LG LAS855M Service Manual page 24

12. IF NOT BOOTING WHEN YOU TURN ON THE SET.
12-1. IC503, IC504 (DDR IC)
12-1-1. Solution
Replace IC503, IC504 on MAIN board. (This chip is so hard to change IC, so we recommend to change PCB.)
12-1-2. How to troubleshoot (Countermeasure)
1) Check 0.75 V of C592. If voltage is abnormal follow the stage 7-1 (IC300).
2) Check 1.5 V of C5A5.
3) If 1.5 V and 0.75 V are abnormal, check the around parts (C5A5, C5A6, R555, R556).
4) If there's no defective component, follow the stage 7-1 (IC300).
5) When you followed above step but it doesn't work, replace the IC503, IC504.
12-1-3. Service hint (Any picture / Remark)
ONE POINT REPAIR GUIDE
IC504 IC504
IC503 IC503
< MAIN board top view >
2-13
C592 C592