LG BH4120SN Service Manual page 45

2. NO BOOTING WHEN YOU TURN THE UNIT ON, NO MESSAGE OR
"PLEASE WAIT" ON FRONT PANEL
When you turn on your set, it will blank / no message or "PLEASE WAIT" display on front panel, and
it will not boot-up.
2-8. IC501 (MPEG IC)
2-8-1. Solution
Replace IC501 on MAIN board.
2-8-2. How to troubleshoot (Countermeasure)
1) Please check 1.2 V.
Please check 3.3 V.
Please check 1.5 V.
Please check RESET# (IC101 pin73).
2) If it doesn't work even though 1.2 V / 1.5 V / 3.3 V power and RESET# are no problem, IC501 MT8560
could have problem.
3) If RESET# isn't high, you may need to replace IC101.
4) After changing it, if the set is still no booting, check MAIN board refer to item 2-9.
2-8-3. Service hint (Any picture / Remark)
IC501
IC504
IC503
< MAIN board bottom view >
ONE POINT REPAIR GUIDE
IC502
2-36
IC101
R153 RESET#
< MAIN board top view >