LG CM8440 Series Service Manual page 42

NO SOUND
There is no sound output in the BLUETOOTH FUNCTION, repair the set according to
the following guide.
6-6. IN THE BLUETOOTH FUNCTION
6-6-1. Solution
Please check and replace IC501 on MAIN board and Bluetooth module on front panel.
6-6-2. How to troubleshoot (Countermeasure)
1) Check BT_RX, BT_TX signal to Pin5, 7 of CN504.
 If no signal, check the signal to Pin5, 7 and Pin1(+3.3 V) of on the Bluetooth module and cable connection state.
 If there are no signal out from module, replace new module.
2) Check if BT_RX/TX is entered from Pin5, 7 of CN504 to Pin169, 170 to IC501 (DSP).
3) Check if MIC_BCK, MIC_MLCK & MIC_O_DATA is entered from IC501 to IC600.
 If no signal, check VCC12(+1.2 V) for IC501. If it is abnormal, change replace it a new one.
4) Check the following I2S signal flow from IC501 to IC600.
 If there is any trouble, check the power for each IC. If the signals are abnormal, replace it a new one.
5) Check if the digital audio AMP block is okay. Refer to "Digital Audio AMP" guide.
 If AMP is damaged, replace it with a new one.
6-6-3. Service hint (Any picture / Remark)
B/T Module
BT_RX,
BT_TX
IC501
MLC3730
MCS_BCK
MCS_LRCK
MIX_DATA_OUT
< BLUETOOTH function signal fl ow >
ONE POINT REPAIR GUIDE
IC600
TAS5548
PWM
IR AMP
IRS2092+IRF6775
< Signal check point >
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