LG MDT505 - Electrical Troubleshooting Guide; SMPS Board Troubleshooting

3-2
ELECTRICAL TROUBLESHOOTING GUIDE
1. SMPS BOARD
YES
YES
YES
YES
YES
No power.
Replace SMPS board.
Connect the open line.
Replace F901.
Check SMPS second part lines short.
Check 3.7 V lines short.
Replace PC951, PC972, IC901.
Check BD901 “+”
to “
- ” Pin impedance .
Check MAIN or AMP board short.
Replace PC972, IC902’s components.
Check around IC901’s components
(Short, Open).
Low impedance:
Replace IC901, BD901.
NO
NO
NO
NO
NO
Check the AC
line pattern.
Check fuse F901.
Check C963
voltage (5.6 V).
Check C978
voltage (3.9 V).
Check IC901
Vcc voltage (10 V ~ 30 V).