-38-
2. SERVO CIRCUIT
(1) Unstable Video in PB MODE
Unstable Video in
PB Mode.
Does the Noise level of the
screen change
periodically?
Do the CTL pulses appear
at the IC501 Pin 89?
Is adjusting the height of
the CTL Head accurate?
Readjust the height of the
CTL Head.
Replace the IC501.
Refer to “When the Y signal
doesn’t appear on the
screen in PB Mode”.
Does the CFG waveform
appear at the IC501
Pin 93?
On tracking do the CTL
pulses move?
Does the Video Envelope
waveform appear at the
IC501 Pin 82?
Replace the IC501.
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
(2) When the Drum Motor
(2)
doesn’t run.
Do the DFG Pulses appear
at the IC502 Pin 8?
Check the IC502 and
the Drum Motor Ass’y.
Aren’t the foil patterns and
the Components between
IC501 Pin 97 and IC502
Pin 8 short?
Replace the IC501.
Check Power. Refer to “(3)
No 12VA of Power section”
Do the Drum PWM Pulses
appear at the IC501
Pin 9?
Aren’t the foil patterns and
the Components between
IC501 Pin 9 and PMD01
Pin 1, 2 short?
Do the DFG Pulses appear
at the IC501 Pin 97?
Do the Drum PWM Pulses
appear at the IC501
Pin 9?
Aren’t the connecting patterns and the Components
between IC501 Pin 9 and PMD01 Pin 1, 2 short?
When the Drum Motor
doesn’t run,
Does 12VA appear at the
IC502 Pin 21?
Does PG+, PG- appear at
the PMD01 Pin 1, 2?
Check the connector
(PMD01) and the Drum
Motor Ass’y.
NO
YES
NO
NO
NO
NO
NO
YES
ELECTRICAL TROUBLESHOOTING -4/13