Audio Electrical Troubleshooting Guide; Power (Smps) - LG CM4330 Service Manual

AUDIO ELECTRICAL TROUBLESHOOTIHG GUIDE

1. POWER (SMPS)

No 3.7 VA
F901 normal?
BD901 normal?
TH901 normal?
Is Vcc
(10 V ~ 18 V) supplied to
IC901 Pin7?
D922 normal?
Is there
about 2.5 V at
IC903 Pin1?
D923 normal?
D921 normal?
D924 normal?
D925 normal?
Power line of Main PCB is short.
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
NO
Replace F901 (Use the same fuse).
NO
NO
NO
Check or replace D904.
NO
NO
NO
NO
NO
NO
3-16
Replace BD901.
Replace TH901.
D904 normal?
NO
Replace D922.
Replace IC903.
Replace D923.
Replace D921.
Replace D924.
Replace D925.