Speaker No Audio - LG CM9750 Service Manual

7. SPEAKER NO AUDIO

Speaker No Audio
7-1. AMP IC (IC700~IC705)
7-1-1. Solution
Replace IC700~IC705 on MAIN board.
7-1-2. How to troubleshoot (Countermeasure)
1) Check supply voltage of AMP(CN110) & PWM signal
Normal supply voltage and signal  Check AMP IC.
Poor supply voltage  Check SMPS Assy.
Poor signal  Check PWM IC.
2) Check CSD of FET driver IC (IRS2092 : EAN60778301).
CSD has about 5 V on normal state.
When AMP has problem, CSD is LOW state or keep change LOW to HIGH.
7-1-3. Service hint (Any picture / Remark)
pin5 of IC700   CSD pin5 of IC700
< MAIN board top view >
ONE POINT REPAIR GUIDE
CN110 CN110
pin1, 2 : +58 V pin1, 2 : +58 V
pin3, 4 : PGND pin3, 4 : PGND
pin5, 6 : -58 V pin5, 6 : -58 V
< MAIN board top view >
CSD
< MAIN - AMP circuit >
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