JVC CD-1770 - Trouble Shooting Guide; Electrical Circuit Issues; Mechanism Section Issues

Trouble Shooting Guide
[ELECTRICAL CIRCUIT]
1. Playback tone quality is poor.
1, Check the record/playback head for dust.
2. Check the record/playback head for wear.
If worn excessively, the loss of treble response will
result.
3. Check wiring for a short-circuit.
Check each transistor for condition.
2. Recording tone quality is poor.
The playback tone quality of a recorded tape such as the
audition tape is good, but the recording by this unit
produces poor tone quality. !n this case, the unit should
be checked in the following manner.
1. By monitoring a music while recording, check the
tone quality.
Capstan and
flywheel
Pinch roller
Flywheel turns heavily.
Rough rotation (Deformation
scratches, or dust).
The angular position of the pinch
roller is not correct.
Back tension is irregular, or back
tension is too strong.
CD-1770/A/B/C/E
No. 4144
a
Capstan shaft has excessive run-out.
(shaft seisure, thrust play, etc.)
The pinch roller pressure is not correct.
Belt Belt has undue run-out. Clean the belt or remove the distortion.
Belt is dirty or slippery. Replace the belt.
Motor Motor shaft has undue run-out. Replace motor.
Motor pulley is oily and dusty. Clean motor pulley.
Take-up idler arm Pulley has deflection.
Pulley is stuck.
2. If found poor, check the wiring of the recording
system for a broken wire and short-circuit.
3. If no irregularity is found, check the recording bias
current. Also check the oscillation circuit.
3. For other failures, check the unit in the same manner as
other amplifiers.
[MECHANISM SECTION] (wow and 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.
Replace flywheel.
Clean the capstan shaft and the groove in the
flywheel.
Apply oil to the metal position.
Replace the capstan assembly.
Replace pinch roller, or pinch roller spring.
Clean the pinch roller or apply oi! to the rotary
shaft.
Adjust the pinch roller so that it is parallel with
the capstan shaft.
Adjust the pinch roller spring.
Replace supply disc, or felt.
Replace back tension spring (under supply disc),
or apply silicon grease.
Replace take-up idler arm.