LG UBK80 Service Manual page 47

2. NO BOOTING WHEN YOU TURN THE UNIT ON, NO GREEN LED ON
FRONT PANEL
When you turn on your set, Green LED doesn't work, it will not boot-up.
2-1. IC201 System 5.1 VA (No 5.1 VA)
2-1-1. Solution
Replace MAIN board.
2-1-2. How to troubleshoot (Countermeasure)
1) Please check 12 VA of IC201 pin1 (VIN).
2) If 12 VA is abnormal, please check SMPS.
3) If 12 VA is OK, but 5.1 VA is abnormal pin2 of IC201(VOUT), replace MAIN board.
2-1-3. Service hint (Any picture / Remark)
[12VA TO 5.1VA]
C201
10pF
DGND
R201 R206
13K (1%) 62K (1%)
DGND
ONE POINT REPAIR GUIDE
R214
390K
6 F B I V N
5 E N S W
B S T
4 G N D
R215
150K
R224
33 C206
DGND
R213
8.2K (1%)
VOUT = 0.798x((62K+8.2K)/13K+1)= 5.107V
< MAIN board top view >
 
C213
C210
10uF
100nF
/16V
1
 
L201
2
4.7UH
3
C214
10uF
DGND
/16V
1uF (1)
3-30
Copyright © 2020 LG Electronics Inc. All rights reserved.
12VA 12VA_Motor
L205 L209
UBW2012-121F
C220
10uF _NC
/16V
5.1VA
DGND
R228
0OHM
C221 C228
C2B1
10uF 10uF
100nF
/16V /16V
DGND
 
 
IC201 IC201
Only for training and service purposes.