JVC KD-A66 - Repair and Electrical Adjustment Location; Troubleshooting Wow;Flutter Issues; Electrical Adjustment Location - Main Amp P.W. Board

KD-A66A/B/C/E/J/U
[It] 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 300 Hz test tape, and defective part can be detected
from the sound.
[section [woe —SSC*~dSC“‘“‘CSO™SCS™C*~#w w=SCSCS~*S
Capstan | Capstan shaft has excessive run-out. Replace flywheel.
Flywheel! turns heavily. Clean the capstan shaft and the groove in the flywheel.
(shaft seisure, thrust play, etc.) Apply oil to the metal position.
Replace the capstan assembly.
Pinch
roller
Replace pinch roller, or pinch roller spring.
Clean the pinch roljer or apply oil to the rotary shaft.
Adjust the pinch roller so that it is parallel with 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 Back tension is irregular, or back tension is too Replace back tension spring (under supply disc).
tension | strong.
Motor Motor shaft has undue run-out. Replace the motor.
Motor pulley is oily and dusty. Clean the motor pulley.
[IV] Electrical adjustment location
Main Amp P.W. Board
Rough rotation (Deformation scratches, or dust)
The angular position of the pinch roller is not
correct.
The pinch roller pressure is not correct.
VRIOS
( —;—L—For VU meter deflection adjustment
_ | eturning in the direction of the arrow
C+ increases the deflection angles)
VR205
| For playback level adjustment
(Turning in the direction of the arrow
vRio2 increases the playback levels)
R
(
(CJvreo2 Ceo!
oe t
VR40l
For playback frequency response
adjustment.
(Turning in the direction of the arrow
For
bias
current
adjustment
increases
in
the
signal
current)
(Turning in the direction of the arrow
increases the bias current value}
Front ¢
a45=