Service manual

Page 17 of 64
4、Trouble shooting chart
If replace “IMAGE BOARD”, Please re-do “DDC-content” program & “WHITE-BALANCE” & Flash
Update.
4-1 PANEL Trouble shooting
Please reference the “PANEL Service Manual”.
4-2 Image board trouble shooting
4-2-1 No display(PANEL)
Image board
(Image processing)
No display
(Raster)
Check the input power(J40)
Check the voltage of STB5V（L49）
Voltage=5V（4.2---5.3V）
Check the voltage of REL-SW in
power IO connector (Is right?
SAMSUNG=low level; LG= High
level ). The testing point:RB22.
High level= 5V（4.2---5.3V）
Low level = 0V
QK4
If right, Please check the other
Voltage.
L44
L50
L60
L61
L48
L49
L49 --Æ 5 V
L48 --Æ 5 V
L61 --Æ 6 V (SAMSUNG PANEL)
L60 --Æ 12 V (SAMSUNG PANEL)
L50 --Æ 12 V (SAMSUNG PANEL)
L44 --Æ 3.3 V
Check the voltage of drive circuit
and logic circuit(Vs, Vset, Vsc, Ve
etc.)
The testing point ： see the
arrowhead。
□
NTSC
□
NTSC / PAL
Va Vsc Vs Ve Vset
VSB D5V D15V VAUDI O VFAN
√
If you find any voltage abnormal,
then judge which board was
defective, and then replace the
board.
The voltage label
RB22