TM 32-5835-005-14 & P
8-13. Tape Motion.
8-11. Capstan Motor.
a. Load cassette into unit and place
a. Place unit in REPRO at 15/16 IPS;
unit into a reproduce mode.
capstan motor should run and have 4.2VDC
across its terminals.
b. Observe the tape motion between
erase head and capstan and also record
b. Place unit in REPRO at 1-7/8 IPS;
play head and capstan. Tape should ride
capstan motor should run and have 7.7VDC
smoothly without skewing.
across its terminals.
c. If skewing is observed, replace
c. Any fault here should be corrected
rubber rollers.
by replacement of motor control board
A1A5. Replacement of A1A5 entails re-
d. Other possible causes are: loose
adjustment for proper motor speeds and
head, loose tape guide, cassette holder
monotone volume.
is not properly secured, defective
cassette or cassette not properly seated.
d. If board replacement does not
correct fault, replace A1V1 capstan
e. Place unit into FAST FWD and then
tach photo transistor.
REWIND. Both tape reels should turn.
Failure of this test will result in
e. Replacement of motor is advised if
damaged tape. Probable defects are
both c and d fail to correct problem.
jammed reel bearings, loose drive belts,
Refer to para. 8-25.
broken cassette spindle collars or bad
motor.
f. Do not overlook mechanical faults
in the transport such as stuck or jammed
f. Any rattling or howling when in
bearings, oil film on drive belt and
REWIND or FAST FWD, would indicate
loose shafts.
bearing problems. Replacement is in-
dicated.
8-12. Bias Oscillator.
8-14. Reproduce Amplifiers.
a. Place unit in RECORD either speed.
a. Board substitution should solve
b. Check signal on bias oscillator
most defects. In the event this does
board A1A4 at TP-3 and TP-4. A signal
not correct faults, test head continuity.
of approximately 50 KHz and 4.0VRMS is
nominal at these points.
b. If RCVR input will not effect a
proper record, check microphone jack
c. If these readings are not obtained,
or cabling for a short.
defects are in the heads or the bias
Check for open coils L1
c. If noise but no signal is present
and L2. A short in the cabling will
on board, probable defects are: Head
also load down the oscillator.
defective, no continuity from head to
input of amplifier, relay K1 on A1A8
d. Replacement at the record\repro-
defective and relay K1 on A1A3 defec-
duce head requires resetting the bias
tive.
oscillator to 4.0 VRMS at TP-3 and TP-4
on A1A4.
8-6
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