3-8
Copyright © 2018 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
ONE POINT REPAIR GUIDE
NO BOOTING (IN CD/USB FUNCTION)
After you turn on power key and displayed message in the following order (HELLO
VOL XX
CD or USB) on VFD, it will not display other message on VFD, and it will not boot-up normally.
4-3. SERIAL FLASH (IC503)
4-3-1. Solution
Please check and replace IC503 on MAIN board.
4-3-2. How to troubleshoot (Countermeasure)
1) If the crystal (X500) does oscillate, check serial flash (IC503) on MAIN board.
Check pin8 (VCC), pin6 (CLK), pin1 (CS), pin2 (DO), pin5 (DI) of below waveform.
2) If pin1, 2, 5, 6 doesn’t come out, check registers (R5B72 ~ 5) of IC503.
If registers of IC503 is OK, then replace IC503. (it need to download program.)
3) After change IC503, if It is still not below waveform, check IC501 (DSP IC).
4-3-3. Service hint (Any picture/ Remark)
VCC
CLK
DO
CS#
< Signal waveform >
< MAIN board bottom view >
IC503
IC503