LG CM 9520 Series Service Manual page 51

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 servo motors in MD don't work. This step is for checking the
TRAY MOTOR among them.
5-3. TURRET MOTOR
5-3-1. Solution
Please check and replace IC406, IC407 on MAIN board.
5-3-2. How to troubleshoot (Countermeasure)
1) Check TUR+ & TUR- signals from Pin60 & 61 of IC501 to IC406.
If no signal, check +5 V to IC406.
2) Check TUR_M+ & TUR_M- from IC406 to CN405 for driving turret motor. It is about 3.8 Vp-p.
If no signal, check +5 V to IC406. If it has any trouble, replace it with a new one.
3) Check if the FFC cable is solidly connected between CN405 and MD.
4) Check the MD.
If the tray motor is sort-circuit or has any trouble, it can not rotate the tray.
Please check the function after changing another MD.
5-3-3. Service hint (Any picture / Remark)
< Waveform of TUR_M±
for driving TRAY motor >
ONE POINT REPAIR GUIDE
3-22
< Signal check point >