LG RAT376B Service Manual page 28

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 TRACKING ACTUATOR.
4-4. LASER TRACKING ACTUATOR
4-4-1. Solution
Please check and replace IC301, IC302 on MAIN board.
4-4-2. How to troubleshoot (Countermeasure)
The tracking actuator makes the laser beam be positioned in the center of a track on CD disc.
1) Check the TRD signal from Pin14 of IC302.
If no signal, check 3.3 V(RF) and X301.
2) Check TR- & TR+ from IC301 to CN301 for driving the tracking actuator.
If no signal, check +1.8 V and +5 V for IC301.
3) Check if the FFC cable is solidly connected between CN301 and MD.
4) Check the MD.
If the pickup module has any trouble, it can not move the laser beam on the left or right side.
Please check the function after changing another MD.
4-4-3. Service hint (Any picture / Remark)
< Waveform of TR±
for driving TRACKING actuator >
ONE POINT REPAIR GUIDE
< Signal check point >
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