LG SN4A - Sound

3-9
Copyright © 2021 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
ONE POINT REPAIR GUIDE
2. NO SOUND
2-1. BLUETOOTH
2-1-1. Solution
Replace MAIN board.
2-1-2. How to troubleshoot (Countermeasure)
1) Please check status of Bluetooth cable connection. (at CN102 and BT module)
2) Please check 3.3 VA
If 3.3 VA is OK, please check USB_BT, BT_RST, BT_WAKEUP, BT_STBY (pin7, 6, 3, 2, 1).
If no signal, please replace MAIN board.
2-1-3. Service hint (Any picture / Remark)
< MAIN board top view >
C124
10uF
C125
100nF
721C Fp2
2
NC
FL101 NC
1
2
3
4
C130 100nF
CN102
1
3.3VA
2
3.3VA
3
NC
4
GND
5
GND
6
USB_DP
7
USB_DN
8
GND
9
GND
10
RESET
11
BT_WAKEUP
12
MCU_STBY
ZD103
Z02W3.9V
1
2
3
FB104
PZ1608U221-1R4TF
USB0_DN_BT
3.3VA
USB0_DP_BT
621CFn00
1
DGND
TB01
TB06
TB12
TB05
TB10
TB07
TB11
R1A1
33
R1A2
33
C133
10pF
C134
10pF
R1A3
15K
R1A4
15K
DGND
DGND
MCU_STBY
BT_WAKEUP
BT_RESET
ZD104
Z02W3.9V
1
2
3
BT
<MAIN<->BT>
CN102
CN102