LG OK75 - Troubleshooting: No MD Operation (Sled Motor)

3-10
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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 servo motors in MD don’t work. This step is for checking the SLED MOTOR among
them.
5-2. SLED MOTOR
5-2-1. Solution
Replace IC400 on MAIN board.
5-2-2. How to troubleshoot (Countermeasure)
1) Check the SLDO signal from pin15 of IC401.
 If no signal, check DVCC_3.3V and X400.
2) Check the SPED+ & SLED- from IC400 to CN401 for driving SPINDLE motor. It is about 2.9 Vp-p.
 If no signal, check M_5 V for IC400.
3) Check if the FFC cable is solidly connected between CN401 and MD.
4) Check the MD.
 If the spindle motor is sort-circuit or has any trouble, it can not rotate CD discs.
Please check the function after changing another MD.
5-2-3. Service hint (Any picture/ Remark)
< Waveform of SLED- & SLED+
for driving SLED motor >
SP-
SP+
SLED+: pin11
SLED+: pin11
SLED-: pin12
SLED-: pin12