JVC KD-A77 A User Manual

KD-A77 A/B/C/E/J/U
Item Adjustment
Adjusting Standard
Remarks
point value
Adjusting Connect a speed meter to the LINE Semi-
3000Hz
If the speed meter functions as a wow
motor speed
OUT
terminals. Play back the fixed
and flutter meter, also, connect the
VTT-656 test tape.
resistor deck to the INPUT terminals of the
Adjust the semi-fixed resistor on the on the meter.
motor P.W. board until the reading of motor
the speed meter
is
3000Hz. P.w.
board
Checking play-
Employ
a
torque testing
cassette
40-70 If the standard torque is not obtained,
back torque tape for the checking, or remove the
gr-cm
replace the take-up disc assembly.
cassette cover
and
use
a
torque
gauge.
Checking fast
Measure the torque in the fast for- More If the standard torque is not obtained,
forward torque
ward mode in the same manner as in than perform the following.
the above. 70 gr-cm 1 . Clean the capstan belt, the idler cir-
cumference, the motor pulley, the
take-up reel disc circumference,
the flywheel circumference, etc.
2. Replace the belt and idler.
Checking re-
Measure
the torque in the rewind More If the standard torque is not obtained,
wind torque mode in the same manner as in the than clean the capstan belt, idler, motor
above. 70 gr-cm pulley, flywheel circumference, rewin-
ding idler circumference, left reel disc
circumference, etc.
Checking wow
Connect a wow and flutter meter to
If the reading becomes moving value
and flutter
the LINE OUT terminals.
even
if conforming to the standard, a
Play
back the VTT-656 test tape. re-claim may be raised. Repairs are
Check to see if the reading of the
necessary.
meter is within 0.04% (WRMS).
[Ill] Repair of wow flutter
If wow and flutter increase, check the following points.
If there is defect in revolving parts, the wow and flutter
generated will increase in proportion to the number of
revolutions.
Play a 3000Hz test tape, and defective part can be
detected from the sound.
Section Trouble
Repair
Capstan and
flywheel
Capstan shaft has excessive run-out Replace flywheel.
Flywheel turns heavily. Clean the capstan shaft and the groove in the
(shaft seisure,
thrust
play, etc.) flywheel.
Apply oil to the metal position.
Replace the capstan assembly.
Pinch roller
Rough
rotation (Deformation scrat-
Replace pinch roller, or pinch roller spring.
ches, or dust)
Clean
the pinch roller or apply oil to the rotary
The angular position of the pinch roller shaft.
is
not correct. Adjust the pinch roller so that it is parallel with
The pinch roller pressure is not correct. the capstan shaft.
Replace
the pinch roller spring.
Belt
Belt has undue run-out. Clean
the belt.
Belt is dirty or slippery. Replace the belt.
Back tension
Back tension
is irregular, or back ten- Replace back tension spring (under supply disc).
sion is too strong.
Motor
Motor shaft has undue run-out. Replace motor.
Motor pulley is oily and dusty. Clean motor pulley.
Damping gear oil
Oil employed - Torque grease specified by JVC (KANTO KASEI GP-608)
Applying method - Apply in both concaved sections as shown in the figure.
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JVC KD-A77 A Specifications

General

Brand	JVC
Model	KD-A77 A
Category	Cassette Player
Language	English