LG OK99 Service Manual page 48

NO SOUND
There is no sound output in the Bluetooth function, repair the set according to the following guide.
10-5. BLUETOOTH FUNCTION
10-5-1. Solution
Replace IC501 on the MAIN board or B/T module on the Front Panel.
10-5-2. How to troubleshoot (Countermeasure)
1) Check BT_RX, BT_TX signal to pin4, 6 of CN504.
 If no signal, check the signal to pin4, 6 and pin10(3.3 VA) 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 pin4, 6 of CN504 to pin K1, L1 to IC501 (DSP).
3) Check if MCS_BCK, MCS_LRCK & MIX_DATAN is entered from IC501 to IC601.
 If no signal, check 1.2 VA for IC501.
 If it is abnormal, change replace it a new one.
4) Check the following I2S signal flow from IC501 to IC601.
  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.
10-5-3. Service hint (Any picture / Remark)
B/T Module
BT_RX,
BT_TX
IC501
MCS_BCK
MCS_LRCK
MIX_DATA_OUT
< Bluetooth function signal fl ow >
ONE POINT REPAIR GUIDE
IC601
PWM
IR AMP
BT_RTS. pin 7 BT_RTS. pin 7
BT_CTS. pin 8 BT_CTS. pin 8
BT_RX. pin 6 BT_RX. pin 6
BT_TX. pin 4 BT_TX. pin 4
< MAIN board top view >
MIX_DATA2_OUT MIX_DATA2_OUT
MIX_DATA0_OUT MIX_DATA0_OUT
MCS_LRCK MCS_LRCK
< MAIN board bottom view >
3-23
Copyright © 2018 LG Electronics Inc. All rights reserved.
CN504 CN504
MCS_BCK MCS_BCK
IC601 IC601
Only for training and service purposes.