LG 42LH250C (CHASSIS:LD91Z) Service Manual ▷ View online
Contents of LCD TV Standard Repair Process
No.
Error symptom (High category)
Error symptom (Mid category)
Page
Remarks
1
No video/Normal audio
1
2
No video/No audio
2
3
Video error, video lag/stop
3
4
Color error
4
5
A. Video error
Vertical/Horizontal bar, residual image,
light spot, external device color error
light spot, external device color error
5
6
No power
6
7
B. Power error
Off when on, off while viewing, power auto
on/off
on/off
7
8
No audio/Normal video
8
9
C. Audio error
Wrecked audio/discontinuation/noise
9
10
No response in remote controller, key error,
recording error, memory error
recording error, memory error
10
11
D. Function error
External device recognition error
11
12
E. Noise
Circuit noise, mechanical noise
12
13
F. Exterior error
Exterior defect
13
First of all, Check whether there is SVC Bulletin in GCSC System for these model.
LGE Internal Use Only
Normal
audio
Y
N
Move to No
video/No audio
video/No audio
No video
Normal audio
Normal audio
Check Back Light
On with naked eye
On with naked eye
On
Y
N
Check Power
Board
12v,5v etc.
Board
12v,5v etc.
Normal
voltage
Y
N
Replace Main Board
Replace T-con
Board or module
And Adjust VCOM
Board or module
And Adjust VCOM
OR
Repair Power
Board or parts
Board or parts
Check Power Board 20V /12V or 24v output
Normal
voltage
voltage
Y
Replace Inverter
or module
or module
N
Repair Power
Board or parts
Board or parts
End
Always check & record S/W Version and White
Balance value before replacing the Main Board
Balance value before replacing the Main Board
Replace Main Board
Re-enter White Balance value
※Precaution
Established
date
Standard Repair Process
Revised date
2008. 3 .05
1/13
LCD TV
Error
symptom
A. Video error
No video/ Normal audio
☞A3
☞A1
☞A2
☞A27
First of all, Check whether all of cables between board is inserted properly or not.
(Main B/D↔ Power B/D, LVDS Cable,Speaker Cable,IR B/D Cable,,,)
☞A7 & A4
1
Normal
voltage?
Check various
voltages of Power
Board ( 5V,12V,20V
or 24V…)
voltages of Power
Board ( 5V,12V,20V
or 24V…)
No Video/
No audio
No audio
Check and
replace
MAIN B/D
replace
MAIN B/D
Y
Replace Power
Board and repair
parts
Board and repair
parts
N
End
Standard Repair Process
A. Video error
No video/ No audio
☞A5
Established
date
Revised date
2008. 3 .05
2/13
LCD TV
Error
symptom
2
A. Picture Problem
Picture broken/ Freezing
Y
N
☞ A6
N
Check RF Signal level
Normal
Signal?
Check RF Cable
Connection
1. Reconnection
2. Install Booster
Check
S/W Version
Booster menu
On→Off: Check
Off→On: Check
Off→On: Check
S/W Upgrade
Check whether other equipments have problem or not.
(By connecting RF Cable at other equipment)
→ DVD Player ,Set-Top-Box, Different maker TV etc`
SVC
Bulletin?
Replace
Main B/D
Check
Tuner soldering
Normal
Picture?
Y
N
Y
Close
Normal
Picture?
Y
Close
■ Menu→Setup →Booster
. By using Digital signal level meter
. By using Diagnostics menu on OSD
. By using Diagnostics menu on OSD
( Menu→Setup→Diagnostic)
- Signal strength (Normal : over 50%)
- Signal Quality (Normal: over 50%)
- Signal Quality (Normal: over 50%)
Normal
Picture?
Y
Contact with signal distributor
or broadcaster (Cable or Air)
N
N
Normal
Picture?
Y
Close
N
☞ A7
Standard Repair Process
Established
date
Revised date
2008. 3 .05
3/13
LCD TV
Error
symptom
3
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