Electrical Troubleshooting Guide; Power Supply On Smps Board - LG CM9750 Service Manual

ELECTRICAL TROUBLESHOOTING GUIDE

1. POWER SUPPLY ON SMPS BOARD

No output 5.6 VA
Is the F901 normal?
YES
Is BD901 or BD902 normal?
YES
Is the VCC
(11 V ~ 25 V) supplied to IC901
pin4?
YES
Power line of MAIN PCB is short.
No 12 V
Is the
VCC 13 VA supplied to IC951
pin2?
YES
Is there
'H' signal at IC951
pin1?
YES
Check and replace IC951.
Or check line of PCB is short or not.
MAIN
NO
Replace F901 (same fuse).
NO
Replace BD901 or BD902.
NO
Is D960/ D961 normal?
Check or replace D960/ D961.
NO
Check or replace D962.
NO
Check P_CTL from μ-com.
3-25