FLOW CHART NO.15 DRUM SERVO TROUBLESHOOTING
Drum servo does not function.
Check peripheral circuit of X801.
Is there 8.00MHz oscillation at
pins(62) and (63) of IC801?
NO
In PB mode
YES
In REC mode
Is there drum FG signal at pin(12)
of IC801 present?
Is the C-SYNC signal (reference)
at pin(78) of IC801?
YES
NO
NO
Check COMPOSIT-SYNC signal line.
Check drum FG signal line.
Is the head switching pulse at pin
(38) of IC801 present?
NO
See FLOW CHART NO.14 HEAD
SWITCHING PULSE TROUBLE
SHOOTING.
YES
YES
Is the drum error output at pin(44)
of IC801 present.
NO
Replace IC801.
YES
YES
Is th drum control voltage applied to
pin(7) of AD connector?
NO
YES
YES
Does the drum error filter circuit
(R843, R836, C821) operation
normally?
Replace drum motor.
NO
NO
Replace IC801.
Check harness between AD and AO.
Is pin(46) of IC801 in high
impedance?
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