LG UBK80 Service Manual page 51

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.
2-5. IC205 System 1.0 V (No 1.0 V)
2-5-1. Solution
Replace MAIN board.
2-5-2. How to troubleshoot (Countermeasure)
1) Please check 12 VA of IC205 pin9 (VIN).
2) If 12 VA is abnormal, please check SMPS.
3) If 12 VA is OK, but 1.0 V is abnormal pin2 of IC205(VOUT), replace MAIN board.
2-5-3. Service hint (Any picture / Remark)
12VA
DGND
L210
 
C237
22uF
/16V
ONE POINT REPAIR GUIDE
R248
100K
IC205
13
VCC
AGND
C239
0.47uF
FB
VOUT
IC205 IC205
12
SS
22nF
C243
PG
9
VIN
EN/SYNC
3
NC
BST
4
NC
C238
C241
6
22uF
NC SW
100nF
/16V
DGND
IC205 IC205
 
< MAIN board top view >
[12VA TO 1.0V_Core]
14
R253 R256
110K (1%) 80.6K (1%)
11
C251
R254 22pF
51K (1%)
10
DGND
7
5 R255
4.7K
PWR_CTL3
1
R252 100 2 C 8 4 0 1 n 0 F
L214
2
1.5uH
C247
82nF
DGND
 
3-34
Copyright © 2020 LG Electronics Inc. All rights reserved.
1.0V_Core
 
C263 C269 C270 C271 C2B9
C2B6
22uF 22uF 22uF 22uF 22uF
100nF
/16V /16V /16V /16V /16V
DGND
Only for training and service purposes.