Audio Electrical Troubleshooting Guide; Power (Smps) - LG CM4740 Service Manual

AUDIO ELECTRICAL TROUBLESHOOTIHG GUIDE

1. POWER (SMPS)

No 5.6 VA
F901 normal?
BD901 normal?
TH901(TH903) normal?
Is Vcc
(10 V ~ 18 V) supplied to
IC901 Pin7?
D933 / D934 normal?
Is there
about 2.5 V at
IC941 Pin1?
D935 normal?
D932 normal?
D931 normal?
Power line of main PCB is short.
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
NO
Replace F901 (Use the same fuse).
NO
NO
NO
Check or replace D902.
NO
Replace D933 / D934.
NO
NO
NO
NO
3-17
Replace BD901.
Replace TH901.
D902 normal?
NO
Replace IC941.
Replace D935.
Replace D932.
Replace D931.