LG CJ87 Service Manual page 37

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.
3-4. SDRAM (IC504)
3-4-1. Solution
Please check and replace IC504 on MAIN board.
3-4-2. How to troubleshoot (Countermeasure)
1) Check below waveform & soldering status of SDRAM(IC504) on MAIN board.
  If pin17(#CAS), pin18(#RAS), pin19(#CS), pin38(CLK), pin29(address), pin2(DQ) doesn't come out,
check damping resistor(R565, R567, R569, R563).
2) If resistor is OK, then replace IC502(SDRAM).
3) After change IC504, if It is still not below waveform, check IC501(DSP IC).
3-4-3. Service hint (Any picture/ Remark)
IC504 IC504
< MAIN board bottom view >
ONE POINT REPAIR GUIDE
V V CC
Reset
Address
Da ta
/ / CS
R AS
/ W E
C AS
< Signal waveform >
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