LG 42LM3450 / 42LM345S / 42LM345T (CHASSIS:LD21B) Service Manual ▷ View online
Contents of LCD TV Standard Repair Process Detail Technical Manual
No.
Error symptom
Content
Page
Remarks
1
A. Video error_ No video/Normal
audio
audio
Check LCD back light with naked eye
A1
2
LED driver B+ 24V measuring method
A2
3
Check White Balance value
A3
4
Power Board voltage measuring method
A4
6
A. Video error_ No video/Video
lag/stop
lag/stop
TUNER input signal strength checking method
A5
7
LCD-TV Version checking method
A6
9
A. Video error_Color
error
LCD TV connection diagram
A7
10
Check Link Cable (LVDS) reconnection
condition
condition
A8
A9
A9
11
Adjustment Test pattern -
ADJ Key
A10
12
A. Video error_Vertical/Horizontal bar,
residual image, light spot
residual image, light spot
LCD TV connection diagram
A8
13
Check Link Cable (LVDS) reconnection
condition
condition
A8
A9
A9
14
Adjustment Test pattern -
ADJ Key
A10
15
<Appendix>
Defected Type caused by T-Con/
Inverter/ Module
Defected Type caused by T-Con/
Inverter/ Module
Exchange T-Con Board (1)
A-1/5
16
Exchange T-Con Board (2)
A-2/5
17
Exchange LED driver Board (PSU)
A-3/5
55” : driver board
Other : PSU
Other : PSU
18
Exchange Module itself (1)
A-4/5
19
Exchange Module itself (2)
A-5/5
Continue to the next page
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,3.5v etc.
Board
12v,3.5v etc.
Normal
voltage
Y
N
Replace T-con
Board or module
Board or module
Repair Power
Board or parts
Board or parts
Check Power Board 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
1/14
LCD TV
Error
symptom
A. Video error
No video/ Normal audio
☞A4
☞A1
☞A2
☞A6 & A3
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,,,)
2012. 01 .14
Normal
voltage?
Check various
voltages of Power
Board ( 3.5V,12V,20V
or 24V…)
voltages of Power
Board ( 3.5V,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
☞A4
Established
date
Revised date
2/14
LCD TV
Error
symptom
2012 . 01
.14
.14
A. Video error
Picture broken/ Freezing
Y
N
☞ A5
N
Check RF Signal level
Normal
Signal?
Check RF Cable
Connection
1. Reconnection
2. Install Booster
Check
S/W Version
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
. By using Digital signal level meter
. By using Diagnostics menu on OSD
. By using Diagnostics menu on OSD
( Menu→ Set up→ Support → Signal Test )
- 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
☞ A6
Standard Repair Process
Established
date
Revised date
3/14
LCD TV
Error
symptom
2012. 01 .14
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