LG RAT376B Service Manual page 27

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 OPEN / CLOSE MOTOR among them.
4-3. TRAY OPEN / CLOSE MOTOR
4-3-1. Solution
Please check and replace IC301, IC302 on MAIN board.
4-3-2. How to troubleshoot (Countermeasure)
1) Check MOT_OPEN & MOT_CLOSE signals from Pin104, 105 of IC801 to IC301.
If no signal, check +1.8 V & + 5 V to IC301.
2) Check LOAD± from IC301 to CN303 for driving the tray open / close motor. It is about 3.85 Vp-p.
If no signal, check +5 V to IC301. If it has any trouble, replace it with a new one.
3) Check if the FFC cable is solidly connected between CN303 and MD.
4) Check the MD.
If the tray motor is sort-circuit or has any trouble, it can not open or close the tray.
Please check the function after changing another MD.
4-3-3. Service hint (Any picture / Remark)
< Waveform
for driving TRAY open / close motor >
ONE POINT REPAIR GUIDE
< Signal check point >
3-8