Kennedy 331 User manual

KENNEDY CO.
Operation and maintenance manual
lVIodel331
Digital Cartridge
Recorder

106-0331-100
SECTION I
APPLICATION DATA
1.1 INTRODUCTION
The Kennedy Model 331 Cartridge Recorder is a
rugged tape handler expressly designed for high re-
liability digital data recording. .
The machine utilizes the 3M DC300A converter 1/4
inch data cartridge, which features a unique isoelastic
drive system for maintaining constant tape tension
and tape motion with a single drive motor. Drive
power is provided by a high quality AC motor/tach-
ometer velocity servo system which provides both
tape and reel drive. The cartridge contains 300 feet
of 0.25 inch computer grade tape, along with internal
tape guides to ensure reliable recording.
The Mode1331 is fully bidirectional at 25 ips normal
speed, resulting in a data transfer rate of 40,000
bits per second at 1600 cpi recording density. For-
ward and reverse search modes as well as rewind
speed are 90 ips.
The drive can be equipped with a variety of heads
for maximum flexibility. One, two and four-track
versions are available. Each track is treated in-
dependently, allowing cartridge interchange between
transports of differing track configurations. Every
track is equipped with a separate erase gap to ensure
against inadvertent data erasure.
The Model 331 is designed to meet the requirements
of the proposed ANSI standard for quarter-inch car-
tridges. The standard provides for a recording
density of 1600 cpi written in aphase encoded format.
A 16 character preamble precedes the data for read
synchronization. Data is followed immediately by a
16
character CRC and then a 16 character postamble.
Record gaps are 1. 2 inches minimum.
The write electronics in the Model 331 consists only
of head drivers. The proper phase encoded data in-
cluding preamble, CRC and postamble must be pre-
sented to the unit in the correct serial order. .
Read electronics consist of preamplifiers and cross-
over detectors. Outputs are in digital form, TTL
compatible.
The Model331 provides an extremely reliable means
of storing digital data. It is well suited to use as a
programming device for minicomputers, a storage
1·-1
•
device for terminal and pOint-of-sale systems, and
any other data processing applications requiring
maximum capability in minimum space.
1.2 ELECTRICAL/MECHANICAL SPECIFICATIONS
Table 1-1 lists the general specifications for the
Model 331. Figure 1-1 is an outline and installation
drawing for this unit.
Cartridge type 3M, DC300A Isoelastic
Data Cartridge
Tape width •• • 0.25 inch, 1. 0 mil
Tape length • • • • • • • • • • • 300 feet
Recording density. • • • • • • • • 1600 bpi
Number of tracks. • •••• 1, 2, or 4
Recording head. • Dual gap read-after-write
wi th separate erase bar for each track
Record format • • Single track, phase encoded
Record mode • • • • • • • Single track serial
Normal tape speed •••••••••••••• 25 ips
Rewind/search tape speed • • • •• 90 ips nominal
Start/stop time •••••• at 25 ips, 30 ms ±1 ms;
at 90 ips, 120 ms nominal
Start/ stop displacement ••• at 25 ips, 0.375 inch;
at 90 ips, 5. 4 inches nominal
Transfer rate •••••••• 40,000 bits per second
Instantaneous speed variation • • ±5 percent
Long term speed variation • • • ±!2 percent
Write Bidirectional
Read ••••••••••
Power requirements
Weight. •••
Bidirectional
• •+5 vdc at 0.5 amp
±24 vdc at 3 amps peak
(unregulated)
• 3.75 pounds
Dimensions • • • • • • • • • • • • 6.5 inches wide,
4.75 inches high, 8.625 inches deep
(16.51 em x 12.06 em x 21. 9 em)
Interface •••••••••••• DTL/TTL low true
Table 1-1. Specifications

1.3 INTERFACE CONNECTORS
The interface connectors on the Kennedy Model 331
cartridge transport are designed for twisted pair in-
puts and outputs. The mating interface connector
consi'3ts of one 44 pin Cinch Jones. Refer to Figure
1-4 for interface assignments.
1.4 INTERFACE SIGNAL CHARACTERISTICS
The tape unit responds to zero-volt true inputs' and
provides zero-volt true outputs. Logic 1 = Ov to
+0.4 vdc, while logic 0 = +2.8 vdc to +5 vdc. Each
signal 'input is terminated in such a manner as to
provide matching for twisted pair cables (see Figure
1-2). Each output line is driven with anopen collector
dri ver. For best results the typical interfacing
circuit configurations shown on Figure 1-2 should be
used. The recommended twisted pair cable will re-
duce the magnitude of intercable crosstalk. Unless
otherwise specified, all wires should be 24 AWG
minimum, with a minimum insulation thickness of
0.01 inch. Each pair should have not less than one
twist per inch, and cable length between transport
and control unit should be no more than 20 feet.
The input receiver circuits, due to zero true current
sinking logic design, will interpret a disconnected
wire or removal of power at the format control unit
as a logic zero or false condition. The logic 1 or
true state requires 25 rnA current sink with less than
0.4 volt •. The logic 0 or false state will be +3 volts
due to the input matching resistors. Each output line
is driven with anopen collector current· sinking logic
driver which is capableof sinking up to 40 milliamp-
eres in the true state. All outputs are disabled' when
the tape unit is not on line and selected.
1.5 TAPE MOTION COMMANDS
The Model 331 responds to four input tape motion
. commands: RUN FORWARD, RUN REVERSE, FAST
FORWARD
and FAST REVERSE. The transport in-
cludes a linear ramp generator which drives the cap-
stan servo and provides linear accelerations from
full stop to required speed, and linear deceleration
from run to stop. Start and stop operations occur
within the interrecord gaps. The ramp time is 30
milliseconds for the standard synch~onous speed
(25 ips). Ramp time for 25 ips is adjusted so that
the amount of tape travel during the ramp-up or
ramp-down is always 0.375 inch.
The ramp time and tape travel during the ramp must
be taken into consideration when writing andgapping.
A delay is required before. writing to insure that the
1-2
106-0331-200
tape is up to speed, and to allow read after write. An
additional delay is required before terminating RUN
FORWARD during a write mode to allow for the spac-
ing between the read and write heads. The timing
diagram, Figure 1-3, provides the necessary infor-
mation to produce properly formatted tapes.
1.6 CONTROL SIGNALS
Pin U - RUN FORWARD COMMAND (RF). A level
that when true and the transport is ready causes tape
to move forward at the normal speed. When the level
goes false, tape motion ramps down and ceases.
Pin T - RUN REVERSE C9MMA~D (RR). A level
that when true and the transport is ready causes tape
to move in the reverse direction at the normal speed.
Pin S - FAST REVERSE COMMAND (FR). A level
that when true and the transport is ready causes tape
to move in the reverse direction at the search speed.
When the level goes false, tape motion ceases.
Pin R - FAST FORWARD COMMAND (FF). A level
that when true and the transport is ready causes tape
to move in the forward direction at the search speed.
When the level goes false, tape motion ceases.
Pin J - CARTRIDGE RELEASE (CR). Apulse which
will cause the cartridge to be ejected. The cartridge
release solenoid is actuated on command from the
interface, releasing the 3M cartridge whenever CAR-
TRIDGE RELEASE
goes true. To protect the car-
tridge release solenoid, the input command is inter-
nallytimed out in the event that CARTRIDGE RELEASE
is not turned off after the cartridge has been ej ected •
Pin N - WRITE ENABLE (WEN). A level that when
true and when a cartridge with the write plug in the
write position has been mounted on the transport
allows writing of data •
1.7 STATUS OUTPUTS
Pin P - READY (RDy). A level that is true when the
tape transport mechanical interlocks are made. When
true, the transport is ready to receive a remote
command.
Pin H -PHOTOCELL B. Output levels which provide
position information for determining load point, EOT,
BOT, end of tape warning, etc.
NOTE: It is required that the photocell
outputs be decodecl and stored in order
to accurately deterinine poSition on tape.

410-4012
CARTRIDGE (IN PHANTOfl)
1........ --------- (l~:~~) ----------I ... ~I
'~HOWN IN OPERATING P~OSITION __
.28 MI N.
(.71).
~, __ ~\==:===========================~==~==;T~
1~(1;1' "AX 1 )!
.75
1. 91)
+
------+i ---4+
2.00
5.08 )
.91
2.31 )
MI N.
~
.203 DIA. THRU
(.52) 4-HOLES
.59
) (1.50)
,
)
)
I
4.53
(11.51)
MIN
j I
I
I~
o
o
o
5.75
I.. ~""--------( 14. 61]
~ ___ l-....,...-=-O __ ----0111111~~;;;..;;
2.00
(5.08 )
3.22 I
(8. J8)~
j
.91
(2.31 )
SUGGESTED PANEL )
MOUNTING DIMENSIONS
-+
HOLES TAPPED
FOR 8-32 SCR£WS~
FIRST DIMENSIONS SHOWN ARE IN INCHES.
DIMENSIONS
IN PARENTHESES ARE IN CENTIMETERS.
4.50
(11.43)
3.75
(9.53 )
1
5.75 - 1--- .38
_ 1......... -------------(14.61) - --(.97)
._ 6.50 ------------Jl.~
(16.51 )
I~
o
5.00
( 12.70)
~CARTRIDGE EJECTOR
ACCESS HOLES (LOCATED ON
BOTH SIDES)
". ~2
( 15.54 )
lOG-0331-800A
8.625 _______________ .... 1
(21.91)
Figure 1-1.
Outline and Installation Drawing

----{>o----< I
TTL 7438 I
OR EOUIVALENT I
TAPE TRANSPORT
~I
I
I~
+5V
20 FT MAX
I
I
+5V
TAPE CONTROL
UN IT
106-0331-500
: >---o<J---
110-0074
SFC
STOP
25IPS
RAMP
WRITE
DATA
INPUT
GAP
DETECT
I
11
.375 IN.
0.1 USEC
l
!;:TYPICAL
FALSE
I~
I -:
TYPICAL WAVEFORM OBSERVED
AT LINE TERMINATION
END OF TRANSMISSION LINE
TYPICAL TRANSMISSION DELAY
Figure 1-2. Typical Interface Circuit ,
U
I
I
30
MS
I
WRITE
~
START
DELAY
WRITE
STOP
~~
TYP
DELAY MIN
-4-.10 IN.
.3 IN. ~
. 35 TY P
.375
.375
~1~2
IN. TOTAL GAP-.
I PREAMBLE
OF FIFTEEN
I DAT A RE
COR DIp )STA r~ [3 LE I
OFASINGLE
10'StONEl
ll, FI FTEEN I
D'S
I . I
I I
I I I I
I
30 NSEC
WRITE
START
DELAY
4-.10
IN.
-'-'1
1..-- APPROX
110-0015
12 CHARACTERS
Figure 1-3. Write Motion Command Timing
1- 5

SIGNAL LEVELS
LOGIC 0: +2.8 TO +5 VDC
LOGIC 1: 0 TO +0.4 VDC
PIN
INPUT
SIGNALS
M
WRITE DATA
K
SELECT A
L
SELECT B
N
WRITE ENABLE
J
CARTRIDGE RELEASE
U
RUN FORWARD
T
RUN REVERSE
R
FAST FORWARD
S FAST REVERSE
BINARY
SELECT
PIN
TRK A B V
-1-
0 0 F
2 0 1 H
3 1 0 P
4 1 1 W
PIN
E
C
D
A
B
Figure 1-4. Interface Pin Assignments
1-6
106-0331-600
110-0082
OUTPUT SIGNALS
READ DATA
PHOTOCELL
A
PHOTOCELL
B
READY
SAFE
POWER
CONNECTIONS
+5.0 VDC (0.5 AMP)
+24 VDC (3 AMP PEAK)
-24 VDC (3 AMP PEAK)
SIGNAL GROUND-
MOTOR GROUND

For example, when the cartridge is ini-
tially inserted a rewind operation should
be performed. A fast reverse command
is issued until both the A and B holes
are detected simultaneously in reverse.
When they are, beginning of tape has been
reached and fast reverse should be
dropped. If it is desired to advance to
load point, run forward should be issued
until the A hole is detected in the for-
ward direction. This position on tape ts
LOAD POINT. The next time the A out-
put is detected in the forward direction,
the end of tape warning position has been
reached. Continued forward tape mo-
tion should only be allowed until both the
A and B outputs are simultaneously
detected signifying end of tape.
1.8 READ/WRITE SECTION
Pin V - READ DATA (RD). Data is presented in serial
format, TTL compatible, and consists of coded flux
transitions. A 0 transition is defined as a voltage
transition from low to high at the interface. A 1
transition is defined as a voltage transition from
high to low at the interface. READ DATA OUTPUT
is forced high (false) during the read gap. The par-
ticular track to be read is selected by means of a low
true SD1, 2, 3, or 4 input, which is determined by the
states of SELECT A and SELECT B interface Sig-
nals. Read Data output is forced high (false) during
the Read Gap.
Pin M - WRITE DATA (WD). Serial input data in the
proper phase encoded format, including preamble,
CRC, and postamble, are presented on this line.
Write data consists of encoded flux transitions. The
polarity of this signal is such that a high (false) input
state generates the ANSI standard erase polarity for
gap generation.
Transport electronics consist only of write head
drivers on the Write Head Driver board. WRITE
ENABLE must be true (high) before write data can be
applied to the selected write head. Write head selec-
tion is accomplished by means of SELECT A and
SELECT B interface signals.
1-7
106-0331-700A
Pin K - SELECT A. When combined with SELECT
B, this level selects one of four tracks for read/write
operation. A table of the logic states required to
select each track is furnished on the Transport Elec-
tronics schematic.
Pin L - SELECT B. When combined with SELECT
A, this level selects one of four tracks for .read/write
operation. A table of the logic states required to se-
lect each track is furnished on the Transport Elec-
tronics schematic.
Pin N - WRITE ENABLE. When true (low) this level
enables the write head selected by SELECT A and
SELECT B signal states. When false (high) this level
disables the write heads.
1.9 POWER SUPPLY
The Model 331 requires ±24 vdc unregulated and +5
vdc regulated supply voltage for operation. The
30 ips version of the Model 331 requires ±27 vdc
nominal +20%-10% , in place of the +24 vdc.
The +24 vdc unregulated is reduced to ±15 vdc regu-
lated by a regulator circuit on the Transport Elec-
tronics board. Table 1-2 lists the current and voltage
requirements of the Model 331.
Voltage
+5v ±3%
+24v
+20% -10%
-24v +20% -10%
Current
Maximum O. 95A
Maximum 3. OA
(100 msec surge whe n
ramping - average 1. OA)
Maximum 3.0A
(60 msec surge when
ramping - average 1.0A)
Table 1-2. Power Supply Requirements

206-0331-100
SECTION II
INSTALLATION AND OPERATION
2.1 INSTALLATION
2.1.1 MOUNTING
Physical dimensions and outline of the transport· are
shown in Figure 1-1. The transport requires 4.56
inches of mounting space on a 7.5 inch rack. The
transport should be located so that the cabling length
between the transport and the format control unit is
no longer than 20 feet.
2.1.2 SERVICE ACCESS
The two circuit boards are readily accessible without
dismantling the chassis. To gain access to the mech-
anical parts inside the chassis, detach the connectors
and Write Head Driver board from the Transport
Electronics board. Then detach the Transport Elec-
tronics board from the bottom of the chassis (four
nuts). The front and sides of the Model 331 are
easily removable as one unit for making certain
mechanical repairs.
2.1. 3 INTERCABLING AND POWER CONNECTIONS
The connector pin· aSSignments and cable require-
ments are specified in Section I of this manual. An
external power supply is required for the tape trans-
port. It may be purchased directly from the Kennedy
Company or may be acquired elsewhere. The power
supply connections and specifications are detailed in
Section I.
2.2 OPERATION
Before operating the unit, make certain that all power
supply and formatter connections have been made.
2-1
2.2.1 OPERATING PROCEDURE
After the interface connections are made as required
and the power supply is connected to the transport,
proceed as follows:
a. Clean the transport read/write head to pre-
vent degradation of magnetic tape.
b. USing a screwdriver, rotate the write enable
plug on the cartridge to the SAFE indication
for the read mode, or away from the SAFE
indication for the write mode. When in the
write mode, the WRITE indicator on the
front panel will be illuminated.
c. To insert cartridge, place bottom plane of
the cartridge on the lower ridge of the car-
tridge guides as shown in Figure 2-1. Slide
cartridge all the way in and press until car-
tridge is engaged as shown in Figure 2-1.
d. To eject a cartridge, issue a CARTRIDGE
RELEASE command, which is automatically
disabled after a predetermined delay. The
tape can also be manually ejected by de-
pressing the cartridge ejection mechanism
within the machine with a small Allen
wrench. Two access holes are provided on
the side panels for this purpose. Alterna-
tely, insert the plastic ejector (Kennedy
Part No. 191-4565-001) provided between the
cartridge and the deck to trip the cassette
latches.

TO LOAD
REST CARTRIDGE ON
LOWER NOTCHES AND SLIDE·-
INTO OPERATING
POSITION.
WRITE ENABLE PLUG
SHOWN IN WRITE MODE.
ISAFEI
ROTATE PLUG TO
SAFE POSITION
FOR READ MODE.
1. INITIAL LOADING STEP
2. LOADED POSITION
Figure 2-1 . Cartridge Loading
2-2
206-0331-200

SECTION III
THEORY OF OPERATION
3.1 TRANSPORT COMMAND SIGNALS
TIll> transp0rt command lines include H.UN FOHWARD,
I--AST FOHWARD, HUN HEVEHSE and FAST RE-
VEHSE. These control command inputs are supplied
from the interface to the Transport Electronics
Board. On that module, the motion controls are
gated and applied to the ramp generator circuitry to
develop the proper ramp ups and ramp downs for
operating the drive motor. A capstan tachometer
feeds back a regulating voltage and current for con-
trolling motor speed.
3.2 A AND B HOLE PHOTOSENSORS
These vertically mounted photo sensors detect the A
and B holes on the tape, which indicate beginning of
tape, end of tape and load point in accordance with
the proposed ANSI standard. This information is
directed back to the interface in the form of Hole A
and Hole B status signals.
Note that the photocell outputs must be decoded and
stored in order to accurately determine position on
tape. For example, when the cartridge is initially
illserted a rewind operation could be performed. A
fast reverse command could be issued until both the
A and B holes are detected simultaneously in re-
verse. When they are, beginning of tape has been
reached and fast reverse should be dropped. If it is
desired to advance to load point, run forward should
be issued until the A hole is detected in the for-
ward direction, the end of tape warning position has
been reached. Continued forward tape motion should
only be allowed until both the A and B outputs are
simultaneously detected, signifying "End of Tape."
3-1
3.3 SELECT A AND SELECT B SIGNALS
The selected read or write track is determined by
the state of these interface signals. For example,
SELECT A high and SELECT B high choose track
four for reading or writing. WHITE ENABLE false
places the machine in the READ DATA mode; WHITE
ENABLE true enables tape writing.
The SAFE SWITCH is activated when the WHITE
ENABLE plug on the 3M tape cartridge is in the SAFE
position. With the SAFE switch on, the write eir-
cuitryon the Transport Electronics Board is disabled
to prevent accidental tape erasure.
3.4 WRITE DATA
The polarity of this signal is such that a high (false)
input state generates the ANSI standard erase polarity
for gap generation.
3.5 READ DATA
A"0" transition in lapse is defined as a voltage trans-
ition from low to high at the interface. A" 1" transi-
tion is defined as a voltage transition from high to
low at the interface. READ DATA OUTPUT is forced
high (false) during t he read gap.
3.6 CARTRIDGE RELEASE SOLENOID
This solenoid is actuated on command from the inter-
f3:ce. releasing the 3M cartridge whenever CAH-
TRIDGE RELEASE goes true. To protect the car'-
tridge release solenoid, the input command is inter-
nally timed out inthe event that CAHTRIDGE HELE..\SE
is not turned off after the cartridge has been ejected.

406-0331-100
SECTION IV
MAl NTENANCE INSTRUCTIONS
4.1 GENERAL
Kennedy Company tape transports are highly reliable
precision instruments which will provide. years of
trouble-free performance whenproperly maintained~
A planned program of routine inspection and main-
tenance is essential for optimum performance and
reliability. The units require very few adjustments
and these should not be performed unless there is
strong reason to believe they are required. All elec-
trical adjustments are preset at the factory and should
not require readjustment except after long periods of
use.
4.2 PREVENTIVE MAINTENANCE
To assure continuing trouble-free operation a pre-
ventive maintenance schedule should be kept. The
items involved are few and simple but very impor-
tant to proper tape transport operation. The fre-
quency of performance will vary somewhat with the
environment and degree of use of the transport so a
rigid schedule applying to all machines is difficult to
define. The periods recommended below apply to
units in constant operation in ordinary environments.
They should be modified if experience shows other
periods are more suitable.
4.2.1 DAILY CHECK
Visually check the machine for cleanliness and ob-
vious misadjustment. If items in the tape path show
evidence of dirt or oxide accumulation, clean thor-
oughly.
4.2.2 CLEANING
All items in the tape path must be kept scrupulously
clean. This is particularly true of the head •. When
cleaning heads, it is important to be thorough yet
gentle and to avoid certain dangerous practices.
4.2.2.1 Head Cleaning
Oxide or dirt accumulations on the head surfaces are
removed using a mild organic solvent and a swab.
Q tips are convenient for this use but must be used
with caution. Be sure the wooden portion does not
contact head surfaces.
4-1
An ideal solvent is 1.1.1 trichlorothane contained in
the Kennedy K21 maintenance kit. However, others
such as isopropyl alcohol will do.
DO NOT USE - acetone or lacquer thinner
- aerosol spray cans
- rubbing alcohol
Do not use an excess of any solvent, and be extremely
careful not to allow solvent to penetrate the ball
bearings of the capstan motor, since it will destroy
their lubrication.
4.2.2.2 Other Cleaning
Use a vacuum cleaner to remove accumulations of
dust inside the dust cover or elsewhere in the unit.
Compressed air may be used if caution is exercised
to avoid blowing dirt into bearings.
4.3 ROUTINE ADJUSTMENT
There are no routine adjustments. Need for adjust-
ment becomes manifest when malfunction occurs.
Under normal circumstances adjustment will be more
likely to cause trouble than to prevent it.
4.4 LUBRICATION
No bearing lubrication is required. All bearings are
lubricated for life and introduction of oil may destroy
their lubrication.
4.5 HEAD WEAR
Head wear is generally signaled by an increase in
error rate. Confirmation is a sizable increase in
output voltage from the read head as measured at the
read preamplifier. When the head becomes worn it
must be replaced. Head replacement is described in
paragraph 4. 9. 5.
Worn heads usually can be resurfaced at least once
if returned to the factory. This is more economical
than replacement with a new head. Consult Section V
for details of head return.
4.6 PERIODIC INSPECTION
Every two months, it is advisable to make a more

UNKNOWN MACHINE
(PARTS ASSUMED GOOD)
POWER ON
CHECK SUPPLIES
(See 338/339
Power Supply Manual)
PHOTOSENSOR CHECK
Paragraph 4.7.1
I,
TAPE SPEED
ADJUSTMENT
Paragraph 4. 7•2
'r
READ LEVEL
ADJUSTMENT
Paragraph 4. 7. 4
RAMP TIME CHECK
Paragraph 4.7.3
Table 4-7. Adjustment Sequence
4-2
406-0331-200

thorough check of machine operating parameters to
insure that no progressive degradation goes un-
noticed. The recommended sequence for checks and
adjustments is shown in Table 4-1.
4.7 CHECKS AND ADJUSTMENTS
4.7.1 PHOTOSENSOR CHECK
Characteristics of the A and B photo sensors vary· a~
pending on age and usage. The photosensors are
checked as follows:
Test Procedure
1. Disconnect capstan motor.
2. Connect voltmeter to test point X of the Trans-
port Electronics board.
3. Insert a tape cartridge.
4. Turn capstan by hand until the small A hole is
opposite the A photosensor. Voltage change at
test point A should measure +3 volts minimum.
5. Reconnect voltmeter to test pointY on Transport
Electronics board.
6. Turn capstan by hand to double set of large holes.
Voltage change at test point B should measure
+6 volts minimum.
7. Remove tape cartridge, disconnect voltmeter,
and reconnect capstan motor.
4.7.2 TAPE SPEED ADJUSTMENT
Procedure No.1 (Use with machines containing read
after write heads)
1. Connect channel 1 probe of a dual trace oscillo-
scope to the input write data. Aconvenient loca-
tion would be P9-1 of the Write Head Driver
board. Trigger scope on channel 1 and select
2 ms/ cm time constant.
2. Connect channel 2 probe to test point B and write
on channel 1.
3. Write short blocks, one to ten characters long.
4. Adjust potentiometer R66 on the Transport Elec-
tronics board so that the delay between the leading
edge of the read data block is 12 ms at 25 ips.
For machines operating at other tape speeds the
406-0331-300
formula for deriving the proper delay time is
0.3 d I .
--;- = e ay In ms
where s = tape speed in inches per second.
Procedure No.2 (Usewithmachines containing com-
bination read/write heads)
Special equipment required: Speed Adjustment Tape
Cartridge, Kennedy Part No. 198-0045-001.
1. Connect oscilloscope probe to test point B. Se-
lect read operation.
2. Select a 2 ms/ cm time constant on the oscillo-
scope.
3. Adjust R66 on the Transport Electronics board
for a 10 ms read pattern which is 44 ANSI com-
patible characters long.
4.7.3 RAMP TIME CHECK
Tape is brought up to speed at constant acceleration.
To control tape velocity, a ramp voltage is generated
by the transport electronics which rises linearly to
the required running speed and falls linearly to zero
volts at stop. Ramp time is 30 ms (+0 -5 ms) at
25 ips and varies inversely with speed.
ov
I
---I
T
110-0103
where
1
I
I
I I
I I
I I
~START~I
• RAMP
T=ls1i...MSEC
S
ramp time in milliseconds
T
T
S
tape speed in inches per second
To Check Ramp Time
1.; Establish rapid start/stop motion.
14-- STOP
RAMP
2. Observe waveforms at test point Aon the Trans-
port Electronics board. Synchronize on RUN
command. Be sure time is long enough to pro-
duce a flat area between ramps.

3. If ramp times vary significantly from specifica-
tions, the ramps should be adjusted by changing
the value of R63. A higher value of R63 results
in a faster ramp time.
4.7.4 READ DATA LEVEL ADJUSTMENT
1. Connect oscilloscope probe to test point B on the
Transport Elect~onics board.
2. Write short 0-1 binary pattern data blocks- on
track 1.
3. While reading track 1, adjust potentiometerR25
. on the Transport Electronics board for 15 volts
p-p output as measured at test point B of the Read
Amplifier board.
4.7.5 INTERLOCK SWITCH CHECK AND
ADJUSTMENT
If READY signal does not go true when the cartridge
is inserted:
1. Remove Transport Electronics board (four nuts).
2. Insert tape cartridge until it begins to engage
with the latching mechanism. Contacts on both
interlock switches should begin to open.
3. Press cartridge inward until it locks in place.
Switch ,contacts should close completely. (This
can be checked by gently pressing the switch
contact toward the switch body. Aily movement
indicates contact is not completely closed.)
Adjustment
If contact will not close completely, loosen switch
mounting screw and readjust switch position for com-
plete contact closure.
4.8 TROUBLESHOOTING
Troubles that can arise in the Model 331 can usually
be classified as either mechanical or electrical. How-'
ever, the classification may often become confusing
because a basically mechanical problem can cause
what appears to be an electronic malfunction and vice
versa. In any case the problem should be thoroughly
analyzed before adjustments are changed.
Electronic troubleshooting is greatly facilitated by
the modular construction - a new card may be sub-
stituted and the effect observed.
~4
406-0331-400
4.8.1· COMPATIBILITY
Model 331
accepts and produces tapes conforming to
the ANSI standards. OccaSionally compatibility prob-
lems can arise. For example:
a. Cartridges written by and acceptable to the
331 are not acceptable to another transport.
b. Foreign cartridges cannot be read by the 331
but its own tapes can.
Tape speed and ramp times are important factors in
tape compatibility. These should be checked as de-
scribed under paragraph 4. 7, Checks and Adjust-
ments.
4.8.2 OTHER MALFUNCTIONS
Normal troubleshooting procedures should be used
to locate and isolate electronic malfunctions. The
first items to check are the power supply voltages
on the Transport Electronics board.
IMPORTANT
Power should be off before remov-
ing or inserting circuit boards.
Assuming the power supply voltages are correct,
Table 4-3 or 4-4 should help to isolate the malfunction.
4.9 PARTS REPLACEMENT
Removal and replacement of most items in the Model
331
are obvious. Certain items, such as the photo-
sensor assembly, require adjustment after installa-
tion. Adjustments and any precautions which should
be exercised are described in the following removal
and installation procedures.
4.9.1 PHOTOSENSOR ASSEMBLY REPLACEMENT
Removal
1. Remove sensor cover (two screws).
2. Detach sensor's molex connector. (Carefully
pry it from its rec'eptacle with a small screw-
driver. Rocking connector back and forth can
ruin the contacts.)
3. Remove two 3/32 inch Allen screws and detach
photosensor assembly from chassis.
Installation

TABLE 4-2
·High Error Rate-clean machine, good cartridge
I
Symptom
I
I Continuous
errors,
every block
(read mode)
:
:
Continuous errors, write
mode only
I
:TABLE 4-3
: iControl M alfun ctions
: Capstan rotates. uncontrolled
when power is on
Cartridge won't release during
I ejection (solenoid clicks)
TABLE 4-4
Loading Errors
Cartridge fails to eject
during unloading
Tape will not move
Possible Cause
Broken connection to interface or
internally
. ,
Bad preamplifier channel
Tape speed wrong
Bad head channel
Broken connection on write data
Bad write amplifier channel
Defective transport elec-
tronics
Defective cartridge casing
sticks in loading tracks
Bad solenoid driver and/or
Shorted eject solenoid
Defective Transport Elec-
tronics board
Indication
Continuity broken
No output at test point on
write test
Tape speed check
No data from preamplifier
Continuity broken
Wrong or no signal at read
amplifier test point in write
test mode
Same as symptom
Same as symptom
Same as symptom
Same as symptom.
Same as symptom
Action
Correct connection
Replace transport
electronics board
Adjust tape speed
Replace head
Correct connection
Replace write head
driver'board
Replace transport
electronics board
Replace cartridge
Substitute new Trans-
port Electronics
board
Check eject solenoid
Substitute new Trans-
port Electronics
board
Ref.
. ,
4.7.4
4.9.5
2.2.2d
4.9.2
~
o
en
I
o
C...:J
C...:J
1-1
I
c.n
o
o

Reverse removal sequence.
NOTE
Check for 1/32 inch. clearance
between photosensor and a loaded
tape cartridge. Carefully adjust
replacement photosensor to achieve
this clearance.
4.9.2 EJECT SOLENOID REPLACEMENT
If the Model 331 has been damaged by a current
overload and the eject solenoid will not actuate, it
probably requires replacement. It should be tested
for shorts and replaced if it is defective.
Removal
1. Remove the Transport Electronics board (four
nuts).
2. Remove press nut A shown in Figure 4-1.
3. Disconnect spring B shown in Figure 4-1.
4. Lift eject solenoid assembly off its mounti.ng
post, then slide solenoid armature off the sole-
noid shaft.
5. Detach solenoid case from the spring arm.
110-0115A
Figure 4-1. Eject Solenoid Replacement
4-6
406-0331-600
Do not change the setting of the
solenoid adjustment arm.
Replacement
Reverse removal procedure. Aft~r replacement,
make certain interlock switches function properly.
(See paragraph 4.7.5 for test procedure.)
4.9.3 BEVEL GEAR REPLACEMENT
1. Remove Transport Electronics board (four
nuts.)
2. Using a 3/32 inch Allen wrench, detach capstan
shaft mounting assembly from chassis. (This
Allen
screw is located on top of the transport
deck. )
3. Loosen capstan bevel setscrew and slip bevel
gear off the capstan shaft.
4. Motor shaft bevel gear can also be easily re-
moved at this time. Simply loosen its setscrew
and slip the bevel gear off the motor shaft.
4.9.4 FILE PROTECT / INTERLOCK ASSEMBLY
REPLACEMENT
1. Unsolder connecting wires from the assembly.
Note wire colors to facilitate reconnection.
2.. Using a No.1 Phillips screwdriver, remove the
twomounting screws and detach entire assembly
from chassis. It is replaceable as an assembly.
Installation
Reverse removal procedure.
NOTE
After installation, check for 1/32
inch clearance between file protect
switch contacts and an inserted tape
cartridge. Adjust file protect assembly
to obtain this clearance as required.
4.9.5 MAGNETIC HEAD REPLACEMENT
1. Disconnect magnetic head's molex connectors.
2. Detach magnetic head assembly from chaSSis
by removing 3/32 inch Allen mounting screws.

NOTE
Since the heads are factory aligned on
their mounting plates, these components
should be replaced as a unit.
Installation
Reverse removal procedure.
4.9.6 CAPSTAN MOTOR REPLACEMENT
1. Disconnect capstan motor's molex connector.
2. Detach Transport Electronics board (four nuts).
3. Detach front and side panel. (Note screw lengths
to facilitate replacement.)
4. From top of transport, remove 3/32 inch Allen
screw fastening capstan shaft mounting assembly
to chassis. Capstan shaft can now be moved,
permitting access to capstan motor screws.
5. Remove capstan motor mounting screws and lift
motor out of chassis.
Installation
Reverse removal procedure.
NOTE
The motor shaft bevel gear must be per-
fectly centered with respect to the cap-
406-0331-700
stan bevel gear before the capstan motor
mounting screws are tightened. Figure
4-2 illustrates bevel gear centering.
Bevel Centering
1. Replace the capstan shaft mounting bl.ock. Mount
the capstan motor in pOSition but leave the mount-
ing screws loose.
2. From the front of the machine, sight down both
edges of the capstan shaft mounting block, lining
them up with the edges of the capstan shaft. (See
Figure 4-2.) Note the amount of motor shaft
bevel gear visible from both sighting positions.
3. Adjust motor position until the same amount of
motor shaft bevel is visible from both sighting
positions. (See Figure 4-2.) Then tighten the
capstan motor mounting screws.
4.10 MAINTENANCE TOOLS
In addition to normal electronic tools and test gear
(oscilloscope, voltohmmeter, etc.) the following
items should be available for service and repair:
Set of nut drivers or open end wrenches,
Phillips and standard slot-head screwdrivers,
Maintenance Kit, Kennedy PN 198-2324-001:
Head cleaner
Hex socket keys 7/64", 5/32", 1/8", 3/32"
Lint-free swabs
CAPSTAN SHAFT
". ) NOTE: Model 331
is in upside
down position.
CAPSTAN SHAft MOUNTING BLOCK
110-0118
Figure 4-2. Motor Shaft Bevel Centering
4-7