LG CM8440 Series - Page 35

3-14
ONE POINT REPAIR GUIDE
NO OPERATION OF MD (DRIVING THE SERVO MOTORS)
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.
5-4. LASER TRACKING ACTUATOR
5-5-1. Solution
Please check and replace IC407, IC408 on MAIN board.
5-4-2. 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 Pin22 of IC407.
 If no signal, check 3.3 V(RF) and X400.
2) Check TR- & TR+ from IC408 to CN404 for driving the tracking actuator.
 If no signal, check +1.8 V and +5 V for IC408.
3) Check if the FFC cable is solidly connected between CN404 and MD.
4) Check the MD.
 If the pick-up 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.
5-4-3. Service hint (Any picture / Remark)
{yRGGju[W[
{yT Gju[W[
ju[W[
{yR
X]GGju[W[
{yT
X^GGju[W[
< Waveform of TR±
for driving TRACKING actuator >
< Signal check point >