LG 42LH40 (CHASSIS:LA92G) Service Manual ▷ View online
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TROUBLESHOOTING
1. Power-up boot check
Check stand-by Voltage.
P700 8pin : +5V_ST
Check X100 clock
12MHz
Check Power connector.
and AC S/W on?
OK
No
OK
Check Multi Voltage.
P700 13pin : 12V, 18pin : 20V
Replace Power board.
Replace X100.
OK
Check Fuse.
OK
No
Check P700 PWR_ON.
2pin : 5V
OK
Re-download software.
No
OK
Check Q706 output level
5V
Replace Q706
No
Replace Mstar(IC100) or Main board
OK
Replace Power board.
No
Check inverter control & error
P700 22pin : Low
P700 20pin : high
OK
Check Power board or Module.
No
Check Mstar LVDS output
R1109, R1110, R1111,... R1120
OK
Replace Mstar(IC100) or Main board.
No
Check URSA2 mini-LVDS output
P1400, P1401
OK
Replace Mstar(IC100) or Main board.
No
Check P1400, P1401
OK
Replace Mstar(IC100) or Main board.
No
Check IC704 output voltage
3.3V
OK
Replace IC704.
No
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2. Digital TV Video
Check RF cable & Signal.
Check Tuner 5V Power
IC1001 4pin
OK
OK
Check Check Demodulator Input
Clock(X1005-25MHz)
Check IC1002.
No
Check IF_P/N Signal
OK
Bad Tuner. Replace Tuner.
No
Replace X1005.
No
OK
Check Mstar LVDS output
R1109, R1110, R1111,... R1120
Check IC1004(LGDT) Output
- AR1070, AR1071
OK
Replace IC1004.
No
Replace Mstar(IC100) or Main board.
No
3. Analog TV Video
Check RF cable.
Check Tuner 5V Power.
IC1001 4pin
OK
Check CVBS signal.
TU1001 #19 Pin
Check IC1002.
No
OK
Replace Tuner.
No
OK
Check Mstar LVDS output
Replace Mstar(IC100) or Main board.
No
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4. Component Video
Check Component Cable.
Check JK1206.
OK
Check input signal format.
Is it supported?
OK
Replace Jack.
No
OK
Check Mstar LVDS output
Replace Mstar(IC100) or Main board.
No
5. RGB Video
Check RGB Cable conductors for
damage.
Check JK1201.
OK
OK
Check input signal format.
Is it supported?
OK
Check signal R/G/B/H/V-Sync
R1234/1235/1236/1233/1232
Replace Jack.
No
Check EDID.
OK
Re-download EDID data.
No
Check other set.
If no problem, check signal line.
No
OK
Check Mstar LVDS output
Replace Mstar(IC100) or Main board.
No
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6. AV Video
Check AV Cable for damage or open conductor.
Check JK1206, JK1202.
OK
Check input signal format.
Is it supported?
OK
Replace Jack.
No
OK
Check Mstar LVDS output
Replace Mstar(IC100) or Main board.
No
Check HDMI Cable conductors for
damage of open conductor.
Check JK500, 501, 502, 503
OK
OK
Check input signal format.
Is it supported?
OK
Check EDID
Replace Jack.
No
Re-download EDID data.
No
Check HDCP key NVRAM(IC105)
power & I2C Signal (pin5, 6)
Replace the defective IC.
No
OK
Check HDMI Signal
Check other set.
If no problem, check signal line.
No
Replace Main board.
No
OK
7. HDMI Video
OK
Check Mstar LVDS output
Replace Mstar(IC100) or Main board.
No
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