LG OK75 - Troubleshooting: No MD Operation (Laser Focusing)

3-13
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Only for training and service purposes.
< MAIN board bottom view >
IC400
IC400
IC401
IC401
ONE POINT REPAIR GUIDE
NO OPERATION OF MD
When no sound output in the CD function, you can not listen to music reading data from a CD
disc if the pickup module in MD doesn’t work. This step is for checking the LASER FOCUSING
ACTUATOR.
5-5. LASER FOCUSING ACTUATOR
5-5-1. Solution
Replace IC400 on MAIN board.
5-5-2. How to troubleshoot (Countermeasure)
The focusing actuator makes the laser beam keep a regular interval with the surface of a CD disc.
1) Check the FDO signal from pin13 of IC401.
 If no signal, check DVCC_3.3 and X400.
2) Check F- & F+ from IC400 to CN400 for driving the focusing actuator.
 If no signal, check M_5V for IC400.
3) Check if the FFC cable is solidly connected between CN400 and MD.
4) Check the MD.
 If the pickup module has any trouble, it can not move the laser beam on the top or bottom side.
Please check the function after changing another MD.
5-5-3. Service hint (Any picture/ Remark)
< Waveform of F±
for driving focusing actuator >
F+: pin14
F+: pin14
F-: pin13
F-: pin13