LG UBK80 Service Manual page 52

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.
2-6. IC206 System 1.5 V_DDR (No 1.5 V)
2-6-1. Solution
Replace MAIN board.
2-6-2. How to troubleshoot (Countermeasure)
1) Please check 12 VA of IC206 pin1 (VIN).
2) If 12 VA is abnormal, please check SMPS.
3) If 12 VA is OK, but 1.5 V is abnormal pin2 of IC206(VOUT), replace MAIN board.
2-6-3. Service hint (Any picture / Remark)
PWR_CTL4
C234
10pF
DGND
R232
R236
13K (1%) 10K (1%)
DGND
ONE POINT REPAIR GUIDE
R243
4.7K
6 F B I V
E N
5
B S T
4 G
C240
1nF _NC
R249
33 C244
DGND
R241
1.5K (1%)
VOUT = 0.798x((10K+1.5K)/13K+1)= 1.5V
 
 
IC206 IC206
< MAIN board top view >
 
C249
100nF
1
N
 
L211
2
S W
4.7UH
3
N D
DGND
1uF (1)
3-35
Copyright © 2020 LG Electronics Inc. All rights reserved.
12VA
L215
C253 C259
10uF 10uF
/16V /16V
1.5V_DDR
DGND
R258
0OHM
C254
C260 C266
C2B7
10uF 10uF 10uF
100nF
/16V
/16V /16V
DGND
Only for training and service purposes.