Protection Error - LG SL4Y Service Manual

3. PROTECTION ERROR

No display or No Sound.
3-1. D(DC) PROTECTION
3-1-1. Solution
Replace MAIN board.
3-1-2. How to troubleshoot (Countermeasure)
1) Check DC Voltage of speaker out FL+/- (CN703 pin1, 2), FR +/- (CN704 pin1, 2, 3)
2) Check resistor crack, cold solder of ESS IC out [FL+(R570), FL-(R571), FR+(R572), FR-(R573)].
3) If ESS (IC501) out is ok and speaker out (FL+/-, FR+/-) has DC voltage replace MAIN board.
3-1-3. Service hint (Any picture / Remark)
R C F 5 0 0
C 5 4 9
Z D 5 0 4
C 5 A 1
C 5 A 2
L 3 0 2
R 5 2 8
C 5 4 8
7
C 3 2 3
C 3 0 0
C 3 2 0
ONE POINT REPAIR GUIDE
R 7 A 1
Q 3 0 0
Q 3 0 1
C 7 C 6
I C 3 0 9
F B 3 1 3
C 7 C 5
C 3 1 3
C 3 1 2
C 3 0 7
C 3 0 1
C 3 7 9
2
F 3 0 1
F 3 0 0
K E Y _ T P
C 5 0 3
F B 5 0 7
< MAIN board top view >
S L 4 / S L 4 Y / S L 4 F M a i n
E A X 6 8 4 0 8 2 0 2 V e r 1 . 1
F R 4 - 4 L 1 . 2 T
2 0 1 8 . 1 2 . 0 6 2 6 1 X 6 7 . 5
MES
C 7 5 9
C 7 4 6
D 3 0 0
C 3 4 8
C 7 4 5
C 7 5 8
C 3 7 8
C 7 4 4
K E Y _ G
F B 5 0 8
Copyright © 2019 LG Electronics Inc. All rights reserved.
3-12
L 7 1 0
CN703 CN703
F L 2 +
F L 2 -
C 7 7 9
C 7 7 8
CN704 CN704
F R 2 +
L 7 0 9
F R 2 -
C 7 7 7
C N 5 0 5
Only for training and service purposes.
C N 7 0 3
L
R
C N 7 0 4