LG CMS9540F 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 >
3-21