LG 42LH90QD (CHASSIS:LT91C) Service Manual ▷ View online
Check Signal format
Is it supported?
Check the RGB Cable
YES
MAIN B’D JK405 Check
Replace MAIN B’D JK405
YES
NO
NO
YES
Check MAIN B’D C2016 (RED)
C2017 (GREEN)
C2018 (BLUE)
Video Signal ?
Video Signal ?
Replace
MAIN B’D C2016 or C2017 or C2018
NO
Replace MAIN B’D IC 100
YES
MAIN B’D JK405
Pin #3 (BLUE)
Pin #2 (GREEN)
Pin #1 (RED)
Video signal ?
Making
Revision
2009. 2 . 1
10/25
LCD TV
Symptom
RGB No Color Problem
23
Check Signal format
Is it supported?
Check the HDMI Cable
YES
YES
Replace MAIN B’D IC 100
Check the ADJUST MENU
EDID OK ?
YES
Download EDID
(Refer to Adjustment Spec)
NO
NO
Replace
MAIN B’D IC601 (HDCP KEY)
Making
Revision
2009. 2 . 1
11/25
LCD TV
Symptom
HDMI 1~4 All No Video Problem
24
Check Signal format
Is it supported?
Check the HDMI Cable
YES
YES
Replace MAIN B’D IC 100
MAIN B’D JACK Check
JK600 -> HDMI1
JK601 -> HDMI2
JK602 -> HDMI3
JK603 -> HDMI4
JK601 -> HDMI2
JK602 -> HDMI3
JK603 -> HDMI4
YES
Making
Revision
2009. 2 . 1
12/25
LCD TV
Symptom
HDMI1 or 2 or 3 or 4 No Video
Problem
Problem
Check MAIN B’D IC600
YES
25
Check The Speaker
Check Speaker Cable
YES
Check P700 Cable
YES
NO
Replace MAIN B’D IC 701
YES
MAIN B’D
L705 Pin #1
L704 Pin #2
L704 Pin #2
PWM Signal ?
Replace Speaker
NO
Replace Speaker Cable
NO
Replace MAIN B’D IC807
NO
YES
MAIN B’D
L824 = 1.8V
MAIN B’D
Check R701, R702, R705
Signal
YES
Replace MAIN B’D IC100
NO
Replace MAIN B’D IC701
NO
Making
Revision
2009. 2 . 1
13/25
LCD TV
Symptom
All Source no Audio Problem
26
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