Digital Equipment TU56 User manual

DEC-OO-HRTC-D
TU56 DECtape TRANSPORT
MAINTENANC~E MANUAL
PUBLICATIONS
MASTER FILE COpy
APPROVED BY
DATE
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digital equipment corporati,on · maynard. massachusetts

1st Edition June 1970
2nd Printing (Rev) March 1971
3rd Printing
October 1971
4th Printing March 1972
5th Printing June 1972
2nd Edition July 1972
Copyright © 1970, 1971, 1972 by Digital Equipment Corporation
The material in this manual is for information-
al purposes and
is subject to change without
notice.
The following are trademarks of Digital Equipment
Corporation, Maynard, Massachusetts:
FLIP CHIP
UNIBUS
PDP
DECtape
DECsystem-l0
DECmagtape

CONTENTS
Page
CHAPTER 1 GENERAL INFORMATION
1.1 Introduction
1-1
1.2 Specifications 1-1
1.3 Options
1-3
1.4 Major Assemblies and Systems 1-4
1.4.1 Controls and Indicators 1-4
1.4.2 Tape Motion System
1-5
1.4.3 Power Supply
1-7
CHAPTER 2 INSTALLATION
2.1 Unpacking and Inspection 2-1
2.2 Mechanical Installation
2-3
2.2.1 Mounting Support Plate Bracket and Spacer Block Installation 2-3
2.2.2 Spacer Support Bracket Installation 2-3
2.2.3 Transport Installation 2-4
2.3 Electrical Installation 2-6
2.4 Operation 2-8
2.4.1 Tape Loading and Unloading 2-8
2.4.2 On-Line Operating Procedures
2-8
CHAPTER 3 THEORY OF OPERATION
3.1 Interface
3-1
3.1.1
Input Interface Lines -Command Cable -A06/A07 3-2
3.1.1.1 Select
0-7
3-2
3.1.1.2 CON STOP 3-2
3.1.1.3
CONGO
3-2
3.1.1.4 CON REV
REM
3-2
3.1.1.5 CON
FWD REM
3-2
3.1.1.6 CON ALL HALT 3-2
3.1.1.7 CON
PWR UP DLY 3-2
3.1.2
Output Interface Lines -Command Cable - A06/ A07 3-2
3.1.2.1 Select Echo 3-2
3.1.2.2 Write Echo
3-3
3.1.3 Bi-Directional Interface Lines -Information Cable -
AB I0/ AB 11
3-3
3.1.3.1 Timing Track (TT)
3-3
3.1.3.2 Mark Track (MT)
3-3
3.1.3.3 Data Tracks
(DO-D2)
3-3
3.2 Functional Information
3-3
3.2.1 Read/Write Head 3-3
3.2.2 DECtape
Format
3-3
3.3 Local (off-line) Operation
3-5
3.3.1 Forward Tape Motion
3-5
iii

CONTENTS (Cont)
Page
3.3.2 Hold Tape Motion
3-5
3.3.3 Reverse Tape Motion
3-5
3.4 Remote (on-line) Operation 3-6
3.4.1 Tape Transport Addressing 3-7
3.4.2 Error Checks 3-7
3.4.2.1 Select Echo 3-7
3.4.2.2 Write Echo 3-8
3.4.3 Tape Motion Control 3-8
3.4.4 Write Operation 3-9
3.4.5 Read Operation 3-11
3.5 Module Description 3-11
3.5.1 G847 Dual Motor Voltage Control 3-11
3.5.2 G848 Motor Control Module 3-11
3.5.3 G859 Clock Regulator Module 3-12
3.5.4 G888 Manchester Reader/Writer Module 3-12
CHAPTER 4 MAINTENANCE
4.1
Recommended Tools and Test Equipment 4-1
4.2 Preventive Maintenance 4-1
4.2.1 Weekly PM Procedure
4-1
4.2.2 Monthly
PM Procedure 4-2
4.2.3 Tape Care and Cleaning 4-2
4.3 Corrective Maintenance 4-3
4.3.1 Control Panel Lamp Replacement 4-3
4.3.2 Reel Motor
4-3
4.3.2.1 Motor Removal
4-3
4.3.2.2 Motor Replacement 4-4
4.3.2.3 Reel Hub Clearance Adjustment
4-5
4.3.2.4 Reel Motor Electronic Brake Adjustment
4-5
4.3.2.5 40-Hz Oscillator Adjustment 4-5
4.3.3 Read/Write Head
4-5
4.3.3.1 Head Removal 4-5
4.3.3.2 Head Replacement 4-7
4.3.3.3 Head
Output Check 4-7
4.3.3.4 Head Skew Check and Adjustment 4-8
4.3.3.5 Write Enable Circuit Check 4-11
4.4 Troubleshooting 4-11
4.4.1 Initial Checks 4-11
4.4.2 Signal Source and Tennination Tests 4-14
4.5 Recommended Spare Parts 4-18
APPENDIX A REFERENCE DRAWINGS
iv

ILLUSTRATIONS
Figure No. Title Page
Jl-1
Controls and Indicators
1-4
1l-2
Tape Motion System
1-6
1l-3
Power Supply Location
1-7
2-1 Outer Packaging
2-1
2-2 Inner Packaging 2-2
2-3
H950 Cabinet Support Plate
2-3
2-4 Tubular Cabinet Spacer Support Bracket 2-4
2-5
Faceplate Removal
2-5
2-6
Hub and Reel
2-7
3-1
TC08 to TU56 Logic Connection 3-1
3-2 Functional Block Diagram 3-3
3-3 Read/Write Head Arrangement 3-4
3-4 Off-Line Manual Operation Flow Chart 3-6
3-5 Read/Write Technique 3-10
4-1
Reel Motor Removal 4-4
4-2 Reel Hub Clearance 4-6
4-3
Head Connector Location 4-8
4-4 Skew Tester to Head Cable Connection 4-9
4-5
Head Skew Waveform 4-10
4-6 G848 Motor Control Module Waveforms 4-13
4-7 M908 Module Layout 4-15
TABLES
Table No. Title Page
1-1
Performance Specifications
1-1
1-2
Logic Modules
1-3
1-3
Controls and Indicators
1-4
2-1
TU56 and TU56H Interface Cabling 2-6
2-2
Interface Module Substitution
2-7
4-1
Recommended Maintenance Equipment 4-1
4-2 Reel Motor Malfunctions 4-11
4-3 Control Panel Malfunctions 4-12
4-4 Local Malfunctions 4-12
4-5
Left Transport Source Test Points 4-15
4-6 Right Transport Source Test Points 4-16
4-7 Right and Left Transport Termination Test Points 4-16
4-8 Recommended Spare Parts 4-18
v

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TU56 DECtape Transport

1.1 INTRODUCTION
CHAPTER 1
G·ENERAL INFORMATION
The TU56 (Dual) or TU56H (Single) DECtape Transport is a solid state, bi-directional, low cost, magnetic tape
data storage device. The Manchester Phase encoding method used in this transport ensures reliable
data transfer
and reduces tape skew problems. Each tape track
is redundantly paired with a second, nonadjacent track, thus
permitting dependable use
of a lower cost (instrumentation) tape without requiring a closely controlled environ-
ment.
The TU56 tape speed
is 93 inches per second, with a data transfer rate of 33,300 3-bit characters per second.
The simple tape transpprt mechanism has no capstans
or pinch rollers. Tape motion is controlled by two ac
induction reel motors. The internal H725 Power Supply furnishes dc operating power for the reel motors only.
DC logic power is externally supplied by the tape controller through connectors located on the back of the
power supply. To maintain proper tape tension during forward tape motion, full torque is applied to the forward
reel
motor while reduced torque is applied to the reverse reel motor. Similarly, during reverse tape motion, full
torque
is applied to the reverse reel motor while reduced torque is applied to the forward reel motor. Electronic
braking ensures a positive
stop from either direction, without appreciable tape backlash.
With the use
of optional interface modules, the solid state switching circuits in the TU56 can be made compatible
with the relay switching circuits in the TU55 and 555 DECtape Transports. This versatile tape transport can
therefore be used in a variety
of installations, including those not employing Digital Equipment Corporation
(DEC) computers.
1.2 SPECIFICATIONS
Table 1-1 lists the performance specifications of the TU56 DECtape Transport.
Characteristic
Controller Type and Output Levels
Integrated Circuits
Relay
Solid State
Table 1-1
Performance Specifications
F = ground
T=+5Vdc
F = open
T = closed
F = ground
T=-3Vdc
1-1
Parameter
(continued on
next page)

Characteristic
Electrical Requirements
Input Voltage
Power Dissipation
Environment
Ambient Temperature
Relative Humidity
Storage Medium
Type
Width
Thickness
Data Capacity
Format
Tape Reel
Outer Diameter
Diameter Ratio
Capacity
Tape Motion Times
(90% full speed)
Start
Stop
Turnaround
Backlash
Tape Transport
Speed
Recording Density
Transfer Rate
Dimensions and Weight
Width
Depth
Height
Weight
Table
1-1 (Cont)
Performance Specifications
Parameter
115/220 Vac, 50/60 Hz @ 3A
+5 ± 0.5 Vdc @
0.8A} . 10 *
+10 ± 1.0 Vdc @ 0.8A eIther +5 or + Vdc, but not both
-15 ± 1.5 [email protected]
TU56 =325W (1073 Btu/hr) max
TU56H = 162.5W (536.5
Btu/hr) max
20 to 80% (no condensation)
Mylar sandwich, magnetic recording tape
3/4 in.
1.25 mil
2.7 x 106 bits
(unformatted)
Manchester Phase Encoding
3-7/8 in.
Approximately
1: 1.4 (min. to max.)
260 ft
150 ± 15 ms
100 ± 10 ms
200 ± 50 ms
<1.0 in. tape motion after braking
93 ± 12 in. per sec (ips)
350 ± 55 bits per in. (bpj)
33,300 3-bit characters per sec
19 in. (0.48m)
]7-3/4 in. (0.43m)
10-1/2 in. (0.27m)
80 lb (37 kg)
* Either +5 or +10 Vdc external voltage may be used; however, the internal logic requires +5 Vdc for normal operation. If +10 Vdc is
used, ensure that it is connected to the correct rear terminal; otherwise circuit damage will result.
1-2

1.3 OPTIONS
The TU56 DECtape Transport is available in the following standard models:
• TU56 (Dual) Transport
• TU56H (Single) Transport
In addition, two customer options, designated TU56M (Dual) and TU56HM (Single), permit
the standard trans-
port models
to be used alone or connected with other nonstandard peripherals. If either option is used, five G888
Read/Write Amplifier modules must be inserted into slots A13, A14, B13, B14, and B
15 of the logic mounting
block. Interface cabling
as indicated in Table 2-1 must be used. If more than one transport is connected to a
single controller, only
the first transport of the "daisy chain" need contain the G888 modules. If the transport is
connected to a controller that has relay driver outputs, the M941 Jumper modules in slots A04 and A05 must be
replaced withW513 Level Amplifier modules. Table
1-2 lists the logic module complement of each transport model.
Quantity
TU56 TU56H
Dual Transport Single Transport
I I
1 I
2 I
I I
2 I
2 I
2 I
3 2
I I
4 2
2 2
2 2
5 5
2 I
I 1
2 1
Tabl{~ 1-2
Logic Modules
Type
(1) G742
G859
(2) M941
(1) M531
M040
G851
MIl7
Ml13
M302
G848
M908
W032
(3) G888 option
M922
(3) M923 option
G847
Module Name
Positive Logic Jumper Card
Clock Regulator
Jumper Card
Bus Converter
Solenoid Driver
Relay
6-4
Input NAND Gate
10-2 Input NAND Gate
Dual Delay
MV
Motor Control
Connector
Cable Connector
Manchester Reader/Writer
Cable Connector
Cable Connector
Dual Motor Voltage Control
(1) M531 used with negative logic controller. G742 used with positive logic controller.
(2) Replace with a W513 when
transport is connected to a relay driver controller.
(3) Required only when
transport is connected with nonstandard peripherals, or is to be used alone.
1-3

1.4 MAJOR ASSEMBLIES AND SYSTEMS
1.4.1 Controls and Indicators
The controls and indicators (Figure 1-1) required for normal operation are located
on the front of the transport
cabinet. Table
1-3 describes the function of each control or indicator.
Controls and Indicators
REMOTE/OFF/LOCAL
(rocker switch)
Figure
1-1 ControIs and Indicators
Table 1-3
Controls and Indicators
Logic Symbol
SW2
Description
Placing this switch in one of the following positions
accomplishes;
1-4
a. REMOTE -disables the Fwd/Hold/Rev switch
and places the transport under computer control
(on-line).
b. LOCAL -enables the Fwd/Hold/Rev switch and
removes the transport from computer control
(off-line).
c. OFF -removes power from the reel motors and
removes the transport from
computer control.
(continued on
next page)

Controls and Indicators
--
Fwd/Hold/Rev
(rocker switch: spring-loaded
to
Hold)
Address Select
(0 to 7 thumbwheel switch)
WRITE ENABLE/WRITE LOCK
(rocker switch)
REMOTE SELECT
(indicator)
WRITE
(indicator)
1.4.2 Tape Motion System
Table 1-3 (Cont)
Controls and Indicators
Logic Symbol
SW3
SWI
SW4
L2
LI
Description
Placing this switch in the Fwd position (provided
REMOTE/OFF/LOCAL is in LOCAL) moves the
tape from left to right across the read/write head.
When this switch is in the spring-loaded Hold position
(provided REMOTE/OFF/LOCAL
is in LOCAL), the
tape remains stationary.
Placing this switch in the Rev position (provided
REMOTE/OFF/LOCAL is in LOCAL) moves the tape
from right
to left across the read/write head.
Configures the transport logic to respond to the ad-
dress indicated
on the thumb wheel.
Placing this switch in the WRITE ENABLE position
liights the WRITE indicator and allows a write opera-
tion.
Placing this switch in the WRITE LOCK position turns
off the WRITE indicator and prevents a write opera-
tion.
Lights when
the transport is in the remote (on-line)
mode and
is selected by the controller.
Goes
off when the transport is in the off or local
(off-line) modes
or is deselected by the controller.
Lights when the WRITE ENABLE/WRITE LOCK
switch is in the WRITE ENABLE position.
Goes
off when the WRITE ENABLE/WRITE LOCK
switch is in the WRITE LOCK position.
Each half
of the dual tape motion system (Figure 1-2) consists of: two ac induction reel motors (mounted
behind the hinged mounting panel), two tape reel hubs, a tape guide assembly, and a read/write head. Tape
motion from the supply reel, over the tape guides and read/write head, and
onto the take-up reel is directly
controlled by the two 600-rpm induction reel motors
that drive the reel hubs .. The solid state switching circuits
that control the reel motors govern the amount of torque applied to each motor. For forward tape motion, full
torque
is applied to the forward motor (take-up reel) and reduced torque is applied to the reverse motor (supply
reel). This condition establishes the direction
of the tape motion and maintains the proper tape tension without
the use of capstans, pinch rollers, or drag pads. Similarly, the opposite reel motor conditions are necessary for
reverse tape motion.
1-5

\
REEL HUB
A. Mounting Panel (closed)
FAN
TB 2,-----------
B. Mounting Panel (opened)
Figure 1-2 Tape Motion System
1-6
READ/WRITE
HEAD
TAPE
~REEL
REEL
MOTORS

Since a separate track containing timing information plus a Manchester Phase encoding technique is used, tape
speed can vary
as much as ±20 percent without affecting the read/write reliability. Dynamic braking of the
reverse
motor causes a positive stop without adverse tape backlash. Whenever the tape is motionless, both motors
apply partial torque
to maintain the tape position.
1.4.3 Power Supply
NOTE
During tape motion, the high harmonic content of the 40-Hz
square wave that supplies the tape reel motors produces small,
cyclic variations in the power
output of the motors. These
variations cause an audible hum which varies in intensity
as the
reel being driven by a particular motor fills with tape. Such
behavior is normal and has no effect on the performance of
the transport.
The H725 Power Supply, located in the left rear portion
of the transport cabinet (Figure 1-3), furnishes +18 and
+38 Vdc operating power for
the reel motors only. A convenience outlet on the back of the supply furnishes
110/220,
50/60 Hz ac power. AC operating power for the cooling fan is obtained directly from the input line
voltage, through terminal connector TB2 located
on the front of the power supply. The +5 Vdc logic operating
power
is supplied by either an external source or is generated internally by a voltage regulator on the G859 Clock
and Regulator module. When +1
0 Vdc is connected to TB 1 (+10 terminal) of the power supply, the regulator
reduces this external level to +5 Vdc for internal use. When +5 Vdc
is connected to TBI (+5 terminal), the
regulator
is bypassed and the external level is directly used internally. For this reason, it is important that the
external dc power connection be made
to the correct TB 1 terminals.
LOGIC
MODULES
Figure 1-3 Power Supply Location
1
~,
- I
CONVENIENCE
OUTLET
POWER
SUPPLY
TB1

CHAPTER 2
INST ALLA TION
2.1 UNPACKING AND INSPECTION
Do not drop or subject the transport to unreasonable impact. Carefully unpack the TU56 DECtape Transport as
follows:
1. Open the outer carton (Figure 2-1) and remove the top four toro pad cushions.
.... ------
Figure 2-1 Outer Packaging
2 .. 1
TORO PAD
8 PLACES:
4 TOP
4 BOTTOM
INNER SHIPPING CARTON
OUTE R SHI PPING
CARTON
Cp-0280

2. Lift out the inner carton and open it (Figure 2-2).
3. Remove the back and side support laminated pieces.
4. Lift the transport out of the inner carton and unbolt the shipping bracket. Replace the shipping
bracket screws in the transport chassis and retain the packing materials for possible return shipment.
S. Inspect the transport and report any damage to the carrier and Digital Equipment Corporation.
BACK SUPPORT
LAMINATED PIECE
CORNER SUPPORT
LAMINATED PIECE
INNER CARTON
SIDE SUPPORT
LAMINATED PIECE
(2)
Figure 2-2 Inner Packaging
2-2
SHIPPING
BRACKET
POWER
E SUPPLY
000
00
REAR OF TRANSPORT
VIEW A
.<'~:jl+----
BACK SUPPORT
LAMINATED PIECE
CP-0282

2.2 MECHANICAL INSTALLATION
To install
the TV56 DECtape Transport in the cabinet, two different mounting support brackets are available.
The mounting
support plate bracket with spacer blocks (7408321 and 7408322) is for transport installation in
an
H950 cabinet. The V-shaped spacer support bracket (7408009) can be ordered separately and is for transport
installation in a tubular-type cabinet. The following paragraphs describe
the bracket installation procedures for
both cabinet types.
2.2.1 Mounting
Support Plate Bracket and Spacer Blo<ck Installation
1. Place the mounting support plate (7408321) in the H950 cabinet and secure it to the front of the
cabinet mounting rails (Figure 2-3).
2. Install the spacer blocks and secure them to the side of the cabinet mounting rails.
3. Secure the spacer blocks to the mounting support.
2.2.2 Spacer
Support Bracket Installation
1. Place the spacer support bracket (7408009) in the tubular cabinet and secure it to the cabinet front
with the mounting hardware (Figure 2-4).
2. Attach four clip-on speed nut fasteners to the spacer support bracket.
SPACER
BLOCK(2)
(7408322)
10/32
TRUSS HEAD(2)
1/4/20 TRUSS HEAD SCREW
~WITH KEEPER NUT (2)
/I MOUNTING BRACKET (7408321)
/ FRONTOFCABINET
CABINET
MOUNTING
RAILS
CP - 0032
Figure 2-3 H950 Cabinet Support Plate
2-3

c: -- -- ----- -- - -- --- -- - ------ --- -- ---- -- -- 51
Mge~tt1~~ 1~~Q m~o !:
HOLES (4) ,0
______________________________ L-,
SPACER SUPPORT
SP- 0281
Figure 2-4 Tubular Cabinet Spacer Support Bracket
2.2.3 Transport Installation
The tape transport may be installed in a cabinet without removing the transport mounting panel; however, the
mounting panel weight makes this practice difficult. It is best, as described in the following procedure, to first
remove the mounting panel, then install the transport.
1. Remove the M922 Ribbon Cable Connectors from slots B04 and B 17 of the logic module mounting
block at the rear of the transport (Figure 2-5A).
2. Disconnect the 22-pin Amphenol head cable connector from the rear of the G851 Relay modules in
slots AB09 and AB 12.
3. Turn the mounting panel side locking fasteners (Figure 2-5B) one-quarter turn to unlock the mounting
panel.
4. Carefully lower the mounting panel until the support struts are fully extended (Figure 2-5C).
5. Disconnect the reel motor cable connectors (Figure 2-5C) by pressing the locking tabs, which extend
from one of the Mate-N-Lok connectors, against the side of the connector body and separating the
connector halves.
NOTE
If the reel motor connectors are held to the chassis by a nylon
cable holder, remove the top of the holder and free the cable.
6. Route the head and ribbon cables from the back to the front of the transport.
7. Support the mounting panel and remove the support strut mounting screws.
8. Tilt the mounting panel slightly upward, pull it forward, then lift up the rear to free it from the
transport.
9. Mount the transport in the cabinet with four Phillips No. 10-32 truss-head screws and keeper nuts.
10. Reinstall the mounting panel by performing Steps 1 through 8 in reverse.
2-4

RIBBON CABLE
CONNECTORS
AMPHENOL
HEAD
CONNECTORS
A. Transport Rear View
B. Locking Fastener Location
LOCK ING
FASTENER
SUPPORT
STRUTS
c. Mounting Panel Opened
Figure 2-5 Faceplate Removal
2-5
REEL MOTOR
CONNECTOR

Control Type
Integrated Circuit
Relay
Solid State
TAPE REEL-
Table 2-2
Interface Module Substitution
Required
Module
G742
M941
W513
M531
M941
M531
31..."REEL-
8
Quantity
I
2
2
1
2
1
SMALLER
CI HCUMFERENCE
Figure 2-6 Hub and Reel
2··7
Position in
Mounting Block
A05
A18, A04
A04,
Al8
A05
A04,
Al8
A05
Logic Level
F=O
T=+5
F = open
T = closed
F=O
T= -3
.017
HUB CLEARANCE
/14--- MOUNTING
PANEL
MOTOR
SHAFT
1 0-0 178