LG SL4Y Service Manual page 35

PROTECTION ERROR
No display or No Sound.
3-2. B(BURNT) PROTECTION
3-2-1. Solution
Replace MAIN board.
3-2-2. How to troubleshoot (Countermeasure)
1) Check voltage 12 V of IC703 at pin1 ~ 2, if 12V has problem refer to STEP 1-1.
2) If 12 V is OK, replace MAIN board.
3-2-3. Service hint (Any picture / Remark)
F L +
F L -
F R +
ONE POINT REPAIR GUIDE
R702
AMP_PROTECT
2
ZD702
NC R703
Z02W3.9V
3 1
C706
PGND
AMP_PDN
FR_OUT_N
FR_OUT_P
VCC33 1
R716 R715
4.7K 47K
FL_OUT_N
FL_OUT_P
AMP_FAULT
R784
DC_PROTECTION
C707 C708
100pF 100pF
R 7 8 5
IC703 IC703
< MAIN board bottom view >
+12V
27K
ZD701 NC
KDZ13V-RTK/P
IC703
10K
C730 1uF
100pF
1
C731 100nF
BST_A
GVDD_AB
2
C741 10uF
BST_B
VDD
3
R775 47K
OC_ADJ
R777 100
4
/RESET
5
OUT_A
INPUT_A
6
OUT_A
INPUT_B
7
C736 100pF
2
PVDD_AB
C_START
ZD703
8
C737 1uF
Z02W3.9V
PVDD_AB
DVDD
9
3 PVDD_AB
GND
R7A2
NC 10
OUT_B
GND
11
PGND
GND
12
GND
13
C738 1uF
OUT_C
AVDD
14
PVDD_CD
INPUT_C
15
PVDD_CD
INPUT_D
16
R782 100
PVDD_CD
/FAULT
17
R783 NC
OUT_D
/OTW
18
2.2K
OUT_D
/CLIP
19
M1
20
M2
R7A3
21
0
M3 BST_C
22
C739 1uF
GVDD_CD BST_D
PGND
Q 7 0 8
R 7 B 4
Q 7 0 9
R 7 B 0
C 7 3 9
R 7 8 4
R 7 8 3
R 7 8 2
C 7 3 8
R 7 7 7
R 7 7 5
C 7 3 1
Z D
Copyright © 2019 LG Electronics Inc. All rights reserved.
3-13
44
43
42
GND
41
GND
40
39
38
37
36
35
34
GND
33
GND
32
31
30
29
28
27
26
GND
25
GND
24
23
R E M O _ T P
C 3 0 6
R 3 0 6
C 3 5 1
R 3 0 1
Only for training and service purposes.
J K 5 0 2