LG SN4A - Page 37

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Only for training and service purposes.
ONE POINT REPAIR GUIDE
NO BOOTING WHEN YOU TURN THE UNIT ON, NO MESSAGE OR “HELLO”
ON FRONT PANEL
When you turn on your set, it will blank / no message on front panel, LCD doesn’t work.
1-4. LCD System power VCC_5V
1-4-1. Solution
Replace MAIN/ LCD Module.
1-4-2. How to troubleshoot (Countermeasure)
1) Please check CN101 VCC_5V of CN101 pin1.
2) If VCC_5 V is abnormal, replace MAIN board.
3) If VCC_5 V OK, replace LCD module.
1-4-3. Service hint (Any picture / Remark)
< MAIN board top view >
DGND
DGND
LCD_DAT
DGND
LCD_BL
LCD_STB
LCD_CLK
LCD_RST
LCD_CD
C128
10nF
C157
10uF
/10V(M)
C120
100nF
VCC_5V
R191
220 (M)
R192
220 (M)
FB105
F_5V
LCD_BL
LCD_STB
LCD_CD
LCD_CLK
LCD_DAT
LCD_3V3
LCD_GND
VB0-
VB1-
VB0+
VLCD
Q104
E
C
B
3.3VA
R193
10M
C132
0.33uF
LCD_RST
VB1+
C156
2.2uF
/10V(X5R)
C155
2.2uF
/10V(X5R)
CN101
1
VLCD
2
VB0-
3
VB1+
4
VB1-
5
VB0-
6
VSS
7
VDD
8
SDA
9
SCK
10
CD
11
RSTB
12
CSB
13
LED(-)
14
LED(+)
Front_LCD
CN101
CN101