DOWNLOAD LG 42LH20FD (CHASSIS:LT91A) Service Manual ↓ Size: 4.29 MB | Pages: 75 in PDF or view online for FREE

Model
42LH20FD (CHASSIS:LT91A)
Pages
75
Size
4.29 MB
Type
PDF
Document
Service Manual
Brand
Device
TV / LCD
File
42lh20fd-chassis-lt91a.pdf
Date
PREV: LG 42LH20D (CHASSIS:LB91A) Service Manual

LG 42LH20FD (CHASSIS:LT91A) Service Manual ▷ View online

B. Power error
No power
Power  LED
On?
Y
N
DC Power on
by pressing Power Key 
On Remote control
Y
N
Normal 
operation?
Check Power 
On ‘”High”
Check Power cord
was inserted properly
Check 
Power LED
Replace 
Power 
B/D
Measure voltage of each output of Power B/D
N
Y
Normal
voltage?
Replace Main B/D
N
Y
OK?
Replace Main B/D
N
Y
Normal?
Check ST-BY 5V
Replace Power B/D
N
Y
Normal
voltage?
Replace Power 
B/D
Y
☞
A18
Standard Repair Process
Established
date 
Electronics 6-3
Revised date 
2008. 3 .05
6/13
LCD  TV
Error
symptom
※
’09 years new model apply 
mechanical power switch
to reduce power consumption in stand-by status.
If mechanical power switch off
→ Doesn’t turn on by remote control
→ Doesn’t appear LED light
Please refer to the A21 Page
6
. Stand-By: Red
. Operating: Green
Check & Repair
Mechanical Power switch 
on Local control of TV
※
Close
B. Power error
Off when on, off while viewing, power auto on/off
Error?
N
Y
Check Power Off
Mode
Fix A/C code & Outlet 
and describe 3 wave 
length
Check A/C code
Check for 3 wave length
Check outlet
Replace Main B/D
CPU
Abnormal 
(If Power Off mode 
is not displayed)
Check Power B/D 
voltage
Y
N
Replace Main B/D
Normal
voltage?
Replace Power B/D
Replace Power B/D
N
Y
Normal?
End
※ Caution
Check and fix exterior   
of Power B/D Part
Established
date 
Electronics 6-3
Revised date 
2008. 3 .05
7/13
LCD  TV
Error
symptom
Standard Repair Process
7
Status
Power off List
Explanation
Normal
"POWEROFF_REMOTEKEY"
Power off by REMOTE CONTROL
"POWEROFF_OFFTIMER"
Power off by OFF TIMER
"POWEROFF_SLEEPTIMER"
Power off by SLEEP TIMER
"POWEROFF_INSTOP"
Power off by INSTOP KEY
"POWEROFF_AUTOOFF"
Power off  by AUTO OFF
"POWEROFF_ONTIMER"
Power off by ON TIMER
"POWEROFF_RS232C"
Power off by RS232C
"POWEROFF_RESREC"
Power off by Reservated Record
"POWEROFF_RECEND"
Power off by End of Recording
"POWEROFF_SWDOWN"
Power off by S/W Download
"POWEROFF_UNKNOWN"
Power off by unknown status except listed case
Abnormal
"POWEROFF_ABNORMAL1"
Power off by abnormal status except CPU trouble
"POWEROFF_CPUABNORMAL"
Power off by CPU Abnormal
*  Please refer to the all cases which
can be displayed on power off mode.
Abnormal 
1
No audio
Screen normal
Check user 
menu  > 
Speaker off
Off
N
Y
Cancel OFF and describe
Check audio B+ 
20V or 24V of 
Power Board
Normal
voltage
Y
N
Replace Power Board and repair parts
Check 
Speaker 
disconnection
N
Y
Replace Speaker 
Replace MAIN Board
End
C. Audio error
No audio/ Normal video  
Disconnection
Established
date 
Electronics 6-3
Revised date 
2008. 3 .05
8/13
LCD  TV
Error
symptom
Standard Repair Process
8
→
Wrecked audio/discontinuation/noise is same after “Check input signal” compared to No audio
C. Audio error
Wrecked audio/ discontinuation/noise 
Wrecked audio/
Discontinuation/
Noise for 
all audio
Check and replace 
speaker and 
connector
Wrecked audio/
Discontinuation/
Noise only 
for D-TV
Wrecked audio/
Discontinuation/
Noise only 
for Analog
Wrecked audio/
Discontinuation/
Noise only 
for External Input
Connect and check 
other external 
device
N
Y
Normal
audio?
Check and fix external device
Replace Power B/D
N
Y
Normal
voltage?
Check input 
signal
-RF
-External Input
signal
Signal 
normal?
(When RF signal is not 
received)
Request repair to external 
cable/ANT provider
Y
Check audio 
B+ Voltage (20V or 24V)
Replace Main B/D
(In case of 
External Input 
signal error)
Check and fix 
external device
Replace Main B/D
N
End
Established
date 
Electronics 6-3
Revised date 
2008. 3 .05
9/13
LCD  TV
Error
symptom
Standard Repair Process
9
Page of 75
Display

Click on the first or last page to see other 42LH20FD (CHASSIS:LT91A) service manuals if exist.

RANDOM: