Servo Circuit - LG TL-AT130M Service Manual

ELECTRICAL TROUBLESHOOTING GUIDE

2. SERVO CIRCUIT

(1) Video is unstable in PB mode
In PB mode
Does noise level on the screen
change periodically?
YES
Does CTL pulse appear at
IC501 Pin 76?
YES
Does CTL pulse move on tracking?
YES
Does Video Envelope wave form
appear at IC501 pin 86?
YES
Replace IC501.
(2) Drum motor stops
When the drum moter stop
Is there 12V at PMC01 Pin8?
YES
Is there 2.8V at PMC01 Pin12?
YES
Check the Ass's between
connector(PMC01) and Drum motor
SECTION3 ELECTRICAL
NO Is adjusting height of CTL
head accurate?
NO
Replace IC501.
NO
Check the Pre-Amp circuit
NO
Check Power circuit
NO
Does Drum PWM pulse
appear at IC501 Pin34?
YES
Aren't pattern or componets between
IC501 Pin34 and PMC01 Pin12 short?
Does DFG pulse appear at
IC501 Pin65?
YES
Does Drum PWM pulse appear
at IC501 Pin34?
YES
Aren't pattern or componets between
IC501 Pin34 and PMC01 Pin12 short?
NO
Readjust the height
of CTL fead.
NO
Does DFG pulse appear at
PMC01 Pin3?
NO
YES
Check the Ass'y between
junction PCB and Drum motor
Aren't pattern or componets between
NO
IC501 Pin34 and PMC12 Pin1 short?
NO
Replace IC501
3-4