64

Proceed as follows to remove the control box:
1.

Disconnect cable at the logic rack.

Disconnect plugs from the EOT/BOT sensor assembly.

Loosen and remove the four nufs securing the control box to the casting.

Caréfully remove the control box to ensure the connecting cable is not damaged.
Repeat Steps 1 through 4 in the reverse order to install the control box.

5.6.10

EOT/BOT Assembly

The EOT/BOT assembly is mounted on the head plate. Proceed as follows to remove and replace this assembly
(see Figure 5-60):

Use a small screwdriver to loosen the mounting screw.

Disconnect the plugs at the rear of the casting.
Carefully remove the assembly to ensure the head or head cables are not damaged while pulling the
connectors through the hole.

Replace faulty assembly and install by repeating Steps 1 through 3 in the reverse order.
Check for proper alignment by ensuring that the EOT and BOT markers are sensed and adjust the
assembly if necessary.

CP-0225

Figure 5-60

EOT/BOT Assembly

5-65

5.6.11

Head Plate

The head plate assembly consists of the tape cleaner, tape guides, heads, and the EOT/BOT assembly. Since the
heads and the tape cleaner are factory-adjustable only, DO NOT ATTEMPT TO ADJUST EITHER OF THESE

ITEMS IN THE FIELD. All new head plate assemblies are now manufactured with a stepped machined relief in
the rear surface (Figure 5-18) and two jacking screws incorporated in the plate front (Figure 5-23). These new

head plate assemblies are directly interchangeable with the older assemblies (no jacking screws or stepped relief)
and are shipped with the Jackmg screws withdrawn from the rear surface of the plate. The jacking screws are to
be used to mechanically align the head plate and should not be screwed down before the plate assemblyis installed and ready to be aligned.

Proceed as follows to replace a head plate assembly and properly set the initial mechanical alignment:
1.

Remove the head cover.

Remove the EOT/BOT assembly (Paragraph 5.6.10).

Before disconnecting the erase head cables, note the color code of the cable connections to ensure
proper reinstallation. Disconnect the read/write head cables.

‘

Remove the three shoulder screws (Figure 5-23) that secure the head plate assembly to the tape deck
casting and remove the head plate assembly.

Position the new head plate assembly on the casting and insert the first shoulder screw through the
lower right reference hole. Tighten this screw finger tight.

Insert the two remaining shoulder screws and finger tighten them until they are not quite touching
the head plate assembly.

NOTE

The head plate assembly can now be slightly rotated
from side-to-side around the lower reference hole
shoulder screw.

Position the head plate assembly approximately half-way between this 81de-to side arc and gently
tighten the reference shoulder screw W1th a screwdriver.

Remstall the EOT/BOT assembly (Paraoraph 5.6.10) and connect the read/write head cables, observing
the erase cable polarity. (Ensure that the black wire is connected to the erase terminal closest to the
operator.)

Using a handled 3/32 Allen wrench, turn in the upper jacking screw until it touches the tape deck

casting and then lightly tighten the upper shoulder screw with a screwdriver. Ensure that the
remaining shoulder screw is not tight and that the middle left jacking screw is not touching the
casting.

10.

Perform the mechanical skew adjustment for the new head plate assembly (Paragraph 5.4.4.1).

5-66

5.6.12

Power Supply

Proceed as follows to remove the power supply:
1.

Disconnect the power cable and fan cable at the rear of the power supply.

Disconnect plugs P3, P4, and P6 on the front of the power supply. Remove ground strap.
Remove the four screws securing the power supply to the frame and lift out power supply.

5.6.13

To install the power supply, repeat Steps 1 through 3, in reverse order.

Capstan Motor

NOTE

No repair must be aftempted on a faulty capstan motor;
return the faulty unit to DEC.

To remove the capstan motor proceed as follows:
1.

Remove the capstan as described in Paragraph 5.6.8.

Unplug the capstan motor connectors located at the rear of the casting.

Use a 3/16-inch Allen wrench to remove the four screws that hold the capstan motor to the casting.
(It is not necessary to remove the tachometer portion of the motor; these two are replaced as an
assembly.)

Replace the motor with a new one, taking care to apply a thin coat of Wakefield Thermal Compound
to the face of the motor that touches the casting.

Replace the four screws and retighten to 10 inch-pounds.
Replace the capstan as described in Paragraph 5.6.8.

5.6.14

Vacuum System Belt Replacement

The procedure for replacing the belt is as follows:

Determine which motor pulley is to be used (the larger diameter for 50-Hz operation; the smaller
diameter for 60-Hz operation).
Place the belt over the appropriate pulley; loop the belt over the blower pulley.
Tighten the belt tension adjustment screw until the belt has about 1/2 inch of play when pressed.

Position the belt tension gauge as shown in Figure 5-61; push against the knob at the end of the
spring until the third tab on the gauge just touches the belt.
Read the tension from the scale just under the spring; adjust the belt tension adjustment screw for

between 14 and 16 1b of belt tension.

5-67

KNOB

BELT TENSION GAUGE .

[

Ll/ DRIVE PULLEY 50 Hz

BLOWER PULLEY‘

0
DRIVE

Figure 5-61

PULLEY

MOTOR PLATE

} TAKE-UP SCREW

60Hz

CP-2119

Belt Tension Gauge |

NOTE

New belts must be run in for 1/2 hour, and then retensioned.
Failure to perform this run-in and retensioning process will
result in excessive pulley wear and possible breakage.

5.7

Replace and retighten all mounting hardware.

BRAKE ADJUSTMENT PROCEDURE

To ensure proper operation of the TU10, an adjustment to the brake circuit may be necessary after normal wear
or long periods of inactivity. In addition, brake operation must be checked after cleaning the brake armature.

The TU10 brake circuit has two adjustments that affect brake opération during REWIND. Both adjustments
affect only the upper brake and upper vacuum column. Vacuum failures caused byAexcessivé tape loop travel in
the lower vacuum column are indicative of a defect in the circuit, the brake, or the associated connectors.

Proceed as follows to perform a visual check of the REWIND operation.

1.
2.

Place the TU10 in the off-line mode and move tape to EOT.
Initiate the REWIND operation from EOT several times. Allow the operation to continue approximately 10 seconds before returning to EOT."

Initiate the REWIND operation and continue to the BOT marker.

Check for an improperly adjusted brake circuit by watching for any of the following symptoms
during the REWIND operation.

Any vacuum column failure.

More than 2 or 3 tape loop excursions exceeding approximately 1/3 of the distance into the

brake zone. During acceleration from EOT, 2 or 3 large excursions are normal.

5-68

Normal tape loop excursions during acceleration, but a sluggish return of the tape loop from the
reel motor zone to the brake zone.

Erratic tape loop excursions during continuous REWIND operation exceeding 1-1/4 inches above
the UPPER VAC SW. Tape motion will always be somewhat erratic, but the magnitude of the

loop “Gumps” should be below 1-1/4 inches.
In almost every case a tape loop failure can be diagnosed as an extreme example of symptoms b, ¢, or d. Continuous large tape loop excursions are probably due to one of the following causes:
1.

High current REWIND time is too short. The high current REWIND time is measured as a positive
pulse at BO5V?2. Typical pulse length is 20—25 ms. It is adjusted using the potentiometer (R61) on
the G9340 Module. Adjustment should be made in intervals not exceeding 3 ms.

Low current REWIND amplitude is too low. The amplitude is adjusted using the potentiometer on
the G9341 Module. Clockwise rotation of the potentiometer increases the current to the brake.
Adjustment should be made at intervals not greater than 2 turns of the potentiometer.

Symptom c is an indication that the low current REWIND amplitude is too high. Counterclockwise adjustment
of the potentiometer (R79) on the G9341 Module will decrease the amplitude. The effects of the adjustment

should be observed at intervals of 2 turns on the potentiometer.

Symptom d is an indication that the high current REWIND time is either above or below the ideal operating
range. The 20—25 ms range is a helpful guideline, but is not absolute, and will depend on the operation of the
brakes.

5.8

CAPSTAN MOTOR TACHOMETER CHECKING PROCEDURES

5.8.1

Equipment Required

The following equipment is required for the procedures described below:
1.

Jumper wires (Figure 5-62) (Two required).

Tachometer filter circuit (Figure 5-63).

Oscilloscope.

5-69

ALLIGATOR

CLIP

WIRE 18 TO 22 GAUGE

APPROX 1.5 FT LONG

IF CRIMPING TOOL
UNAVAILABLE, SOLDER
FEMALE
MATE-N- LOK
PIN
HEAT SHRINK
TUBING

CP-2128

Jumper Wires — 2 Required

Figure 5-62

AQ_ 9

22K

»
9

.01 MF

027 MF

22K

JVA'Av

TACH

VOLTAGE

Lo
S1K

)

= .01MF

== .027MF

FILTERED
VOLTAGE

ouT

cpP-2127

Figure 5-63

Tachometer Filter Circuit

5-70

Plastic shim, 0.015 inch. (Two pieces of 0.075-inch plastic shim can be used; DEC part number

48-50023-07 is a 10-inch X 20-inch piece of 0.075-inch shim.)

5.8.2

Checking Tachometer Voltage

The procedure for checking tachometer voltage is as follows:
1.

Turn power OFF; dismount tape.

Unplug the capstan motor Mate-N-Lok connector from the H603 Driver Module.

Use jumpers (Figure 5-62) to connect motor leads to the 5-volt supply. To prevent blowing the 5-volt
fuse (F6, 6 Amps, fast-blow), disconnect the red 5-volt supply wires from the Jones strip just beneath

the vacuum motor assembly and clip one of the jumper wires to it. Clip the other jumper wire to the
ground lead. Disconnect the 15-volt supply wires also, and push them out of the way.

NOTE
Motor leads originate at studs closest to casting. Tachometer
leads originate at studs farthest from casting.

Connect the +5 jumper to the red motor lead, the GND jumper to the black motor lead. Connect
filter lead A (Figure 5-63) to red tachometer lead, and filter lead B to black lead. Connect scope
probe and ground strap across the 0.027 mF capacitor (Figure 5-63).

Turn power ON.

Tachometer voltage should read +1.0V, -1.1V. Plus or minus voltage reading depends on the scope
probe location. Tachometer ripple should be no more than 30 mV peak-to-peak.

Reverse motor jumper (+5 to black and GND to red).

Tachometer voltage should reverse; ripple must remain less than 30 mV peak-to-peak.

NOTE

On PMI motors with model numbers beginning with 4J and
earlier, tachometer leads are reversed from above.

5.9

RECOMMENDED TEST EQUIPMENT AND SPARE PARTS

The following tables provide a recommended test equipment list and a spare parts list for the TU10. Table 5-5
lists the test equipment and alignment tools recommended for maintenance purposes. Tables 5-6 through 5-9
contain spare parts requirements for the modules, control box, power supply, and miscellaneous categories.

5-71

Table 5-5

Recommended Test Equipment and Alignment Tools

Description

Model or Part Number

Dual Beam Oscilloscope with

Tektronix Model 453 or equivalent

Two X10 Probes and Two X1 Probes

Multimeter

Triplett 630 or equivalent

Capstan Gauge

29-18609

Roller Guide Gauge

29-18607

Reel Hub Gauge

29-18611

Write Interlock Gauge Set

29-18608 and 29-18610

10 in./lb Torque Driver*

29-18360

19 in./Ib Torque Driver*

29-18361

* Torque Driver Blades

8/32 Allen Tip

29-18504

10/32 Allen Tip

29-18505

5/16 Screwdriver Blade

29-18509

Table 5-6

Control Box Spare Parts |
Description

Part Number

12-11239

Lamp Control Box*

12-10078

Switch (Digitran)

12-05941

Switch (Rocker #RS-50-FB-PC)

12-09614

Switch (Rocker)

*This is a new part number, it designates a lamp with a significantly longer life than the old lamp.

5-72

Table 5-7
Module Spare Parts

Type

Name

Quantity

G9340
G9341

Brake Actuator
Brake Actuator

H603

Servo Amplifier

MO50

Lamp Driver

M514

Bus Transceiver

M763

Write Buffer

M765

Read Buffer

M765-YA

Read Buffer

M767

Clock Skew Delay

M768

Delay Transmitter

M769

Function Control

M8&90

Motion Control

M7670

Forward BOT Timer

W726

Switch Filter

1
1

G050

Read Amplifier

G060

Compressor

G060-YA

Compressor

G062

Peak Detector

G093

Peak Detector

G064

Slicer

G094

Slicer

G350

Head Driver

G741

Terminator

G741-YA

Terminator

G932

Servo Preamplifier

G933

Reel Motor Amplifier

Table 5-8
Power Supply Spare Parts

Part Number

Description

11-10051

Diode (MDA990-3)

90-08838

Fuse (#3AG, 10 amp)

90-07221

Fuse (#3AG, 5 amp)

90-07999

Fuse (#3AG, 6 amp)

90-07225

Fuse (#3AG, 10 amp, SB)

90-07222

Fuse (#3AG, 5 amp, SB)

54-08924

Power Control Board

12-10102

Relay

15-03068

Transistor (2N3715)

54-08928

Voltage Regulator Board

5-73

Table 5-9

Miscellaneous Spare Parts

Part Number

Description

12-11581

Belt, Vacuum System

12-11582

Blower, 3-Stage, for Vacuum System

29-22265

Gauge, Belt Tension

29-12291

Brushes, Vacuum Motor

70-10316*

Cables

74-07957

Capstan

74-07958

Clamp (Lock-Ring), Capstan

74-07960

Clamp, Roller Guide Shaft

12-10721

Elapsed Time Indicator Assembly

12-10336

EOT/BOT Sensor Assembly

12-09956

Filter, Reel Motor (Atomuffler)

70-09885-4

Head Assembly, 9-Track

70-09885-3

Head Assembly, 7-Track

91-07716

Hose, Vinyl 3814-1

12-09786

Motor, Capstan

12-11639

Motor, Induction, for Vacuum System

12-09677

Motor, Reel

12-05944

Motor, Vacuum

74-07996

Plug, Air

12-11659

Relay, Motor Starting, for Vacuum System

12-10145

Roller Guide Assembly

12-10021

Ring, Compression

91-07717

Rubber Tubing #192

90-09397

Screw Set Knurled Cup PT #8-32 X 1/4 1g.

12-09378-01

Socket Housing (Mate-N-Lok)

12-09868

Solenoid (Deltrol Controls)

12-09870

Switch, Read/Write Interlock

12-10477

Switch, Vacuum (Fairchild)

90-07834

Tape, Stock Mount (3M #4032)

*The following table lists the variations of cable 7010316 that apply to specific
vendors. The head assembly includes cables.
Cable Vendor

Hamilton Digital

9-Track Read

-1

9-Track
Write/Erase
-3

with cables having
blue male connec-

tors (up to October,
1974)

DEC and Hamilton
Digital heads with
cables having

black female
connectors

5-74

7-Track Read

-2

7-Track
Write/Erase
-4

APPENDIX A

VOLTAGE, FREQUENCY, AND
7 TO 9 CHANNEL CONVERSIONS

A.1

GENERAL

This appendix provides all information necessary to perform the various conversions possible on TU10 DEC
magtape drives.

Because there are currently 16 different voltage, frequency, and 7/9 track options of TU10 available, 240
different conversions are possible. Rather than list all conversions and the steps required to effect them, this
appendix lists the various types of conversions together with part numbers and specific procedures for carrying
them out.

Whenever the operating voltage, frequency, or 7/9 track status of a TU10 is altered, the configuration tag located
just above the serial number tag behind the lower right hand corner of the machine must be changed to reflect
that alteration.

Consult Table A-1 for proper TU10 configuration designations.

Table A-1

TU10 Configuration Designations

A.2

115V,

230V,

60 Hz

50 Hz

60 Hz

50 Hz

O-track Master Transport

TU10-EA

TUI10-EB

TU10-EC

TU10-ED

9-track Slave Transport

TUI10-EE

TUI10-EF

TU10-EH

TU10-EJ

7-track Master Transport

TUI10-FA

TU10-FB

TU10-EC

TU10-FD

7-track Slave Transport

TU10-FE

TUI10-FF

TU10-FH

TUI10-FJ

APPLICABLE DOCUMENTS

TU10 Maintenance Manual — EK-TU10-MM-005

TU10 Engineering Drawings — specifically, D-MU-TU10-0-18

Vacuum Assembly Drawing — E-AD-7012052-0-0
A.3

VOLTAGE CONVERSION

A.3.1

115 VAC-to-230 VAC Conversion

To change from 115 VAC operation,to 230 VAC operation, proceed as follows:

Delete these items:

Male AC Receptacle, 115 VAC
Male plug-on power cord
Female plug-on power cord

On jumper plug J-1:

delete connection pin 1 — pin 2
delete connection pin 4 — pin 5

delete connection pin 8 — pin 7
delete connection pin 11 — pin 12
Power Control 861C (TU10 Master only)

Add these items:

Male AC Receptacle, 9008854
Male plug-on power cord, 9008853

Female plug-on power cord, 9008855
On jumper plug J-1:
add connection pin 2 — pin 3

add connection pin 4 — pin 5

add connection pin 10 — pin 11
Power Control 861B (TU10 Master only)

A.3.2 230 VAC-to-115 VAC Conversion
To change from 230 VAC operation to 115 VAC operation, proceed as follows:

Delete these items:
Male AC Receptacle, 230 VAC
Male plug-on power cord

Female plug-on power cord
On jumper plug J-1:

delete connection pin 2 — pin 3
delete connection pin 4 — pin 5

delete connection pin 10 — pin 11
Power Control 861B (TU10 Master only)

Add these items:

Male AC Receptacle, 1201252
Male plug to power cord, 9008938
Female plug to power cord, 9008939
On jumper plug J-1:

add connection pin 1 — pin 2
add connection pin 4 — pin 5
add connection pin 8 — pin 7
add connection pin 11 — pin 12
Power Control 861C (TU10 Master only)

A.4

FREQUENCY CONVERSION

A.4.1

60 Hz-to-50 Hz Conversion

To change from 60 Hz to 50 Hz operation, proceed as follows:

Remove leads from hour meter and insulate, using shrink tubing (9107685).

Remove hour meter and replace with blank cover plate (7414614) per ECO H730-14.

On TU10’s having belt driven vacuum blowers, remove the cover plate and perform the following steps:
c.1

Loosen motor plate, back off belt tension adjusting screw, and remove belt and motor pulley.

c.2

Move motor to other (unused) set of mounting holes. (see E-AD-7012052)

c.3

Remount pulley.

Set pulley 0.820 in. up from assembly chassis using gauge block 7416187. Tighten set screw.

Adjust belt tension as described in E-AD-7012052.

A.4.2

50 Hz-to-60 Hz Conversion

To change from 50 Hz to 60 Hz operation, proceed as follows:

A.5

Perform steps a, b, and c.

Set pulley 0.520 in. up from assembly chassis using low side of gauge block 7416187. Tighten set screw.

Adjust belt tension as described in E-AD-7012052.

SEVEN/NINE CHANNEL CONVERSION

A.5.1

7-Channel-to-9-Channel Conversion

To convert from 7-channel to 9-channel operation, proceed as follows:

Remove 7-channel head plate with cables and replace with 9-channel head filateWith cables. (7009885-04)
Remove 7-channel logo and add 9-channel logo. (7409373)
Add jumper from A21J1 to ground (A21C2).
Modify M768 per paragraph 5.5.12 of this manual.

Deskew unit.

A.5.2

9-Channel-to-7-Channel Conversion

To convert from 9-channel to 7-channel operation, proceed as follows:

Remove 9-¢hannel head plate with cables and replacé with 7-channel head pléte with cables. (70-09885-03)
Remove 9-channel logo énd édd 7-channel logo. (7409294)
Remove jumper A21J1 to ground.

Modify M768 per parégraph 5.5.12 of this manual.
Deskew unit.

A.6

A.6.1

MASTER/SLAVE CONVERSION

Master-to-Slave Conversion

To convert from a TU10 Master to a TU10 Slave, remove all modules indicated on D-MU-TU10-0-1 8, slots 6
through 15 inclusive.

A.6.2

Slave-to-Master Conversion

To convert from a TU10 Slave to a TU10 Master, add all modules indicated on D-MU-TU10-0-18, slots 6 through
15, inclusive.

A.7 OVER/UNDER-VOLTAGE RANGE CONVERSION
Later units with the T9147D Transformer have extra primary taps to cover extreme voltage ranges. Simply resolder the wires going to terminals 2 and 4 to 2L or 2H and 4L or 4H respectively:
95-115 Vac,

190-230 Vac 2L, 4L

105-125 Vac,

210-250 Vac 2,

115-135 Vac,

230-270 Vac 2H, 4H.

A-4

T U10 DECmagtape Maintenance Manual
EK-TU10-MM-007

R e ad er ’ S C omments

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Telephone: Bristol 651-431

EALING

- Telephone: (617) 897-5111
From Metropolitan Boston, 646-8600
TWX: 710-347-0217/0212

AUSTRALIA

Digital Equipment Corporation S.A.
GENEVA
20. Quai Ernest Ansermet
Boite Postale 23, 1211 Geneva 8, Switzerland
Telephone No. 022 20 4C 20 and 20 58 93 and 20 68 93
Telex: 28 92 01

BIRMINGHAM

T
g

Digital Equipment Australia P!y Ltd.
ADELAIDE

Titismaantie 6

Digital Equipment Co. Ltd.

Fish Ponds Road. Fish Ponds
Bristol. England BS163HQ

Telex 610-929-2006

Cable: DIGITAL MAYN

FINLAND

Mariahilferstrasse 136, 1150 Vienna 15, Austria

BRISTOL

Rio De Janeiro
— GB

SAO PAULO

Telex: 94-8457

Digital Equipment Corporation Ges.m.b.H.
VIENNA

Telephone: 021-355-5501

Rua Ceara, 104, 2 e 3 andares ZC 29

Telephone: 264- 7406/0461/7625

Y146 Main Street. Maynard, Massachusetts 01754

COPENHAGEN

Telex: 841-722-393

Telephone: (0771)-45-50-65

Telex: 012-2284

British Columbia. Canada V6P

REGIONAL OFFICE

DENMARYK
Digital Equlpment Aktlebolag )

STUTTGART
D-7301 Kemnat. Stuttgart
Marco-Polo-Strasse 1,

Telephone: 52-3185

RIO DE JANEIRO — GB

644 S.W. Marine Dr., Vancouver

GENERAL INTERNATIONAL SALES

Telex 19079 DEC N

BUENOS AIRES
Coasin S.A.
Virrey del Pino, 4071, Buenos Aires

Ambriex S.A.

TWX: 403-255-7408

Telex: 385-9056

ARGENTINA

Telephone: (403)-435-4881

Telephone: (604)-325- 3231

Telex: 922-952

Santurce. Puerto Rico 00912

Telephone: (809) 723-8068/67

BRAZIL

Suite 202

Digital Equipment Corp. A/S

Am Forstaus Gravebruch 5-7
Telephone: 06102-5526
Telex: 41-76-82

Digital Equipment Corporation De Puerto Rico
407 del Parque Street

CALGARY /Edmonton
Suite 140, 6940 Fisher Road S.E.
Calgary, Alberta, Canada
VANCOUVER

NORWAY

Telephone: 586-2771
Telex: )-26428
Rikei Trading Co.. Ltd. (sales only)

PUERTO RICO
TWX: 610-562-8732

TORONTO
2550 Goldenridge Road, Mississauga, Ontario
Telephone: (416)-270-3400
TWX: 610-492-7118

108 Rue D'Arlon

GERMAN FEDERAL REPUBLIC
Digital Equipment GmbH

Arndale

P.O. Box 11500

MANILA

Stanford Computer Corporation
P.O. Box 1608
416 Dasmarinas St., Manila
Telephone: 49-68-96
Telex: 742-0352

Telex

790-20740

NEW ZEALAND

Digital Equipment Corporation Ltd.

AUCKLAND

BARCELONA

Hilton House, 430 Queen Street, Box 2471

Ataio Ingenieros S.A., Granduxer
76, Barcelona 6

Auckland. New Zealand

Telephone: 221 44 66

Telephone: 75533

VENEZUELA
CARACAS
Coasin. C.A.
Apartado 50939

Sabana Grande No. 1, Caracas 105

Telephone: 72-8662; 72-9637
Cable: INSTRUVEN

Dataphone: 505-294-2330

No. 18-14 Nishishimbashi 1-Chome
Minato-Ku, Tokyo. Japan
Telex: 781-4208
Telephone: 5915246

Oltawa Ontano Canada
K2H
8
Telephone (613)-592-5111

BELGIUM

Tour Mangin

NEW MEXICO

Kozato-Kaikan Bldg.

CANADA

Albuquerque

Minato-Ku, Tokyo 107, Japan

Telex: 922-33-3163

Digital Equipment of Canada, Ltd.
CANADIAN HEADQUARTERS

Rijswijk/The Hague, Netherlands
Telephone: 94 9220
Telex: 32533

Digital Equipment France

Telephone: 32705

Tel Aviv, lsra

7901 E. Bellevue Avenue

JAPAN

Telephone: (03) 443114/440763

Sir Winston C‘hurchulllan 370

Telex: 26810

)

Suite 5, Englewood, Colorado 80110
Telephone: (303)-770-6150
Dataphone: 303-770-6628

Kowa Building No. 16 — Annex, First Floor
9-20 Akasaka 1-Chome

Suite 103, Southern Habakuk Street

Digital Equipment N.V.
THE HAGUE

Centre Silic — Cidex L 225

]

Dataphone: 213-478-5626

Digital Equipment Corporation International

DEC Systems Computers Ltd.

NETHERLANDS

94533 Rungis. France
Telephone: 687-23-33

UNITED KINGDOM (cont.)
READING

81 route de |'Aire
1211 Geneva 26, Switzerland
Telephone: 427950
Telex: 22 683

West Los Angeles

INTERNATIONAL
Digital Equipment Corporation International Europe

Dataphone: 415-562-2160

Telephone: (505)-296-5411/5428

TEXAS

Telephone: (317)-243-8341

253 Passaic Ave.. Fairfield, New Jersey 07006

Dataphone: 918-749-2714

~ 400 Penn. Center Boulevard, Pittsburgh, Pennsylvania 15235
Telephone: (412)-263-9404
Dataphone: 412-824-9730

Indianapolis

NEW JERSEY

OKLAHOMA

PENNSYLVANIA
Pittsburgh

21 Beachway Drive, Suite G

COLORADO
Dataphone: 513-298-4724

Uil
Dataphone: 415-964-1436

Qakland

Telephone: (213)-479-3791/4318

‘ulsa

Dataphone: 714-280-7825

7850 Edgewater Drive, Oakland, California 94621

Telephone: (918)-749-4476

INDIANA

NORTH CAROLINA
Durham/Chapel Hill
Executive Park
3700 Chapel Hill Blvd.
Durham, North Carolina 27707
Telephone: (919)-489-3347
Dataphone: 919-489-7832

B
e

3140-S. Winston
Winston Sq. Bldg., Suite 4, Tulsa, Oklahoma 74135

Suite 110, San Diego, California

1400 Terra Bella, Mountain View, California 94040

Dayton

Dataphone: 312-498-2500

6154 Mission C.nrge Road

Tciephonc. (415)-964-6200

CENTRAL
Telephone: (312)-498-2500

2815 Clearview Place, Suite 100
Atlanta, Georgia 03040
Telephone: (404)-451-7411
Dataphone: 305-859-2360

San Di~go

San Francisco

3101 Kettering Boulevard
Dayton, Ohio 45439
Telephone: (513)-294-3323

1850 Frontage Road, Northbrook, Illinois 60062

Atlanta

Dataphone: 714-979-7850

Maryland Heights, Missouri 63043
Telephone: (314)-878-4310
Dataphone: 816-461-3100

WASHINGTON D.C.
Lanham 30 Office Building
4900 Princess Garden Parkway, Lanham, Maryland
Telephone: (301)-459-7900
Dataphone: 301-459-7900 X53

REGIONAL OFFICE:

GEORGIA

Santa Ana
2110 S. Anne Street, Santa Ana, California 92704

St. Louis

2500 Euclid Avenue, Euclid, Ohio 44117
Dataphone: 216-946-8477
Telephone: (216)-946-8484

Dataphone: 615-584-0571

CALIFORNIA

Teiephone: (714)-979-2460

Telephone: (714)-280-7880/7970

OHIO
Cleveland

6311 Kingston Pike, Suite 21E

Telex: 710-347-0348

4358 East Broadway Road, Phoenix, Arizona 85040
Telephone: (602)-268-3488
Dataphone: 602-268-7371

Telephone: (816)-252-2300

Suite 110, 115 Progress Parkway

1740 Walton Road, Blue Bell, Pennsylvama 19422
Telephone (215)-825-4200

MASSACHUSETTS

Dataphone: 612-854-1410

MISSOURI
Kansas City
12401 East 43rd Street, Independence, Missouri 64055
Dataphone: 816-461-3100

PENNSYLVANIA

Syracuse
6700 Thompson Road, Syracuse, New York 13211
Telephone: (315)-437-1593/7085
Dataphone: 315-454-4152

Marlborough
One Iron Way
Marlborough., Mass. 01752
Telephone: (617)-481-7400

8030 Cedar Ave. South, Minneapolis, Minnesota 55420

Telephone: (612)-854-6562-3-4-5

Telephone: (212)-582-1300

Dataphone: 716-244-1680

Dataphone: 313-557-3063

MINNESOTA
Minneapolis

Dataphone: 516-293-5693"

Telephone: (203)-255-5991

NEW YORK

ARIZONA
Phoenix

Suite 189
Southfield, Michigan 48075