LG 42LG70YD (CHASSIS:LJ83A) Service Manual ▷ View online
- 21 -
Check Q903 Pin #1
Voltage Level 12V
Check
Power connector
Replace Power board
Check P900, P902
#34(TXAC-) , #33(TXAC+) ,
#18(TXBC-) , #17(TXBC+)
Check all power domain of FRC-
9459M(IC1200)
(1.3V_CORE, 1.3V_PLL,1.8V,2.5V)
Check crystal output.
(X1200 / 20.25MHz)
Check “ FRC_RESET” signal
(R1211, R1229)
Check LVDS Cable
Check LCD Module
Control board
Y
N
Y
Y
N
Check L900
Voltage Level 12V
Replace L900
Y
N
Y
Replace Cable
N
2. No OSD
- 22 -
Check RF Cable
Check TP Clock, Data, Sync
R853 (38.1MHz), R804, R803
Check RF signal, PLL locking…
Maybe Tuner(TU800) has problems
Check BCM3553(2) Output TP Clock,
Data, Sync
R153, R155, R152
Check BCM7412 Clock, Hsync, Vsync
R1088 (Typ. 74.25MHz), R1087, R1086
Y
Y
N
Check Tuner 5V, +2.5V, D3.3V Power
TU800 #1,2,3 Pin
Power Problem
Y
N
Y
Maybe BCM3553(2)(IC100) has problems
N
Maybe BCM7412(IC1000) has problems
N
Check PLD Clock, Hsync, Vsync
R1102 (Typ. 74.25MHz), R1100, R1101
Y
Redownload PLD file or replace
N
Maybe BCM3553(2)(IC100) has
problems
Y
Check BCM7412 Input Clock
R107 (27MHz)
Replace it
N
Y
3. Digital TV Video
- 23 -
Check RF Cable
Check CVBS signal
TU800 #17 Pin
Check RF signal,
Maybe Tuner(TU800) has problems
Check CVBS signal
IC808 #8 Pin
Check CVBS signal
C658
Y
Y
N
Check Tuner 5V Power
IC802 #3 Pin
Replace it
Y
N
Y
Replace IC808 or check L800 5V power
N
Replace it
N
Y
Maybe BCM3553(2)(IC100) has
problems
4. Analog TV Video
- 24 -
Check signal format
Is it supported?
Check signal
L700, L701. L702 / L704, L705, L706
Replace it.
Check signal
C638, C639, C640 / C628, C629, C630
Y
Y
N
Check JK700 / JK702
Replace connector
Y
N
Y
Replace it
N
Maybe BCM3553(2)(IC100) has
problems
Y
Check Component Cable
5. Component Video
Click on the first or last page to see other 42LG70YD (CHASSIS:LJ83A) service manuals if exist.