LG OM7550 - Page 35

3-14
ONE POINT REPAIR GUIDE
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9. 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 spindle motor among
them.
9-1. SPINDLE MOTOR
9-1-1. Solution
Replace IC401 or IC400 on MAIN board.
9-1-2. How to troubleshoot (Countermeasure)
1) Check the SPDO signal from pin16 of IC401.
 If no signal, check 3.3 V (RF) and X400.
2) Check the SP- & SP+ from IC400 to CN401 for driving SPINDLE motor. It is about 3.6 Vp-p.
 If no signal, check +1.8 V and DVCC +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 short-circuit or has any trouble, it can not rotate CD discs.
Please check the function after changing another MD.
9-1-3. Service hint (Any picture / Remark)
< Waveform of SP- & SP+
for driving SPINDLE motor >
< MAIN board top view >
SP-
SP-
pin8 of CN401
pin8 of CN401
SP+
SP+
pin6 of CN401
pin6 of CN401
IC400
IC400