LG CM9520, Service Manual

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3-26
ONE POINT REPAIR GUIDE
6. NO SOUND
There is no sound output in the CD FUNCTION, repair the set according to the follow-
ing guide.
6-1. IN THE CD FUNCTION
6-1-1. Solution
Please check and replace IC501, IC602, IC801 on MAIN board.
6-1-2. How to troubleshoot (Countermeasure)
1) Check CD_BCK, CD_LRCK, & CD_DATA signals from IC407 to IC501.
If no signal, check if the RF & servo signals from MD is entered to IC407.
Refer to the “No operation of MD” guide.
2) Check the following I2S signal flow.
< I2S audio signal Interface >
- DAC_BCK: IC501_pin4 --> IC507_pin14, 16 --> R821 of IC801 (Beat option) & IC602_pin4
- DAC_LRCK : IC501_pin5 --> IC507_pin5, 7 --> R820 of IC801 (Beat option) & IC602_pin5 (44.1 kHz)
- DAC_DATA : IC501_pin6 --> R817 next to IC801(Beat option) --> IC602_pin6, 9
- DAC_MCLK : IC501_pin3 --> R818 next to IC801
If there is any trouble, check the power for each IC. The power is normal but, if the signal waveform to
the IC is distorted or no signal, replace it with a new one.
3) Check if “Digital audio AMP block”.
6-1-3. Service hint (Any picture / Remark)
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AMP IC
TAS5631B
IC407
BU9543KV
< Waveform of I2S audio interface signals >
< I2S Signal Flow >