LG 42LB7DF (CHASSIS:LJ81A) Service Manual ▷ View online
- 21 -
Check P800, P801 All
Voltage Level (19V, 12V, 6V, 3.3V)
Check Power connector
OK ?
Replace Power board
Y
NY
Check IC804 #2 Pin / L805
Voltage Level 3.3V
Replace IC804 / L805 &
Recheck
Y
N
Check IC803 #5 Pin / L807
Voltage Level 2.6V
Replace IC803 or L807 &
Recheck
Y
N
Check C830, C853, C856
Voltage Level 1.2V
Replace IC802 or IC805 &
Recheck
Y
N
Check X200 Clock
54MHz
Replace X200
Y
N
Check R154 Clock
33MHz
Maybe BCM3553 has troubles.
Y
N
Replace IC101 Flash Memory
N
N
N
Check
Micom
IC407
Redownload
or replace
TROUBLESHOOTING
1. Power-Up Boot Fail
1-2. Troubleshooting
- 22 -
Flash
(32MB)
DDR1(128MB)
(16Mx16x4)
DDR1(128MB)
(16Mx16x4)
TEA6420
Audio
SW
MTV416
(M
icom
)
NTP3000
(Digital AMP)
64Bit I/F
RGB-PC
HDMI
1/2/3
COMP 1
COMP 2
AV1
AV2
RGB-PC
I2S
MCLK
Digital out
COMP1
COMP2
AV1
AV2
BCM7412
(MPEG4
Decoder)
Analog
/Digital
Tuner
TC90512
DVI
I2S
SIF
SPDIF Out
CVBS
CVBS/Y/C
Y/
Cb
/Cr
R/G/B
DDR1
(64MB)
CS5340
L/R
Serial TP
20bits
12bit YC 4:2:2
NIM TUNER
TMDS_RX+-
EPM240F
MNT out (Audio Only)
TMDS341A
(3x1,S/W)
CVBS/Y/C
MC33078
(AMP)
L/R
RS232
RX/TX
DVI
4:2:2 20bit YC
Full HD(1080P)
WXGA(768P)
RF
Switch
DM1/DP1
Serial
TP
74HC04
SPDIF Out
(Coaxial)
Video
Front
End
Dual
HDMI
Rx
HD/SD
Video
Encoder
Audio
DSP
USB2.0
PKT
HSX
PCI/
EBI
HD-DVI
IB0
Parse2
RSBUF
XCBUF
RMX0
BCM3553
Local KEY
24C16
74LVC14APW
X-tal(54M)
Reset
KIA7029
NVRAM
I2C
TROUBLESHOOTING
2. No OSD
2-1. Block Diagram of Troubleshooting
- 23 -
Check D901 Pin #1
Voltage Level 12V
Check
Power connector
Replace Power board
Check P903
#33(TXAC-) , #32(TXAC+) ,
#17(TXBC-) , #16(TXBC+)
Maybe BCM3553 has problems
Check LVDS Cable
Check PDP/LCD Module
Control board
Y
NY
Y
N
Check L901
Voltage Level 12V
Replace L901
Y
N
Y
Replace Cable
N
TROUBLESHOOTING
2. Power-Up Boot Fail
2-2. Troubleshooting
- 24 -
Flash
(32MB)
DDR1(128MB)
(16Mx16x4)
DDR1(128MB)
(16Mx16x4)
TEA6420
Audio
SW
MTV416
(M
icom
)
NTP3000
(Digital AMP)
64Bit I/F
RGB-PC
HDMI
1/2/3
COMP 1
COMP 2
AV1
AV2
RGB-PC
I2S
MCLK
Digital out
COMP1
COMP2
AV1
AV2
BCM7412
(MPEG4
Decoder)
Analog
/Digital
Tuner
TC90512
DVI
I2S
SIF
SPDIF Out
CVBS
CVBS/Y/C
Y/
Cb
/Cr
R/G/B
DDR1
(64MB)
CS5340
L/R
Serial TP
20bits
12bit YC 4:2:2
NIM TUNER
TMDS_RX+-
EPM240F
MNT out (Audio Only)
TMDS341A
(3x1,S/W)
CVBS/Y/C
MC33078
(AMP)
L/R
RS232
RX/TX
DVI
4:2:2 20bit YC
Full HD(1080P)
WXGA(768P)
RF
Switch
DM1/DP1
Serial
TP
74HC04
SPDIF Out
(Coaxial)
Video
Front
End
Dual
HDMI
Rx
HD/SD
Video
Encoder
Audio
DSP
USB2.0
PKT
HSX
PCI/
EBI
HD-DVI
IB0
Parse2
RSBUF
XCBUF
RMX0
BCM3553
Local KEY
24C16
74LVC14APW
X-tal(54M)
Reset
KIA7029
NVRAM
I2C
TROUBLESHOOTING
3. Digital TV Video
3-1. Block Diagram of Troubleshooting
Click on the first or last page to see other 42LB7DF (CHASSIS:LJ81A) service manuals if exist.