Table of Contents
Advertisement
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 point Y 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.
A convenient 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.
Advertisement
Table of Contents
