LG CM5660 Service Manual page 37

6. NO SOUND
There is no sound output in the MIC IN FUNCTION, repair the set according to the following guide.
6-7. MIC IN FUNCTION
6-7-1. Solution
Please check and replace IC200, IC203 on MAIN board.
6-7-2. How to troubleshoot (Countermeasure)
1) Check MIC_SIG signal to pin2 of CN200.
  If no signal, check the signals to pin7 of CN210 on the MIC board.
Check if the signal is entered from pin7 of CN210 to pin2 of CN200.
2) Check if MIC_SIG is entered from pin2 of JK210 to pin2 to IC200 (PRE AMP).
3) Check if the amplified signal comes out from pin2 of IC200.
  If no signal output, check DVCC_3.3V for IC200, replace IC200 with a new one if it has a problem.
4) Check if MCS_BCK, MCS_MLCK & MCS_LRCK is entered from IC500 to IC203.
5) Check if MIC_DATA_IN is entered from pin9 of IC203 to pin T1 of IC500.
  If no signal, check DVCC_5V & DVCC_3.3V for IC203. If it is abnormal, change replace it a new one.
6) Check the following I2S signal flow from IC203 to IC500.
  If there is any trouble, check the power for each IC. If the signals are abnormal, replace it a new one.
7) Check if the digital audio AMP block is okay. Refer to "Digital Audio AMP" guide on item 6-2.
  If AMP is damaged, replace it with a new one.
6-7-3. Service hint (Any picture/ Remark)
IC203 IC203
ADC/MIC_DATA: pin9 ADC/MIC_DATA: pin9
MCS_BCK: pin8 MCS_BCK: pin8
MCS_LRCK: pin7 MCS_LRCK: pin7
MCS_MCLK: pin6 MCS_MCLK: pin6
ONE POINT REPAIR GUIDE
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