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3400 MAGNETIC TAPE UNITS
FIELD ENGINEERING MAINTENANCE
MANUAL
PN
9043
®
STORAGE TECH NOLOGY CORPORATION
3400 MAGNETIC TAPE UNITS
FIELD ENGINEERING MAINTENANCE MANUAL
TECHNICAL WRITER
Part No. 9043
Herman Marshall
September 1975
I
First Edition - September, 1975
This manual contains the most current material available at the
time of writing. However, Storage Technology reserves the right to
modify or revise the contents at any time. Contact Storage Technology Corporation to obtain any updated material.
This publication was prepared by Storage Technology Corporation,
Publications Department, P. O. Box 98, Louisville, Colorado 80027.
Copyright
® September, 1975
by
StorageTechnology Corporation
All Rights Reserved
ii
PREFACE
The 3400 Magnetic Tape Units Field Engineering Maintenance Manual contains a description of the STC 3400
series tape units. The description covers general information, tape unit operation, explanation of the elements comprising the tape unit and the maintenance information.
It is intended for use in helping to train
neers and to aid the Field Engineers in
equipment. Photographs, block diagrams,
flow charts, tabular material and line art
support the text.
STC Field Engimaintaining this
simplified logic,
are included to
The material is organized into four chapters, generally flowing from the most basic to the more detailed information.
Chapter I is General Information, Chapter II covers the
Operational Description, Chapter III goes into more depth
on the Functional Description and Chapter IV pertains to
Ma intenance_ The first three chapters contain the support
and background material necessary to understand and conduct the maintenance procedures included in Chapter IV.
Comments concerning the contents of this manual should
be directed to the Publications Department, Storage Technology Corporation. A prepaid Reader's Comment Form is
provided at the back of the manual. Reqeusts for additional copies of the manlJal should be directed to Machine
Level Control, Storage Technology Corporation.
iii
LIST OF EFFECTIVE PAGES
Publication No. 9043
Original Issue Date SEPT. 1975 .
Total number of pages in this volume is 140 ,consisting of the following pages:
Page
Cover
Cover Back
Title
Copyright
iii
iv
v
vi
vii thru ix
x
xi thru xii
1·1 thru 1·11
1·12
2·1 thru 2-22
3·1 thru 3·34
4-1 thru4·51
4·52
1·1 thru 1-4
Reader's Comment Form
Mailer
Issue
Original
Blank
Original
Original
Original
Blank
Original
Blank
Original
Blank
Original
Original
Blank
Original
Original
Original
Blank
Original
Original
Original
v
CONTENTS
CHAPTER I
GENERAL INFORMATION
PAGE
TITLE
1-1
1·1
1-1
1·2
1·2
1·9
SUBSYSTEM OPERATION
Tape Control Unit
Tape Unit
Operator Panel
Pushbutton Operation
Indicator Operation
1·10
TAPE UNIT DESIGN
CHAPTER II
OPERATIONAL DESCRIPTION
2·'
2·1
2·3
TAPE UNIT CONTROL
Sensors
Delay Counter
2-3
2·12
2·12
THREAD/LOAD OPERATION
Short Leader Load/Midtape Load
Load Operation Checks
2·14
2-14
2·14
REWIND OPERATION
Control Signals
Rewind Sequence
2·17
UNLOAD OPERATION
CHAPTER III
FUNCTIONAL DESCR IPTION
3·1
3·2
3-5
3-9
REEL CONTROL SYSTEM
Low Speed Reel Control
Column Reel Control
Emergency Power Off
3·9
3·10
3-13
3-16
3-16
3-16
CAPSTAN CONTROL
Power Driver
Velocity Control Circuits
Capstan Starting
Capstan Stoppin~
Interblock Gap Control
3·19
3-19
3·20
3·24
3·26
3·27
3-27
3·27
3·31
3·31
3·32
3·33
READ/WRITE CONTROL
Write Operation
Read Operation
INPUT LINES
. OUTPUT LINES
POWER SUPPLY
AC Section.
DC Section
PNEUMATICS
Pressure and Vacuum Control
Pneumatics Generation
COOLING SYSTEM
vii
CONTENTS (CONT)
CHAPTER IV
PAGE
TITLE
4-1
4-1
4-2
4-4
4-4
4-4
4-4"
FIELD TESTERS
Field Tester (PN 10489)
Field Tester Controls (PN 10489)
Field Tester (PN 16086)
Functions and Controls
Operating Considerations
Field Tester Switches (PN 16086)
4-6
4-7
4-7
4-7
4-8
4-9
4-10
4-11
PREVENTIVE MAINTENANCE
Maintenance Equipment
Inspection
Tape Transport Cleaning
Limited Cleaning/Inspection
General Cleaning/Adjustment
Cleaning/ Adjustment/Replacement
Inspection/Replacement
4-11
4-11
4-11
4-12
4-12
4-15
ADJUSTMENT/ALIGNMENT PROCEDURES
Automatic Hub Positioning
Auto-Hub Solenoid Check and Adjustment
Belt Tension Adjustments
Capstan Alignment
Capstan Specifications
4-15
4-17
4-18
4-18
4-18
4-19
4-22
4-23
4-27
4-27
4-30
4-34
4-36
4-36
4-37
4-38
4-38
4-38
4-40·
4-40
4-40
4-41
4-41
4-42
viii
MAINTENANCE PROCEDURES·
Cartridge-opener Switch Adjustment
Delay Counter Check and Adjustment
Door Latch Adjustment
Erase Head Check
High-Speed Rewind Adjustment
Pneumatic Checks and Adjustments
Pulley Alignment - Pneumatic Supply
Read/Write Data Verification
Restraint Alignment
Sensor Adjustments
Skew Check and Adjustment (Mechanical)
Skew Check and Adjustment (Electrical NRZI)
Tachometer Adjustment
Vacuum Column Door Adjustment
Vacuum Transfer Valve Adjustment
Voltage Adjustments
Window-Limit Switches Adjustment
Window Adjustments
REPLACEMENT PROCEDURES
Automatic Hub Replacement
Auto-Hub Cover Replacement
Auto-Hub Solenoid Replacement
Belt Replacements
Capstan Motor Replacement
CONTENTS (CaNT)
PAGE
TITLE
4-44
4-45
4-45
4-46
4-46
File Protect Assembly Replacement
High Speed Foot Replacement
Machine Reel Replacement
Phototransistor Column Bar Assembly Replacement
Pneumatics Motor Replacement
4-46
4-47
4-48
4-48
4-49
Power Supply Removal and Replacement
Power-Window Glass Replacement
Pressure Pump Replacement
Read/Write Head Replacement
Reel-Motor Cooling Assembly.Replacement
4-50
4-50
4-50
Tape Cleaner Block Replacement
TR lAC Board Replacement
Vacuum-Column-Bar Lamp Assembly Replacement
4-50
4-51
Vacuum Pump Replacement
Vacuum Transfer Valve Replacement
ix
FIGURES
PAGE
FIGURE
1-6
1-7
1-1
1-2
1-3
1-4
Basic Specifications
Major Components Locations
Magnetic Tape Subsystem
System Configuration
1-8
1-9
1-11
1-5
1-6
1-7
Tape Unit Field Testers
Tape Unit Operator Panel
Tape Unit Overall Block Diagram
2-2
2-4
2-5
2-11
2-1
2-2
2-3
2-4
Tape Path
Delay Counter
Thread/Load Flow Chart
Thread Sequence Timing Chart
2-11
2-13
2-15
2-17
2-5
2-6
2-7
2-8
Columns Load Sequence Timing Chart
Write Enable Ring and File Protect Mechanism
Rewind Operation Flow Chart
Rewind Operation Timing
2-18
2-19
2-21
2-22
2-9
2-10
2-11
2-12
Rewind Operation Simplified Logic
Unload Operation Flow Chart
Unload Operation Timing
Unload Operation Simplified Logic
3-3
3-1
3-2
3-3
3-4
Reel System Simplified Schematic
Column Sensors and Zones
File Reel Current Path - Forward Motion Right Zone "A" Violation
Machine Reel Current Path - Forward Motion Left Zone "C" Violation
3-10
3-5
3-6
3-7
3-8
Dynamic Brake Current Path (CCW Rotation)
Dynamic Brake Current Path (CW Rotation)
Velocity Feedback Control
Capstan Power Amplifier
3-11
3-11
3-11
3-13
3-9
3-10
3-11
3-12
Capstan
Capstan
Capstan
Capstan
1-3
1-4
3-4
3-5
3-5
3-6
3-6
3-8
3-14
3-15
3-17
3-18
Motor Current
Motor Current Path (Backward Motion)
Dynamic Brake Current Paths
Driver Voltages and Modes
3-13 Capstan Velocity Control Block Diagram
3-14 Digital Tachometer Configuration
3-15 ·IBG Counter
3-16 Interblock Gap Diagram
3-18
3"17
3-19
3-18
3-20
.3-21
3-19
3-20
Forward Creep IBG
Read/Write Block Diagram
Write Driver Simplified
Read Circuit Simplified
3-22
3-23
3-23
3-25
3-21
3-22
3-23
3-24
R/W Head Amplifier Card
DAC Operational Block Diagram
DAC Operational Waveforms
Tape Unit I/O Connector
xi
FIGURES (CONT)
xii
PAGE
FIGURE
~·28
3·29
3·30
3·31
j·25
3·26
3·27
3·28
Power Supply (Top View)
TRIAC Board and Fuse Panel
DC Distribution Terminals
Power Supply Fuse Values
3·32
3-33
3·29
3·30
Pneumatics, Threading Mode
Pneumatics, Running Mode
4·6
4·13
4·14
4·15
4·1
4·2
4·3
4-4
Preventive Maintenance Schedule
Tensiometer Operation
Capstan Motor Assembly
Go Holdover Distance in Tach Lines
4·16
4·16
4·17
4·18
4·5
4·6
4·7
4-8
Stoll Distance Including Go Holdover in Tach Lines
Start Stop Timing
Cartridge Opener
Read Bus Pin Location
4·18
4·20
4·23
4·25
4·9
4·10
4·11
4·12
Erase Head Polarity Check
Pneumatic Specifications
PneumaticSupply Assembly (Front View)
Expanded Read Bus Signal
4·26
4·26
4·28
4·29
4·13
4·14
4·15
4·16
Phase Encoded Read Signal Waveforms
NRZI Read Signal Waveforms
Scope View of Recorded Data
Phase Encoded Write Operation
4·29
4·31
4·31
4·31
4·17
4·18
4·19
4·20
NRZI
Right
Right
Right
4.·32
4·33
4·34
4·35
4·21
4·22.
4·23
4·24
NRZI Skew Delay Taps
Mechanical Skew Alignment
NRZI Skew Chart
NRZI Write Skew Delay Adjustment Potentiometers .
4·35
4·36
4·37
4·38
4·25
4·26
4·27
4·28
NRZI Write .Amplitude Adjustment Potentiometers
Tachometer Board
Vacuum Transfer Valve
Power Window Switches
4·39
4-42
4·43
4-45
4·29
4·30
4·31
4·32
Power Window Adjustments
Pneumatic Supply Assembly
Capstan Mounting Assembly
File Protect Assembly Mounting
4-47
4-49
4·33
4·34
Pneumatic Supply Assembly
Reel Motor Cooling Assembly
Write Operation
Guide Assembly (PE Only)
Guide Assembly (3470 DO Only)
Guide Assembly (All DO Except3470)
CHAPTER I
GENERAL INFORMATION
INTRODUCTION
This manual is intended as a source of
adjustment and alignment specifications
for STC 3400 series tape units.
It incorporates the theory of operation and
field engineering practices and procedures.
Basic machine specifications are listed
in Figure 1-1. Figure 1-2 shows the location of major components and assemblies and may be referred to throughout
this manual.
SUBSYSTEM OPERATION
Figure 1-3 is an illustration of the
magnetic tape subsystem showing how
the optional features and the tape unit
variations come together in a simplified form.
The 3400 series tape units
may interface with either a 3800-III or
a 3800-IV tape control unit via a radial interface. This interface provides
individual I/O and ac power cables to
each tape unit, and consists of twentyone output signal lines,one ground
line and two dc voltage lines.
The ac
power cables are separate from the I/O
cables.
TAPE CONTROL UNIT
The Tape Control Unit (TCU) controls and
checks data coming from the channel to
be wri tten on tape and also controls and
monitors operations performed by the
tape unit.
The three main functions of the TCU are
(1) channel interface, (2) tape unit
control and (3) read detection.
The TCU
accepts up to sixteen data bytes from
the channel while the tape unit is preparing to receive it; it also buffers
data bytes coming from tape unit that
are to be accepted by the channel. An
illustration of a partial Data Processing System is shown in Figure 1-4.
Functions of the TCU, with respect to
the tape unit are to, monitor error and
status conditions, time operations, and
select the tape unit for use.
In addition, it controls the initiation and
termination of tape movement and monitors the amplitude of read signals.
TAPE UNIT.
Up to eight tape units can be attached
to one Teu. The Teu provides write data
and gating lines to the tape units;
Error-checking circuits in the TCU verify the validity of information exchanged
during a read or write operation. When
connected to the Teu the tape unit will:
•
•
Read tape (forward or backward).
. Write tape (forward only) .
•
Space forward or backward over sections of previously written tape.
•
Erase a section of tape.
•
Rewind tape to load point.
•
Rewind and unload the tape.
1-1
The tape unit can also operate offline -disconnected from the TCU and cabled to
a tester -- under the control of a Field
Tester (see Figure 1-5). The tester
provides write data and gating lines
allowing the Field Engineer to.perform
tape unit maintenance without tieing up
the customer's entire system. The tester, however, does not perform a validity
check of read/write data. The commands
that the field tester 9an transmit to
the tape unit are:
The pushbuttons are used to manually operate the tape unit.
The indicators
provide information on the tape unit mode
of operation and status.
PUSHBunON OPERATION
Pressing the pushbuttons results in the
following actions:
•
•
Read tape.
•
•
•
Write tape.
•
Sense data.
Initiates the thread/load operation,
provided the tape unit is NOT already loaded.
If the tape unit is
loaded, it initiates a rewind to
load point.
This pushbutton is operational only when the READY and
MACHINE CHECK indicators are not lit.
Rewind to load point.
Rewind and unload.
•
With the tape unit switched offline (see
the OFFLINE switch in Figure 1-2) but
still cabled to the TCU, Channel Command
Words may be entered into the FE buffer
of the TCU.
The TCU is then time-shared
between the channel and the remainder of
the tape units.
Between channel operations, commands can be directed to the
offline tape unit from the FE buffer.
A very important source of information
and control for the Field Engineer is
the tape unit operator panel.
It is located at the top front of each tape unit
and contains a row of indicators above a
row of pushbuttons (see Figure 1-6).
1-2
START
Enables the tape unit to accept commands from the TCU (ready state)
provided the tape unit is loaded.
If the tape unit is in a thread/load
operation when START is pressed, it
will enter the ready state upon detection of load point.
•
The tape unit can also operate under the
direction of the Subsystem Program for
Analysis and Repair (SPAR), an STC patented diagnostic approach operated either online or offline by the TCU microprogram. All tape unitswithiri a
subsystem can be tested from any TCU
within the subsystem.
OPERATOR PANEL
LOAD/REWIND
UNLOAD/REWIND
Operative only when the READY and
MACHINE CHECK indicators are not lit.
If tape is present in the columns, a
rewind to load point occurs. The
tape continues winding onto the file
reel until tape is no longer present
in the columns. This conditions the
power window, cartridge and hub to
allow removal of the reel.
•
RESET
If the tape unit is not loaded, RE. SET prepares it for threading by
latching the hub and closing the
window.
It can also be used to
terminate a load operation by forcing a machine check.
3430
FEATURE
3440
3450
3470
3480
Tape Speed (ips)
75
100
125
200
250
Data Rate (KB)
120
160
240
320
400
Density (bpi)
1600/800
556/200
1600/800
1600/800
556/200
1600/800
556/200
1600
Recording Mode
PE/NRZr
PE/NRZI
PE/NRZI
PE/NRZI
PE
Start Time (ms)
3.5
3.0
2.7
2.1
2.3
Rew Time (sec)
55
55
55
45
45
7/9
9
7/9
7/9
9
8.30
6:25
5.0
3.13
2.50
Quantity of Tracks
Max Bit Spacing (usee)
ENVIRONMENTAL CAPABILITIES:
Operating temperature 60 0 to 90 0 F (160 to 39 0 C).
Operating relative humidity 20% to 80% at 780 F.
(Condensation must notoccur.)
Non-operating temperature 50 0 to 110 0 F (10 0 to 43 0 C).
Non-operating relative humidity 8% to 80% at 80 0 F.
(Condensation must not occur.)
DIMENSIONS:
Height to base of operator panel: 60 in.
Width:
30 1/2 in.
Depth:
29
1/2 in.
PRIMARY VOLTAGES:
208/230 Vac ± 10 percent, 3-phase 60 ± 1 Hz
or 220/235 Vac ( .6. ) 3-phase 50 ± 1 Hz
. or 380/408 Vac ( Y ) 3-phase 50
±1 Hz
Figure 1-1.
Basic Specifications
1-3
POWER WINDOW
(OPEN POSITION)
OPERATORS
PANEL
AUTOMATIC
REEL HUB
CARTRIDGE
OPERATING
PIN
DRIVE
CAPSTAN
LIGHT
SOURCE
LIGHT OPERATED
TAPE SENSORS
TI L T OUT LOG IC_.-Jl------------;mr4t:~~~'f/
GATE FOR EASY
MAINTENANCE
OFFLINE
SWITCH
MAGNETIC TAPE UNIT
(FRONT VIEW)
Figure 1-2.
1-4
Major Components Location (Sheet 1 of 2)
CAPSTAN
MOTOR
VACUUM HOSE
(THREADING)
PNEUMATIC
TEST POINTS
FUSE PANEL
MAGNETIC TAPE UNIT
( REAR VIEW)
Figure 1-2.
Major Components Location (Sheet 2 of 2)
1-5
3800 III
BASIC TAPE CONTROL UNIT
(HAS PE CAPABILITY ONLY)
WITH 9-TRACK NRZI CAPABILITY INSTALLED
WITH 7-TRACK
N RZI CAPABI LlTY
INSTALLED
i
0
i
1
i
i
2
3
t
4
t
5
i
6
7
"
"
3400
TAPE
UNIT
PE
3400
TAPE
UNIT
PE
3400
TAPE.
UNIT
PE
3400
TAPE
UNIT
PE
,
3400
TAPE
UNIT
DUAL!
DENSITY
,
,
3400
TAPE
UNIT
3400
TAPE
UNIT
7-TRACK
7-TRACK
Figure 1-3.
1-6
i
Magnetic Tape Subsystem
3400
TAPE
UNIT
DUAL!
DENSITY
CENTRAL
PROCESSING
UNIT
SELECTOR
CHANNEL 1
o
SELECTOR
CHANNEL 2
.....
3800
3800
TAPE CONTROL UNIT
TAPE CONTROL UNIT
2
3
4
5
6
7
89ABCDE
EACH TAPE UNIT IS
CONNECTED DIRECTLY
TO THE TAPE CONTROL
UNIT IN RAPIAL FORM.
3400
TAPE
UNIT
3400
,
1
~
' - - - -......y~-LINES .FOR
OTHER
TAPE UNITS
F
TAPE
UNIT
I
- -.....'r.....--~
LINES FOR
OTHER
TAPE UNITS
,
3400
3400
TAPE
UNIT
TAPE
UNIT
Figure 1-4.
System Configuration
1-7
TIPASS
~ TI STOP
GAPS~
WRITE~
.
AUTO RWND
READ
OFF-5
7
3
~ .~
ON
P
~
~.
2
~
OFF
~
~
0
6
~
~
~
~
T.
~
"--i-",,
(@)
GND
4-0FF
~
OFF
A
GO
READ BUS
OLD MODEL PN 10489
Read
..
St-St
Auto
Cycle.
Sh-Sh
TI
Pass
Write
Stop
Q
Go Up
Fr~q
~~J,?
Fwd
Mod
Freq
@ @ H-@
GO@BkW@~tU~@
@
PE
NRZI
TI
Auto
Lo
FreQ
GCR
Raw
TIOn
Ready
5.
4
7
6
@ @ @ @ @ @
Wr Inh
BOT
2
0
Status
Control
Run
~~~
@ @ @ @ @ @
3
0
Go Down
Write
0
5
7
.p
3
2
-Go
6
@@
@-@
.Gnd
Gnd
NEW MODEL PN 16086
Figure 1-5.
.
1-8
Tape Unit Field
, Testers
ON
,~G)~,
<@>
WRITE
~
2
-GO u p ·
-KHZ
GO DOWN
.
1
Om 0
,:C)~ ...~.
.
2
Tach
4
D
1«:::1
RED
D
WHITE
B.
~" R" ~O" W" ~N" D, , D~
Figure 1-6.
G
TAPE
INDICATE
::-0"18".6.8 (.."I:~6:
.:.:.:.:-:.:.:.:.:.:-:.:.:::
........................
~" ~" ~" ~", ~, , ~, , g~
B
:::MACi-iiN:E;:
::::::CH"EC"K::::"
':::::::::::::::;:::;:::::::'
ItW-IN-:-~-:-U-p-l:1
Tape Unit Operator Panel
A machine check is cleared by pressing RESET, if the condition causing
it is no longer present. Pressing
and releasing RESET slows a highspeed rewind to normal tape speed.
" Rewind stops completely if the pushbutton is held in or is pressed a
second time.
If it is pressed during a rewind/unload operation, it
affects rewind as noted and keeps
unload from occurring or halts it
if already initiated.
SELECT (white)
Indicates the tape unit has been selected for use and is under the direction of the TCU o.r the field
tester (whichever is connected).
READY (green)
Indicates the tape unit is loaded
with tape and is ready to accept
commands from the Teu or the field
tester (whichever is connected).
Pressing RESET ends tape unit ready
status, allowing use of the other
operator panel pushbuttons.
•
18
................
.. .. .. .. .. .. .. .. .. .. ......
...........
..............
..............
.........
....
::';::WRlt"E:::::
WRITE DISABLED (red)
"HUB/WINDOW UP
Opens the power window if the tape
unit is not in ready status.
It
also releases the file reel from
the automatic hub if a machine check
exists or if WINDOW OV~RRIDE is active.
INDICATOR OPERATION
The indicators and the messages they
provide are:
Indicates that a write-enable ring
is NOT in place on the file reel
when the tape unit is ready.
TAPE INDICATE (white)
Lights when the End-of-Tape sensor
detects the trailing edge of the
End-of-Tape marker.
It goes out
when a rewind operation moves the
marker back past the End-of-Tape
sensor.
1-9
•
MACHINE CHECK (red)
(1) FLASHING light: Signals a Load
Check which is operator correctable.
(2) STEADY light: Machine failure
requiring service by a Field
Engineer, or a column check
which may be reset by the operator.
The capstan moves tape across the write
head in a forward direction during
write. Write circuits then condition
current through the write head to write
on tape in response to control commands
and WRITE BUS signals.
The capstan may move tape in either direction during a read operation. The
read circuits process raw analog data
from the tape and condition it to drive
the READ BUS.
TAPE UNIT DESIGN
The following design features .are required to enable the tape unit to per~
form its function.
•
Machine and file reel motors and
associated servo system.
•
Capstan motor and servo system.
•
•
Read/write circuits.
Control logic.
•
pneumatics supply.
•
Cooling system.
•
Input/output lines.
•
Power supply.
The machine and file reels move tape,
with the aid of the pneumatic supply,
to accomplish the automatic thread/load
operation. They do not move tape during
normal operation, a function accomplished by the capstan.
As the capstan moves tape forward or
backward, the reels take up or dump
sufficient tape to maintain proper loop
position in the colunms. Loop position
is monitored by sensors in each tape
column.
1-10
In addition to directing tape during the
automatic load operation, the pneumatic
supply provides pressure and vacuum for
use during normal operation. The pressure and vacuum provide a cushion for
tape to ride on, thus reducing tape drag
on the capstan motor and reducing tape
wear.
It also aids the vacuum columns
.in buffering tape between the capstan
and reels.·
The cooling system keeps the tape unit
and its components within the predetermined temperature parameters.
The input/output lines serve as the tie
with the TCD, allowing the transfer of
data, commands and other signals.
The power supply is comprised of an ac
section and a dc section.
It also
houses the main power circuit breaker
for the tape uni t ..
Detailed descriptions of these elements
are found in Chapter III, Functional
Description.
Shown in Figure 1-7 is an overall block
diagram of the Tape Unit. The Tape Control Unit is included to show how it
interfaces with the Tape Dnit.
If.• .· .· • i i ·····.··i i
i
'ii
it
i/
~~
•••••••••••••.••••••••••••••• •• .•I·.I·•••.•••.••.•.••• / ...•••••
WINDOW
CONTROL
READ
BUS
WRITE
BUS
READ
CIRCUIT
THREAD!
LOAD
CONTROL
PNEUMATICS
CONTROL
WRITE
CIRCUIT
WRITE
CONTROL
CONTR.OL
LINES AND
INTERNAL
TIMING
MACHINE
REEL
AND
MOTOR
I
)~WW'i"
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-----..
I'~S
I.··.:'
CAPSTAN
CONTROL
FILE
REEL
CONTROL
------.
ro-
START/STOP
IBG
CONTROL
OPERATOR
PANEL
Figure 1-7.
Tape Unit Block Diagram
1-11
CHAPTER II
OPERATIONAL DESCRIPTION
INTRODUCTION
The tape path incorporates air bearings
that reduce friction and wear to a minimum.
Tape movement is buffered by
vacuum columns which virtually eliminate
tape stress. After tape has been loaded
all tape movement is the result of motion imparted to it by a single drive
capstan.
These tasks require basic design features such as reel and capstan motor
assemblies and logic. Sensors and
switches located in the tape path control reel and capstan motion. Also in
this' Chapter is a description of the
delay counter, which provides internal
timing for the various operations.
unit operation is initiated by commands
from the TCU or from pushbuttons on the
operator panel.
Control is predominantly a function of
the tape control unit. However, to accurately start, maintain the speed of,
and stop tape without incurring damage
requires considerable control and must
be accomplished by the tape unit.
SENSORS
The types of sensing devices used in
this control operation are phototransistors, a pressure switch and mechanical switches (see Figure 2-1).
The
sensing devices and their functions
are:
In addition to the basic design features,
STC tape 'units utilize an automatic
thread/load feature to make the tape
unit easier to use. The thread/load operation is covered in this chapter.
This chapter also covers the rewind operation and the unload operation. A
more detailed description of the operation of the tape unit is found in Chapter III, Functional Description.
The Cartridge On Switch - detects
the presence of a cartridge on the
file reel.
•
The Cartridge Open Switch - Signals
,that the cartridge on the file reel
is open (if present).
•
The Cartridge Closed Switch - Signals that the cartridge on the file
reel is closed.
The Window Open Switch - signals
that the power window is open.
TAPE UNIT CONTROL
The tape unit operates in response to
external commands, internal timing and
sensing devices in the tape path. Tape
•
The Window Closed Switch - signals
the power window is closed.
2-1
REELS LDD
SWITCH
READ/WRITE
HEAD
HI SPEED FOOT
ERASE
HEAD
FILE REEL
OUTBOARD
AIR BEARING
(STATIC)
RIGHT TAPE
GUIDE
AIR BEARING
("D" BEARING)
LSA SENSOR
TAPERED VACUUM COLUMN
BOT/EOT
SENSORS
TAPERED VACUUM COLUMN
VACUUM PORT
AIR BEARING
(HYDRODYNAMIC)
AIR BEARI G
(HYDRODYNAMIC)
STRAIGHT
COLUMN
UUM
STRAIGHT VACUUM
COLUMN
Figure 2-1.
2-2
RIGHT UPPER
COLUMN SENSOR
Tape Path
•
The Reels Loaded Switch -signals
the reels are loaded when tape draws
taut during the thread operation.
•
The File Protect Switch - A combination pneumatic pressure nozzle and
back-pressure sensor that detects
the presence of a write-enable ring
on the file reel.
The Override Switch - inhibits window operation to facilitate troubleshooting.
•
The Tape-Present Sensor - signals
when tape is present in the head
area.
The Low-Speed Area Sensor - detects
the beginning-of-tape reflective
marker during a rewind operation.
Its output is used to signal the
logic to step down from a highspeed rewind to nominal speed.
•
The Beginning-of-Tape Sensor (BOT)
detects when the beginning-of-tape
reflective marker on the outside
edge of the tape is in the head
area.
The End-of-Tape Sensor (EOT) - detects when the end-of-tape reflective marker on the inside edge of
the tape is in the head area.
•
The Vacuum Column Phototransistors detects the position and direction
of movement of the tape loop in the
column. They are an integral part
of the reel control system.
The operator panel pushbuttons are described in the Operator Panel section of
Chapter I. Once an operation starts,
no other operation can interrupt until
the first one is completed, or in some
cases, the operation is aborted by pressing the RESET pushbutton. The INTERNAL
READY signal raises when the tape unit
is loaded.
It can then accept commands
from the TCD as soon as the START pushbutton is pressed.
DELA V COUNTER
The delay counter provides timing for
all operations and checks during the
operational sequences. The delay counter is normally started at the beginning
of an operation and reset at the end.
It is an eight-stage counter consisting
of two four-stage counter modules (see
Figure 2-2) that are advanced by the
output of a single shot oscillator
every 23 milliseconds.
The output of the delay counter is eight
stages of timing pulses designated DC1,
DC2, DC4, through DC128.
The delay
counter outputs are also ANDed to develop additional timing pulses necessary to tape unit operation (see Figure
2-2) .
THREAD/LOAD OPERATION
The automatic thread/load operation on
the STC tape units is a convenience feature. The thread sequence moves tape
from the file reel, threads it through
the tape channel and winds it onto the
machine reel (see Figure 1-2). The load
sequence dumps tape from the reels into
the vacuum columns and then moves the
tape to load point (the point at which
the beginning-of-tape marker is sensed
by the beginning-of-tape sensor).
To help supplement the text, a flow
chart of the thread/load operation is
provided in Figure 2-3. Reference to
the figure will help organize the sequence in which the various functions
occur. Figures 2-4 and 2-5 provide a
thread sequence timing chart and a
columns load sequence timing chart.
2·3
DC 48
DC 116
DC 2
DC 4
,
+ ADV DC
1------I
I
r-
I
I
~ULSE~
PE~IOD
DC 8
14 STAGE
ICOUNTER
1
1
1
23mS
43ms
,
DC 1
DC16
I
1
1
I
1
1
DC 32
DC 2
I
I
I
1
I
I
L
I
I
1
1
I
DC 64
DC 4
1
1
I
1
I
IL ___________________ ....
DC 128
Figure 2-2.
To initiate the thread/load operation,
the operator places the file reel on
the hub and presses the LOAD/REWIND
pushbutton. This locks the file reel
to the automatic hub, closes the power
window and sets both the Load Delay
latch and the Load latch (see Figure
2-3) .
Setting the Load latch results in the
following actions:
•
Power is applied to the pneumatic
system.
•
Pressure is transferred for threading.
•
The cartridge opens.
•
The delay counter starts.
Load Delay allows time for the pneumatic
system to build pressure and vacuum up
2-4
Delay Counter
to proper operating levels, to transfer
vacuum for threading and permits interrogation of the file protect switch.
File protect is a feature designed to
protect the data stored on a tape (keep
it from being written over by mistake) .
If a write enable ring is detected by
the file protect mechanism at delay
count 32, the Not File Protected latch
sets to enable writing on the tape.
If no ring is present, the Not File Protected latch does NOT set and writing
CANNOT occur.
(If a write command is
received, COMMAND REJECT is set in the
TCU) .
At delay count 116 load delay ends, the
delay counter is reset and the Thread
latch sets, activating file and machine
reel motion.
(For additional reel motion explanation, refer to the Reel Control Circuitry section of Chapter III.)
Both reels begin moving clockwise with
the file reel turning at 60 r/min and
the machine reel turning at 140 r/min.
NO
ACTIVATE HUB
TO HOLD FILE
REEL ONTO
MACHINE
SET
WINDOW
DOWN
LATCH
SET
LOAD
LATCH
SET
LOAD DELAY
LATCH
SET
MIDTAPE LOAD
LATCH
Page 2·9
Sheet 5 of 6
START
WINDOW
MOTOR
NO
OPEN CARTRIDGE
START
PNEUMATIC
MOTOR
START
DELAY
COUNTER
ACTIVATE PRESS
SOLENOID (FOR
THREAD MODE)
ACTIVATE VAC
TRANS SOLENOID
(FOR THREAD
MODE)
Page 2·6
Sheet 2 of 6
Figure 2-3.
Thread/LoadFlow Chart (Sheet 1 of 6)
2-5
MACHINE REEL
TURNS CLOCKWISE
(140 RPM)
FILE REEL
TURNS CLOCKWISE
(60 RPM)
NO
SET NOT
FI LE PROTECTED
LATCH
NO
NO
YES
SET
THREAD
LATCH
NO
RESET
DELAY
COUNTER
NO
RESET
LOAD DELAY
LATCH
Page 2-7
Sheet 3 of 6
Page 2-7
Sheet 3 of 6
Figure 2-3.
2-6
Thread/Load Flow Chart (Sheet 2 of 6)
Il"'""--'
Page 2-6
Sheet 2 of 6
Page 2-6
Sheet 2 of 6
SET
THREAD CHECK
LATCH
SET
REELS LOADED
LATCH
RESET
DELAY
COUNTER
REWIND TAPE
TO FILE REEL
NO
YES
NO
YES
SET
COLUMNS CHECK
LATCH
RESET
DELAY
COUNTER
SET
LOAD COLUMNS
LATCH
SET
MACHINE
CHECK
RESET
THREAD
LATCH
AUTOMATICALL Y
RETRY THREAD
OPERATION
DEACTIVATE
VACUUM TRNSFR
SOLENOID
(FOR RUN MODE)
Page 2-8
Sheet 4 of 6
Figure 2-3.
Thread/Load Flow Chart (Sheet 3 of 6)
2-7
Page 2-7
SheE'lt 30f6
MACHINE REEL
BEGINS TURNING
COUNTERCLOCKWISE
YES
RESET
REELS LOADED
LATCH
,NO
SET COLUMNS
LOADED LATCH
DEAcTIVATE
PRESSURE
SOLENOID
(FOR RUN MODE)
DROP
LOW-SPEED
REEL CONTROL
Page 2-9
Sheet 5 of 6
Figure 2-3.
2-8
Thread/Load Flow Chart (Sheet 4 of 6)
Page 2-8
Sheet 4 of 6
SET
SEARCH
LATCH
RESET
DELAY COUNTER
RESET
LOAD COLUMNS
LATCH
Page 2-5
Sheet 1 of 6
YES
ACTIVATE
MIDTAPE
SEARCH
SET
GO
(TAPE MOVES
FORWARD)
NO
YES
YES
SET
COLUMNS CHECK
LATCH
SET
MACHINE CHECK
LATCH
SET
REWIND
OPERATION
Page2-10
Sheet 6 of 6
Figure 2-3.
Thread/Load Flow Chart (Sheet 5 of 6)
2-9
--""'I Page 2-9
Sheet 5 of 6
SET
REWIND
LATCH
RESET
DELAY
COUNTER
RESET
HIGH-SPEED
STEP LATCH
RESET
LOAD LATCH
NO
RESET
SEARCH
LATCH
YES
SET
HIGH-SPEED
STEP LATCH
RESET
HIGH-SPEED
LATCH
NO
RESET
REWIND
LATCH
PRESS
START
PUSHBUTTON
SET
HIGH-SPEED
LATCH
NO
YES
NO
TAPE UNIT
READY
Figure 2-3.
2-10
Thread/Load Flow Chart (Sheet 6 of 6)
- LOAO/R EW PB
-SET LOAD
----u
---u
During the threading mode, pressure and
vacuum guide tape from the file reel into the right threading channel, Tape
entering the head area blocks light from
the tape-present photosensor, activating
+TAPE PRESENT. The tape-present sensing
element is a phototransistor located in
the tip of the right threading channel
immediately adjacent to the tape cleaner
block.
-OPEN HUB
---1
-DOWN
~.
+ LOAD
---1
-OPEN CARTR
~
- TRANS VAC
---,~----------~
- PNEU ON
---,~-------------------
+ NFP
---..I
r-----------·
DCl16~
+ THREAD OP
------~I~--------~~------
- LO SPD CNTL
+ RT DRIVE D
+ LT DRIVE C
+ TAPE PRESENT _ _ _ _---'
+ REELS LOADED--------.....
+LTDHIVED
Figure 2-4.
Thread Sequence Timing Chart
+ LOAD
I
- LOW SPD CNTL
+ RT DRIVE D
+ LT DRIVE D
- LT ZA
- RTZA
-COLLDDCATCH-------------~
-SEARCH
- FWD STATUS
+GO
-BOT FF
Figure 2-5.
Colums Load Sequence Timing Chart
As tape movement continues, the tape
floats up to the machine reel where it
is pulled onto the reel hub· by vacuum.
The faster moving machine reel pulls
the tape taut, which activates the Reels
Loaded switch to set the Reels Loaded
latch.
The Reels Loaded latch then resets the delay counter. Both reels continue turning clockwise winding tape onto the machine reel until delay count
128 is reached. At this time the Thread
latch, Reels Loaded latch and delay
counter are reset and the Load Columns
latch is set.
Resetting the Thread latch starts the
machine reel turning counterclockwise,
while the file reel continues turning
clockwise.
It also causes vacuum and
pressure to be transferred from the
threading channel to the vacuum columns.
Reel movement unwinds tape from both
reels and the vacuum draws it down into
the columns. When tape filling the
column reaches the appropriate position
(zone B), the Columns Loaded latch is
set.
Setting the Columns Loaded latch transfers reel control from low speed control to column control. Resetting low
speed control resets the delay counter
and the Load Columns latch and, in addition, it sets the Search latch.
If
beginning-of-tape has already been detected (due to a short leader), search
is immediately aborted, rewind is set
and a mid-tape search is begun (see
Short Leader Load/Midtape Load) .
with the tape unit in forward status,
GO'becomes active and is applied to the
2-11
capstan control system. This starts the
capstan motor, moving tape forward in
search of the beginning-of~tape (BOT)
marker.
The BOT sensor located in the
tape path detects the trailing edge of
the BOT marker activating the BOT pulse.
.The BOT pulse is logically ANDed with
the SEARCH signal to set rewind.
The High Speed Step latch then sets,
but the tape unit remains at normal rewind speed until delay count 48. Normally the BOT marker is detected moving
back across the sensor during the delay
and high-speed rewind never occurs.
If
the BOT marker is not detected during
the delay, the. High Speed latch sets to
put the tape unit into high-speed rewind.
NOTE
A high-speed rewind is highly unusual during search, even though
the logic exists for it.
When the low-speed area (LSA) sensor detects the BOT marker, the High Speed Step
latch and High Speed latch reset" The
tape unit returns to normal rewind speed
until the BOT sensor detects the BOT
marker and sends out a BOT pulse. This
BOT pulse is ANDed with a BOT DELAYED
pulse to set the BOT latch. GO becomes
inactive and the rewind function ends.
This completes the thread/load operation.
If the START pushbutton is or has
been pressed, the tape unit is ready to
accept commands from the tape control
unit.
In the event that the mounted tape has
a short leader, the thread operation begins as in a normal thread/load sequence.
But because the leader is
short, the BOT marker passes the BOT
sensor during the thread operation.
The sensor detects the early passing
of the BOT marker and sets the Short
Leader latch.
When the columns are loaded, the Short
Leader latch activates midtape search.
Midtape search causes the tape to rewind to load point -- there is no need
to search forward for the BOT marker
which has already been detected. When
load point is reached short leader load
ends and the tape unit is ready to accept commands from the tape control.unit.
Midtape load occurs if the LOAD/REWIND
pushbutton is pressed when tape is present in the head area.
Pressing LOAD/
REWIND sets the Midtape Load latch,
which sets the Load Columns latch if
the columns are NOT loaded. Tape is
then dumped into the columns and the
load operation proceeds in a normal
fashion.
When the columns are loaded, setting the
Midtape Load latch activates midtape
search. As was the case in the short
leader load, tape rewinds to loadpoint.
The tape unit is once again ready to accept commands from the tape control unit.
LOAD OPERATION CHECKS
SHORT LEADER LOAD/MIDTAPE LOAD
The normal load operation as just described varies under two conditions -short leader load and midtape load.
Short leader load is a condition caused
by the tape not having a leader of approximately 10.5 feet or more.
(For. a
successful load operation, the leader
must be at least 7.5 feet).·
2-12
During the thread/load sequence, many
checks are made of individual operations.
If an error condition is detected during thread/load, either a
retry operation or a machine check can
result. Anytime the Machine Check
latch is set, the MACHINE CHECK indicator (on the operator panel) is on.
This in turn resets the operation in
progress, turns off pneumatics and opens the power window.
One check, file protect, was mentioned
in the Thread/Load section. The file
protect switch senses the presence or
absence of a write enable ring on the
file reel (see Figure 2-6). Lack of a
ring inhibits the write circuits.
File protect is keyed by a pressure sensitive switch. During the thread/load
operation, the pneumatic system sends a
blast of air through a port in the file
protect assembly.
If the air strikes
a write enable ring, the air deflects
back onto the pressure sensitive switch.
This deactivates +FILE PROT SW and thus
sets the Not File Protected latch. The
loaded tape can then be written on.
If no ring is present on the file reel,
there is no deflected back pressure onto
the pressure sensitive switch.
In this
case +FILE PROT SW is active, keeping
the Not File Protected latch from set-
ting. When this occurs, the loaded tape
cannot be written on.
The logic circuits, which sense the position of the file protect switch, are
designed for fail-safe operation. Thus,
if the switch fails such that it indicates a ring is present when in fact it
is not, the logic detects the error.
This occurs once tape is loaded into
the columns. Pneumatics to the file
protect assembly drop, removing back
pressure from the switch. The switch
should then return to its normal position causing +FILE PROT SW to become
active.
If +FILE PROT SW remains inactive (due
to a file protect failure) +READY INHIBIT stays active. Because ready
status is not presented to the tape
unit unless +READY INHIBIT is inactive,
a device check results -- bringing the
tape unit to a halt -- after a delay
count of 48.
RITE ENABLE RING
Figure 2-6.
Write Enable Ring and File Protect Mechanism
2-13
Two checks are made during the load operation. At delay count 64 a check is
made to see if the tape-present sensor
detects tape. Then at delay count 128
the Reels Loaded latch is interrogated
to determine if the reels are loaded.
If either condition is not satisfied,
the .Thread Check latch is set and the
delay counter is reset.
If there is no
cartridge on the machine, the Check
latch is set which, in turn, sets machine
check.
If a tape cartridge is in use, the
thread operation is retried.
The Thread
Check latch causes +RT DRIVE C and +L
DRIVE D to become active and the tape
to be rewound into the cartridge. At
delay count 208, the Thread Check latch
arid the delay counter are reset.
The
Retry latch sets, initiating another
thread operation with the normal checks
for tape present and reels loaded.
If
the thread operation fails the second
time, the Thread Check latch is again
set and tape is rewound onto the file
reel. The thread operation halts when
-COL CHK LTCH sets a machine check.
A missing BOT marker can also result in
machine check.
If during the search
mode the BOT sensor has not detected the
BOT marker by delay count 128, the two
signals are ANDed to set a machine check.
A manually. induced check -- pressing the
RESET pushbutton --can be used to halt
machine operations during the load sequence.
Pressing RESET results in the
signals RESET 2 and LOAD LATCH being
ANDed to set machine check. To restart
the load operation, tape must be cleared
from the tape present sensor by handwinding the tape onto the file reel.
generated, under certain conditions,
during the thread/load operation.
CONTROL SIGNALS
The -SET REWIND/UNLOAD signal (from TCU)
or the -UNLOAD PB signal (from the REWIND/UNLOAD pushbutton on the tape unit
operator panel) initiates the rewind
operation by activating SET UNLOAD.
Activating SET UNLOAD also conditions
the unload operation, so that unload occurs following the completion of rewind
(see the Unload Operation section of this
chapter):
The third signal that can initiate rewind
is -SET REWIND (from the TCU). Unlike
the first two signals, activating -SET
REWIND results only in a rewind to load
point. The final signal capable of initiating rewind, -MIDTAPE SEARCH, is
activated either by a short leader load
during a thread/load operation (see the
Thread/Load section of this chapter) or
by pressing the LOAD/REWIND pushbutton
on the tape unit operator panel.
-MIDTAPE SEARCH also results only in a rewind to load point.
To aid in the understanding of rewind,
Figure 2-7 provides a flow chart of the
operation. Figure 2-8 is a series of
rewind operation timing signals.
REWIND SEQUENCE
REWIND OPERATION
The -SET REWIND/UNLOAD signal and -UNLOAD PB signal are gated together, the
output of which is -SET UNLOAD.
-SET
UNLOAD is then gated with -MIDTAPE
SEARCH and -SET REWIND.
If any of these
three signals are active, a rewind operation is initiated when their gated
output sets the Rewind latch (see Figure 2-9).
The signals that initiate a rewind operation can originate from anyone of
four possible sources -- two from the
tape control unit, one from the tape
unit operator panel and one that can be
The Rewind latch sets backward status
and activates GO, causing tape to move
backward at normal speed.
In addition,
the High Speed Step latch sets (see Figure 2-9) and starts the delay counter.
2-14
REWIND/
)
UNLOAD
PUSHBUTTON
FROM TCU
I
I
SET
REWIND/UNLOAD
SIGNAL
UNLOAD PB
SIGNAL
I
I
FROM TCU
~
GENERATED
IN THE TAPE UNIT
SET
UNLOAD LATCH
I
I
SET REW
SIGNAL
MIDTAPE
SEARCH
SIGNAL
I
~
I
A.
'"
I
1
RESET
DELAY COUNTER
SET
REWIND LATCH
I
I
I
1
SET
BACKWARD
STATUS
SET
GO
START
DELAY
COUNTER
l
. ...
I
SET
HIGH-SPEED
STEP LATCH
~ Page 2-16
A
Figure 2-7.
Sheet 2 of 2
Rewind Operation Ffow Chart (Sheet 1 of 2)
2-15
RESET
HIGH-SPEED
LATCH
YES
NO
YES
SET
HIGH-SPEED
LATCH
RESET
REWIND
LATCH
NO
RESET
GO
STOP
TAPE
MOTION
RESET
HIGH-SPEED
STEP LATCH
NO
NO
YES
SIGNAL TCU
TAPE IS AT
LOAD POINT
INITIATE
. UNLOAD
SEQUENCE
Figure 2-7.
2-16
Rewind Operation Flow Chart (Sheet 2 of 2)
- LOAO/REW PB
---u------!! ~
u
- MIDTAPE SEARCH
.! I~--------
. ~ I
- TRANS VAC
- TRANS PRESS
----,
.
-SETREW
_ _ _ _ _ ' I ___
L-_-t._
-+\
DC 116 ,-
- SET REW/UNLOAD
- UNLOAD PB
- SET UNLOAD
U
- SET REWIND
U
- REWIND
GO
- FWD STATUS
-·H.S. REWIND
--!~-----..;..--.
!!
/ !
I
/I
r
UNLOAD OPERATION
L
The unload operation is initiated only
after tape has been rewound to load
point.
It is activated by either of
two signals, -SET REWIND/UNLOAD (from
the TCU) or - UNLOAD PB (from the REWIND/UNLOAD pushbutton on the tape unit
operator panel) .
~~
- H. S. REW RESET
/~
-STEP DOWN
/~DC2
-BOT FF
/ !
L
- AT LOAD POINT
/I
L
Figure 2-8.
The BOT marker triggers the BOT sensor
(load point), setting the BOT latch.
The BOT latch resets the Rewind latch,
deactivating GO and signaling the reel
and capstan control logic to end tape
movement.
In addition, setting the BOT
latch signals the.TCU that the tape is
at load point and ready.
Rewind Operation Timing
After a delay count of 48, the High
Speed latch is set. This starts the
capstan motor ramping up to high-speed
rewind, where it remains until the BOT
marker activates .the Low-Speed-Area sensor. The delay keeps the system at normal backward speed in case the BOT marker is between the low-speed-area sensor
and the BOT sensor.
The delay is important because the BOT
marker on the tape triggers the lowspeed-area sensor,· signaling rewind is
nearly complete. Triggering the lowspeed-area sensor generates -HS REWIND
RESET, which inputs to the High Speed
Step latch causing the High Speed latch
to reset and -STEP DOWN to activate.
-STEP DOWN signals the capstan to brake
from high-speed rewind to normal backward speed. Tape movement then contin~
ues at normal backward speed until the
BOT marker triggers the B·OT sensor
(load point), setting the BOT latch.
Figure 2-10 is a flow chart which illustrates the unload operation sequentially. A list of timing signals for
the unload operation is found in Figure i-ll.
When either -SET REWIND/UNLOAD or
-UNLOAD PB is active, the UNLOAD latch
sets and a rewind operation is initiated
(refer to the Rewind Opera·tion section
of this chapter). Once the unload latch
sets, the unload operation remains inactive until the tape reaches load
point.
When the BOT sensor detects the BOT
marker, the BOT latch sets and the output is ANDed with the output of the Unload latch to activate UNLOAD (see Figure 2-12). UNLOAD starts the delay
counter, deactivates pneumatics and returns the tape unit to low speed control;.
In addition, UNLOAD controls reel motor
motion during the unload operation.
It
activates +REEL DRIVE C to turn the file
reel counterclockwise, pulling the tape
out of the columns and winding it onto
the reel. When tape tension transfers
2-17
LOAD PB
-
BOT
LATCH
BOT
0
A
BOT LATCH
A
100
TAP~
200
PRESENT-
100
-
SEARCH~~__1~_0__~
o
120
.....---.....
-
'
SHORT LEADER----:-
-
120
MID TAPE SEARCH
REWIND~--O-'"
UNLOADPB
'REWIND
COMMAND
~~------------~------------~R~E~W~'N~D~
MACHINE CHECK
240
o
BOT LATCH
-
A
DC 48
BACKWARD STATUS
150
160
H.S.
LATCH
t--r-
'160
160
~
I
A
190
, H.S.
STEP
LATCH
160
o
REWIND
160
GO
.-
LATCH
r-----.
170
r-
I
630
REEL DRIVE
LOGIC
I
780
630
ISTEP
UP
I
L--
GO
150
L--
1
LINEAI'!
CONTROL
680
I
150
I
'--
A
8ACKWARDGO
630
CAPSTAN
CONTROL
POWER AMP
STEP DOWN
160
Figure 2-9.
2-18
Rewind Operation Simplified Logic
640
SET
LOAD LATCH
NO
YES
START
DELAY
COUNTER
REEL MOTION
TO LOW-SPEED
CONTROL
DEACTIVATE
PNEUMATICS
START FILE
REEL MOVING
COUNTERCLOCKWISE
NO
START MACHINE
REEL MOVING
COUNTERCLOCKWISE
11"'""........., Page. 2-20
Sheet 2 of 2
Figure 2-10.
Unload Operation Flow Chart (Sheet 10f 2)
2-19
NO
BRAKE
FILE REEL
TO STOP
DROP DRIVE
POWER TO
MACHINE REEL
NO
YES
RESET
DELAY
COUNTER
CLOSE
CARTRIDGE
NO
SET
END UNLOAD
LATCH
Figure 2-10.
2-20
OPEN
POWER
WINDOW
Unload Operation Flow Chart (Sheet 2 of 2)
- SET REW/UNLD or
- SET UN LOAD PB
~r---------lll
- SET UNLOAD
~""'-----~l 1
- UNLOAD LATCH
~~-----~il~----------------~
- BOT FF
~----~l I~------------------------------- UNLOAD
+ PNEU ON
~----~l I~------------------~
~I----~l ~I____________________________-=
+ RT DRIVE C
~I----~l ~I----------------~
~DC16
- LO SPEED CNTR L
-------""1
+ REELS LOADED
+ TAPE PR ESENT
DC 8
+ RT DRIVE D
I+-!>I
-------~------~l ~I-----~------~-~~
DC2
14
I)j DC 16
U";';---
- CLOSE CART
II
-UP
l~I----------------~.~
-OPEN HUB
----------~--~l~l------------------~~
_______
l~I------------------~.~~
. - UNLOAD COMPL
Figure 2-11.
Unload Operation Timing
the reels loaded switch, activating
REELS LOADED, +UNLOAD is gated through
to activate +LEFT DRIVE D (see Figure
2-12). This turns the machine reel
counterclockwise, dumping tape from it.
When the machine reel is empty, the
reels loaded switch deactivates and
thus drops power to the machine reel.
The file reel continues turning, pulling
the tape out of its path. When TAPE
PRESENT goes inactive, the delay counter
resets. At delay count six UNLOAD is
gated to set the End Unload latch (see
Figure 2-12), activating -END UNLOAD.
Activating -END UNLOAD results in the
following actions:
The file reel brakes to a stop.
The cartridge closes.
The power window opens.
The
and
The
the
automatic hub releases the file reel
the unload operation is complete.
file reel may now be removed from
tape unit.
2-21
RIGHT COL
LOADED
WINDOW CLOSED
TAPE PRES
A
A
DC 16
230
230
A
CARTRIDGE
ON SWITCH
END UNLOAD
CARTRIDGE CLOSED
230
A
CARTRIDGE
CLOSED
SWITCH
A
230
210
A
RL~
INT READY
A
f-- UNLOAD
-
e-
A
f-210
~
A
""-
UNLOAD
LOAD
180
....
1-.
160
RT DRV.C
180
A
UNLOAD
COMPLETE
WINDOW
UP
LATCH
210
CLOSE
CARTRIDG E
LT DR\/, D
180
~WINDOW
. OPENS
WINDOW
CLOSED
A
DC8
COL LDD
LATCH
DC2DC4-
220
A
DC 16-
A
. COL CHK
220
RESET PNEUM
180
LATCH
190
RWD
UNLD
CMD
1
A
TAPE PRES
A
END
UNLOAD
160
TO FIG.15
RWD
~
P8
.---
~
I
240
START
LATCH
270
DC6
-
I
UNLOAD
.--
240
END
I--- UNLOAD
A
160
160
SET UNLOAD
UNLOAD
LATCH
LOAD
RESET 1
(PWR
FAIL)
R ESET PB
RESET
0
r-L
.--
~
0
160
MACH CHK
160
BOT
160
PNEUM
LATCH
PNEUM ON
TO MOTOR
230
135
Figure 2-12.
2-22
A
Unload Operation Simplified Logic
~
UNLOAD
BRAKE
CHAPTER Iii
FUNCT!ONAL
INTRODUCTION
DESCRIPT~ON
~
Reel control system.
~
Capstan control system.
Neither reel is responsible for the
movement of tape across the read/write
heads -- an operation performed by the
capstan. The reels, however, are responsible for maintaining proper tape
loops in the vacuum columns during operation. The Reel Control system operates the reels in two basic modes
during tape unit operation -- Low Speed
Control and Column Control.
Read/write control.
Low speed control is in effect during:
The various assemblies and subassemblies which comprise the tape unit are
described in this chapter. The subject
matter covered is:
o
Input/output lines.
Threading
Power supply.
Loading
Pneumatics.
Unloading
Tape unit cooling.
This chapter is a prime source of information and provides a working knowledge of tape unit operation. The information is necessary when deter"mining
whether the tape unit is functioning
properly. Thus during troubleshooting,
the information aids in the progression
from symptom to problem to solution.
REEL CONTROL SYSTEM
Two tape reels are used on each tape
unit -- a file reel and a machine reel.
A file reel is used for storage of tape,
and therefore must be interchangeable.
The machine reel is permanent and its
only function is to take up tape during
tape unit operation.
During these low speed operations, the
reels function under the direction of
signals from the Control Logic.
Operations are initiated either by commands
from the operator panel or from the interface. The operations are monitored
and terminated by sensors in the tape
threading path and tape columns. The
reel motors are powered by -10 volt
"power during low speed operations.
Once tape is loaded in the columns, the
reels operate under Column Control which
constantly strives to keep the tape
loops in zone B (see Figure 3-2).
Column Control is in effect during:
•
Normal forward and backward
operation.
High-speed rewind.
3-1
During Column Control, the capstan may
move tape across the read/write heads
and when this occurs the reels take up
or feed tape to maintain proper loop
position in the tape columns. The reel
motors are powered by -46 volt power,
with sensors in the tape columns monitoring loop position, direction and
velocity. When the tape is not moving,
the loops are held in a quiescent state
by -10 volt power.
Column control logic circuits and -46
volt power switching circuits are located on the Right (3A) and Left (3C)
Reel boards of the power gate assembly.
The Miscellaneous board (3D) contains
the -10 volt power control, motor field
control, Emergency Power Off (EPO) circuits and armature and field currentlimiting resistors.
lOW SPEED REEL CONTROL
During threading, loading ana unloading,
the reel motors are driven by either
Drive C or Drive D, with a path through
a current limiting c~rcuit to -10 volts.
The current limiting circuits provide
the correct amount of torque for the
reels to operate in.these modes.
All four of the -10 volt lines (two per
motor) are normally enabled to and balanced across the motors. The file or
right reel is supplied -1.0 volts by Ql
or Q2 being enabled. The machine or
left reel is supplied -10 volts by Q3
and Q4 being enabled. To obtain current
flow through the motors, either Ql or
Q2 and Q3 orQ4 must be disabled, which
will in turn end the balanced condition
of the voltages.
Figure 3-1 is a general schematic for
the reel motor showing the power H configuration, -10 volt armature control,
field control and EPO. The figure is
valid for both reels. The difference
3-2
being that driver C turns the machine
reel clOckwise (CW) and the file reel
counterclockwise (CCW). Conversely,
driver D turns the machine reel counterclockwise and the file reel clockwise.
During the thread sequence, low speed
logic raises signals ~LT DR C and
-RT DR D. Left Driver C is turned on
by -LT DR C, which also turns off Q4
creating a -lOv current path through
the machine reel motor. This turns the
machine reel in a CW direction. -RT
DR D turns on Right Driver D and turns
off Q2 creating a -lOv path through the
file reel motor. This causes the file
reel motor to turn in a CW direction.
File reel armature current is limited
allowing the machine reel to turn
faster (140 r/min) than the file reel
(60 r/min). The faster moving machine
reel draws tape taut signaling that
threading is complete. Then, after a
delay of about 3.2 seconds, -LT DR C
is dropped and -LT DR D is raised to
turn the machine reel CCW at about 110
r/min. With the machine reel turning
CCWand the file reel moving CW, tape
is fed into the columns until the loops
cover the lower photosensors in zone A
(see Figure 3-2). When the lower zone
A sensors in both columns are covered-signaling that the columns are loaded -the system switches into column control.
If the tape unit is in the rewind/unload
mode, reel operation enters low speed
control at load point. Left Driver C
and Right Driver Cturn on, moving the
machine reel CW and the file reel CCW
with just enough torque to overcome
column vacuum in pulling tape out of the
columns. When tape clears both columns
and become's taut, (activating the reels
loaded switch), Left Driver C turns off
and Left Driver D turns on. Both reels
are then turning CCW, with less current
limiting in the file reel current path
giving it greater torque. The file reel
continues turning CCW until tape clears
R4 (5)
- 46 V o---------.:...--~
ARMATURE
~~--~~~------------~
CURRENT
Q 35,34
I
i
~--~~":-,~)---\...1---_J
SOURCE
6 - 46
3480
ONLY
V
R 47 (48)
- DR A
- DR
LOOP
STABILIZATION
B
-.10 V
. D 12
- DR C
D13
DRIVER
- DR D
FIELD
WINDING
GND
HIGH-SPEED
REWIND
-6 V FIELD
SWITCH
3480
ONLY
HIGH-SPEED REWIND
- 23 V FIELD SWITCH
R 42
TO FIELD WINDING
L - - - - - - - - - - - - - c > OF OPPOSITE REEL
MOTOR
-46V~--0_~----@_---.
FIELD
CURRENT
SOURCE
R 43
Figure 3-1.
Reel System Simplified Schematic
HIGH-SPEED SOLENOID
LOOP MOVING UP
THROUGH ZONE A
ZONE A
ENABLE DRIVERS
AAND D
ZONE B
..
LOOP MOVING OUT
OF ZONE C AND
INTO ZONE B
-"dd-·_·_·_·_· _._. _.-._._._._._._._._.-.
ZONE C
Figure 3-2.
3-4
Column Sensors and Zones
ENABLE DYNAMIC
BRAKE
the tape present sensor signaling that
unload is complete.
COLUMN REEL CONTROL
column toward right zone B. Tape sensed
in left zone C turns on left drivers B
and C (see Figure 3-4). This powers the
machine reel motor to turn in a CW direction, pulling tape up in the left
column toward zone B.
Once tape is loaded in the columns,'
setting the Columns Loaded latch, the
reels are under -46 volt column control.
As the capstan moves tape, each reel
control system feeds or pulls tape to
maintain the loop in its tape column.
While moving tape forward, loops are
maintained in left column zone C and
right column zone A. Conversely, the
loops are maintained in left zone A and
right zone C while moving tape backward.
,FORWARD OPERATION - When the columns
are first loaded, the tape loops are
both maintained at zone B levels until
the capstan receives a command to move
tape forward.
The forward motion pulls
tape in the right column up into zone A
and dumps it into the left column violating zone C. Tape sensed in right
zone A turns on right drivers A and D
to power the file reel motor in a CW
direction (see Figure 3-3). This moves
the tape loop back down in the right
-46 V
I
I
I
RIGHT
DRIVER
A
J
I
~-l
RIGHT
DRIVER
D
GROUND
Figure 3-3.
File Reel Current' PathForward Motion
Right Zone A Vioi.ation
t
I
I
LEFT
DRIVER
B
r--------q*------------~
LEFT
DRIVER
C
1
GROUND
Figure 3-4.
Machine Reel Current Path-Forward
Motion Left Zone C Violation
Both reel motors continue to drive as
long as the tape loops remain stationary
in the violated zones or if the loops
continue to move up in the violated
, right zone A or down in the violated
left zone C.
If downward tape motion
(maintaining proper loop position) is
sensed in right zone A, right driver A
is turned off and the reel motor begins
to coast.
If upward tape motion (maintaining proper loop position) is sensed
in left zone C, left driver B is turned
off and the machine reel begins to
coast.
The reel motors continue to coast if
the tape loops continue to move toward
zone B or until the loops move back into the, zone B.
When tape is sensed
dropping from right zone A into right
zone B, +RT BRAKE C turns off right
drivers A and D and turns on right driver C. This applies a dynamic brake to
the right reel motor by shorting the
3-5
current from the armature back EMF to
ground (see Figure 3-5).
In the same
way, if the tape loop is sensed moving
up from left zone C into left zone B,.
+LT BRAKE D is activated to apply a dynamic brake to the machine reel motor
through left driver.D (see Figure 3-6).
This protects against over-coasting in
zone B.
,-....RIGHT
DRIVER
~,
1
D13
1
C
L
~_J
Reel response of the 3480 tape unit i.s
enhanced by reducing armature currentlimiting when the power supply is most
heavily burdened. This is accomplished
by switching a second resistor in parallel with the normal armature currentlimiting resistor to increase the current available. This occurs automatically if the armature supply voltage
(normally -46 V) drops below -43 V (see
Figur'e 3-1).
Anytime the tape loops drop far enough
to cover the bottom sensors in either
column, -RT COL BTMD or -LT COL BTMD is'
raised to set the Columns Check latch,
set Machine Check and reset the Columns
Loaded latch. This drops the system
out of column control.
Should the upper sensor in either column uncover,
-LT COL LDD or -RT COL LDD drop and
reset the Columns Loaded latch and set
Column Check and Machine Check.
GROUND
Figure 3-5.
D12
r
I
I
'II
Dynamic Brake Current Path (CCW
Rotation)
--1_---,
1
_ _,.,-J
LEFT
DRIVER
D
GROUND
Figure 3-6.
Dynamic Brake Current Path (CW
Rotation)
BACKWARD OPERATION - Reel control dur-.
ing backward motion is the same as for
forward motion, except the loop control
is maintained by left zone A and right
zone C.
3-6 .
In the 3480 model tape unit, the reel
motor field voltages are reduced allowing the reels to turn faster once the
tape loops enter either the upper half
of zone A or the lower half of zone C
in either column. This is accomplished
by switching a resistor in series with
the motor field winding to reduce the
field voltage from -46 volts to -23
volts. The switching is controlled by
the midpoint sensors (PT A-4 and PT C-4)
in each zone.
VELOCITY FEEDBACK CONTROL - Drive to the
reel motors is controlled by velocity
feedback.
As described in the section
on Column Reel Control, the reel motors
are turned on in order to dump tape into or pull tape out of the columns,
thus maintaining proper column tape
loop.
If the reel motors are over driving the loops (pulling or dumping excess
tape), -DR A for the file reel and -DR B
for the machine reel are inhibited by
20 millisecond pulses. The inhibit
pulses are a function of the rate at
which the 22 phototransistor arrays are
covered and uncovered. A simplified
diagram of velocity feedback control is
shown in Figure 3-7.
The outputs of the zone A and zone C
phototransistors for the individual columns are tied together and fed into summing amplifier OPA 1. The output of
OPA 1 is shown in Figure 3-7 as VI, the
function of tape loop position in the
column. VI is +8 volts when the tape
loop covers all phototransistors in the
columns and -8 volts when the tape loop
covers none of the phototransistors in
the columns (the uppermost portion of
zone A). When the tape loop covers the
phototransistors in zone A and none of
those in zone C, the loop is in zone B
and the summing amplifier output voltage
is zero.
The output of summing amplifier .oPA.l
is fed into differentiator OPA 2.
If
the tape loop is moving downward, VI increases in positive steps, thus producing an output of negative 5v pulses
(V2) from OPA 2. These negative pulses
are then applied to the, +DOWN single
shot and produce a 20 millisecond positive pulse for each negative input
pulse.
The +DOWN pulses are gated only for
zone A and they inhibit -DR A, incrementally turning off driver A. The +UP
pulses are gated only for zone C and
they inhibit -DR B, incrementally turning off driver B. The faster the tape
loop moves down in zone A, the shorter
the period of +DOWN pulses and the more
driver A is inhibited.
If the period
of the +DOWN pulses becomes less than
20 milliseconds, driver A remains off
and the reel motor coasts.
In the same
way, the faster the tape loop moves up
in zone C, the more driver B is inhibi~
ted until it remains off and the reel
motor coasts.
A protective squelch circuit is included in addition to the normal velocity feedback signals +UP and +DOWN.
If
the opposite single-shot signal goes
positive, the existing single-shot signal is squelched. For example, the
+DOWN signal is in the middle of its 20
millisecond pulse. The tape loop suddenly reverses (goes up) and the output
of the +UP single-shot becomes positive.
The -up signal immediately inhibits the
+DOWN signal via the squelch circuit.
On the other hand, if the +DOWN signal
becomes positive while the +UP singleshot is in its 20 millisecond period,
the output of the +UP single-shot is
inhibited.
HIGH-SPEED REWIND REEL CONTROL - Highspeed rewind differs very little from a
normal forward or backward operation
except that tape always moves backward
during high-speed operation. During
high-speed rewind, the field current in
both reel motors is reduced to obtain a
faster rewind speed.
The capstan drive
cuts out and reel coasting is inhibited
if the tape loop moves above the middle
sensor in left zone A or below the middle sensor in right zone C.
Field current is reduced by switching a
resistor in series with the -46 volt
supply common to both reel motor fields.
This resistor is normally shorted out
but during high-speed rewind it is
switched in, thus reducing the voltage
across each motor field to -6 volts.
During high-speed rewind on the 3480
model, the field current reduction in
upper zone A and lower zone C is inhibited.
Reel motor coast inhibit occurs when
the tape loop moves up in left zone A
uncovering the midpoint sensor or when
the tape loop drops low enough to
cover the midpoint sensor in right column zone C. Uncovering the left zone A
midpoint sensor raises -LT CAP CUTOUT
which inhibits the machine reel motor
from coasting (coasting normally occurs
when the loop begins to move downward
in zone A) and cuts out capstan drive.
Left driver A remains on causing the
machine reel to dump tape into the
3-7
V 1
~TAPE
f-
-1..,
LOOP MOVING
DOWN IN ZONE A
TAPE LOOP MOVING
UP IN ZONE C
'-1
1 v1
+ 15 V
/
z
V 1
0
N
E
I I II
A
I I I I
__ L.1. ..1....1
z
o
+ DOWN (-DR AJ
20 ms PULSES
N
E
C
.JUUlJl
I" I
e-----.-+ DOWN
A
B
c
D
.--_..... SINGLE
SHOT
SQUELCH
CIRCUIT
I I I I
+ UP
__ l.LLJ
'-------+..... + UP
(-DR B)
20 ms PULSES
r,
_....I
r1 rl n
L.J L.J L.J I
SINGLE
SHOT
Figure 3 .. 7.
3 .. 8
Velocity Feedback Control
column until the tape loop moves through
zone A and into zoneB. Capstan drive
restarts when the left zone A midpoint
serisor is covered. Coast inhibit drops
when tape enters zone B~
Covering the ·midpoint sensor in right
zone C produces much the same results
as previously noted. The tape loop
covers the midpoint sensor activating
-RT CAP CUTOUT.
It cuts out capstan
drive and sets the latch which holds
right driver B on.
Holding driver B
on inhibits coasting (coasting normally occurs when the loop begins to
move upward in zone C) until the tape
loop enters zone B. Capstan drive restarts when the right zone C midpoint.
sensor uncovers.
Coast inhibit drops
when the tape enters zone B.
LOOP STABILIZATION (ANTI-BOBBLE)
Whenever GO drops and the capstan stops,
the reel motors begin to coast driving
the loops into the zone B.
Having tape
enter zone B under these conditions
activates +BRAKE C and +BRAKE' D ending
reel motion. Once the GO line drops,
the delay counter counts to 8, at
which time Driver D is deactivated and
-DR C and -D BIAS DE GATE are raise.d.
-D BIAS DEGATE disables the normal lowspeed control paths for the C driver.s.
In this mode all normal low-speed armature paths are disabled. A small
amount of current leaks through the
40-ohm resistors R47 and R48 (see Figure 3-1), allowing enough armature current through the C drivers to balance
the tape loops in the vacuum columns
against .the pull of the vacuum in the
column when there is no tape movement.
ure 3-1). The EPO relay is normally
energized through transistor Q9 which
is controlled by the +10 volt, -10 volt
and -46 volt power lines.
If +10 volt,
-10 volt or -46 volt power fails, the
relay de-energizes shorting out the motor armatures and field current resistance.
CAPSTAN CONTROL
Tape movement across the read/write
head is under the direction of the Capstan Control System. The control system comprises the capstan motor assembly and velocity control circuits.
The velocity control circuits are listed
below.
Q
A tachometer which measures the
rate of rotation.
Q
A crystal oscillator which is uSed
as a time reference.
Q
A counter that accumulates oscillator pulses during each tach period.
Q
A digital-to-analog converter which
converts the contents of the counter to an analog voltage proportion. al to capstan rotational velocity.
Q
A comparison circuit that compares
the analog voltag~ with a predetermined voltage that is indicative
of the desired rate of capstan rotation and thereby determines whether the actual rate is high, low
or nominal.
•
A driver circuit which, under the
control of the comparitor, provides
an appropriate current path to the
capstan motor that Will produce the
proper rate of rotation.
EMERGENCY POWER OFF (EPO)
A power failure could result in abnormal reel motor speeds and possible tape
damage. To protect against such damage,
an EPO relay shorts out the motor arm- .
atures during a power failure (see Fig-
3-9
rent path is through drivers A and
D. Backward motion current path is
through drivers Band C. Drivers
A and B operate in increments between on and off. Drivers C and D
operate as either on or off (see
Figures 3-8, 3-9 and 3-10).
The capstan motor assembly includes
the capstan motor, the capstan and a
digital tachometer assembly. A high
torque, low inertia motor provides
quick starting and stopping of the capstan.
Due to the nature of the tape
unit, the capstan motor is designed for
intermittent high-current operation.
All STC tape units use a single capstan
constructed of a light-weight alloy.
•
Magnetic coupling is employed to
provide dynamic braking. With dynamic braking no surfaces make contact, thus there is no wear. Braking is accomplished by enabling
drivers C and D which, in conjunction with the adjacent diodes, pro"\ridf~ a brake current path from one
side of the armature to the other.
In other words the armature is
shorted.
Braking is also in effect
when the capstan is stopped. This
prevents motion from occurring as a
result of a disturbance in the tape
path area (see Figure 3-11).
POWER DRIVER
The capstan power driver operation is
broken down into the following four
functions:
•
Direction Control
This is accomplished by providing
the appropriate current paths for
the dc motor." Forward motion cur-
+DRIVE C
Dynamic Braking
DRIVE C
DRIVE D
CONTROL
CONTROL
-46V----~. .~~----~~
~~~~--o-~"------46V
+BKWD HP
DRIVE
+FWD HP
DRIVE
-DRIVE A
ANALOG
CONTROL
DRIVE A
DRIVE B
CONTROL
"CONTROL
O.50HM
-46V
Figure 3-8.
3-10
+DRIVE D
Capstan Power Amplifier
-DRIVE B
ANALOG
CONTROL
r-------- t
I
GND_
DRIVER 0
DRIVER C
DRIVER A
DRIVER B
-46V
-46V
Figure 3-9.
Figure 3-10.
Capstan Motor Current Path
(Backward Motion)
(Forward Motion)
DRIVER
C
(\
~
Capstan Motor Current Path
-------...
\
---«
,'""
,
---- ,
(
,
~-)
BACKWARD BRAKING
--'-- --~
... ----------
C
DRIVER
C
0
/
~
-----..
- - ---io--_
DRIVER
I
,
FORWARD BRAKING
'\
~.-
--'-- "--'--
')
---'--_.
~
'""\
)
DRIVER
o
---~.
HOLDING
Figure 3-11.
Capstan Dynamic Brake Current Paths
3-11
•
High Power Drive
Interblock gaps (IBG 0.6") between
the individual records on tape require that the capstan be up to operational velocity within 20 degrees
of rotation. This is accomplished
by applying full supply power to
the capstan motor until it reaches
88 percent of the desired steady
state rotational velocity. After
this is achieved, high power drive
is terminated. The capstan motor is
then powered by a signal referred to
as linear control.
•
Linear Control
Once the capstan is operating at or
very near the correct rotational
velocity, it must be monitored and.
controlled to ensure that it remains
within tolerance. To accomplish
this, a signal , proportional to the
velocity error controls the capstan
driver conduction. This in turn,
controls the rotational velocity of
the capstan motor., This signal is
referred to as linear control.
The following description of forward
tape motion illustrates the four driver
functions in operation.
Itime. The high power drive line
activates just prior to driver A
being enabled. This provides a
high-current path through driver A,
the motor and driver D. As a result, the motor starts rapidly (see
Figure 3-9).
When the motor reaches approximately 88 percent of the desired steady
state rotational velocity, the high
power drive line becomes inactive.
At this point in the sequence of
events, linear control takes over.
Linear control is a rotational velocity error signal used to keep the
capstan motor rotating at the correct
velocity. Upon completion of the operation,-GO becomes inactive and
disables drivers A and D. After a
120 microsecond delay, drivers B
and C and backward high power drive
are enabled. This provides a reverse current path to the motor
which causes it to attempt reverse
rotation. The net result is rapid
deceleration.
An adjustable single-'shot governs
the deceleration period by disabling driver B when it times out.
Dynamic braking is applied 120
microseconds later by enabling
driver D.
This brings the capstan
motor to a complete stop.
NOTE
•
Forward Motion Control
Initially the capstan motor is in a
dynamically braked condition. This
means drivers C and D are enabled
(see Figure 3-8). To initiate forward motion, the forward line must
be active. When the GO line becomes
active, due to the motion requirement of the operation to be performed, driver C disables. After
120 microseconds" driver A enables.
This delay ensures that drivers A
and C are not enabled at the same
3-12
There is a write single-shot
and a read single-shot used
for reverse current deceleration. They are adjustable
to compensate for initial
tolerances and to provide'
the correct stopping distance.
Total write stop distance is
0.20 inches. Total read stop
distance is 0.35 inches.
Shown in Figure 3-12 are the five modes
of operation for the capstan drivers.
DRIVE
A
STATUS
VOLTAGE
TOLERANCE
+
DRIVE
D
STATUS
VOLTAGE
TOLERANCE
+
FORWARD
HIGH
POWER
DRIVE
DRIVE
B
STATUS
VOLTAGE·
TOLERANCE
STATUS
VOLTAGE
TOLERANCE
+
DRIVE
C
STATUS
VOLTAGE
TOLERANCE
+
BACKWARD
HIGH
POWER
DRIVE
STATUS
VOLTAGE
TOLERANCE
FORWARD
LINEAR
DRIVE
FORWARD
HIGH
POWER
DRIVE
BACKWARD
PLUG
BACKWARD
LINEAR
DRIVE
BACKWARD
HIGH
POWER
DRIVE
FORWARD
PLUG
DYNAMIC
BRAKE
ACTIVE
ACTIVE
INACTIVE
INACTIVE
INACTIVE
OV
OV
1.3V
1.3 V
1.3 V
(OV TO O.4V)
(OV TO O.4V)
(1.2V TO 1.5V)
(1.2V TO 1.5V)
(1.2V TO 1.5V)
ACTIVE
ACTIVE
INACTIVE
INACTIVE
ACTIVE
1.3 V
1.3 V
OV
OV
1.3V
(l.2V TO 1.5V)
(l.2V TO 1.5V)
(OV TO O.4V)
(OV TO O.4V)
(1.2V TO 1.5V)
INACTIVE
ACTIVE
INACTIVE
INACTIVE
INACTIVE
OV
5V
OV
OV
OV
(OV TO O.4V)
(3.0 TO 5.00)
(OV TO O.4V)
(OV TO O.4V)
(OV TO O.4V)
INACTIVE
INACTIVE
ACTIVE
ACTIVE
INACTIVE
1.3V
1.3 V
OV
OV
1.3 V
(1.2V TO 1.5V)
(1 .2V TO 1.5V)
(OV TO O.4V)
(OV TO O.4V)
INACTIVE
INACTIVE
ACTIVE
ACTIVE
ACTIVE
OV
OV
1.3V
1.3V
1.3 V
(OV TO O.4V)
(OVTO O.4V)
(1.2V TO 1.5V)
(1.2V TO 1.5V)
(1.2V T01.5V)
INACTIVE
INACTIVE
INACTIVE
ACTIVE
INACTIVE
OV
OV
OV
5V
OV
(Ov TO 0.4V)
(OV TO O.4V)
(OV TO O.4V)
(3.0V TO 5.0V)
(OV TO O.4V)
. Figure 3-12.
(1.2V TO 1.5V) .
Capstan Driver Voltages and Modes
VELOCITY CONTROL CIRCUITS
The velocity control system senses capstan speed as defined by the tachometer
pulse time period.
It then compares
the speed to a fixed reference and generates an error signal to the power
driver which varies the voltage to the
capstan· motor (see Figure 3-13). Oscillator pulses are counted during each
tachometer period. The count is inversely proportional to the capstan velocity.
The oscillator frequency is
fixed for tape unit speed so that other
capstan system constants are the same
for all models.
•
Digital Tachometer Assembly
This consists of two phototransistor light pairs, an etched glass
disk and a mask.
The glass tachometer disk, mounted
on the capstan motor shaft, has 500
etched radial lines. As shown in
Figure 3-14, ·a light source is
3-13
CNTR
REG
r--
r---
128
128
r-- t--
I
~
-
64'
...... t--
I
64
r--
~
32
.- I--
'j
"
~
16
I
~
-
16
DtA
CAP
CONV t-- t-- CNTRl t -
,....
8
8
.--
~ I--
P--
I
L-
4
4
KvJ
!
TACH
DISC
I
PHOTO
XSTR
I-A
~ I--
I--
INV
t--
,...--
TACH
PREAMP
,...2
I
..-
2
t--
t--
SQUARE
WAVE
CKT
~
~
1
A
OSC
f---'CLOCK
.-
1
~
CNTR RESET
lOGIC
IBG COUNT
REG SET
H.
P. DRIVE
REG RESET
FigUre 3-13.
3-14
POWER
AMP
•
~
+GO
~
t--
I
~
- CNT255
A
32
Capstan Velocity Control Block Diagram
OTO XSTERS
rr~~r---;TACHOMETER
BOARD
TACH OUT
..IL
I------~~
CAPSTAN
MOTOR
PHOTO
XSTER
SWITCH
Figure 3-14.
Digital Tachometer Configuration
mounted on one side of the disk and
a phototransistor on the other. A"
stationary mask (not shown in Figure
3-14) confines the light and in conjunction with the disk produce a
shutter action as the capstan rotates. The light which passes
through the disk and mask flashes
as a result of the shutter action at
a rate proportional to capstan rotation. These light flashes strike
the phototransistor causing it to
alternately turn on and off thereby
producing a sine wave output. The
sine wave is shaped into a square
wave which is used to monitor and
control velocity and stop distance.
•
TO CAPSTAN BOARD
PIN 13 OF
TACH CONNECTOR
Due to the tach period being inversely proportional to the capstan's rotational velocity, the
pulse count decreases as the capstans's rotational velocity increases. Also since the tach
period is the quantity of time
during which the pulse count is
made, the pulse count is a digital
indication of the capstan's rotational velocity.
By sending the
pulse count through a digital-toanalog converter, a rotational velocity analog is developed. This
rotational velocity analog is compared to a fixed reference voltage
which corresponds to the desired
steady state rotational velocity.
Oscillator Pulse Counter
The previously mentioned tachometer
pulses are not adequate in themselves to monitor rotation accurately.
However, the tach pulse duration or tach period is indicative
of capstan rotational velocity and,
by counting fixed frequency pulses
during these periods, a high degree
of accuracy is obtained. A crystal
controlled oscillator provides the
fixed frequency pulses and they are
counted by an eight stage counter.
The oscillator, counter and associa"ted circuitry are shown in a block
diagram in Figure 3-13.
The resultant difference produces
a rotational velocity error signal
used for linear control.
An additional function of the pulse
counter is to terminate high power
drive after start. This is accomplished by monitoring for a pulse
count of less than 255 during two
successive tach periods. When this
situation exists, the 88 percent of
steady state rotational velocity has
been reached and high power drive is
terminated.
3-15
CAPSTAN STARTING
During capstan start, the input to the
D/A converter is held at a count of 192
by an inhibit gate. When -GO becomes
active the power driver logic raises
the high-power driver to override the
analog control and start the capstan
motor at maximum acceleration. As capstan speed increases, the tachometer
pulse frequency increases and tachometer
pulse width decreases. When the oscillator count within a tachometer period
is less than 255 for two consecutive
tach pulses the Linear Control latch
sets. This signals the power driver
logic to switch from high-power to linear control.
It also removes the inhib"it gate and puts the actual velocity
count into the register and the D/A converter.
The capstan motor continues to
accelerate under linear control until
steady state velocity is reached.
CAPSTAN STOPPING
an inch. This is accomplished by counting the total number of tachometer pulses that occur during the stopping and
starting of tape motion (see Figure
3-16) .
When the GO line becomes inactiv.e upon
completion of a write operation, the
IBG counter counts tach pulses while
the capstan is coming to a stop. This
tach count is indicative of the distance
tape was moved while stopping and is retained for use on the next Write command.
When GO from the next Write command is
received and the capstan starts to rotate, the counting is resumed and continues until a count of 31 is reached.
At this time a check is made of the capstan control "registers contents to determine if the capstan is at the correct operating speed.
If the capstan is
not at the correct speed, the contents
of the IBG counter remain at 31 until it
is.
To stop the capstan in the required distance, controlled plugging or dynamic
braking must be applied. Whe"n GO becomes inactive, the capstan remains in
linear control until Go Holdover logic,
which provides proper stopping distance,
allows GO 1 to become inactive. GO 1
becoming inactive applies dynamic braking to the capstan.
When the capstan attains 95% of the
proper velocity, the IBG counter is once
more allowed to count. Two additional
tach pulses are counted (33 total),
which causes the +WR INH (write inhibit)
signal to go negative (inactive). This
causes "write condition" to become active in the TCo". This in turn allows
the first byte of data to be transferred
to the tape unit.
INTERBLOCK GAP CONTROL
FORWARD CREEP - During a "Write-Backspace-Write" sequence of operations
there is a possibility of producing a
short IBG. This arises as a result of
a possible difference between backward
stopping distance and forward starting
distance.
The interblock gap (IBG) is created during the stopping and starting of tape
motion on Write commands. This is accomplished by leaving the write and
erase heads on (with no data).
The
length of the interblock gap is controlled by the IBG counter.
The IBG counter is a six stage binary
"counter (see Figure 3-15) which controls
the write gap to approximately 0.6 of
3-16
To prevent this situation from being a
problem, all operations involving backward motion followed by a Write command
are treated in the following manner
(see Figure 3-17).
+WR STATUS
-WR STATUS
I
r--
A
32
r----
1
16
I
r--
8
U
31CNT fr--
'EXP
4
+GO
HOLDOVER
J
8CNT
I
I
2
WR INH
+TA
-
I
I--
f-'--
1
r-TACH
SQUARE
WAVE
A
~
L.-
'--
A
-GO
-0
~
VELOCITY
CIRCUIT
Figure 3-15.
IBG Counter
3-17
,
.......
1
STOP
DISTANCE
·loCI
1
START
DISTANCE
~
...
1
1
I
I
I
I
I
PRE VIOUS
DATA
BLO CK
I
NEW
DATA
BLO CK
1
I
INTERBLOCK GAP
.....
....
.....
0.6 INCH
I
I
I
"
Figure 3-16.
Interblock Gap Diagram
14l....
1 - - - - ' - - - - - - - - 0.6"
- - - - - - - - - - I..~
NEW GAP CREATED LARGER DUE TO
RESETTING THE IBG COUNTER.
1
1
1
I
1i"-<;!IIIt---- 0.3"
.1'-
0.3" - - - - . :
1
1
D
1
D
1
A
I
A
T
A
II
....
0.6"
I
I
T
A
OLD IBG
I
I
I
1-----'-------- NEW IBG AFTER ONE ROLLBACK ----------i.~
1<11
....
Figure 3-17.
3-18
Forward Creep IBG
The IBG counter ·is reset to zero. Write
Inhibit (WR INH) remains active until
the thirty-third tach pulse is counted.
If consecutive "Write-Backspace-Write
etc." commands, or rollbacks are performed, the tape will gradually creep
forward due to a larger lBG being generated a~ the beginning of each write
operation. This is referred to as
Forward Creep.
incoming one (1) bits of data.
Each
bit has its own busline, driver and
track on tape. The tape moves under
the write head and read head at a specific rate in that order. This allows
the data that has just been written to
be read and thereby checked for accuracy. The read head is much like the
write head but the circuitry is different. Since the read signal is very
weak, it must be amplified a considerable amount.
WRITE OPERATION
READ!WRITE CONTROL
The read/write circuits are the heart
of the tape unit. All other subsystem
operations function to provide the support necessary for reading and writing
to occur. Writing is accomplished by
having a current driver connected to a
write head which is triggered by the
The write circuits are located in the
R/W logic gate, and comprise the following cards: Write Status (lA3) , Write
Driver (lA4, lAS, lA6), and the Load
Card (lA7) (see Figure 3-18).
The write
bus paddle is inserted at lAl; the head
connector plugs into lA7. The logic-toread/write gate paddle is inserted into lA2. This cable contains all control
WRITE
HEAD
I
WD B
ENABLE
WRITE
WRITE
STATUS
WRITE
DRIVER
CENTER TAP
LINE
LOAD
CARD
CENTER TAP
LINE
WOE
WRITE
DATA
FORWARD
MOTION
WRITE
BUS
MAGNETIC TAPE
(OXIDE SURFACE)
READ
HEAD
READ
DATA
READ
BUS
LINE
DRIVER
Figure 3-18.
PREAMP
I
READ
HEAD
AMP
Read/Write B lock Diagram
3-19
lines necessary to operate the read and
write circuits. The resistor pack
(mounted on a 14-pin, dual-in-line package) plugs into the Write Status card at
lA3. This pack is part of the head assembly, and establishes the write. current for each track. However, the resistor pack is not required with a
seven-track head.
The Write Driver card receives inputs
from the Write Bus which control the
driver action. The output is current
limited by the load card and applied to
the write head coils. Figure 3-19 is a
simplified drawing of the Write Driver
circuit.
The Write status card causes the write
drivers to operate in a high current
mode during the initial write delay operation to aid in erasing tape. For a
phase-encoded write operation, the high
current mode ends when the data appears
on the write bus. NRZI write operations
require the high current. The Write
status card also originates an automatic
head degaussing signal. This occurs
when a write operation is followed by a
read operation and the GO line is inactive.
READ OPERATION
The read operation occurs both to obtain data stored on the tape and to
check the validity of data being written. Flux signals from the read head
are routed through the head amplifier
to the preamplifiers. The preamps output this signal to the line drivers for
transmission to the Teu via the Read
bus (see Figure 3-20).
,-----_._---------------------------,
! WRITE
.
.
I DRIVER
iCARD·
. 1A4
CONSTANT
VOLTAGE
1
!wRiTE
I
I
I
1
1
I
I
--·----1
! LOAD
I CARD
i 1A7
MAGNETIC
TAPE OXIDE
SURFACE
WRITE
HEAD
i
VOLTAGE
TO
,..----t CURRENT
NETWORK
DRIVER
TRANSISTORS
.!i .ii
POWER
LIMITING
NETWORK
1 I
iI .i
.I
1
i
CURRENT SETTING
SIGNAL FROM THE
WRITE STATUS CARD
WRITE DATA
BUS INPUT
Figure 3-19.
3-20
ii
I I
.
I_._._._._._._._._. _______
. . ___ ._. ___
I1"1i
.~.
___ . __ J.
.L. ____________
Write Driver Simplified
~
CENTER
TAP LEAD
FROM THE
WRITE STATUS
CARD
r'---'-'-'-'-'-------'--l
i
! PREAMPLIFIER CARD
I
H~I------I
~
I
i
READ
~
.
i
I
j
1
READ
HEAD
AMPLIFIER
....L~
! •...
_ _ _ _-r'~
I
I-~-----~~
PREAMP"
...
LINE!
'1
DRIVER
READ
BUS
TO THE TCU
.
H-
~
i
[
I
I
L.. _________ .___________ ._.i
'----MAGNETIC
I~TAPE
(OXIDE
SURFACE)
DYNAMIC
AMPLITUDE
CONTROL
NOTE:
OPERATION ONLY.
Figure 3-20.
Read Circuit Simplified
HEAD AMPLIFIER
The R/W Head Amplifier card is shown
in Figure 3-21. The head amplifier amplifies the signals from the read. head
before they are routed through the drive
to the preamplifier. The output of the
head amplifier is calibrated to be 440mv
at 3200 flux reversals per inch at the
speed appropriate for each model drive.
The signals from the head enter this
card at the solder terminals.
Power and
output signals travel to the Read/Write
gate through the flat-shielded cable.
Dual operational amplifiers in five Ie
modules (including an extra, unused
amplifier) and associated components
provide amplification.
necessary to handle a nine bit data
byte. The preamplifier cards are in
locations lBS, iB6, and lB7 on the R/W
logic board gate. Each preamp has a
gain control for adjusting the Read bus
amplitude, and a selectable tap type
delay for adjusting read skew. The input signals come from the R/W head amplifier card via a flat cable which connects at location lB4. The R/W motherboard distributes the input signals
from lB4 to the proper preamplifier
channel. The output of preamplifier
goes to a line driver located on the
same card. The line driver outputs to
the R/W termination card and to the Read
bus.
PREAMPLIFIERS, PHASE ENCODED
PREAMPLIFIERS, NRZI
There are three preamplifier cards containing three preamps each. The combined total of th~ three cards is nine
preamp channels which is the quantity
There are two preamplifier cards containing five preamps each. The combined
total of the two cards is ten preamp
channels, nine of which are used for data. The remaining preamp is unused.
3-21
DYNAMIC AMPLITUDE CONTROL (DAC)
9A12=-15V
9A13=+15V
1000000
7 0000000
573
P21064
0880000
14 4
.
0000000
8
4
2
t-...
AMP.
V
DAC is employed only during phase encoded read operations.
It continually
monitors tracks 2, 6 and 7 at the output
of the line drivers.
However, it makes
no gain changes to alter the amplitude
of the present record.
Instead DAC records the amplitude levels of the present record to control the gain of the
next record .
...........
AMP~
V
1
3
14 t-...
13 AMP.
.12 V
11 10- ...........
AMP.
98- V
[J
5
-1
-2
-3
-4
-5
-6
-7
r--.....
AMP·
V
...........
There are three signal levels which are
gating factors for DAC; 300, 500 and
800mv. The DAC circuit introduces the
following gain changes to the preamplifiers:
AMP·
V
•
DAC does not respond to signal levels that are less than 300 mY.
(below 300 mV is considered noise)
•
Signal levels greater than 300 mV
but less than 500 mV are increased
by stepping up the gain.
•
Signal levels greater than 500 mV
but less than 800 mV are within the
acceptable gain of the preamps.
•
Signal levels greater than 800 mV
are considered too high and DAC
will decrease the gain of the preamps.
000000000
~:m 210 6 4 J 7
\
READ HEAD
I
LCONNECTION POINT
SOLDER TERMINALS
Figure 3-21. . R/W Head Amplifier Card
The preamplifier cards are in locations
lB2 and lB3 in the R/W gate. Their input signals come from the read head amplifier card via a flat cable which connects at location lB4. The R/W motherboard distributes the input signals from
lB4 to the proper preamplifier channels.
The basic amplification factor of the
preamplifier is 1.5x, but due to DAC
(Dynamic Amplitude Control) this varies.
The output of the preamplifier goes to
a line driver located on the same card.
The line driver outputs to the R/W termination card and to the Read bus.
3-22
Figure 3-22 is a block diagram of DAC.
The line driver signals monitored by .
DAC are rectified to an average dc level, which is compared to a fixed reference voltage. The outputs of the
three comparators condition the step
latches. The Step latch outputs are
transferred to the binary counter
(0-0-1) which biases the preamplifiers
to a maximum gain.
~:
• PRE,'MPLIFIER CARD
READ
HEAD
AMP
READ
BUS
TO TCU
PRE
AMP
L....,-_....I
DAC ANALOG INfUT
i
.COMP
>
BINARY
COUNTE~
-
SS
300 mV
~
.....
DETECTOR
TRK 6
r+
INTEGRA
TOR
AND
SUMMER
,....,....----<
~
CaMP
>
500 mV
-
r-.
f-;>
STEP
DOWN
LATCH
r---r--
LOGIC
GATES
-
F/F
~
~
:-+ DETECTOR
~
TRK 7
CaMP
4
>
800 mV
- f-+
4
STEP
UP
LATCH
,....,....-
-4:
~:~:
LOGIC
GATES
-
F/F
GAIN 1m:
~
Figure 3-22.
DAC Operational Block Diagram
The analog portion of DAC can best be
explained with the aid of the waveforms shown in sketches A thru G of
Figure 3-23. The 40 zeros burst is
coupled into the first stage of the
DAC board, which is a half wave rectifier.
The input to this circuit is
shown in sketch A and the output is
shown in sketch B. The following stage
integrates and averages the signal to
form an output shown in sketch C. This
signal is then coupled to three comparators, each of which has a different
threshold level. The active state of
the comparator indicates the different
amplitude levels of the signal on the
Read bus.
A
-'\f#.NI!Vv--
40 ZEROS BURST
DETECTED 40 ZEROS BURST
~
c ""\..
I~
II II
I I
I I
JI
I
D
NEGATIVE INTEGRATOR!
SUMMER OUTPUT
I
I I
I
I
; I
I
I
I
LOUTPUT OF> 300mv COMPARATOR
I
E J i L - O U T P U T OF>500mv COMPARATOR
F
~OUTPUT
OF>800mv COMPARATOR
G -----'nL----SAMPLING
DAC is logically reset each time tape
motion changes direction or when the
tape unit is in write status.
Figure 3-23.
PULSE
DAC Operation Waveforms
3-23
INPUTLINES
•
This line puts the tape unit in
Write Status until SET READ STATUS.
All input lines have a maximum active
(down) level of +0,7 volts dc, with a
maximum noise of 0,5 volts; and a minimum inactive (up) level of +2,8 volts,
with a maximum noise of 0,8 volts,
Figure 3-24 shows the interface lines
at the tape unit I/O connector,
•
NOTE
Since write checking is
accomplished by reading,
Read circuits .are conditioned during both read
and write operations.
SELECT (Blv)
The Select signal line "gates" the
tape unit common to the line which
allows it to transmit and receive
subsequent signals to and from the
control unit,
•
•
SET BACKWARD (B1B)
This line puts the TU in backward
status,
It remains in this status
until the Set Read Status or Set
Write Status lines are activated,
Since the tape can be written forward only, Read Status is set by
the BACKWARD line,
•
•
•
3-24·
B2~, B2~,
(B2~,
B2~,
B2~,
B2!,
B2~,
B21,
B2~)
SET NRZI
(B1M)
With the dual density 800/1600 bpi
feature, and tape at load point,
this line sets the NRZI latch for a
write operation.
•
REWIND (B1K)
This input ·line causes the tape unit
to perform a rewind operation (to
load point) .
•
REWIND UNLOAD
(B1P)
This line also causes the tape to
rewind to load point.
In addition
tape unloads and the power window
opens so that reels may be changed.
SET READ STATUS (B1H)
This line sets the tape unit in Read
Status and degates the write circuits, The tape unit remains in
Read status until SET WRITE STATUS
becomes active, SET READ STATUS
assumes forward read, resetting
Backward Status,
WRITE BUS
The nine input signal lines (0-7 and
P) "gate" data from the control unit
directly to the write head drivers.
Data sent by the control unit determines the time duration of write
head flux reversals.
GO (B1A)
This line controls tape motion,
It
is conditioned after the status
lines have been set, to establish
the operation to be performed, The
GO line must be active foralloperations that move tape, except
REWIND and REWIND-UNLOAD,
During
these times, tape motion is under
internal logic control,
SET WRITE STATUS (B1C)
•
METERING OUT (B1R)
This line enables the Elapsed Time
Meter to run when the tape unit is
ready and not at load point.
B2
B1
GO
SIGNAL
D
GO
SHIELD
H
SET
READ
SIGNAL
L
SET
READ
SHIELD
P
REWIND
UNLOAD
SIGNAL
T
REWIND
UNLOAD
SHIELD
W
B
E
SET
BKWRD
SHIELD
A
SIGNAL
F
SET
WRITE
SHIELD
K,
SET
NRZI
SIGNAL
SIGNAL
SET
NRZI
SHIELD
SHIELD
READ
BUS P
SHIELD
RE·AD
BUS 2
SHIELD
READ
BUS 2
SIGNAL,
READ
BUS 5
SIGNAL
T
V
READ
BUS 5
SHIELD
U
METER
OUT
SHIELD
SIGNAL
D
P
S
R
METER
OUT
SIGNAL
C
r
L
N
REWIND
M
READ
BUS P
H
REWIND
J
~
.... oJ
SET
WRITE
SET
BKWRD
SIGNAL
r"\
~:.:)
C
A
B4
r ....
r"'
.... ,.,
\ '.", )
Y
B
READ
BUS 0
SIGNAL
E
READ
BUS 0
SHIELD
J
READ
BUS 3
SIGNAL
M
READ
BUS 3
SHIELD
R
READ
BUS6
SHIELD
U
READ
BUS 6
W
READ
BUS 1
SIGNAL
F
READ BUS 1
SHIELD
K
READ
BUS 4
SHIELD
N
READ
BUS 4
SIGNAL
S
READ
BUS 7
SIGNAL
V
READ
BUS 7
SHIELD
Y
SIGNAL
X
X
Z
-b
Z
~
.Q
.!!..
.£..
WRITE
BUS 1
SHIELD
d
.i
l.
f
-WRITE
h
BUS 1
SIGNAL
.k
.k
II
WRITE
BUS 4
SIGNAL
!!!
E.
.i.
P
WRITE
BUS 4
SHIELD
L
.1.
1-
::i...
SELECT
SHIELD
.!:!..
'f)L
K
WRITE
BUS 7
SHIELD
't:!.
SELECT
SIGNAL
WRITE
BUS 7
SIGNAL
rA--
A
I
I----J
I
----/
I
MUX
BUS 5
SIGNAL
I
1--I
MUX
BUS 5
SHIELD
r---,
L __
I
-..,
I
MUX
BUS 4
SIGNAL
L __
I
--,I
MUX
BUS 4
SHIELD
I
1--~--I
--1I
L __
I
I
WRITE
BUS 2
SIGNAL
p
,
Q
WRITE
BUS 2
SHIELD
hWRITE
BUS 5
SHIELD
m
-WRITE
BUS 5
SIGNAL
..!.
WRITE
BUS P
SHIELD
.!:!.
WRITE
BUS P
SIGNAL
e
WRITE
BUS 3
SHIELD
iWRITE
BUS 3.
SIGNAL
1---.,
I
1
---~
---I
I
S
-WRITE
BUS 6
SHIELD
::i...
WRITE
BUS 0
SHIELD
K
WRITE
BUS 0
SIGNAL
~ --
r---l
I
-1
I
i--
1--- ....,
__ J
I
II
WRITE
BUS 6
SIGNAL
WRITE
INHIBIT
SIGNAL
T
WRITE
r---I
INHIBIT
L____ SHIELD
I
--l
w
1
--1
L __
I
t---....JI
---J
I
~---
I
LOAD
POINT
SIGNAL
z
LOAD
POINT
SHIELD
.£..
SPARE
SHIELD
SPARE
SIGNAL
--,
i
I
j--
L---{
I
~:.)
Figure 3-24.
K
MUX
BUS 2
SIGNAL
J
MUX
BUS 3
SIGNAL
MUX
BUS 3
SHIELD
MUX
BUS 2
SHIELD
MUX
BUS 6
SIGNAL
XTAPE
INDICATE
OFF
SHIELD
~
!
V
MUX
BUS 6
SHIELD
U
MUX
BUS 7
SHIELD
I
!
,
S
R
MUX
BUS 7
SIGNAL
~~
N
M
Y
NOT
READY
SHIELD
-b
NOT
READY
SIGNAL
.£.TAPE
INDICATE
OFF
e
SIGNAL
STATUS
CONTROL
d
2 SIGNAL
360b
SIGNAL
h
3600
SHIELD
j
STATUS
CONTROL
2 SHIELD
II
!!!
E.
.i.
L
1-
::i...
.\!
't:!.
~
+5
+ 15
VDC
TESTER
POWER
VDC
TESTER
POWER
r ....
~0
~J
MUX
BUS 0
SHIELD
MUX
BUS 1
SHIELD
..Is.
L __
I
I
----..J
I
I
L __
.-I
F
E
.i
~---'1
I
MUX
BUS 1
SIGNAL
L
~---t
MUX
BUS 0
SIGNAL
B
H
~--I
- - iI
C
D
r---I
E.
.£.
--.,
(, )
'-J
r ....
(
.:.,.,)
'-
Tape Unit I/O Connector (Connector Side)
3-25
•
STATUS CONTROL 1 (B4d)
•
Not presently used.
•
STATUS CONTROL 2
NRZI
This line is active when:
(B4e)
1.
A tape unit which has the dual
density feature (800/1600 bpi)
installed is operating in 800
bpi NRZI mode.
2.
A tape unit which has the 7Track feature installed is operating.
The STATUS CONTROL 2 line conditions
the eight status lines as follows:
STATUS CONTROL
2 ACTIVE
Mod 4
Mod 2
Mod 1
NRZI
Tach Pulse
Rd Status
Bwd Memory
NFP
BIT
0
1
2
3
4
5
6
7
STATUS CONTROL
2 INACTIVE
Mod 4
Mod 2
Mod 1
NRZI
Seven Track
Rd Status
Bwd Memory
NFP
•
READ STATUS
(B4A)
STATUS CONTROL 3 (B4f)
When active, indicates that the
selected tape unit is in read status; when inactive, indicates the
selected tape unit is in write status.
Not presently used.
OUTPUT LINES
•
All output lines have a maximum down
level of 0.4 volts and a minimum up level of 2.5 volts.
•
SEVEN TRACK (B4H)
When active, indicates that the
7~Track feature is installed.
•
•
(B4J)
MOD 1, 2, 4 (B,K)
BACKWARD MEMORY (B4S)
When active, indicates the selected
tape unit is in backward status.
•
These lines indicate that the tape
unit is selected and ready.
A ·summary of the coding is as follows:
NOT FILE PROTECTED (B4R)
When active, indicates the selected
tape unit may perform a write operation; that is, the file reel contains a write enable ring.
MOD Lines
4
•
2
000
N9t selected or not ready.
o
3480 (250 ips).
0
o
3430 (75 ips).
o
o
0
3440 (100 ips).
3450 (125 ips).
3470 (200 ips).
3-26
WRITE INHIBIT (B4P)
When active, and the selected tape
unit is in write status, it indicates to the control unit that the
proper amount of tape has not been
passed for the IBG.
When the tape
unit lBG counter counts the proper
number of tach pulses the WRITE
INHIBIT line becomes inactive,
thereby indicating to the TCU that
it maycornrnence writing.
When active, and the selected tape
unit is in read status, it prevents
the TCU from activating a read condition. After the proper number of
tach pulses have been counted by
the IBG counter, the WRITE INHIBIT
line becomes inactive.
LOAD POINT (B4W)
When active, indicates the selected
tape unit is positioned at. load
point. The line is reset if the
tape unit is unloaded or if the tape
moves forward.
TAPE INDICATE OFF (B4a)
When active, indicates that .the
tape unit has not reached the EOT
marker. Tape indicate is set by
sensing the light to dark transition
of the trailing edge of the EOT
marker while moving tape forward.
It is reset by sensing the light to
dark transition of the opposite
edge of the reflective marker while
moving tape backward.
REW NOT READY (B4b)
When active, indicates the tape unit
is physically connected but not ready. A tape unit is not ready if it
is unloaded, in reset status, or
rewinding.
If the TCU has tape
switching capability, it may also
signify that the tape unit is operating with another TCU.
On a Rewind/Unload command, the tape
unit drops the MOD 1, 2, and/or 4
lines before activating the NOT
READY line.
READ BUS (B2A, B, C, L, J, N, P, U,
S)
These lines carry data read from
tape to the control unit during a
read operation. They are also used
during a write operation to permit
the checking of write data on tape.
POWER SUPPLY
The power supply consists of an ac
section and a de section. The ac section accepts ac power from a tape control unit and provides primary power to
solenoids, motors, and the dc section
of the power supply. The de section
feeds directly to the using functions
within the drive (see Figures 3-25, 26
and 27 for parts location).
CAUTiON
Do not disconnect all of
the load from the regulated
power supplies when troubleshooting power supply problems. Due to the type of
regulators used in the tape
unit, disconnecting all of
the load will cause the fuse
to blow and could damage the
regulator' card.
AC SECTION
The ac section consists of an input
connector that furnishes ac power to
a 3-phase circuit breaker. The circuit
breaker functions as an overcurrentlimiting device to all ac loads within
the tape unit. A triac board (solid
state switches for ac power) located
within the power supply, turns the motor and solenoids on or off. The 3phase power from the circuit breaker
is fed directly to the ac section.
DC SECTION
Power from the ac section is fed to
terminal board 4, a tap change block,
which feeds two transformers Tl and T2.
This tap change block allows voltage
selection from 208 volts to 230 volts
to be made for proper operation of the
constant voltage (Tl) and 3-phase (T2)
transformers. The 3-phase transformer
feeds a 3-phase, full-wave rectifier.
3-27
T2
@
F
@
G
REGULATOR
CARDS
TOP VIEW
Figure 3-25.
3-28
Power Supply (Top View)
-- -- -- --- ----
0
0
e
er-
0-
.r---;C:::O-..c...-------....::::,....".-----,
o
o
0
(EXTERNAL
VIEW)
~
0
0
0
\
_
r-
TRIAC
BOARD
TB
B
TRIAC
BOARD
MOUNTING
PLATE
TB
1
o
0
'---
0
0
---
--- --
\
\
\
\
\
\
\
\
FUSE PANEL
oFl
oF2
oF3
oF4
o
00
0
/
/
000 0/
F5
F6
F7
000
F9
FlO/Fll
/'"'
00
00
/
,/'
FB
o
F12
./
Figure 3-26.
TR lAC Board and Fuse Panel
3-29
o
o
------- -------
00
0
0
t....._
,...--
1
o
0
o
-0
ra
~
00
00
00
00
0 0
0 ~
50tia1
600
o0
00
00
00
9
o
00
00
o0
00
~ ~ ~
-*
00
0 ~
-.
13. 0 0
10
11
~ ~
14
15 n.
-23V
o
-15V
+5V
+10V
00
00/
Dee
TB3
-
'CI"
Figure 3-27.
3-30
o
0
+15V
DC Distribution Terminals
The rectified output .is fed into a large
capacitance bank. The output of this
capacitance bank is divided among the
various -46 volt fuses (see Figure 3-28).
From the fuses, the dc voltage is applied to the two reel boards, the capstan board, and the miscellaneous board.
POWER SUPPLY FUSES
Fl
+ 15 V@ 3A
3AG
F7
-
10V@15A
3AB
F2
+ 10 V@ 8A
3AG
F8
-
10V@15A
3AB
F3
+
5V@
2A
3AG
F9
-
46 V @ 8 A
3AG
F4
-
15 V@
2A
3AG
FlO
-
46V@15A
3AB
F5
-
23 V@
2A
3AG
Fll
-
46 V @ 15 A
3AB
F6
-
10V@15A
3AB
F12
-
46 V @ 15 A
3AB
FAC
110 V ac @ 1A 3AG for Hub Solenoid
Figure 3-28.
Power Supply Fuse Values
The constant-voltage transformer provides all the remaining voltage levels
within the machine.
Its outputs are
full-wave rectified and capacitor filtered.
Three of these rectified voltages, +5, +15 and -15 are regulated.
All are then channeled through the
proper fuses, (see Figure 3-28) and
outputted.
The interchangeable regulator cards each contain over currentlimiting and overvoltage protection.
A
small potentiometer on each card allows
adjustment of the regulated voltage as
required.
For adjustment procedures refer to Adjustment and Alignment Procedures in
Chapter four.
PNEUMATICS
The pneumatic system supplies the vacuum and pressure which guide the tape
during thread mode, reduces friction
between tape and machine components,
and provides buffering between reels
and capstan during run mode. The system utilizes a vacuum pump and a pressure pump to supply the pneumatics,
with both flow restrictor and bleed
valves to regulate vacuum and pressure
levels.
Pneumatics stabilize approximately 2.25 seconds after LOAD/REWIND
is pressed.
PRESSURE AND VACUUiVl CONTROL
The vacuum and pressure transfer valves,
as mentioned in the Thread/Load section,
control the routing of the pneumatics.
The controlling factor is whether the
machine is in thread mode or run· mode.
See the Thread/Load Flowchart, Figure
2-3, for the vacuum and pressure transfer timing.
During threading, the pneumatic system
supplies pressure and vacuum to the
thread area (see Figure 2-1) at the
following points:
o
The left threading channel (pressure ·only).
o
The right threading channel
uum and pressure).
o
The upper and lower restraints
around the file reel (pressure only) .
o
The machine reel hub
(vac-
(vacuum only) .
The air jets in the lower-left air
bearing (pressure only).
o
The file protect switch (pressure
only) .
The transition from thread mode to run
mode is accomplished by the reels loaded
switch closing and rerouting the pneumatics.
Pressure functions primarily as
a cushion on which the tape rides during
operation.
The air cusion reduces friction between the tape and machine surfaces which decreases drag on the capstan motor thereby increasing tape life.
3-31
During run mode, the pneumatic system
supplies pressure to the following
points:
•
•
•
•
•
The lower left air bearing.
The lower right air bearing.
The upper right air bearing.
The left tape guide.
The right tape guide.
The components listed above are illustrated in Figure 2-1. During run mode,
vacuum is applied to the tape columns
to provide tape buffering. The vacuum
ports are located at the bottom of each
vacuum column and in the tapered columns formed by the Z bars.
PNEUMATICS GENERATION
Pressure is derived from a small air
compressor. Vacuum is derived from a
five stage turbine-like vacuum pump.
This vacuum pump is similar to a home
vacuum cleaner's air propelling mechanism. At higher altitudes it must
rotate more rapidly than at sea level
to move the same quantity of air.
Since the vacuum pump is belt driven
it employs pulleys. A change in the
diameter of a.pulley will provide the
required change in rotational rate.
There are only two pulleys involved,
one for low altitude (below 2,000 feet)
and one for high altitude (above 2,000
feet).
High or low altitude is stamped
oh the pulleys. Functional diagrams
UPPER RIGHT
AIR BEARING
LOWER RIGHT
AIR BEARING
LOW RESTRICTOR
VALVE
PRESSURE
TRANSFER
VALVE
CLEANER
BLOCK
·LEFT
VACUUM
COLU
RIGHT
VACUUM
COLUMN
BLEED
VALVE
VACUUM
MANIFOLD
LEFT
TAPERED
COLUMN
LEFT GUIDE
RIGHT GUIDE
Figure 3-29.
3-32
Pneumatics, Threading Mode
RIGHT
TAPERED
COLUMN
no servicing other than inspection and
cleaning.
Specific areas to be cooled.
are:
of the pneumatic system show air flow
during both thread mode (Figure 3-29)
and run mode (Figure 3-30).
COOLING SYSTEM
The importance of an adequate cooling
system is reflected by the tape unit
BTU output, ranging from 4,400 to 8,200
BTU (depending on the model). Tape
unit cooling is obtained by directing
cool air into some areas and by pulling hot air out of other areas. The
system is non-adjustable and .requires
Q
The power resistor assembly.
Q
The reel motors.
0
The capstan motor.
0
The power supplies.
0
The logic and power gates.
Q
The pneumatic supply area.
Three small cooling fans, located directly above the air filter in the base
of the tape unit frame, draw air into
UPPER RIGHT
AIR BEARING
00
LEFT
THREADING
CHANNEL
TAKE-UP
REEL
AIR JET
LOWER LEFT
AIR BEARING
LOWER RIGHT
AIR BEARING
FLOW RESTRICTOR
VALVE
PRESSURE
RIGHT
VACUUM
COLUMN
LEFT GUIDE
RIGHT GUIDE
Figure 3-30.
Pneumatics, Running Mode
3-33
and direct it thro~gh the general box
area. This air cools the pressure pump,
then circulates through the pneumatic
supply before exiting through a duct in
the rear.
A fan, located at the bottom of the
logic gate, provides cooling by directing air upward through the gate. Two
additional fans, located on the bottom
of the power gate, cool the capstan,
reel and miscellanE;:!ous boards in a similar fashion.
3·34
The power supply is cooled by a single
fan located on the right side of the
power supply enclosure. The same fan
cools the regulator card.
A twin squirrel-cage blower, set between
the two reel motors, draws air through
the reel motors from vents in the front
of the motor housings. The capstan motor uses a different method of cooling.
A vacuum hose, connected to the rear of
the housing, draws fresh air through the
motor.
CHAPTER IV
MAINTENANCE PROCEDURES
INTRODUCTION
The importance of equipment maintenance
is obvious. To help the Field Engineer
perform the maintenance function, this
chapter provides information on the
following topi9S:
There are currently two types of field
testers designed for STC tape units.
The older model (PN 10489) is for use
only with 3400 tape units.
The newer
model (PN 16086) may be used with both
3400 and 3600 tape units.
Field tester.
FIELD TESTER (PN 10489)
Preventive maintenance.
To operate the older model, the tape
unit must be OFFLINE and not in ready
status. The power and command cables
connect at location 2A6 in the logic
gate.
Adjustment and alignment procedures.
Replacement procedures.
The section on the field tester describes the testers capabilities and the
function of each switch. The preventive
maintenance section includes information
on the tasks to be performed and the
specific intervals for performing them.
If the tape unit does not perform within specifications, it is necessary to
proceed with the adjustments and alignments which are also covered in this
chapter. Should the problem be a defective part or assembly, the information
in the section on replacement procedures
will be an aid in changing .the defective
part.
The significant features of this field
tester are as follows:
CI)
o
Per·forms Read forward and backward
operations.
Performs write operations.
Has an auto-cycle which allows con-.
tinuous operation of tape unit for
long periods of time.
Enables the tape drive to Write at
normal PE frequencies, 1/2 normal
PE frequencies, and normal NRZI free
.quencies.
FIELD TESTERS
The field tester is a portable unit
signed to allow the testing of tape
its when they are disconnected from
TCU. The field tester is housed in
black, molded plastic case using an
aluminum bracket to mount it to the
of the tape unit.
Manual control of Go-up, Go-down
times (2 ms to 2 sec).
deunthe
a
top
On/Off control of write lines.
•
•
Test points for all nine tracks .
Logic ground test point •
4·1
active. Wnen it is in the ST-ST
position, the drive operates in a
Start-Stop mode.
(See paragraph on
GO UP/GO DOWN potentiometers below.)
The GO position causes a continuously active GO line in the tape
unit.
FIELD TESTER CONTROLS (PN 10489)
NOTE
When using the tester in
the TI PASS MODE, the EOT
latch is set when EOT
marker is detected.
If
stopped at this point and
rewind is inltia.ted, tape
goes back to BOT, stops
momentarily, then rewinds
off the left reel.
Since
this is a procedure problem
in the use of the Field
Tester, there is no fix in
process. This information
is furnished to advise the
field of what will happen
in TI PASS MODE.
The following list of switches and po...,
tentiometers are used to operate the
tape unit (see Figure 1-5).
•
This is a three-position toggle
switch marked SH-SH/FWD/BKWD.
It
is functional only when GO isactive. The FWD position causes
forward tape motion. The BKWD position causes backward tape motion.
The SH-SH position causes alternating forward/backward tape motion
with a 16 ms. turn-around delay
(see paragraphs on GO UP/GO DOWN
and Auto Functions beloW).
•
NOTE
1. To write valid data, because the frequencies
are inaccurate.
2. To set skew during NRZI
setup.
3. To check feedthrough or
cross talk.·
When in the GAPS position with the
GO control in the ST-ST position,
blocks of data will be written on
tape. The length of the IBG will
be controlled by the tape units
Write Inhibit line feeding into
the tester.
4. To check amplitudes, even
on prewritten tapes.
All these steps must be checked
using a Tape Control Unit.
GO Control
This is a three-position switch
marked GO/ST-ST/STOP. With the
switch in the Stop position, the
GO line to the tape unit is in-
4-2
Read/Write Control
This three-position toggle switch is
marked GAPS/WRITE/READ. When the
switch is in the WRITE position, the
Write Status line is active in the
tape unit.
If a write enable ring
has been installed, and the GO line
is active, the tape unit will write
on tape (see following paragraphs
on Bit Switches). When the switch
is in the READ position, the tape
uni t will reset Wri·te Status. This
allows a read operation to take
place if the GO line is active.
Engineering recommends that
this Field Tester (PN 10489)
not be used for the following:
•
Direction Control
•
End-of-Tape Control
This three-position toggle switch
is marked TI PASS/TI STOP/AUTO RWND.
Bit Switches
It determines tape unit operation
when the end-of-tape (EOT) reflective marker (Tape Indicate) is
sensed. The AUTO RWND position
causes a Rewind Status in the drive
when EOT is sensed. The tape unit
then rewinds to BOT in normal high
speed rewind. The TI STOP position
de-activates the GO line when EOT
is sensed; the tape unit remains in
this status until a rewind or a
backward operation is initiated.
The TI PASS position allows the GO
line to remain active after EOT is
sensed.
There are nine two-position bit
switches that allow a choice of
tracks where data can be written.
When a bit switch is in the OFF
position, no data can be written
in the corresponding track during
a write operation initiated by the
tester; previously written data is
erased.
Rotary Read Bus Switches
CAUTION
NOTE
Do not ground the scope at
any other place.
GO will remain active until
the tape comes off the file
reel.
The two rotary read bus switches
channel the read signal from the
track to which they are set to the
read bus test point located directly below the rotary switch. When
scoping the read bus test points,
use the ground test point for the
scope ground.
.Recording Format
This is a two position switch marked PE/NRZI that sets the tape unit
to the desired recording format.
With tape units having the Dual
Density feature, setting the switch
to the NRZI position sets NRZI Status in the tape unit.
The switch
also channels NRZI read bus to the
read bus test points. With the
switch in the PE position, the PE
read bus is channeled to the test
points. Once the tape unit has
been set to NRZI Status it cannot
be reset until the tape is back to
BOT.
The format switch must be
used in conjunction with the Rotary Frequency switch.
NOTE
The Field Tester read bus
amplitudes are usually
lower than the online read
bus. This is due, in part,
to the differences between
the write frequencies of
the Control Unit and that
of the Field Tester.
The GO test point may be used for
scope trigger when a read envelope
is being observed.
Rotary Frequency
This switch selects the correct
write frequency for the operation
to be performed.
•
Format
Sw.
Rotary
Sw.
NRZI
PE
PE
80
160
320
GO UP/GO DOWN Potentiometers
Results in:
NRZI
PE
PE
(800 BPI)
(800 BPI)
(1600 BPI)
These two potentiometers vary the
time periods for an active and inactive GO line. They are used in
conjunction with the ST-ST and GO
position of the direction control.
4-3
FIELD TESTER (PN 16086)
A ten~foot cable connects the tester to
tne same receptacle that the TCU I/O
cable connects to. Control switches located on the field tester allow manual
operation of the tape. ·uni t to check out
its operation. The light emitting diode
(LED) readouts provide direct read~Qllt
of the tape unit sense lines (see Figure
1-5) .
When reconnecting the TCU to the tape
unit, check again that the pins are not
bent or unseated. Once the TCU is reconnected to the tape unit, restore the
TCU operator panel switches for the particular tape unit to the ON position.
Also, notify operations that the tape
unit is again available for online operation.
FIELD TESTER SWITCHES (PN 16086)
FUNCTIONS AND CONTROLS
Typical functions of the field tester
are:
•
To provide a means of manually duplicating machine operation to isolate errors.
•
To provide a means for manually operating the tape unit while perform-.
ing checks and adjustments.
•
To provide a means of continually
cycling the tape unit manually to
ensure reliability.
The Field Tester switches and their settings are:
•
The Read/Write switch is of the twoposition toggle design. Placing the
switch in the WRITE position activates the write Status in the tape
unit.
If a write enable ring is installed on the file reel, the tape
unit will write on tape (for additional material refer to the paragraphs on the Bit switches). When
the sw.i tch is in the READ position,
the tape unit resets Write Status
allowing a read operation to take
place.
Field Tester cont~ols and displays are
divided into three groups:
•
•
•
Motion Controls·-- control the movement of tape.
Read/write controls and test points.
Status controls and status line
readouts.
OPERATING CONSIDERATIONS
To use the field tester, the tape unit
must be taken offline and all TCU operator panel switches on all TCU's for the
tape unit under test must be turned off.
The I/O connector should be checked for
bent or unseated pins.
4-4
READ/WRITE. SWITCH
•
ST-ST/GO/STOP SWITCH
The field tester GO line is controlled by this switch (the -GO signal
can be monitored at the test point
labled -GO).
Placing the switch in
the STOP position inhibits the -GO,
SET READ, SET WRITE and BACKWARD
signali.
Setting the switch to the
GO position enables -GO continuously
to the tape unit, except for a delay
when the tape is changing direction.
When the switch is placed in the STST position, the -GO signal falls
under the control of the GO UP and
GO DWN potentiometers. The tape
unit operates in a start/stop mode
when the switch is in the ST-ST
position.
•
SH-SH/BKWD/FWD SWITCH
•
When under the control of the field
tester, tape movement is dictated by
the position of the SH-SH/BKWD/FWD
switch on the tester. Placing the
switch in the FWD position drops the
BACKWARD line, allowing tape to move
forward whenever GO is raised.
(Any
time this switch is toggled between
the FWD an~ the BKWD position, GO
is interrupted by the turnaround delay. )
This switch in conjunction with the
MED FREQ/HI FREQ/LO FREQ switch,
determines the write frequency.
MED FREQ/HI FREQ/LO FREQ SWITCH
The tester decodes the MOD lines to
determine at what write frequency
the tape unit is operating. The
only frequency control available to
the Field Engineer is through the
MED FREQ/HI FREQ/LO FREQ switch.
Placing the switch in the HIGH FREQ
position sets the tape unit for
normal PE write frequency.
The MED
FREQ setting places the tape unit at
one-half the normal PE write frequency. The LO FREQ position is used
only for NRZI operations.
At the SH-SH position switch setting, the ,BACKWARD line raises on
alternate active GO signals.· GO is
under the control of the GO UP and
GODWN potentiometers in what is
called a shoe-shine operation. The
result is an alternating forward/
backward tape motion with a 16 millisecond turnaround delay.
(GO is
interrupted by the turnaround delay.)
•
STATUS CONTROL 2
When STATUS CONTROL 2 is inactive
or a zero (0), the Status byte is
on the Bus lines. When STATUS CONTROL 2 is active or a one (1), bit
4 of the Status byte is modified.
Bit 4 norrr.ally contains Seven Track
information, but with STATUS CONTROL 2 active, it is connected to
the Tach Pulse output.
AUTO CYCLE/AUTO STOP/AUTO REW SWITCH
'This switch is a convenience device
that operates properly ONLY if the
TI switch is in the TI AUTO position.
When the AUTO CYCLE/AUTO STOP/AUTO
REW switch is in the AUTO CYCLE position, the operating mode (forward
or backward) reverses every time
either EOT or BOT is reached. This
allows for continuous motion between
EOT and BOT without a high speed rewind.
In the AUTO STOP position, GO
is dropped whenever either EOT or
BOT is detected.
Setting the switch
in the AUTO REW position sets the
tape unit to automatically rewind
anytime it reaches EOT.
PE/NRZI/GCR SWITCH
•
WRITE SWITCHES AND READ TEST POINTS
TI PASS/TI AUTO SWITCH
Nine two-position WRITE BIT switches
feed the write bus and thereby allow
a choice of what is to be written.
When a WRITE BIT switch is in the
"zero" position, zeros are written
on tape in the designated track.
When a WRITE BIT switch is in the
"one" position, ones are written on
tape in the designated track.
This switch sets the tape unit to
either pass the EOT marker in the
TI PASS position or to enable the
AUTO CYCLE/AUTO STOP/AUTO REW switch
(as mentioned above) in the TI AUTO
position.
Each of the READ BUS terminals is
individually terminated. The termination is internally controlled
for the PE mode. The Read test
points allow each of the nine tracks
to be monitored.
4-5
•
GO UP AND GO DOWN POTENTIOMETERS
•
Moving parts must be properly lubricated to maintain optimum operation and to avoid excess wear (Field
Engineer responsibility).
Tpe GO UP and GO DOWN potentiometers
vary the time periods for active and
inactive GO.
The potentiometers are
operational when the ST-ST/GO/STOP
switch is in the ST-ST position and
when the SH-SH/BKWD/FWD switch is
inth@ SHSH p05ition
•
REW SWITCH
The Rew switch causes the tape to
rewind and unload.
•
PREVENTIVE MAINTENANCE
Preventive maintenance encompasses those
activities which must be performed at
regular intervals to prevent conditions
from arising that could lead to costly
down-time of the equipment. Minimizing
down-time and avoiding conditions that
jeopardize equipment performance are
necessary in building good customer relations.
Preventive maintenance activities may
be classified into the following categories:
Visual Inspection
This requires only.minimum training
-- e.g., what conditions to look for
and how ~o remove protective covers
so that the equipment can be viewed
(operator and Field Engineer responsibili ty) .
•
Regular Cleaning
Certain portions of the .equipment
will not function properly if they
are not kept clean.
4-6
•
Complex aaintenance
Complex maintenance involves periodic performance checks, adjustments
or replacement of components and assemblies (Field Engineer responsibility) .
RUN SWITCH
The Run switch causes ·the tape to
rewind and unload.
•
Lubrication
Regular preventive maintenance time periods are listed in Figure 4-1. Additional preventive maintenance is recommended for performance at random intervals, based on whether subsystem operation permits placing one or more tape
units offline. When the preventive
maintenance activity is the obligation
of the customer, the Field Engineer
need not be present.
Such maintenance
is intended for the customers employee
to perform as needed and required.
ACTIVITY
Inspection at Random
CODE
SCHEDULE
(both)
Tape Transport Cleaning
*
Each 8·Hour Shift
Limited Cleaning
*.
Monthly
General Cleaning
**
Quarterly
Adjustment
**
Semiannual
Parts Replacement
**
Annual
* Customer Ob·ligation
** FE Responsibility
Figure 4-1.
Preventive Maintenance Schedu Ie
MAINTENANCE EQUIPMENT
INSPECTION
To perform preventive maintenance, the
following equipment is necessary:
Inspection of the tape units should be
conducted no less than once a week. For
best results, remove the" cabinet panels
and other protective covers and check
the following:.
Q
Cleaning kit (PN 6164)
The cleaning kit is necessary for
all tape unit cleaning. The kit
includes a LINT-FREE cloth for
dusting and wiping and FOAM-tipped
applicators for small cavaties and
hard to reach areas.
•
o
Verify that all column lights are
lit.
o
Be sure that all the indicators on
the operator panel light.
Check the physical condition of the
indicators and pushbutton switches
on the operator panel.
Field testers (PNs 16086 new model
and 10489 old model )
The field tester permits offline
testing of the tape unit as described in the front of this chapter under Field Tester.
o
Listen for unusual noises in the
pneumatic system which .may imply
undue wear or misalignment.
o
Check operating tape units for reel
response and proper distribution of
tape loops in the vacuum columns.
o
Remove bits of tape or other foreign
material from the vacuum columns.
Tool kit (PN 4019)
The tool kit contains the tools necessary to remove the covers and to
repair and replace the subassemblies.
Be sure that all cooling fans within
the tape unit are fully operational.
STC Hub Cleaner (PN 12120)
Verify that the inspection lamp for
the read/write head is operational.
The hub cleaner is the only cleaning
fluid to be used on the automatic
hub. Other materials, especially
tape transport cleaner, may cause
reel slippage.
Check for unusual capstan wear which
might indicate capstan contact with
the column door or tape path contaminants.
Tape-transport cleaner fluid (PN
6167)
The listed items do not exhaust the possibilities for visual inspection and
should be used only as a starting point.
The tape transport cleaner is used
for general cleaning and degreasing.
TAPE TRANSPORT CLEANING (Each 8·hour shift)
In addition to the listed equipment,
there are a number of consumable or disposable items, such as air filters,
which are required as part of the preventive maintenance effort.
The tape transport should be cleaned at
least once each eight hour shift. Prior
to cleaning the tape transport, be sure
the tape unit is unloaded and the file
reel is removed, then:
4-7
•
•
Clean the read/write head and the
tape cleaner block using a lintfree cloth moistened with tapetransport cleaner fluid (PN 6167).
To clean the slots in the read/
write head of oxide particles, use
the sharp corner of a data processing card. Check to be sure the
tape cleaner block is free of oxide.
(Sponge-tipped applicators should
be used when necessary in this
cleaning process.)
Clean the threading channels, tape
guides and air bearings with a lint
free cloth moistened with tapetransport cleaner fluid.
Also, inspect and clean the ceramic flanges
of the tape guides.
(Sponge-tipped
applicators should be used when necessary in this cleaning process.)
•
Clean the vacuum columns and the
door glass using a lint-free cloth
moistened with water.
Oxide buildup in the corners can be cleaned
with the corner of a folded data
processing card.
Remove bits of
dirt and tape from the vacuum columns.
•
Check for and remove any bits of
tape present on the stubby column
screens.
•
Clean the rubber surfaces of the
automatic hub using a lint-free
cloth moistened with STC Hub Cleaner (PN 12120).
CAUTION
Do not use any other cleaning
fluid.
•
Clean the capstan by wrapping a
lint..:free cloth, moistened· (not
saturated) with tape-transport
cleaning fluid, around the index
finger.
Then, while rotating the
capstan with the free hand (slowly
turning it two turns), apply the
cloth draped finger to the capstan.
Use the upper Z-bar as a partial
support to avoid too much direct
pressure on the capstan itself.
CAUTION
Do NOT touch the surface of
the capstan with the bare
hand, as it is sensative to
contamination. Also, care
should be exercised NOT to
clean the capstan excessively-two revolutions during the
cleaning process is generally
sufficient.
•
4-8
Wipe the light sensor with a dry,
lint-free cloth.
LIMITED CLEANING/INSPECTION (Monthly)
Clean and adjust the following on a
monthly basis:
•
Inspect the grommet on the upper
cartridge restraint for damage and
replace if necessary.
•
Run the tape unit SPAR kernels.
•
Check for stagger wrap on the reels
after a h~gh-speed rewind operation.
•
Check the power window alignment and
verify that the window position
switches are properly adjusted -- no
binds or bounce as it stops at eithe:
end (see the Adjustments section of
this chapter).
•
Check the thread/load operation.
Be sure that tape threads smoothly
off the chute on the lower restraints, does 'not hang-up in the
tape path and threads onto the machine reel properly.
GENERAL CLEANING/ADJUSTMENT (Quarterly)
Clean and adjust the following on a
quarterly basis:
e
Inspect for cartridge-on switch position and operation.
Remove and
The filter
or rotated
place when
clean the base air filter.
should be vacuumed clean
o
180 and re-used (reno longer serviceable).
To remove filter:
•
In addition to the daily cleaning
of the automatic hub, the toggles
should be cleaned and checked to be
sure that they retract sufficiently.
To lubricate the hub proceed as
follows (hub lubrication frequency
is determined by account needs) :
1. Remove the file reel hub cover
and loosen the allen screw securing the hub collar and remove the hub.
2. Remove the screws that hold the
toggle.
Remove the toggle and
then remove the pivot pin from
the toggle itself.
1. Remove the tape unit front kick
plate.
2. Kneeling and facing the front of
the machine, push back on the
filter finger ring and then pull
down on it.
To ensure proper vacuum sealing,
check for loose vacuum-door glass
and nicks on the column bar edges
and the air bearing surfaces (replace or repair defective parts as
necessary) .
Check the vacuum door hinge pins and
screws. Check the inside of the
door for contact with the capstan
and align the door as necessary (see
the Adjustments section). Also,
check the center guide to see if it
is bent out of alignment, causing
binding. Check that it clears the
tape path components when the vacuum
column door is closed.
Check the vacuum door seal by placing a strip of magnetic tape between
the vacuum-column door and the column assembly. Close the door and
pull the tape out -- a drag should
be felt as the tape is withdrawn.
This check should be made at various
points around the perimeter of the
vacuum-column door.
3. Place a small amount of Molykote
on a small screwdriver. Use the
screwdriver to put the Molykote
into the pin opening on the toggle.
4. Place the pivot pin back in the
toggle and wipe off the excess
Molykote from the ends of the
pin.
5. Place the toggle back into the
hub asseIT~ly and secure in place
with the holding screws.
6. Install the hub assembly back on
the tape unit and tighten the hub
collar allen screw.
CAUTION
Be sure all excess Molykote is
wiped off the hub before installation.
Check the cleanliness of the tape
path and clean as required.
If the
tape path is excessively dirty, instruct the operators on proper
cleaning methods and schedules.
4-9
•
•
Check the belts on the vacuum and
pressure pumps for tension, alignment, and wear.
Replace as necessary (see the belt tension adjustments and pulley alignments in this
chapter) .
•
•
4-10
•
Check the tape unit reliability
and performance using standalone
diagnostics orOLTS if possible.
Check the cooling fans for proper
Special attention should
be given to the reel cooling blower to see if binding
exists.
It is possible that
the blower will slow if excess tension is applied by
the reel motor shrouds.
If
this binding does exist,
try loosening up the shroud
mounting screws to allow repositioning of the shroud.
Once binding is corrected,
r-etighten the mounting
screws.
•
Check the high-speed rewind time
and monitor the_tachometer waterfall.
opeLatioll and Leplace if necessary.
NOTE
•
•
CLEANING/ADJUSTMENTS/REPLACEMENT
(Semiannual)
Perform the following cleaning, adjustments on a semiannual basis:
•
Remove and clean the tape/guides and
ceramic flanges.
•
Replace the pneumatic line filters.
There are two such filters on the
pressure pump --one intake and one
exhaust. The intake filter element
can be removed by unscrewing the
jar and popping the clip plate holding it in. The filter is then replaced by a clean filter.
The dirty filter is washed with soap and
water and put up to dry.
The exhaust filter is a throw-away canister type. and is to be replaced
every six months.
•
Check the tape path for wear.
•
Check the file protect mechanism for
proper operation with and without a
cartridge.
•
Check tape tracking (see Tape Tracking Adjustments in this chapter).
•
Creck skew (see skew adjustments in
this chapter).
•
Check tape unit operating voltages
using a digital voltmenter (see
Voltage Adjustments in this chapter).
•
Check the read/write head by testing
all tracks for forward to backward
amplitude ratio at the head amplifier output.s listed in figure 4-8.
Check the operation of the High
Speed _Rewind Foot for complete extension and retraction.
-Remove the door cover and test
the high-speed rewind for proper
operation -- be sure it does not
bind.
Remove the tape cleaner block and
flush it clean using tapetransport cleaning fluid.
Replace
worn or damaged blocks as necessary. After reinstalling the
cleaner block, be sure that vacuum
holds the tape against the cleaner
blade.
Check for proper pneumatic values
(see the Adjustment section) and/
or possible restrictions.
The backward read amplitude must be
85% of the forward amplitude as the
possibility of a worn head or tracking error exists.
To make this section easier to use, the
adjustments and alignments are listed
in alphabetical sequence.
Check the capstan start times (see
Capstan Specifications in this
chapter) .
AUTOMATIC-HUB POSITIONING COLLAR
ADJUSTMENT
1.
Remove th~ file reel hub cover and
loosen the allen screw securing the
collar clamp and slide the hub and
collar off the shaft.
2.
Remove the screws (2) holding the
pivot plate. Do not lose the spacer
on each screw.
3.
Remove the hub actuator assembly.
4.
Loosen the allen screw securing the
positioning collar.
5.
Place the positioning collar alignment tool (PN 4632) on the motor
shaft until it rests against the
transport plate (purple plate) .
Move the positioning collar forward
until it rests against the alignment
tool and tighten the allen screw.
6.
Replace the pivot plate. Make sure
the spacers are in pla8e (the
grooves on the plate must align
over the actuator lever).
7.
Slide the hub onto the reel motor
shaft until it rests against the
collar.
8.
Slide the collar clamp over the hub
and align the splits in the collar
with the splits in the motor shaft.
Tighten the collar clamp allen
screw.
9.
Alternately press the LOAD/REWIND
and RESET pushbuttons to check hub
operation.
INSPECTION/REPLACEMENT (Annual)
Inspect the following on an annual basis:
Check for proper capstan stop distances and ensure that the interblock gap is within the tolerances
specified in Figures 4-4 and 4-5.
Also check to see that the trace
meets the requirements shown in Figure 4-6.
Check the capstan start times by
monitoring the output of the Velocity D/A Converter. Refer to Figure
4-6 to verify that the times and
voltages are within tolerances.
Check the READ BUS to ensure that
the waveshapes are within specified
tolerances (see Figures 4-13 and 414) .
ADJUSTMENT/ALIGNMENT PROCEDURES
The adjustments and alignments necessary
for proper operation of the tape unit
and the steps to complete them are described in this section. These adjustments and alignments are an extremely
important facet of the maintenance
function.
Some of the procedures must
be performed whenever the assembly or
component is removed or replaced. Other
adjustments must be performed whenever
preventative maintenance checks reveal
problems or indicate various parts of
the tape unit do not meet specifications.
AUTO-HUB SOLENOID CHECK AND ADJUSTMENT
1.
Activate the hub solenoid by pressing the LO"~/REWIND pushutton.
4-11
2.
3.
4.
5.
Remove the hub (see Automatic Hub
Replacement procedure) .
BEL T TENSION ADJUSTMENTS
•
Slide the positioning-collar alignment tool onto the reel motor shaft
until it is flush a9ainst the pivot
plate (resting over the screws securing the plate) .
1. Loosen the pump mounting screws
(4) (see Figure 4-11).
2. Place the tensiometer (PN 0157)
on the belt as shown in Figure
4 2. Then shlft the pump until
the tensiometer reads high altitude 10-13, or low altitude 6-10
pounds.
Measure from the rear edge of the
alignment'-tool shaft. to the positioning collar..
The measurement
must be .268 + .007 inch.
If the measurement does not meet
specifications, remove the grill
cover from the top of the tape
unit.
3. Re-tighten the pump mounting
screws (4) when correct tension
is obtained.
•
When power is applied to
the tape unit, 208 Vac is
present on the reel-latch
solenoid.
PROCEED WITH
CARE.
Loosen the screws (4) securing the
solenoid to its mounting bracket.
7.
Adjust the solenoid f6r the correct
measurement as stated in step 4.
and tighten the screws (4) securing
the solenoid.
8.
Remove the positioning-collar alignmenttool and re-install the hub.
9.
Check the hub for proper operation
by alternately pressing the LOAD/
REWIND and the RESET pushbuttons.
The hub should not clatter as it
activates and deactivates.
10. Re-install the grill cover on the
top of the tape unit.
4-12
PRESSURE PUMP
1. Remove the upper screws (3) and
loosen the lower screws (3) to
remove the pneumatic-supply left
side cover.
WARNING
6.·
VACUUM PUMP
2. Loosen the pressure pump mounting
nuts (4).
3. Place the tensiometer (PN 0156)
on the belt as shown in Figure
4-2. Then shift the pressure
pump until the tensiometer reads
9.5-11 pounds.
4. When correct tension is obtained,
tighten the mounting nuts (4).
CAPSTAN ALIGNMENT (Tracking)
Correct alignment of the capstan assembly ensures that the tape will track in
the center of the left tape guide.
There should be no distortion of tape
channel from tape creeping up the front
or rear tape-guide flanges.
The capstan
alignment procedure is:
1.
Loosen the locknuts on adjustment
screws #1 and #3 approximately two
1.
Place the tensiometer
(PIN 0157) on the belt
as shown at right.
2.
With the forefinger on
the spring tip. pull the
spring in the direction
shown at right.
3.
Figure 4-2.
When the right hand tab
of the Tensiometer just
touches the top of the
belt (A). read the belt
tension (on the left edge
of the spring) in pounds
on the scale (8).
Tensiometer Operation
4-13
turns (see Figure 4-3). Ensure that
the vacuum column back plate is 17/
32 .:!=. 1/64 inch from the front edge
of the capstan (check at three
points around the circumference
of the capstan). See CAUTION note
in step five of this procedure.
4.
Load a good work tape on the tape
unit.
Using the field tester, perform forward and backward continuous read
operations to check the tape tracking. For any tracking corrections,
use the adjustment screws shown in
~2~.~_R~e~m~0~v~e~tkh~e~0~u~tks~i~d~e~g~1~]l~'d~e~f~l~a~n~g~e~~fJr~o~mli---------~nT_~~~.__
F'lgure 4 3.
the left tape guide then re-insert
the screw to hold the tape guide in
place. Remove ·the decorative metal
CAUTION
cover from the vacuum column door.
3.
5.
Adjust screw #2 ONLY ~~EN
NECESSARY .to meet the capstan measurement covered in
step one of this procedure.
When adjusting screw #2,
turn all three of the adjustment screws a like amount in the same direction.
USE EXTREME CARE.
Loosen the screws (2) holding the
upper Z-bar in place and slide it
away from the capstan until the gap
is approximately the width of two
punched cards. Re-tighten the
screws.
CAUTION
DO NOT exceed this width,
as it may allow tape to
wrap around the capstan
and damage both the tape
and capstan motor.
For component location, see Chapter 2,
Figure 2-1. Tape tracking conditions
and necessary adjustments are:
ADJUSTMENT·____
SCREW NO.1 -
--------------------------~~~
o
ADJUSTMENT
SCREW NO.3
LOCKNUT
ADJUSTMENT
o
SCREW NO. 2
-------------t~
SIDE VIEW
Figure 4-3.
4-14
Capstan Motor Assembly
a.
The tape tracks over the front edge
of the left guide during both forward and backward operation. To
correct, turn adjustment screw #3
counterclockwise in 60 0 intervals.
9.
b.
The tape tracks over the front edge
of the left guide during forward
operation. To correct, turn adjustment screw #1 counterclockwise
in 60 0 intervals. Too much contact with the rear of the left
guide causes tape to creep up the
guide during forward operation. To
correct, turn adjustment screw #1
clockwise in 60 0 intervals.
CAPSTAN SPECIFICATIONS
c.
Shown in Figures 4-4 and 4-5 are the
tach pulse quantities involved in go
holdover and stopping distances for the
various tape unit models.
MODEL
The tape tracks over the front edge
of the left tape guide during backward operation. To correct, turn
adjustment screw #1 clockwise 60 0 •
NOTE
VisuaL setting of tracking
is satisfactory when NO
flutter or side-to-side tape
movement is observed. Excessive flutter is often the
result of excess air pressure on the right tape guide
and can be checked by referring to Pneumatic Adjustments.
6.
7.
Unload the tape unit and install the
front tape-guide flange on the left
tape guide. Then, re-install the
decorative metal cover on the vacuum
column door.
Loosen the screws (2) holding the
upper Z-bar in place and slide it
toward the capstan until the gap
is approximately equal to the thickness of one data processing card.
Re-tighten the screws.
Once tracking is visually set, mechanical skew should be checked (see
Mechanical Skew Adjustment) .
WRITE
READ
3430
8
20
3440
0
16
3450
0
16
3470
0
8
3480
0
0
Figure 4·4.
Go Holdover Distance in Tach Pulses
The actual stopping distance of the capstan must be controlled rather than the
time period during which it stops.
Voltage relationships relative to start
stop timing are gtven in Figure 4-6.
CARTRIDGE OPENER SWITCH ADJUSTMENT
Before adjusting the switches in the
cartridge opener (see Figure 4-7), be
sure the switch plate is secure and
then adjust the switches as follows:
1.
Loosen the screws (2 each) on the
two switches:
CAUTION
8.
Rotate the capstan checking to be
sure it is .not touching anything
(DO NOT touch the capstan surface
with the bare hand).
Do not turn the screws more than
one complete revolution. Further
loosening will result in the nut
plate (on the backside) falling
out of place.
4·15
-
READ STOP
DRIVE
TACH LINES
-
WRITE STOP
TACH LINES
PRE EC 1066
AFTER EC 1066
3430
· ...
+ 1
27 - 1
. ...
+ 1
15 - 1
3440
· ...
+ 1
26- 1
+ ?
1.4 - 6
+ 2
14- 6
AFTER EC 1066
PRE EC 1066
,..
T
I
~
I
3450
21 - 6
26- 1
15 -.5
15 - 5
3460
· ...
+ 1
26- 1
+ 1
15 - 1
+ 1
15 - 1
+ 1
26- 1
+ 1
15 - 1
+ 1
15 - 1
+ 1
20- 1
+ 1
16 - 1
+ 1
16 - 1
3470
+ 1
26 - 10
34S0
+ i
20 - 1
"
Figure 4-5.
.--t---.·i -r -·.---- . J_ -_--E
b
- ---
t1
-7.5V
Stop Distance Including Go Holdover in Tach Pulses
A
•
-S.OV
-S.5V
-
t2
-9.0V
.'
-9.5V
~ 'r -
r
Test equipment set-up for monitoring this waveshape.
-
Field test er setti ngs:
start/stop on
horizontal sweep .5 ms/cm
go up 15 ms
vertical gain 2 V/cm
go down 100 ms
sync on GO
MILLISECONDS
Tl
Scope settings:
VOLTS
A
T2
B
C
D
E
TU TYPE
MIN
NOM
MAX
MAX
MIN
NOM
MAX
MAX
MAX MAX
MIN
NOM
MAX
3430
2.2
2.95
3.S5
4.35
-7.95
-7.6~
-7.50
0.50
0.40
0.20
-8.1
-7.85
-7.4
(After
EC 1066)
1.6
2.25
3.1
3.6
3440
1.4
2.1
2.7
3.2
3450
1.65
2.4
3.0
3.5
3470
1.05
1.55
2.1
2.3
3480
1.1
1.7
2.35
2.65
-7.95
-7.65
-7.50
0.50
0.40
0.20
-8.1
-7.85
-7.4
Figure 4-6.
4-16
Start Stop Timing
PIN
OPENER
ARM
•
DOWEL
PIN
Figure 4-7.
2.
3.
4.
Cartridge Opener
Place a 0.007-.008 feeler gauge
(about the thickness of one data
processing card) against the dowel
pin without interferring with the
switch actuator. Rotate the cartridge opener arm so that it holds
the feeler gauge in place.
loading sequences, the delay counter
period should be checked and adjusted
as follows:
1.
Move the switch toward the cartridge
opener arm until the switch JUST
transfers. Then, re-tighten the
switch screws.
With no file reel installed on the
tape unit, cover the tape present
sensor and press the LOAD/REWIND
pushbutton. This forces a machine
check and keeps the delay counter
running.
2.
Remove the shim and ensure that the
switch transfers before the arm
hits the dowel pin.
Monitor delay count 1 and verify
that the pulse period is 46 milliseconds.
3.
If the delay count period is incorrect, adjust (PI) on 2A4.
4.
Once the correct pulse period is
attained, remove cover from tape
present sensor and press the RESET
pushbutton to clear the machine
check.
DELAY COUNTER CHECK AND ADJUSTMENT
If there is insufficient tape being
loaded on the machine reel to allow
proper column loading, or machine
checks recur during loading and un-
4-17
DOOR LATCH ADJUSTMENT
1.
Loosen the screws (2) securing. the
nylon latch to the vacuum column
backplate (white plate) .
2.
Close the door until the spring
catch on the door touches the nylon
latch.
will not produce a pulse. Polarity can
be changed by reversing the wires at
the erase head. There is no other adjustment for the erase head.
TRACK.
4
B09
PIN
CARD
3.
Raise or lower the nylon latch until
it centers on the spring catch.
·Holding the nylon latch in that position, open the door and tighten
the screws on the nylon latch.
4.
Repeat this procedure for the bottom
latch.
5.
Once both nylon latches have been
adjusted, open and close the vacuum
column door to check the latch
alignment.
0
6
1
B10 B11
B12
2
3
7
B08 B09 B10 811
1E3
Figure 4-8.
P
5
812
182
Read Bus Pin Location
ERASE HEAD CHECK
To verify that the erase head is functioning:
1.
2.
Unplug the write drivers.
3.
Initiate a continuous Write operation from either the TCU or the
field tester.
4.
5.
0.1 usee/em
Mount a scratch tape, write all
. ~'ones". on it for a suitable distance then rewind to BOT.
Rewind to BOT and scope any read bus
line (Figure 4-8). The peak-to-peak
amplitude of the signal left after
erasure should be less than 30 mv.
Figure 4-9.
HIGH·SPEED REWIND ADJUSTMENT
The high-speed rewind adjustment is accomplished with the aid of the field
tester.
1.
Once the field tester is attached,
move tape forward until it reaches
the EOT marker and then stop.
2.
Monitor the tachometer square wave
with an oscilloscope. Set the
scope at 2 volts per division and
5 seconds per division.
3.
Press the LOAD/REWIND pushbutton.
Connect write drivers.
TO verify erase head polarity, scope any
bus line listed in Figure 4-8 while writting a record. If the pulse circled in
Figure 4-9 is observed, the erase head
polarity is incorrect--correct polarity
4-18
Erase Head Polarity Pulse
4.
Adjust the high-speed rewind potentiometer on the tachometer card for
the following duration tachometer
periods:
TACH PERIOD IN
MICRO-SECONDS
TAPE UNIT
MODEL
1.
Check the vacuum-column door seal
by placing a strip of magnetic tape
between the door and the column assembly. Close the door and pull
tape out--a drag should be felt as
the tape is withdrawn.
This check
should be made at various points
around the perimeter of the vacuum
column door.
If the seal is bad the
door hinges and or latches must be
adjusted.
2.
Load a tape and allow the tape unit
to run for about 15 minutes before
continuing with the pneumatic checks
and adjustments.
3.
Open the bleed valve located on the
high speed foot solenoid one turn
from fully closed.
4.
Adjust RUN Pressures to the values
listed in Figure 4-10.
32
27
22
22
3430
3450
3470
3480
5.
test points listed in Figure 4-10, are
located on the left and right sides of
the tape unit (and are so designated)
as the viewer faces it from the rear.
The pneumatic adjustment procedure is:
Disconnect the field tester and reconnect the tape unit to the control unit.
PNEUMATIC CHECKS AND ADJUSTMENTS
Proper pressure settings are very important to tape unit operation. Each
pressure and vacuum point has an individual pneumatic output. Thus, it is
necessary to test and adjust these
points.
One pressure adjustment can affect the
other pressure settings and, likewise,
one vacuum adjustment can affect the
other vacuum settings. As a result,
ALL pneumatic adjustments must be checked, adjusted, rechecked, and possibly,
re-adjusted. Vacuum and pressure readings may be taken with a magnehelic type
gauge (0-100" H2 0). '
o If RUN Pressures are easily obtained, open the bleed valve a
little more and readjust the
pressures.
• If unable to obtain proper RUN
Pressures, close the bleed valve
a little, then adjust the pressures.
NOTE
For elevations above 2,000 feet,
use the high altitude pulley (PN
6868--High Altitude is stamped
on the pulley) on the vacuum
pump. Below 2,000 feet, use the
low altitude pulley (PN 6867-Low Altitude is stamped on the
pulley) .
The color reference noted in each test
refers to the color of the pneumatic
test tube serving that point. These
NOTE
The purpose of the bleed valve
is to prevent the pump from
overheating and subsequent life
degeneration.
5.
Adjust RUN Vacuums to the values
listed in Figure 4-10.
4-19
RUN MODE SETTINGS
MACHINE TYPE AND PRESSURE!VACUUM SETTINGS
Tube Asm.
Item to be
Adjusted
&
Color
D. D. & 7-Track
2430,2445,2460
3430,3440,3450
P. E.2445,2450,
2460,3430,3440
& 3450 Only
P. E. 2470 &
3470 Only
D. D. & 7-Track
3470 Only
P. E.3480
Only
33" - 35"
33" - 35"
33" - 35"
34" - 35"
30" - 35"
Try to get Max.
Columns
Vacuum
6
Purple
Rt Upper Air
Bearing
Pressure
10
Pink
48" - 50"
48" - 53"
48" - 53"
48" -53"
48" - 53"
Right Guide
Pressure
10
Green
40" - 60"
60" -70"
60" -70"
44" - 48"
60" -70"
Tape Cleaner'
Block
Vacuum,
10
Black
Left Guide
Pressure
10
Brown
40" - 60"
60': - 70"
Valve Closed
40" - 60"
Valve Closed
Right Lower
Air Bearing
Pressure
10
Clear
48" - 53"
48" - 53"
48" - 53"
48" - 53"
48" - 53"
Left Lower
Air Bearing
Pressure
6
Green
40" - 42"
40" - 42"
40" -42"
40" - 42"
40" - 42"
Adjust the vacuum level on the tape cleaner block so that the tape seals the perforated cleaner blade.
Start at 5" H20 and increase to a maximum of 8" H2O. When tape seals the blade, put machine into
moderate shoeshine mode to ensure tape does not part from the perforated blade. The intent is to use
as little vacuum as possible (about 5" H20) to meet spec parameters. The door cover must be removed
for this setting.
THREAD MODE SETTINGS
Lower Restra int Pressure
Metal
Plastic
10
Red
Upper
Restraint
Pressure
5" -6"
10"-12"
5" -6"
10"-12"
5" -6"
10" - 12"
5" 6"
10"-12"
5" 6"
10" -12"
10
Blue
16" - 20"
16"-.20"
16"-20"
16" - 20"
16" - 20"
Rt Thd Chan
Pressure
10
Yellow
4.5" - 6.5"
7" -8"
7" -8"
4.5" - 6.5"
7" -8"
Rt Thd Chan
Vacuum
10
Purple
3" -4"
3" -4"
:1" -4"
3" -4"
3" - 4"
Lt Thd Chan
Vacuum
10
Orange
8" -10"
3.5" - 4.5"
3.5" - 4.5"
8" -10"
3.5" -4.5"
Lt Thd Chan
Pressure
6
Yellow
8" -10"
8" -10"
8" -10"
8" -10"
8" -10"
Figure 4-10.
4-20
Pneumatic Specifications (Sheet 1, of 2)
P. E.2470&
3470 Only
P. E. 2445, 2450,
2460,3430,3440
& 3450 Only
P. E.3480
Only
D. D. & 7-Track
3470 Only
Tube Asm.
&
Color
D. D. & 7-Track
2430,2445,2460
3430,3440,3450
Vacuum Reel
Vacuum
6
Red,
21" - 23"
21" - 23"
21"-23"
21" - 23"
21"-23"
Air,Jet
Lt Upper A.B.
Pressure
6
Blue
15" Min
15" Min
15" Min
15" Min
15" Min
Item to be
Adjusted
These are the thread pneumatic specifications for drives only with the "Easy Load II" cartridge feature (Slim line). This is in addition to
the current drive settings and is not meant as a replacement for all drives. Do not use these specifications on drives not having slim line restra ints installed.
THREAD PNEUMATICS SPECIFICATIONS - EASY LOAD II, HIGH AND LOW ALTITUDE
Item to be
Adjusted
Tube Asm.
Color
Machine
Type
All
Lower
Restraint
Pressure
10
Red
3-5
Upper
Restraint
Pressure
10
Blue
16 Min.
Note 2
Note 3
Right Thd
Channel
Vacuum
10
Purple
30
Left Thd
Channel
Vacuum
10
Orange
N.A.
Left Thd
'Channel
Pressure
6
Yellow
30
Note 2
Thread Pneumatics Specifications - Easy Load II
NOTES:
Vacuum Reel
Vacuum
6
Red
19 - 21
Air Jet
Left Upper
A.B. Pressure
6
Blue
15 -17
Figure 4-10.
1.
No low altitude presets.
2.
Most important settings are threading channels. Adjust upper
restraint for as much' pressure as possible.
3.
If reworked metal upper restraint is installed, this setting is 23.
Pneumatic Specifications (Sheet 2 of 2)
4-21
6.
7.
Unload the tape unit and install a
file reel with the Easy Load II
Cartridge. Then jumper pin 2A2 B07
to logic ground apd press the LOAD/
REWIND pushbutton (located on the
tape unit operator panel). The tape
unit is now set to allow adjustment
of the thread mode pneumatics.
pneumatic motor pulley, the vacuum pump
pulley and the pressure-pump pulley.
The pulley alignments must be accomplished in the following sequence:
•
1. Check to see that the distance
from the motor support bracket
to the backside of the motor
pulley is .68 ± .03 inch (see
Figure 4-11).
Adjust the THREAD Pressures and Vacuums to the values listed in Figure
4-10.
NOTE
2. If the pulley is out of specification, loosen the pulley setscrews (2) and adjust the pulley
to proper tolerances.
The Pressures and Vacuums should
be adjusted to the specified minimum with the exception of the AIR
JET in the upper left air bearing.
This should be adjusted to a minimum plus value (a little more than
minimum). When the tape reaches
the air jet it should shoot up towards the mqchine reel hub with a
minimum of flutter. The Thread
operation can be' simulated to ensure that the adjustments are correct. This is done by grasping the
file reel with the right hand and
rotating it clockwise at the approximate speed of a thread operation(remove reel divider while performing this operation). The tape
should move smoothly out of the
cartridge and be picked up by the
right threading channel. It should
glide along smoothly through the
head area and the channels. Upon
reaching the upper left air bearing,
it should be deflected up towards
the machine reel by the air pressure. The vacuum on the machine
reel should then catch and hold the
tape. If tape flutters severely
while threading, it usually means
that threading channel pressure is
too high or the vacuum level is too
low.
3. Re-tighten the pulley setscrews
(2) •
Vacuum Pump Pulley
1. Place a straightedge across the
front flange of the motor pulley
not the pulley hub -- so that it
extends across the front of the
vacuum pump pulley.
(The
straightedge must extend to the
farthest edge of both pulleys -see Figure 4-11).
2. If the vacuum pump pulley is not
flush with the straightedge that
is resting on the motor pulley,
loosen the setscrews (2) securing
the vacuum pump pulley.
3. Shift the vacuum pulley until it
does align with the straightedge
that is resting on the motor
pulley.
4. Re-tighten the vacuum pump pulley
setscrews.
•
PULLEY ALIGNMENT-PNEUMATIC SUPPLY
There are three pneumatic-supply pulleys
which require periodic checks: the
4-22
Pneumatic-Motor Pulley
Pressure-Pump Pulley
1. Place a straightedge across the
rear surface of .the motor and
pressure pump pulleys (the
VACUUM
TRANSFER
VALVE
PNEUMATIC
INPUT
HOSE
PNEUMATICS
MOTOR
PULLEY
VACUUM
PUMP
SUPPORT
BRACKET
VACUUM PUMP
D............~--MOUNTING SCREW
MOTOR
MOUNTING
SCREW
Figure 4-11.
STRAIGHTEDGE
POSiTIONS
Pneumatic Supply Assembly (Front View)
,straightedge must extend to the
farthest edge of both pulleys-see Figure 4-11). The pressurepump pulley should align ,flush
with the straightedge (using the
motor pulley as the guide).
2. If the pressure-pump pulley is
not flusl:J. with the straightedge
that is resting on the motor
pulley, loosen the setscrews (2)
securing the pressure-pump pulley.
5. Check for proper belt tension adjustment.
READ AMPLITUDE ADJUSTMENT (NRZI)
See WRITE AMPLITUDE (NRZI)
READ/WRITE DATA VERIFICATION
3. Shift the pressure-pump pulley
, until it does align with the
straightedge that is resting on
the motor pulley. , '
4. Re-tighten the pressure-pump
pulley setscrews (2).
The information contained herein verifies the accuracy of the tape unit data
handling capabilities. Due to the immense variation of problems that may be
encountered, there is no sequence to accomplish this verification. Therefore
only the information necessary for verification is provided.
4-23
•
READ AMPLITUDE
The operating range of the tape unit bus
is defined as the peak-to-peak read bus
amplitude measured at the tape control
unit .
•
•
.Phase Encoded (all ones @ 3200 frpi,
500-900 mV.
NRZI (all ·ones @ 800 frpi) 8-10
volts.
The instantaneous bit period is measured by averaging 5 bit periods
about the bit spacing measurement
in question.
NOISE
Noise at the read bus can be caused by
any of·three independent factors discussed below.
The PE preamplifiers are controlled by
Dynamic Amplitude Control and have a
nominal gain of 1.5. The NRZI preamplifiers have an adjustable amplitude control and must be adjusted.
Feedthrough: This is noise coupled
from the write head to the read head
while writing. To measure feedthrough write 3200 frpi on all
tracks.
(Use field tester: Do not
move tape.)
Take measurements at
read bus test points. Peak-tovalley readings in this mode should
be less than 8 percent of full amplitude at the test point.
The read backward amplitude. should be
within 15 percent of the read forward
amplitude.
NOTE
Do not remove the DAC card from
the logic gate; this would leave
a floating level on the base of
the hex invert·er transistors of
the. preamp which will adversely
affect the read bus amplitudes.
•
1. Turn field tester Write Switch
to OFF for the track under test.
2. Write all ones in all other
tracks.
BIT SPACING
3. Read forward measuring peak-tovalley amplitude at the read bus
test point on the test track.
The reading should be less than
3 percent of full amplitude at
the test point while reading 3200
frpi.
The four paragraphs below ~re specifications for the instantaneous spacing
between two transitions at the read bus.
•
The spacing between successive 1600
frpi transitions must be be.tween 88
and 105 percent. of the instantaneous
bit period.
C
•
The spacing between successive 3200
frpi transitions must be between 47
and 59 percent of the instantaneous
bit period.
•
The spacing between alternate 3200
frpi transitions must be between 95
and 109 percent of the instantaneous
l?it period.
4·24
Crosstalk: This is noise coupled
between tracks.
To measure:
Random noise:
This noise is .the hash line seen on the
oscilloscope when measuring the read bus
test points; it can. be seen by exercising the machine with erased tapes.
The hash should be less than 10
percent of full amplitude at the read
bus test point while reading 3200 frpi
(see Figure 4-12)~
PEAK-TO-V
LEY
P AK-TO-PEAK
Figure 4-12.
Expanded Read Bus Signal
Output missing from only one track may
indicate either a bad track or a malfunctioning operational amplifier. The
track output should be at least 5 mV.
Check for breaks in the cable between
the head amplifier and Read/Write gate.
Output missing ,from two tracks, but fed
through the same operational amplifier
indicates a malfunctioning operational
amplifier. Oscillations are usually
caused by a loose component in that
track.
READ PROBLEMS
DATA WAVEFORMS
Problems in the read area may be caused
by the following:
Figures 4-13 and 4-14 illustrate the
transformation a signal undergoes from
the time it leaves the WRITE BUS until
it is received in the TCU after a read
operation.
o
No output from any amplifier_
Output missing from one head amplifier of the same IC module.
o
Output missing from two head amplifiers of the IC module.
o
Oscillation in an output line.
When there is no output from any preamplifier, a mechanical check should determine if the cards are inserted properly in the read gate. Check for correct voltage at the IC modules as follows:
NOTE
These voltages pertain to the R/W
Head amplifier modules only.
Location
Voltage
Pin 1 4 + 1 5 volts
Pin 7
-15 volts
Head Output + 5 mv minimum
CAUTION
Do not attempt to disconnect head
while power is oni this could result in damage to the circuits.
o
PHASE ENCODED -- See Figure 4-13
Line 1 shows a WRITE BUS signal and
line 2 depicts the same signal as
it appears as a tape flux waveform.
Line 3 is the waveform produced when
that signal is differentiated by the
read head and after amplification by
the head amplifier. The original
transition point op the WRITE BUS
is now a peak at the read head output.
In order to convert this peak
back to a transition, the preamplifier differientiates the waveform.
It then a~pears on the READ BUS as
shown in line 4.
The TCU limits the
READ BUS and the resulting waveform
(LIHITED DATA, line 5) looks like
the original WRITE BUS signal. At
this point the data is ready for
decoding by the read circuits in
the Teu.
NRZI -- See Figure 4-14
Line 1 shows a WRITE BUS signal and
line 2 depicts that same signal as
it appears as a tape flux waveform.
Line 3 is the waveform produced when
that signal is differientiated by
the read head and after amplifica-
4-25
(1) WRITE BUS
___....Ir-
---,--~
(2) TAPE FLUX WA.VE FORM
(3) HEAD AMP OUTPUT SIGNAL
(4) READ BUS
(5) LIMITED DATA (IN TCU)
1 . .___. .
Figure 4-13.
L
Phase Encoded Read Signal Waveforms
I
(1) WRITE BUS
(2) TAPE FL!JX WAVEFORM
AMPLITUDE = lV
(3) HEAD SIGNAL
AMPLITUDE
= 9V
(4) READ BUS
(5) OUTPUT OF PEAK
DETECTOR (TCU)
~----,n------..nl--_-...IInioo-Figure 4-14.
4-26
NRZI Read Signal Waveforms
_ _n
tion by the head amplifier.
The
original transition point on the
WRITE BUS is now a peak at the read
head output.
In order to convert
this peak to a transition, the preamplifier differientiates the waveform.
It then appears on the READ
BUS as shown in line 4. Line 5
shows the signal after peak detection in the TCU.
READ FORMATS
RESTRAINT ALIGNMENT
1.
Place the restraint alignment tool
(PN 11146) on the automatic hub in
the same manner a file reel is
mounted. The two ears set farthest
apart must border the upper restraint. The two ears set closest
together must border on the lower
restraint.
2.
Loosen the screws (3) securing the
upper restraint and the screws (3)
securing the lower restraint.
3.
Remove the pressure adjustment
screw from the upper restraint
pressure valve.
4.
Insert the pressure port alignment
pin in the pressure valve opening
and align the valve and the port.
5.
Set the upper restraint against
the restraint alignment tool and
tighten the restraint securing
screws.
6.
Lift the lower restraint until it
touches the alignment tool and
tighten the restraint securing
screws.
7.
Remove the alignment pin from the
pressure valve and reinstall the
pressure adjustment screw. Check
and adjust the pressure according
to the Pneumatic Adjustments in
this section.
8.
Remove the restraint alignment
tool.
Figure 4-15 illustrates the formats
for both PE and NRZI recorded data
as displayed on an oscilloscope.
Example "A" is a phase encoded eight
character record of all ones data.
The record is bordered by all ones
markers which in. turn are bordered
by the preamble and postamble all
zeros bursts.
Example "B" is an expansion of example "A" showing the all ones markers clearly.
Example "c" is a NRZI record consisting of all ones, a CRC character
and an LRC character. Notice the
three bit spaces on each side of the
CRC character.
WRITE WAVEFORMS
To ensure that the write operation is
being performed correctly requires that
certain voltage levels and time references exist. To verify that the proper
voltage and time conditions exist necessitates the use of a scope and reference
information. This reference information
is provided in Figures 4-16 and 4-17
which are drawings of the waveforms as
they must appear.
Other write specifications are contained
in the skew check and adjustment procedure.
SENSOR ADJUSTMENTS
This procedure ensures that the tape
unit recognizes EOT, BOT and tape present. The tape unit must be loaded
for fifteen minutes to allow for heat
drift stabilization in the sensors
before making any adjustments. All
4-27
"A"
Phase Encoded Data
"B"
Example "A" expanded to show data
and all ones markers.
All Ones Markers
"c"
NRZI Data
NRZI Recorded Data
LRC Character
Figure 4-15.
4-28
Scope View of Recorded" Data
II-"
IIII
--'~----------~!--------------~i~----------~~------~
-WRITE ENABLE
n
II
i1
+GO
II
WRITE BUS
+14.3V
.-J
WRITE STATUS
LfU
II
II
ILl
I
II
+4.3V
DEGAUSS OR OFFLINE WRITE'
I
_1
H
~
2 KHZ
-SL ROY WR NRZI
-,~------~!--------------H·
Ii
II
u
GND
II
+3.7V
r
U
+5V
~~_!~~~I
WDB
\..J
+5V
l~23V
WOE
'~~I-----II'(
,Figure4-16.
-ENABLE WRITE
+5V/
Phase Encoded, Write Operation
--,
~--------~!!pl--------------_!~I--------------~I~I------~
~----~I!~I--------------~!!pl----------------~!I~--~
I
+GO
I~LJ-----~!l-l- - - - - -
WRITE BUS
+14.3V
WRITE STATUS
+4.3V
Xl
J
II
+5V
DEGAUSS+OFFLINE WRITE
n
~----------~!~l--------------_l~!--------------~I~
+3.7V
-SL ROY WR NRZI
II
II
r-
~ ~
II
+5V
+SLWR NRZI
~---------II~I----------~--~I~I--------------_!lI--------~
--.I
+5V
WDB
+5V, (
I
+5V
~ ~I-- +5_VJ~
WDE
__
Figure 4-17.
_____
NRZI, Write Operation
4-29
adjustments must be made with an insulated tool to avoid shorting test
points to voltages.
2. Adjust (P4) for down level of
+2.0 V.
3. Check and ensure that up level
is greater than B.O V.
NOTE
When replacing the 2Cl card,
turn all potentiometers to
maximum resistance (full clockwise) before inserting card.
•
1. Load drive with a reel of tape
which has EaT marker located
approximately 7 feet", from BOT.
3. With no tape present less thap
(more negative) ~.4 V.
BOT
2. Adjust down level for +1.5 V
(P2) or maximum if less than
+1. 5 V.
3. The up level should be greater
than +7.5 V.
4. Stop tape motion with reflective
marker away from the EaT/BOT
block.
Press and release H.
S. foot a number of times and
assure dc level never goes above
3 V.
If leVel goes above 3 V,
adjust P2 for 3 V and recheck
normal tape motion settings for
less than 1.5 V and greater than
7.5 V.
EaT
Scope 2Cl BOB and repeat BOT steps
2, 3 and 4. Adjust (PI) if necessary.
•
1. Scope 2Cl B17.
2. Adjust (P3) for a signal greater
than +4.0 V with tape present.
1. Scope 2Cl B09, Sync Positive.
•
TAPE PRESENT
EQUIPMENT SET-UP
2. Connect the Field Tester, adjust it to AUTO-REWIND and
allow the tape unit to autocycle.
•
•
LSA
1. Scope 2Cl BIB.
, NOTE
If the tape indicate light
assembly on the operator's
panel has an incorrect bulb
or no bulb installed, highly
intermittent EaT failures
will occur. The EaT is
sensed going forward and the
latch is set. If the tape
is then moved backwards and
the EaT marker is positioned
over the sensor, the latch
will reset. on the following
forward ope~ation. Such a
condition could exist if the
last record had an error and
retry is attempted. The correct bulb is type 349, and
the incorrect bulb is type
330. The cold resistance of
a 349 bul~ is 3.4 ohms. The
.330 bulbs ,have 17 to 19 ohms.
The incorrect bulbs are easily
noticed as they glow more
dimly than the correct ones.
SKEW CHECK AND ADJUSTMENT (MECHANICAL)
The purpose of this procedure is to
ensure that the data bytes are written
within a specified space. A portion
of this space is called a "bit cell".
The purpose of this adjustment is to
align all nine bit cells perpendicular
to the tape edge.'
TAPE GUIDES
Before skew is adjusted, the NRZI guide
must be checked, and. adjusted if necessary. The NRZI. guide tension is adjustable and must be between 40 - 44
grams on the left guide and 60 - 65
grams on the right guide. Measurement
is made by monitoring the tension of
the spring loaded portion of the guide
at the first movement of compression.
These adjustments are obtained by
placing shims, PN 6041 (.003, green)
and PN 6042 (.004, tan) behind the·
guide springs. If the guide springs
have too much tension, and there are
no shims to remove, file the button
behind the springs. A Gram Gauge, PN
4015, can be ordered.
o
LOCATOR
PIN
AIR
HOLE
SCREW
HOLE
Figure 4-19.
Right Guide Assembly
3470DDOnly
DESCRIPTION
There is a difference between PE
and NRZI Right Guides. Three different guides are used depending
on the feature and model as shown
below. They are as follows:
Figure 4-18 - PE only, Figure 4-19
Dual Density (3470 only), Figure
4-20 - All other models (except
3470) .
1 > - - - LOCATOR
AIR
HOLE
PIN
SCREW _---t-----"i"
HOLE
Figure 4-20.
SCREW
HOLE
o
Figure 4-18.
Right Guide Assembly PE Only
Right Guide Assembly (all DD
except 3470)
INSTALLATION INFORMATION
All NRZI machines must have the
top air hole in the RED PLATE
blocked with a set screw. This
set screw can be seen by removing
the right guide and looking through
the upper hole. This screw must
be slightly recessed into the red
plate. Note also that this screw
must be removed for PE Only machines, so that it matches the
air hole in the guide.
4-31
MECHANICAL SKEW
3.
Mechanical skew is checked and adjusted
with the aid of the field tester. After
the tester has been connected, load a
master skew tape (STC PN 6013) onto the
tape unit under test. Then proceed.as
follows:
1.
NOTE
The values given in steps
4, 6 and 7 are maximum acceptable limits. Skew should
be adjusted to a minimum as
near zero as possible.
Set the field tester Read/Write
switch to the Read position, the
Sh-Sh/Bkwd/Fwd switch to the forward position and the Auto Cycle/
Auto Stop/AutoRew switch to the
Auto Stop position.
4.
NOTE
If the tape unit has the
NRZI feature, the skew delay
taps listed in Figure 4-21
must be set to zero.
2.
Trigger an oscilloscope on the
negative slope of track 4.
(Use
the READ BUS test points on the
field tester.)
Monitor track 5 and check to see
if the negative slopes·of tracks
4 and 5 coincide. Figure 4-22
illustrates what must be avoided
and accomplished.
Verify that skew, the time between the slopes, does not exceed these limits:
Model
Skew Limit
3430
2.3 microseconds
3450
1.4 microseconds
3470
0.9 microseconds
3480
0.7 microseconds
DELAY TAPS
FWD
AMP
PIN
BKWD
AMP
PIN
TRACK
BIT
DELAY
CARD
1
5
187
816,817,818,819,820,821
A16
A17
2
7
187
809,810,811,812,813,814
A09
A10
3
3
187
801,802,803,804,805,806
A01
A02
4
p
186
816,811,818,819,820,821
A16
A17
5
2
186
809,810,811,812,813,814
A09
A10
6
1
186
801,802,803,804,805,806
A01
A02
'7
0
185
816,817,818,819,820,821
A16
A17
8
6
185
809,810,811 i 812,813,814
A09
A10
9
4
185
801,802,803,804,805,806
A01
A02
Figure 4·21.
4-32
NRZI Skew Delay Taps
READ/WRITE HEAD
~ ~
11
t~IH
iI
&
,,~
~
:<-..'v
~~
\>:-0
6
1~
0
'~1
L~
II
~~
~
4
I
2
II
III
P
Ii
1.\\
,\1
IiI
\'\
i\.
\\
3
,
7
I
II
f~\!
PHYSICAL
BIT
POSITIONS
5
I
lit'
B
A
C
A.
Shows the head cocked across the tape causing bit 4 to be read from one byte and bit 5 from an adjacent byte.
B.
Shows the head cocked across tape to an extreme, thus each bit is taken from a different byte. However, the
amplitude will appear weak.
c.
Shows the head aligned straight across the tape which is the correct mechanical skew alignment.
Figure 4-22.
Mechanical Skew Alignment
5.
If skew does exceed the limits of
step 4, turn the adjustment screw
at the right front of the skew
block to achieve minimum skew.
Recheck to be sure skew is below the
limit specified in Step 4.
6.
Measure the time between the negative slope of track 4 and the negative slope of the other eight tracks
to be sure the head is not misadjusted by 1 bit or more. The maximum time between the negative slope
of track 4 and the other eight
tracks must not exceed:
Model
Time Limit
3430
3.1 microseconds
3450
3.2 microseconds
3470
2.0 microseconds
3480
1.6 microseconds
7.
8.
Leaving the field tester Read/Write
switch in the read position, set
.the Sh-Sh/Bkwd/Fwd swi tchto the
backward position.
Repeat the skew
measurement in step 4, syncing on
the positive slope this time.
Backward skew should not exceed forward skew by more than:
Model
Time
3430
3.1 microseconds
3450
1.9 microseconds
3470
1.2 microseconds
3480
1.0 microseconds
If the read/write-head output amplitudes are below the specified
levels, it is possible mechanical
skew is misaligned by exactly 9
bytes. This can be checked by reading very small records written on a
known good tape unit.
4-33
SKEW CHECK AND ADJUSTMENT
(ELECTRICAL) ••. NRZI
Mechanical skew must be correct before
electrical skew compensation is accomplished. Otherwise electrical skew
would compensate for a·misaligned head
. 'rather than head imperfections as it
is intended.
The skew adjustment will be easier if
a systematic list of accomplishments
is maintained, as it is difficult to
remember the bits, tracks and times
involved. For the purpose of illustrating what is needed, there is a
chart in Figure 4-23.
2
3
4
5
Corinect the field tester and set
the Read/Write switch to the Read
posi tion,' the Sh-Sh/Bkwd/Fwd switch
to the Forward position and the
Auto Cycle/Auto Step/Auto Rew switch
to the Automatic Rewind position •
5.
With a scope monitor the Read Bus
test points on the field tester and
find the "latest bit" track.
6.
Connect the oscilloscope's negative
sync input probe to the lagging
bits test point.
7.
Adjust all other tracks to coincide
with this lagging bit by changing
the delay taps listed in Figure
4-22. Delay tap incremental values
are:
OPERATION
BEING
PERFORMED
TRACK
1
4.
6
7
8
9
TAPE UNIT
SPEED IN
INCHES
PER SECOND
LAGGING
BIT
LOCATION
.1
2
3
4
5
6
7
8
9
READ
FORWARD
1
2
3
4
5
6
7
8
9
READ
BACKWARD
1
2
3
4
5
6
7
8
200
150
125
250
112.5
280
420
75
NOTE
9
Since bits cannot be
speeded up, the earlier
.ones are delayed and
caused to occur in synchronization with the
later ones as one byte on
the Read Bus.
WRITE
Figure 4-23.
DELAY VALUE
BETWEEN TWO
ADJACENT TAPS
IN NANOSECONDS
NRZI Skew Chart
READ FORWARD SKEW (NRZli
READ BACKWARD SKEW (NRZI)
1.
NRZI skew delay taps shown in
Figure 4-21 must be set to zero.
2.
Mechanical skew must be checked,
and if necessary, adjusted~
3.
Load a Master Skew tape (STC PN
6013) .
To adjust skew during Read Backward,
proceed as in Read Forward with the
following exceptions:
1.
4-34
Change switch positions on the
Field Tester to accomplish a
Read Backward operation.
2.
Sync the oscilloscope on positive
slope.
3.
Align the positive peaks.
3.
Sync the scope negative and connect
the trigger input lead to the test
point where the "lagging bit" was
found.
4.
Adjust all other bits to coincide
with the "lagging bit" track.
NOTE
Unload the Master Skew
tape and load a good
scratch tape.
There is no write skew tolerance because
the write skew delay potentiometers provide for infinite adjustment.
WRITE SKEW (NRZI)
1.
2.
Turn the write skew delay potentiometers listed in Figure 4-24
fully counterclockwise. These
are one turn pots and this provides a minimum bit delay.
WRITE AMPLITUDE (NRZI)
Locate the "lagging bit" track;· it
is to be used as an adjustment
reference.
1A4
1A5
e
1A6
2
e
e
A
Figure 4-24.
A
e
1B5
3
TRACK
1 2 345 6 7 8 9
BIT
5 7 3 P 2 1 064
N RZI Write Skew Delay Adjustment
Potentiometers by Track Location
1B6
9
A
Figure 4-25.
e
1B7
6
3
2
5
A
e
9
9
8
6
A
@)
e
e
5
4
Adjust each track for 9.0 volts peak-topeak on the read bus.
This adjustment
is to be made while writing all "ones"
on a known good tape.
The adjustment
potentiometers are listed in Figure 425.
A
N RZI Write Amplitude Adjustment
Potentiometers by Track Location
4-35
TACHOMETER CHECK AND ADJUSTMENT
5.
Stop tape motion and initiate a
forward motion command.
The following procedure lists the steps
required to set the dc level for the
phototransistor and lamp assemblies.
6.
Check to ensure a peak-to-peak
signal of between 4 V and 9 V
at the same test point previously
used.
7.
Allow tape to continue moving forward until it reaches EOT, then
stop it.
8.
Disconnect the +5 V line (small
white plastic single wire connector between tach board and
capstan tachometer assembly) from
lamp A. Thi.s causes the circuit
to automaticallY switch to assembly B.
9.
Substitute potentiometer Pl with
potentiometer P2 and repeat steps
4, 5, and 6.
1.
2.
Connect a field tester to and mount
a scratch tape on the tape unit to
be checked.
Move tape forward to the EOT marker
and stop it.
3.
Connect a scope to the sine output
test point on the tach board shown
. in Figure 4-26~
4.
Press the LOAD/REWIND pushbutton
and adjust potentiometer Pl for a
peak-to-peak signal of between 4 V
and 6 V.
10. Reconnect the +5 V line to the lamp
A assembly.
VACUUM COLUMN DOOR ADJUSTMENT
CONNECTOR
The vacuum column door is correctly aligned when the door glass counterbore is
centered on the capstan and the door
swings freely on its hinges.
It should
maintain vacuum seal after a minimum of
ten openings and closings. Check capstan and R/W head to door clearance before proceeding with the following adjustments:
•
vertical adjustment
1.
.SINE OUT
TEST POINT
Figure 4-26.
4-36
Loosen the hinge mounting screws
on the rear of the vacuum-column
back plate .
NOTE
GROUND
Tachometer Board
DO NOT loosen both
hinge mounting blocks
simultaneously.
2.
VALVE LOCKNUT
Adjust the lower hinge first,
retighten the screws and then
adjust the upper hinge.
SOLENOID
MOUNTING
Horizontal adjustment
1.
VALVE POSITION NUT
\\
Loosen the hinge mounting screws
on the side of the hinge mounting block.
NOTE
DO NOT loosen both
hinges simultaneously.
2.
Adjust the lower hinge first,
retighten the screws and then
adjust the upper hinge.
Once the vacuum door adjustments are
completed, test .the vacuum seal by placing a piece of magnetic tape between the
door and the vacuum column bars. Close
the door. A drag should be felt as the
tape is pulled out. Check both the
right and left sides for a good seal
along the muffler plate and glass area.
(See Door Catch section for further adjustments.) If a good seal cannot be
accomplished, check for protruding air
bearings and screws or for warped parts,
burrs and foreign material.
VACUUM TRANSFER VALVE ADJUSTMENT
0.0002 TO
0.003 IN
CLEARANCE
Figure 4-27.
Remove the top fire wall to obtain
access to the transfer valve, and
loosen the solenoid mounting screws
(4) •
2.
Loosen the valve shaft nuts until
maximum shaft movement is obtained.
Then press the valve shaft~end with
the thumb until the valve is fully
seated. While still holding the
shaft in, move the solenoid coil
VALVE
SHAFT
Vacuum Transfer Valve
forward until it touches and is
square with the plunger face (making
contact on both sides).
3.
Release the shaft and retighten the
mounting screws (4).·
4.
Repeat this portion of the procedure
if the plunger and coil do not seat
when flush on both sides.
5.
with the valve shaft in normalposition (running mode), rotate the position nut (the nut closest· to the
valve assembly) until it makes contact with.the end plate. Using two
wrenches, lock the locknut against
the position nut being careful not
to disturb the setting of the position nut.
6.
To complete the adjustment, press on
the valve shaft-end until the valve
seats. Then rotate the shaft in
either direction to obtain .002 to
.003 inch clearance between the solenoid .plunger and the core. Tighten
the solenoid locknut -- do not allow
the shaft to rotate when tightening
the locknut.
The vacuum transfer valve (see Figure
4-27) switches pneumatics from the
thread mode vacuum por~s to the run mode
ports. To adjust the vacuum transfer
valve:
1.
SOLENOID
LOCKNUT
4-37
VOLTAGE ADJUSTMENTS
Limit switch adjustments are made with
the window down as follows:
The +5, +15 and ~15 volts must be adjusted to within ±4 percent of nominal.
+5 V ± 0.2 V
+15 V ± 0.6 V
-15 V ± 0.6 V
These voltages may be monitored on Terminal Board 3 (TB-3) shown in Figure
3-27. The nonadjustable voltages that
may be monitored on TB-3 are -23 V and
+10 V.
1.
Loosen the two screws securing each
switch.
2.
Move the desired switch up or down
with respect to the actuator cam.
Correct switch position is determined
by trial and error according to the following guidelines:
•
The remaining voltages are -10 V and
-46 V.
They are not adjustable and may
be monitored on the back of the power
gate.
The down switch should be adjusted
so that the window closes fully
with~ut bouncing.
The up switch should be adjusted so
that powe~ is cut off just before
the window reaches the stops.
WINDOW LIMIT SWITCI-IES ADJUSTMENT
WINDOW ADJUSTMENTS
The window-limit switches are located
near the left end of the power-window.
drive shaft. The switch nearest the
front of the machine senses the down position. The rear switch senses the up
position (see Figures 4-28 and 4-29).
HORIZONTAL ADJUSTMENT
The power window horizontal adjustment
procedure is:
1.
Loosen the byo cap screws on each
window guide (see Figure 4-30 for
the cap screws location).
2.
Align the guides to allow the window to swing out freely without interference or contact with the sides
of the tape unit.
3.
Retighten the cap screws.
ACTUATOR CAM
VERTICAL ADJUSTMENT
The power-window vertical adjustment
procedure is:
DOWN
SWITCH
Figure 4-28.
4-38
Power Window Switches
1.
Loosen the two cap screws on the
drive-shaft coupling (see Figure
4-29 for the cap screws location).
2.
With the coupling loosened, close
the window completely and then retighten the cap screws.
SPRING
REEL
SPRING
REEL
MOTOR
SHAFT
COUPLING
DRIVE
PLATE
DRIVE
PLATE
HORIZONTAL
ADJUSTMENT ---~
SCREWS
/
;1/
/
/
VERTICAL
ADJUSTMENT
SCREWS
(REAR OF OPERATOR PANEL)
STOP - - - " , , 1 : 1
BLOCK
ASSEMBL Y
Figure 4-29.
Power Window Adjustments
4-39
TENSION ADJUSTMENT
1.
Remove the screws (6) holding the
operator panel in place and set the
panel back on the top of the tape
unit.
2."
Disconnect the cable from the spring
reel by removing the screw securing
it (see Figure 4-29) .
3.
Hold the spring reel in place and
remove the allen screws attaching
the reel to the drive plate.
REPLACEMENT PROCEDURES
This section incorporates. the replacement procedure for tape unit assemblies
and individual parts.
In many cases,
removing an assembly may result in the
need for adjustment and alignment of the
assembly. The adjustment information
is described in the Adjustment/Alignment
Procedures section of this chapter. As
an aid to locating a particular replac.ement procedure, they are arranged in
alphabetical sequence.
CAUTION
Keep a firm hold on the spring
reel once the screws are removed.
Releasing the reel results in the reel unwinding until tension is removed.
Should
this happen, rewind the spring
reel until proper tension is
attained.
4.
5.
Rotate the spring reel either a
quarter or half turn to adjust the
tension. This is a trial-and-error
adjustment.
Reinstall the screws (2) that hold
the spring reel to the drive plate.
6.
Reconnect the cable to the spring
reel.
7.
Follow this sequence for the second
spring reel.
8.
Test window operation.
9.
Set the operator panel in position
and secure in place with the allen
screws (6). One of the screws also
connects the ground wire.
AUTOMATIC HUB REPLACEMENT
1.
Loosen the allen screw securing the
collar clamp and slide the hub off
the shaft.
2.
Slide the new hub onto the reel motor shaft until it rests against the
hub locating collar.
3.
Slide the collar clamp over the hub
splits and align the splits in the
clamp with the splits in the hub assembly.
4.
Tighten the collar clamp allen screw.
5.
Alternately press the LOAD/REWIND
and RESET pushbuttons to be sure the
new hub is working.
6.
If the hub chatters, perform the Hub
Actuator Adjustment.
CAUTION
DO NOT change the hUb position on the motor shaft, as
it may result in tape damage.
NOTE
The cable to the operator
panel runs between the left
spring reel and the panel.
Do not pinch the cable and
be sure it does not interfere with the proper window
operation.
4-40
AUTO-HUB COVER REPLACEMENT
1.
Pull the cover straight off. Pry
between the cover and hub with a
screwdriver if necessary.
2.
3.
4.
To install the new reel-hub cover,
position it with the notch down and
then insert the cover pin in the
notch.
Rotate the cover clockwise around
the cover pin until the two springs
on the left slip into the hub.
7.
Attach the solenoid retaining bracket to the transport plate.
8.
Connect the wires to their appropriate connectors on the solenoid.
9.
Apply power to check hub operation
and adjust the solenoid as necessary
(see the Adjustment section of this
chapter) .
Rotate the cover counterclockwise
around the cover pin until the two
springs on the left slip into the
hub.
BELT REPLACEMENTS
5.
Rotate the cover counterclockwise
until it is concentric with the hUb.
6.
Use a screwdriver to insert the
third spring under the cover and
then push the cover on.
7.
Check to be sure that all three hub
latch clamps are in up position.
CAUTION
DO NOT roll the new belt onto
the pulleys as it will permanently damage the belt.
VACUUM PUMP
1.
Loosen the vacuum pump mounting
screws (4) and slide the pump
toward the pneumatic motor (see
Figure 4-30).
2.
Replace the old belt with a new one.
Then slide the pump away from pneumatic motor to take up slack in the
belt.
3.
Check belt tension and pulley
ment_
AUTO-HUB SOLENOID REPLACEMENT
CAUTION
208 VAC present
1.
Disconnect all wires to the solenoid
(note their locations).
2.
Remove the hex-head screws (2) used
to fasten the solenoid r~taining
bracket to the main transport.
3.
4.
5.
6.
Pull the linkage pin from the solenoid arm and remove the solenoid assembly from the tape unit.
Remove the screws (2) holding the
old solenoid to the retaining bracket.
PRESSURE PUMP
1.
Mark the pressure pump position on
the pneumatic supply frame.
2.
Loosen the pressure pump mounting
nuts (4) and slide the pressure
pump assembly toward the pneumatics
motor (see Figure 4-30).
3.
Replace the old belt with a new one.
Then slide the pressure pump assembly away from the pneumatics motor
to take up the excess slack in the
belt.
4.
Check belt tension and pulley alignment.
Secure the new solenoid to the retaining bracket.
Install the linkage pin in the solenoid arm while holding the solenoid
,assembly in the t'ape unit.
align~
4-41
PNEUMATICS
MOTOR
Figure 4-30.
Pneumatic Supply Assembly
CAPSTAN MOTOR REPLACEMENT
The capstan motor assembly is removed
or installed from the rear of the tape
unit. To remove the capstan motor assembly:
1.
Remove the screws (3) that hold the
capstan in-place on the motor shaft
and remove the capstan.
CAUTION
DO NOT touch the capstan surface with the bare hand.
4-42
2.
Disconnect the following wires and
cables (noting their orientation to
aid in the subsequent motor replacement) :
• Capstan power cables (2) from TB15.
• Frame ground wire (color coded
green and yellow) by removing the
screw attaching it to the motor.
• Tachometer cable, which is colored
grey and clamped to the tachometer
board.
3.
Remove the 1-1/4 inch flexible cooling hose that connects the capstan
motor to the vacuum pump.
4.
Tighten the spacer guides (2)
against the motor casting.
This
helps prevent cocking the assembly
during removal (see Figure 4-31) .
5.
Remove the motor mounting nuts
and both mounting sleeves.
6.
Remove the washers by sliding them
off the mounting shaft and onto a
screwdriver to maintain proper
washer arrangement.
7.
3.
Slide the motor forward until the
adjustment screws touch the main
transport plate (purple plate).
Be sure that no cables or pneumatic
tubes are between the motor assembly and the transport plate.
4.
Replace the 20 belleville washers
onto each of the mounting studs
(these are the washers that were
placed on a screwdriver to maintain
proper arrangement).
5.
Install the mounting sleeve and nut
on each mounting stud and lock them
down snugly.
6.
Loosen the spacer-guide locking
screws one full turn.
7.
Connect the capstan motor wires and
cables as follows:
(2)
Withdraw the motor assembly by pulling it straight toward the rear of
the tape unit.
If the assembly is
cocked, gently pull and push on both
sides of the motor to free it.
To install the capstan motor:
1.
2.
Be sure the capstan is removed
from the motor to be installed,
then place the motor assembly on
the mounting studs.
Tighten the spacer guides (2) while
taking care to keep the motor assembly squarley aligned on the
mounting studs.
~
Capstan power cables
TB15.
o
Frame ground wire (color coded
green and yellow).
o
Tachometer cable.
o
Ensure that other connections in
the same area have not been accidently disconnected.
BELLEVILLE
WASHERS
MOUNTING
STUD
(2) to
CAPSTAN
MOTOR
(20)
.....!'-__-+--~SPACER
GUIDE
LOCKING SCREW
Figure 4-31.
Capstan Mounting Assembly
4-43
8.
Connect the 1-1/4 inch cooling hose·
to the capstan motor.
9.
Carefully, and without touching its
surface with the bare hands, install
the capstan on the motor shaft (from
the front of the tape unit). Be
sure that the upper Z-bar does not
interfere wi·th capstan. movement.
·10. Loosen the allen screws (2) on the
upper Z-bar and adjust the Z-bar until it is .006 inches (one data processing card thickness) from the
capstan.
11. The final step is to perform capstan
tracking and mechanical skew adjustments according to the procedures in
the Adjustments section of this
chapter.
2.
Disconnect the file-protect cable.
3.
Remove the two mounting screws that
hold the file-protect assembly in
place.
4.
Work the file-protect assembly carefully to the rear and left for removal from the tape unit.
To install the new file-protect assembly:
1.
Place the new file-protect assembly
in the tape unit making sure that
the nozzle is not being pushed
against the rear of the hub.
2.
Insert and lightly tighten the
mounting screws (2) -- the fileprotect assembly should still be
moveable.
3.
Adjust the nozzle so that the distance from it to the hub assembly
(gap B in Figure 4-32) is approximately the depth of ·one data processing card. Also verify that the
flange of the hub assembly extends
0.05-0.09 irich beyond the nozzle of
the file-protect assembly (gap B
in Figure 4-32).
4_
Tighten the mounting screws and
then recheck the dimensions at
points A and B.
5.
If dimension A is incorrect, the
mounting surface of the file-protect
assembly can be filed down to reduce the gap. Shims (use card
stock) can be added between the assembly and the main transport casting to increase the gap.
CAUTION
Before mounting a tape, check
the capstan for possible "run
away" condition. The check is
accomplished by simulating a
mid-tape load and monitoring
capstan speed. If the condition does exist, the excessive
speed can force tape into the
space between the capstan and
the upper Z-bar locking-up tape
motion. Not only does this
damage the tape but it will
ruin the motor. Check wiring if
·"run away" exists.
FILE PROTECT ASSEMBLY REPLACEMENT
To remove the defective file-protect
assembly:
1.
4-44
Remove the file reel and then pull
the file-protect pneumatic supply
hose free from its connector (pull
straight back) with one hand,
whil~ holding the file-protect assembly with the other.
NOTE
Be sure to check for correct
position and adjustment of the
file-reel latch.
TOP PERSPECTIVEVIEW
"A"
~
FILEOR
ADD SHIMS
HERE
HUB ASSY
' -_ _ _ TRANSPORT
PLATE
MOUNTING
SCREWS
Figure 4-32.
File Protect Assembly Mounting
6.
Reconnect the pneumatic supply hose
to the rear of the file-protect assembly.
7.
Connect the file-protect cable, then
check for proper operation of the
file-protect mechanism with and
without a file-protect ring.
Repeat
the check with a cartridge in place.
6.
Adjust the foot to obtain approximately 0.06 inch gap between the
foot and the tape in the tape path.
Tighten the screws.
7.
Manually actuate the foot assembly
by pressing and holding the button
on top of the high speed foot
solenoid. The foot should hold
tape clear of the read/write head
without hitting on the center guide.
If tape does not clear the head,
increase ~he gap between the foot
(when inactive) and the tape -- the
foot must not touch the tape at
this time. Manually actuate the
foot again to see if it holds tape
off the read/write head.
HIGH SPEED FOOT REPLACEMENT
1.
Remove the screws (2) securing the
foot to the main transport plate.
2.
Remove the high speed foot and disconnect the pneumatic hose.
3.
Connect the new foot to the pneumatic hose.
4.
5.
Align the pins on the foot in the
guide groove and reinstall the retaining screws (do not tighten
down) .
Lo"ad a tape.
MACHINE REEL REPLACEMENT
1.
Remove the hub cover.
2.
Loosen the screw-in clamp which
holds the reel in place, then remove the clamp and reel from the
motor shaft.
4-45
3.
4.
Place the new reel on the machinereel motor shaft so that the flanges
are centered on the threading channel,
Position the screw-in clamp so that
the slot in the clamp matches the
slot in the hub. Then tighten the
screw to secure the assembly in
place.
5.
Reinstall the hub cover.
6.
Recheck to be sure that the mounted
tape does not rub the reel flanges
at any point.
PHOTOTRANSISTOR COLUMN BAR ASSEMBLY
REPLACEMENT
1.
Disconnect the electrical leads at
the connector.
2.
Remove the allen-head screws (2)
attaching the column bar assembly
to the tape unit and withdraw the
assembly.
3.
4.
5.
Thread the wires of the new phototransistor column bar assembly
through the same holes the old ones
were removed from.
Attach the assembly with the allenhead screws (2), obtain the correct
vertical alignment of the column bar
and then tighten the screws.
Proceed as follows to remove the pneumatics motor:
1.
Loosen the pressure pump nuts (4)
and the vacuum pump mounting screws
(4), slide the pumps toward the motor and remove the belts (see Figure 4-33).
2.
Loosen the set screws (2) on the
pneumatics motor triple-grooved
pulley and remove the pulley, using
a wheel puller if necessary.
3.
Disconnect the motor mounting screws
(4) and lift the pneumatics motor
out of the tape unit.
To install the new pneumatics motor,
reverse this sequence and then perform
the vacuum transfer valve replacement
(installation) .
POWER SUPPLY REMOVAL AND REPLACEMENT
This procedure ensures an orderly removal of the power supply. Follow the
steps in reverse order for installation.
1.
Remove primary power cables and I/O
connectors from tape unit.
2.
Remove machine covers.
3.
Remove ground strap located below
vacuum pllinp by removing slot screw
from base of tape unit.
4.
Open rear hinged panel and remove
two slotted hex screws (nuts are
located beneath the tape unit),
they are labeled D and E in Figure
3-25.
5.
Loosen three allen-head cap screws
on the left side and two on the
right side of the power supply.
These five screws are shown in Figure 3-25 and are labeled A, B, C, F,
Connect electrical leads.
PNEUMATICS MOTOR REPLACEMENT
NOTE
Before starting the pneumatics motor replacement procedure, complete the Vacuum
Transfer Valve Assembly Replacement section (removal).
4-46
G.
Figure 4-33.
6.
Pneumatic Supply Assembly
Remove and LABEL the external cables
connected to TB-3 and the DCC bus
bar on the front of the power supply.
7.
Remove the voltage distribution cable from the power gate in the rear
of the machine.
(LABEL CAREFULLY)
Note the groups of 4-3-3-1 wire
breakout and the exact board on
which they are located.
8.
Remove the flat cable and external
ac distribution cables from the
triac board.
(LABEL CAREFULLY FOR
TB LOCATION) .
.9.
Remove power supply assembly by
sliding straight out from rear of
machine.
[WARNING
I
Sliding the power supply is
physically a two-man requirement. A 4x4 block on which
to slide the power supply
helps prevent crushing of
toes.
Gross weight of the
power supply is 149 pounds.
POWER-WINDOW GLASS REPLACEMENT
1.
Remove the allen screws (2) securing the block assemblies (see Figure
4-29) .
4-47
2.
3.
Lower the window until the stops on
the cable ends are clear.
Place a 1/2 inch wrench on the motor
shaft coupling and lift the window
glass until it rests on the muffler
door. The wrench thus holds tension
off the cable, allowing the stops
to hang free.
4.
Remove the stops, tilt the ·window
out at the bottom then slide the
glass down and out.
5.
Insert the new glass and follow the
above steps in reverse sequence.
READIWRITE HEAD REPLACEMENT
Read/write head replacement is performed
with the tape unit powered down.
CAUTION
Connecting or disconnecting
the read/write cables with
power ON may result in damage to the internal coils
of the head or damage of
the tape.
Place a cover similar to a bandaid over
the read/write head surface to protect
it.
PRESSURE PUMP REPLACEMENT
1.
Remove the right, pneumatic-supply
side cover (as viewed from the front
of the machine).
1.
Remove the allen screws (3) -- two
on the right and one on the left
securing the read/write head decorative cover.
2.
Remove the high
3.
Remove the cable ground strap from
the Read Head Amplifier card (see
Figure 3-21).
sp~ed
foot assembly.
2.
Disconnect the Pneumatic line can
filter (see Figure 4-30).
3.
Mark "the pressure pump position on
its mounting plate.
4.
Unplug the read cables from the
Read Head Amplifier card.
Remove the nuts (4) holding the
pressure pump in place.
5.
Unplug the resistor pack from the
Write Driver (TL) card. Because
the resistor packs are matched to
the read/write heads, a new resistor pack will be supplied with the
replacement read/write head. Return the old resistor pack to the
factory with the defective read/
write head.
6.
Carefully pull the read/write head
forward and off, rocking it slightly
to loosen binding locator pins.
Keep a cover on the read/write head
when it is out of the tape unit.
7.
Installation of the new read/write
head and resistor pack is accomplished by reversing the removal
sequence (steps 1-7).
4.
5.
Slide the pressure pump toward the
pneumatics motor and then remove
the belt from the pressure-pump
pulley.
6.
withdraw the pressure pump through
the opening in the side of the tape
unit.
7.
Remove the pressure pump pulley (2
set screws) from the pump shaft and
place it on the new pressure pump.
8.
Reverse the first seven steps of
this procedure to replace the pressure pump.
4-48
8.
After the new head is installed, adjust mechanical skew and check
tracking following the procedures in
the Mechanical Skew Adjustment and
Capstan Alignment section of this
chapter.
necessary to pull the reel motor
wires through the grommets on the
rear of the reel-motor covers.)
4.
Remove the screws. (3 each) that
hold the blower collars to the
reel-motoL covers and detach the
reel-motor covers from the old
cooling assembly.
5.
Remount the reel-motor covers on
the new cooling assembly. Fasten
the cooling assembly in place with
the screws (3 each) that hold the
blower collars to the reel-motor
covers ..
6.
Place the reel-motor covers and the
cooling assembly back in the tape
unit, being sure to draw the reel
motor wires through the grommets on
the covers.
7.
Attach the reel-motor covers in
place and then reconnect the reel
motor wires to the terminal boards.
8.
Reconnect the input power cable to
the cooling motor.
REEL-MOTOR COOLING ASSEMBLY REPLACEMENT
The reel-motor cooling assembly uses
two squirrel-cage fans to draw cool air·
through the reel motor. The assembly
rests between the two reel motors and
is replaced as follows:
1.
Disconnect the cooling motor input
power cable.
2.
Disconriect the reel motor wires at
the terminal blocks located on the
rear of the two reel motors (see
Figure 4- 34) .
3.
Detach the covers from the rear of
the reel motors. This allows the
removal of the covers and the cooling assembly as a unit.
(It is
REEL MOTOR _ _--.
COVER
r------
TERMINAL
BLOCK
TERMINAL
BLOCK
BLOWER
COLLARS - - - - - - - - ,
COOLING
MOTOR
REEL MOTOR
COVER
GROMMET - - - \ - - - - * , C l
~!------,I-----
GROMMET
SQUIRREL-CAGE
FANS
Figure 4-34.
Reel Motor Cooling Assembly
4-49
TAPE CLEANER BLOCK REPLACEMENT
The tape cleaner block is located adjacent to the right threading channel just
above the BOT/EaT sensors. To remove
the cleaner block:
1.
Remove the single allen-head screw
holding the block in place.
2.
Pull the cleaner block forward with
slight side motion to disengage the
locating pins and remove.
3.
Check the vacuum port for obstructions ..
4.
Push the new cleaner block into
place and secure it with the allenhead screw.
5.
Check to be sure cJ..eaner block vacuum holds the tape against the block
during both forward and backward
operation.
TRIAC BOARD REPLACEMENT
7.
Carefully remove the four (4) screws
labeled 2 in Figure 3-26 and remove
the triac board.
8.
Replace the old triac board with a
new one and reverse this procedure
for installation.
VACUUM-COLUMN-BAR lAMP ASSEMBLY
REPLACEMENT
1.
Disconnect the assembly input line
on the back-side of the vacuum column back-plate.
2.
Remove the allen-head cap screws
holding the assembly to the vacuumcolumn back-plate (the lower column
bars are held by hex-head machine
screws) and withdraw the column-bar
lamp assewbly from the tape unit.
3.
Remove thE binding-head screws that
hold the lamp circuit board to the
column bar and detach the old circuit board (retain the spacers) .
4.
Attach the new lamp circuit board
to the column bar (be sure to insert
the spacers). The lamps on the circuit board should face the holes in
the column bar.
1.
Disconnect the ac power connector
from the tape unit.
2.
Remove the wheel chocks under the
tape unit and move it forward or
backward so access to the right side
cover panel can be gained.
5_
Attach the column-bar lamp assembly
to the vacuum-column back-plate with
the allen-head cap screws.
3.
Remove the right side cover panel
from the tape uhit.
6.
Vertically align the column-bar
lamp assembly and tighten in place.
4.
Remove the four (4) screws labeled
. 1 in Figure 3-26 from the triac
board plate at the bottom of the
tape unit.
7.
Connect the vacuum-column-bar lamp
assembly input line.
5.
Carefully fold down the triac board
mounting plate while feeding the
small grey cable in. from the front
to allow for the movement.
VACUUM PUMP REPLACEMENT
1.
6.
4-50
Label and disconnect the cable and
terminal connections from the triac
board.
Loosen the vacuum pump mounting
screws (4), slide it toward the
pneumatics motor and remove the
two belts (see Figure 4-33).
2.
Loosen the set screws (2) on the
vacuum pump double pulley and remove
the pulley.
3.
Disconnect the flexible pneumatic
hose on the input side of the vacuum pump.
4.
5.
Remove the machine screws (9) that
attach .the t.op firewall to the tape
unit frame and move the fuse bracket
to one side.
CAUTION
Extreme stress on the cable
may break the fuse holders.
Remove the mounting screws (4) and
lift the vacuum pump out of the tape
unit.
To install the vacuum pump, reverse this
sequence. Be sure to check belt alignment and tension.
6.
Disconnect the vacuum hoses where
they pass through the firewall.
7.
Carefully remove the top firewall
from the tape unit.
VACUUM TRANSFER VALVE REPLACEMENT
8.
Viewing the tape unit from the rear, the
vacuum transfer valve is located to the
left of the vacuum pump (see Figures
4-30 and 4-33). To replace the vacuum
transfer valve:
Remove the three flexible hoses on
the transfer valve assembly and disconnect the rigid hose running between the transfer valve and the
bulkhead.
9.
Remove the plastic, safety shield
on the solenoid and disconnect the
two wires.
l.
Power down the tape unit.
2.
Disconnect the signal and power
cables.
3.
Remove the tape unit back and side
covers.
11. Remove the old vacuum transfer valve.
Remove the sheet metal screws (2)
that attach the fuse bracket to the
top firewall.
12. To install the new transfer valve
assembly, follow the above steps in
reverse sequence.
4.
10. Remove the hex-head screws (7) that
secure the transfer valve mounting
plate to the vertical support.
4-51
Secti.on Si.x:
REFERENCES
6.0.0. 0
6. 1.
o. 0
STC Logic Card Configuration
NOTE:
-
"A" Side is the PIN side
liB" Side is the COMPONENT side
SING LE- ENDED CARD
• •••••
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6.2.0.0
Tape Unit Logic Gates
Read/Write Gate
Logic Gate
(a)
Refer to logic page T U 930 for voJtage di.stribution
information.
6-2
(1.)
.
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LOAD/REWIND SEQUENCE FLOW CHART
LOAD/REWIND
FROM "CARTRIDGE ON" CHART
1.
2.
3.
4.
5.
6.
DROP OFF LINE READY
PNEUMATICS ON 230
TRANSFER PRESSURE I(If
TRANSFER VACUUM 1<8
PICK LOAD LATCH
STJ\RT DELAY CTR
;t.'10
f/VO
,.0
FROM "CARTRIDGE ON"
CHART
~________- r________~'JO
0
OIl
TO "CARTRIDGE ON"
CHART
:z,zo
~____~~~~____~/~O
PICK NFP TRIG
IF RING PRES
FILE PROTECT
SOLENOID
DROPPED
11.f0
N
S_T I"~ ZI>
M~ttH' CHIC:#<
1"10
7-1
LOAOIREWIND SEQUENCE FLOW CHART
. lD DELAY COMP
•\
'OO
THREAD
1.
2.
3.
4.
6.
e.
I,.
PICK THREAD l T
RESET Dl Y CTR 150
DROP lOAD Dl Y ...
BRING UP +RT DRV D
BRING UP +lT DRV C
DlY CTR RESTARTS
fto
MUST BE BEFORE
DC 18.F CTRG ON
AND RETRY IS ON
~~____TH_R_E_A_D~E_R_R_O_R____~
,
(SEE THRD ER FLOW CHART)
RESET AND RESTART
DELAY COUNTER
N
---1___
...
TH_R_E_A_D.,.E_R_R_O_R_ _.JJ
(SEE THRD ER FLOW CHART)
SET S.L. lATCH
N
~--------------------eY
'r
II
LOAOCOLS
c;:J
7-1
if
.
\/)'-\
.
LOAD/REWIND
SE~UENCE
FLOW CHART
C
~P-~~~~__~----~----~
1.
2.
3.
4.
5.
6.
7.
RESET AND RESTART DL Y CTR 130
LOAD COlS TRIG SET
110
RESET THREAD lATCH
100
DROP+lTDRVC
•
BRING UP +L T DRV 0
DROP TRANSFER VACUUM
+RT DRV D CONTINUES
TURNS l T REEL CCW
"0
TAPE LOADS INTO COlS
N
I~O
100
• SHORT lEADER ROUTE & MDTP ROUTE
----------------,
SEARCH
1.
2.
3.
4.
5.
6.
7.
PICK COlS lDD lATCH
DROP lOAD COlS TRIG
DROP TRANSFER PRESSURE
PICK SEARCH lATCH
RESET l!c REST ART Dl Y CTR
GO FWD TO CAPSTAN
DROP lOW SPEED CTRl
If.
liD
fO
110
110
• RICO)
'10
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
REelS NOW UNDER
COL CTRL; TAPE
SEARCHES FWD FOR
BOT
PICK COlS lDD lATCH
'CJO
DROP LOAD COlS TRIG
110
DROP TRANSFER PRESSURE 2!1O
PICK SEARCH lATCH
/10
RESET & RESTART Dl Y CTR
130
PICK MDTP SEARCH
'00
PICK REWIND. DROP lOAD L T ,~
DROP SEARCH
"0
DROP S.L. LATCH
DROP lOW SPEED CTRL
GO BKWD TO CAPST AN
'SO
••
.'0
REELS NOW UNDER
COL CTRl; TAPE
SEARCHES BKWD
FOR BOT
r;;;;j~
r-
1L ___
FIRES -'
CHK
/ """,C~
7-3
( '/ i
190
,-_--1..----,
I
1
BOT
~·u Ji~_5.EI_L08D LT _ ..
(2) SEARCH LT RESET
(3) RWD LT SET, FWD
DROP, 8KWD SET
(4) DlY CTR RESET & SET
(1) BoT LATCH ·sri·
(2) RESET RWD LT
fJo,/ofO
~--------r-------~
;$D
TAPE GOES 8KWD TO BOT
BOT SENSED IN
BKWO DIRECTION.'
N
Y
RESET REWIND LT
STOP DLY CTR
I~".
110,''''
I
.:...1
>----N
y
TURN ON
READY
a70
...
I~ ~
tn'~T
•
TU-70 WILL SENSE THE TRAILING EDGE OF THE BOT
STICKER AND LOCATE WITH All OF THE STICKER TO THE
OF THE BOT BlogK.
7-J(
I(t e
"";.leo -
,'0
- -.....f
TU 100
+LD RWD
+OFF-LINE READV
L
+LOAD
1....:1
,;....
I~
f
1°
'rl~T~U~10=0~------------------------------------------------------~--------~I~
1'1
(j)
lfi
+LD DLV
TU 100
1['
RESET BV THREAD
'----~
IS
.----------------------------------------~{
-PNEU ON
TU 230
I!.
11-3
_TRANSFER Ir-----------------------------------------------~--------tl S
PRESSURE
TU 230
Ii
~
- TRANSFER
VACUUM
I
I~
L,~
I
TU 230
____-In
DC 32
I
+LDDLVC~8
I
+THREAD LATCH
.,
START DLY
COUNTER TU 130
88
TU 100
1
I
REELS L_D_D_S_W_ _T.......U_1_0--l0 SHOULD, OCCUR
BEFORE DC 128
.
-CHK WRITE ENABLE
TU 100
+L T DRV C
I
I
II
L-_ - - ' -
48
1
1
,
.128
I
TU 180
(CLOCKWISE)
TU 180
(CLOCKWISE)
+TAPE PRESENT
I
I
IIII1 , 111 [ I t 1111 , I U II 111111111 'U llllllill , III I r 1111111-ru IIIII /111 U
+RT DRV D
{
~---------------!
SHOULD OCCUR
BEFORE DC 48
1 of 2
+COLS LDD
TU 180
-LD~
+LoArP____________~-------C-O-M-P-L-E-T-E--------------------~
+LD
I
I
hu 110
COLS
I
+LT ZONE
IA
+RT ZONE IA
:
SHIFT DtIE TO
TAPE LOOP TU 180
~'-i
: .•.:
:_.1 :._.
'- .• j
;-.. : :··i
'. __ ;
.••!
SHIFT DUE TO
TAPE LOOP TU 180
:. .•
I
-TRAf\lSFER
PRE'3SURE
-l
~
L
-TRM'JSFER
I
VAQ.JUM
+SEARCH
I
+GO FWD·
REElS LDD SW
--
. ;-- -
ITU 110
L-
TU 150
+BOT
I .
I
n
+BKWD STATUS
+BOT
'-------~
I TU
(IN BKWD)
TU 200
150
t
+GO BKWD
+THFfAD LATCH
I
t
•I
128 ~~.t~~TT~,_~~~~_r~~~~~~~
: 11TIlUilitillllllllllllllllJ IJlJIIIIIIIL
+RT pRV b
+L T I()RV C
·
I
I
L:.
I NOW UNDER
+READV
ITU
270
COL CTRL
.I
NOW UNDER COL CTRL
•I
• GO FWD delayed by count of 16.
2 of -
7.2. O. 0
Rewuid Flow Chart
REWIND
AS
ACTIVATE SET REWIND
SEiT REWIND LATCH
BRING UP BKWD STATUS & GO
SET HS STEP LATCH '{,/J
BRING UP REWIND GATE
ADV DELAV CTR
4t)
"0
ISO
I~
I~
I~
N----.J
If0
v
"0
SET HI SPEED LT
BRING UP HS RWD I~'
''''
BRING UP STEP UP Q«> ____ CAPSTAN GOES BKWD
BRING HS/RT/LT FIELDS ,~O
AT HIGH SPEED
DROP RWD GATE
I~
N---'
y
RESET HS STEP LT I
CAPSTAN DROPS TO
BRING UP RWD GATE
NORMAL RUNNING SPEED
DROP HS REWIND
DROP STEP UP
, 10
DROP HS RT/LT/FIELDS ,90
BRING UP STEP DOWN
,~
START DLV COUNTER
I~
N
y
v
RESET HI SPEED LT
DROP RWD GATE
RESET GO
BKWD STATUS STAYS UP
,6o
TO A? OF UNLoAD/
REWIND IF ENTERED
FROM A8
7-7
If/)
,S"o
.
....
-.:J
SE~
REWIND LT
N
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GO RESET, BKWD STAT STAYS UP
I
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LOAD/REWIND
:5
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Unload/Rewind Flow Chart
UNLOAD/REWIND
(COMO OR P.B.)
N-----,
§-_._. - - -
IITD
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I
I
I
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BRING UP SET UNLOAD
RESET DElY CTR
START DEl.V CTR
SET UNLOAD lATCH
SET BKWD LATCH
RESET PNEUMATICS
19D RESET COlS LDD LT
7110 BRING UP +RT DRIVE C
700 BRING UP +IT DRIVE C
REWIND
(AB)
- - - TAPE PUllS OUT
OF BOTH ColS
NJ-- -TAPE
TAUT ACROSS
THREADING CHANNEL
v
___L__.---,
230
700
700
BRING UP TRSF VACUUM
DROP +LT DRIVE C
BRING UP +IT DRIVE 0
--TAPE NOW WINDING
ON RIGHT REEL
N
I
1 of 2
7.3. O. 0
[continued1
- -TAPE CONTINUES TO
WIND ON RT REEL
N
SET END UNLOAD LT
I~
RESET UNLOAD LT
I~
CLOSE CRTG
a30
WINDOW UP
~'O
RESET END U~LoAD LT 160
RESET XFER VACUUM
~Jo
v
BRING UP UNLD CMPL
STOP DRIVE TO CRTB MTR
RESET BOT LATCH
"0
titSO
~
N
v
DROP DRIVE TO WIND MTR
~/O
7-10
2 of 2
THREAD ERROR- - _. SET THRD
1#0 (1) NO
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(3) NO
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TAPE PRESENT BV DC 48
REELS LOO BY DC 126
TAPE PRESENT BV DC 66 AND RETRV ON
~
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Q
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100
I~
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r--------------------~------------------- ~
SET THREAD CHK LATCH
CHECK 1
en MACH CHK LINE
(4) ADV DLY CTR ---- CHK 1
(5) RESET LOAO LATCH
(6) RESET THREAD LATCH
(7) RESET THREAD CHK LT
(8) TURN ON FLASHING CHK LIGHT ----- DC 16
( 1)
(2)
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IREEL MOTION STOPS AT POINT OF ERRORl
RETRY ON INDICATES
ONE ERROR HAS
ALREADY OCCURRED
Y
v
CHART
-----------.,1
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I~CJ
MACH CHK LINE
1'to
ADV DLY eTR
100
RESET LOAD LT
/0()
RESET THREAD LT
RESET THREAD CHK LT
/;'0
TURN ON FLASHING CHK --- DC 16 ,~
1 of 2
~
~
~
n
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FRDM SEARCH CHK - FROM LOAD/REWIND CHART
A1
ISET CHK 2 j/.%o
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START DLV CTR
RESET LOAD LT
100
TURN DNFLASHING CHK LT 1:tD
L. REEL
MOTION STOPS AT POINT OF ERROR
I
20£2
7.5. O. 0
Capstan Operation -
CAPSTAN - --DRIVE
FWD
BKWD
DRV
C
(1) CAPSTAN STARTS TO MOVE
GENERATES TACH PULSES.
(2) BRING UP GATED oSC.
(3) FORCE REG TO 192.
(4) GENERATE T2, T3 PULSES.
(5) SET, RESET COUNTER WITH
RISE OF EACH TACH PERIOD.
I >~) DON'T AllOW REG SET PULSE.
~) GATE OSC COUNTS TO COUNTER.
r - - - - --1
I SHOULD OCCUR I
N ------,
1.3 TO 1.5
I ms AFTER GO
I
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UP
_ _ _ _ _ ...1I
RESET COUNTER WITH
RISE OF TACH PULSE
GATE IN NEW CNTS
Y
-
-
-
-
-
-
-
-1
1
RESET REG T
RESET REG T2
SET REG
T3
RESET CNT T2, T3
SET LINEAR CTl lATCH
DROP FWD OR BKWD HP DRV
I WR INHIBIT WILL DROP
I AT THIS POINT IF CNT
1......
__- - - - - - - - - - - - - ,
I
I HAS REACHED A CNT OF I
33 FOR A WRITE OR
ICNT 8 FOR A READ;
I_VELOCITY
CHECK
_ _ _ _ _ _ _ _ _ ...J
COUNTER, REG, D/A CoNV, PWR AMP, TACH
MAINTAIN SPEED WHILE GO IS UP
GO
~"""
Y -.---------'
N
7-13
.
. .I
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'.
,
y
BKWI> H P DrIVE
SUFFICIEf(T TO STOP
r.,.,
'3-IS TACH PEl'lof>$
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Sa.FFZC.'t.£NT TO STOP
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.
-.1
,----v
N----.
,----~~~
N-----'
Q
y-----1
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v
TAU ISSUES __ _
BACK HITCH
GO BKWD
2.5 ms
COND GO FWD
....
.....I
CJ1
DELAY FWD
GO 2.3 ms
CAPSTAN DRIVE IS IDENTICAL
FOR ALL MODELS FROM THE
TIME GO COMES UP TO THE
CAPSTAN UNTIL GO DROPS
FROM THE TAU. SEE CAPSTAN
DRIVE 2450, 2470 FOR DETAIL
CAPSTAN DRIVE IS IDENTICAL
FOR ALL MODELS FROM THE
TIME GO COMES UP TO THE
CAPSTAN UNTIL GO DROPS
FROM THE TAU. SEE CAPSTAN
DRIVE 2450, 2470 FOR DETAIL
N---y
GO
N
TO COMPLETE
READ BACK
CHK
- - -
~Rg:O:A~
V
V
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~
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INDEX
AC Section (Power Supply)
3-27
Adjustment Procedures 4-11
Air Filter Removal (Base)
4-9
Air Filter Removal (Pressure Pump)
4-10
Alignment Procedures 4-11
Automatic Hub Lubrication
4-9
Automatic Hub Cover Replacement 4-40
Automatic Hub Positioning Collar Adjustment 4-11
Automatic Hub Replacement 4-40
Automatic Hub Solenoid Check And Adjustment 4-11
Automatic Hub Solenoid Replacement 4-41
Cartridge Open Switch
2-1
Cartridge-Opener Switch Adjustment 4-15
Cleaning/Adjustment, General (Quarterly)
4-9
Cleaning/Adjustments/Replacements (Semiannual)
4-10
Cleaning/Inspection, Limited (Monthly)
4-8
Cleaning Kit 4-1
Cleaning, Tape Transpo(t (Daily)
4-7
Column Reel Control
3-5
Control Signais, Reel
2-14
Cooling Assembly Replacement (Reel Motor)
4-49
Backward Reel Operation
3-6
Backward Skew Adjustments 4-34
Basic Specifications, Tape Unit 1-3
Beginning-Of-Tape Sensor 2-3
Beginning-at-Tape Sensor Adjustment
Belt Replacements 4-41
Vacuum Pump 4-41
Pressure Pump 4-41
Belt Tension Adjustments
4-12
Vacuum Pump 4-12
DC Section (Power Supply)
3-27
DAC 3-22
Data And Control Lines (Input)
3-24
Data And Control Lines (Output)
3-26
Data Waveforms 4-25
Phase Encoded 4-25
NRZI
4-25
Delay Counter 2-3
Delay Counter Check and Adjustment 4-17
Digital Tachometer A3sembly
3-13
Dimensions, Tape Unit 1-3
Door latch Adjustment 4-18
Dynamic Amplitude Control
3-22
Pressure Pump 4-12
Bit Spacing 4-24
BOT Sensor 2-3
BOT Sensor Adjustment 4-30
Capstan Alignment (Tracking)
4-12
Capstan Linear Control
3-12
Capstan Control
3-9
Capstan Direction Control
3-10
Capstan Dynamic Braking 3-10
Capstan High Power Drive 3-12
Capstan Motor Replacement 4-42
Capstan Power Driver 3-10
Capstan Specifications 4-15
Capstan Starting 3-16
Capstan Stopping 3-16
Capstan Tachometer, Digital
3-13
Cartridge Closed Switch
2-1
Cartridge On Switch
2-1
4-30
Cooling System
::l-33
Emergency Power. Off (EPO)
3-9
End-Of-Tape Sensor 2-3
Environmental Parameters 1-3
EOT Sensor AdjustmEmt 4-30
EPO 3-9
Erase Head Check 4-18
Field Tester
1-8
Field Tester (PN 10489)
4-2
BIT Switches 4-3
GAPS!WR ITEIR EAD Switch 4-2
GO/ST-ST/STOP Switch 4-2
1-1
Indicator Operation 1·9
Input Lines 3·24
Input/Output Connector 3·25
Input Lines 3·24
Inspection/Replacement (Annual)
Inspection, Tape Unit 4·7
Interblock Gap Control 3·16
GO UP and GO DOWN Potentiometers 4·3
PEIWRITE/NRZI Format Switch 4·3
READ BUS Switches 4·3
SH·SH/BKWD/FWO Switch 4·2
TI PASS/TI STOP/AUTO RWND Switch 4·2
Field Tester (PN16086)
4-4
Functions and Controls 44
Operating Considerations 44
Field Tester Switches (PN 16086)
44
AUTO CYCLE/AUTO STOP/AUTO REW Switch
GO UP and GO DOWN Potentiometers . 4·6
MED FREO/HI FREO/LO FREO Switch 4·5
PE/NRZI/GCR Switch 4-5
READ/WRITE Switch 44
SH-SH/BKWD/FWD Switch 4-5
ST·ST/GO/STOP Switch 44
STATUS CONTROL Switch 4·5
TI PASS/TI AUTO Switch 4-5
WRITE SWitches and READ Test Points 4·5·
File Protect 2·5
File Protect Assembly Replacement 444
File Protect Sensor 2·3
Filter Removal (Air)' 4·9
Filters Replacement (Pressure Pump) 4·10
Forward Creep 3·16
Forward Motion Control (Capstan) 3-12
Forward Operation (Reel)
3-5
Forward Skew Adjustment 4·34
Fuse Locations 3·29
Fuse Specifications 3-31
Glass Replacement (Window)
4·47
Head Amplifier 3·21
Head Replacement (Read/Write) 448
High·Power Drive (Capstan) 3·12
High·Speed Foot Adjustment 445
High·Speed Foot Replacement 4·45
High·Speed Rewind Adjustment 4·18
High·Speed Rewind (Reel Control) 3·7
High·Speed Rewind Potentiometer 4·18
Hub (Automatic) Replacement 440
Hub Cleaner 4·7
Hub Cover Replacement 440
Hub Solenoid Check And Adjustment 4·11
Hub Solenoid Replacement 441
Hub/Window Up Pushbutton '·9
1·2
4·11
4·5
Load Operation Checks 3·12
LOAD/REWIND Pushbutton 1·2
Loop Stabilization 3-9
Lower Restraint Alignment 4·27
Low·Speed·Area Sensor 2·3
Low·Speed·Area Sentor Adjustment
Low·Speed Control 3·1
Low·Speed Reel Control 3·2
LSA Sensor Adjustment 4·30
4-30
MACHINE CHECK Indicator 1·9
Machine Reel Replacement 445
Main Power Circuit Breaker 3·28
Maintenance Procedures 4·1
Maintenance Equipment 4·7
Manual Check 2·14
Master Skew Tape 4·32
Mechanical Skew Check And Adjustm!!nt
Midtape Load 2·12
Midtape Search 2·12
Motor Pulley Alignment 4'·22
Motor Replacement (Capstan) 4·42
Motor Replacement Pneumatics 4-46
4-32
Noise, Random 424
Noise, Read 4·24
Not File Protected 2·5
NRZI Preamplifiers 3·21
NRZI Skew Check and Adjustment (Electrical)
NRZI Waveforms 4·25
Offline Operation 1·1
Online Operation 1-2
Operator Panel 1·2
4·34
Oscillator Pulse Counter
Output Lines 3-26
Override Switch 2-3
3-15
Phase Encoded Preamplifiers 3-21
Phase Encoded Waveforms 4-25
Phototransistor Column Bar Assembly Replacement
Pneumatics 3-31
Pneumatic Checks And Adjustments 4-19
Pneumatics Generation 3-32
Pneumatics, Run Mode 3-33
Pneumatics Supply Belt Replacement 4-41
Pneumatics, Thread Mode 3-32
Positioning Collar Adjustment 4-11
Power Driver Operation Modes 3-13
Power Requirements 1-3
Power Supply 3-27
Power Supply Replacement 4-46
Power-Window Glass Replacement 4-47
Preamplifiers, NRZI
3-21
Preamplifiers, Phase Encoded 3-21
Pressure And Vacuum Control 3-31
Pressure Pump Air Filter Removal 4-10
Pressure Pump Belt Adjustment 4-12
Pressure Pump Belt Replacement 4-41
Pressure Pump Motor Replacement 4-46
Pressure Pump Pulley Alignment 4-23
Pressure Pump Replacement 4-48
Preventive Maintenance Schedule 4-6
Primary Voltages 1-3
Pulley Alignments, Pneumatics 4-22
Pulse Counter 3-15
Pushbutton Operation 1-2
Random Noise 4-24
Read Amplitude 4-24
Read Backward Skew (NRZI)
4-34
Read Head Amplifier 3-21
Read Formats 4-27
Read Forward Skew (NRZI)· 4-34
Read Noise 4-24
Read Operation 3-20
Read Problems 4-25
Read Preamp Gain 4-24
Read Preamps 3-21
Read/Write Control 3-19
Read/Write Data Verification 4-23
446
Read/Write Head Replacement 448
Ready Indicator 1-9
Reel Control System 3-1
Reels Loaded Switch 2-3
Reel Motor Control 3-1
Reel Motor Cooling Assembly Replacement
Replacement Procedures 4-40
RESET Pushbutton '-2
Restraint Alignment 4-27
Rewind Operation 2-14
4-49
SELECT Indicator 1-9
Sensor Adjustments 4-27
Sensors 2-1
Short Leader Load 2-12
Skew Check And Adjustment (Electrical)
4-34
Skew Check And Adjustment (Mechanical)
4-30
SPAR 1-2
Specifications 1-3
START Pushbutton 1-2
Status Control 2 3-26
Subsystem Operation
1-1
Tachometer Assembly, Digital 3-13
Tachometer Check And Adjustment 4-36
Tape Cleaner Block Replacement 4-50
Tape Control Unit 1-1
Tape Guides 4-31
Tape Indicate
1-9
Tape Present Sensor 2-3
Tape Present Sensor Adjustment 4-30
Tape-Transport Cleaner Fluid 4-7
Tape Transport Cleaning 4-7
Tape Unit Control 2-1
Tape Unit Design 1-10
Tape Unit Inspection 4-7
Tensiometer 4-13
Thread/Load Operation 2-3
Tool Kit 4-7
Triac Board Replacement 4-50
Unload Operation 2-17
UNLOAD/REWIND Pushbutton
Upper Restart Ali{jnment 4-27
1-2
1-3
Vacuum And Pressure Control 3·31
Vacuum Column Bar Lamp Assembly Replacement
Vacuum Column Door Adjustment 4-36
Vacuum Column Phototransistors 2·3
Vacuum Column Sensor Replacement 446
Vacuum Pump Belt Replacement 441
Vacuum Pump Motor Replacement 446
Vacuum Pump Replacement 4·50
Vacuum Transfer Valve Adjustment 4·37
Vacuum Transfer Valve Replacement 4·51
Velocity Controi Circuits (Capstan) 3·13
Velocity Feedback Control (Reel)
3~6
Voltage Adjustments 4·38
1·4
4·50
Window Adjustments 4·38
Window Closed Switch 2·1
Window Glass Replace .....ent 447
Window Limit Switch Adjustment 4·38
Window Open Switch 2·1
Write Amplitude (NRZI) 4·35
Write Disabled Indicator 1·9
Write Enable Ring 2·13
Write Operation 2·19
Write Skew (NRZI) 4-35
Write Waveforms 4·27
READER'S
COMMENT
FORM
Please give us your comments on this manual.
Your constructive criticism can help us produce better publications in the future. Give specific page and line references
where they areappropriate. If you would like a reply, be sure to include your name and address.
Thank you for your comments.
No postage is required if mailed in the U.S.A.
3400 Magnetic Tape Units FEMM
I
I
l-n
,I~g...
YOUR COMMENTS PLEASE
This manual is a Field Engineering tool. If it contains incorrect or inadequate information, it is no better
than a broken screwdriver. Your comments and suggestions could help us make this manual and others
into more useful tools. Won't you take a few minutes to jot down your suggestions on the back ofthis
form?
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No postage is required if mailed in the U.S.A.
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----~----------.-.-------------.---------~~
First Class
Permit 2
Louisville,
Colorado
I
I
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I
I
I
I
BUSINESS REPLY MAIL
No postage stamp necessary if mailed in the U.S.A.
Postage will be paid by:
I
I
Storage Technology Corporation
P.O. Box 98
Louisville, Colorado 80027
I
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Att;,: Tecnnical Publications
----.-~-~-----.--------.--.-------.--'-----------~~
I,
I
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®
I
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STORAGE TECHNOLOGY CORP.
P.O. Box 98
Lou isville, Colorado 80027
Form No. STC 0708
I
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