Booting When You Turn The Unit On, No Message Or "Hello" On Front Panel - LG SL8YG Service Manual

NO BOOTING WHEN YOU TURN THE UNIT ON, NO MESSAGE OR
"HELLO" ON FRONT PANEL
When you turn on your set, no message on the front panel, and LED doesn't work.
1-2. IC604 System 3.3 VA (No 3.3 VA)
1-2-1. Solution
Replace MAIN / FRONT board.
1-2-2. How to troubleshoot (Countermeasure)
1) Please check 3.3 VA of IC311 pin2.
2) If 3.3 VA is abnormal, replace MAIN board.
3) If 3.3VA is OK, replace FRONT board.
1-2-3. Service hint (Any picture / Remark)
[12VA to 3.3VA]
R381 150K
C3K5
10pF
R380
100K
R379
13K
(1%)
R382
R385
1.2M NC
DGND
C 3 T 1
7
F B 2 0 6
R 1 5 1 R 1 5 8
R 1 5 3 R 1 5 9
R 1 5 6 R 1 6 0
R 1 4 9 R 1 6 1
R 1 4 7 R 1 6 2
R 1 4 6 R 1 6 3
R 1 4 3 R 1 6 4
R 1 4 2 R 1 6 5
R 1 4 1 R 1 6 6
R 1 6 7
R 1 6 8
A R 1 0 1
R 1 5 7
R 4 3 4
R 1 7 0
R 4 1 6 R 1 K 2
1 1
C 1 8 1
C 4 1 3
R 1 J 7
ONE POINT REPAIR GUIDE
390K
R378
IC311
1
FB
6 VIN
2
EN
5 SW
3
4 BST GND
DGND
R384 33 1uF
C3K4
R383 2.7K
39K
(1%)
(1%)
VOUT = 0.798x(41.7K/13K+1)= 3.36V
I C 3 1 6
C 3 5 1
C 3 5 2
C 4 3 5
C 4 3 7
C 3 H 7
C N 4 0 1
R 3 0 8
I C 4 0 3
R 4 2 3
R 1 G 7
F B 4 1 0
F B 4 0 6
R 1 G 6
C 1 0 5
F B 1 0 3
I C 1 0 0
R 1 E 9
R 1 F 1
R 1 F 2 R 1 F 3
R 1 F 4
R 1 F 5
W _ L E D
< MAIN board top view >
12VA
FB316
C3H8
100nF
 
DGND
L310
10UH
C3K3 C3K2 C3K1
1uF
10uF 10uF
C N 1 0 1
C 3 7 0
C 3 7 1
R 1 2 9
C 3 5 7
C 3 7 3
C 3 5 5
C 3 7 4
C 3 8 2
R 1 0 2
R 1 F 8
R 1 D 9
R 1 E 0
R 1 E 4
R 1 E 5
R 1 T 3 R 1 T 4
R 1 E 7
R 1 E 8
T P 1 7 5
T P 1 7 6
MES
R 1 F 0
R 1 P 1
IC311 IC311
C 2 F 4
3-6
Copyright © 2019 LG Electronics Inc. All rights reserved.
C3K6
100nF
3.3VA
2018.12.07
R377 del.
C300 C301 C302
100nF 100nF 100nF
DGND
C N 1 0 0
1
R 1 5 2 R 1 J 4
R 1 J 3
R 1 J 2
R 1 J 1
R 1 J 0
R 1 H 9
R 1 3 8
R 1 H 8
R 1 H 7
R 1 H 6
R 1 K 1 C 1 8 2
R 1 H 5 C 1 7 7
R 1 H 4 C 1 7 6
R 1 H 3 C 1 7 5
L310 L310
 
R 1 H 2 C 1 7 4
R 1 H 1
R 1 H 0
F B 3 1 6
C 3 4 1
C N 1 0 5
Only for training and service purposes.