LG UBK80 Service Manual page 50

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.
2-4. IC204 System 1.8 VA (No 1.8 VA)
2-4-1. Solution
Replace MAIN board.
2-4-2. How to troubleshoot (Countermeasure)
1) Please check 5.1 VA of IC204 pin1 (VIN).
2) If 5.1 VA is abnormal, please check IC201.
3) If 5.1 VA is OK, but 1.8 VA is abnormal pin2 of IC204(VOUT), replace MAIN board.
2-4-3. Service hint (Any picture / Remark)
[12VA TO 1.8VA_STB]
PWR_CTL
C204
10pF
DGND
R204
13K (1%)
DGND
ONE POINT REPAIR GUIDE
R271
4.7K
6 F
E
5
B
4
C2A5
1nF_NC
R227
R212
DGND
15K (1%)
R221
1.5K (1%)
VOUT = 0.798x((15K+1.5K)/13K+1)= 1.8V
< MAIN board top view >
1
B I V N
 
L204
2
N
S W
4.7UH
3
S T
G N D
DGND
33 C209 1uF (1)
IC204 IC204
 
 
3-33
Copyright © 2020 LG Electronics Inc. All rights reserved.
5.1VA
L208
 
C222 C229
C215
10uF 10uF _NC
100nF
/16V /16V
1.8VA_STB
DGND
R231
0OHM
C223
C230 C233
C2B3
10uF 10uF 10uF
100nF
/16V /16V
/16V
DGND
Only for training and service purposes.
TP201