LG 42LT760H-SA (CHASSIS:LJ3AZ) Service Manual ▷ View online
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TROUBLE SHOOTING
Power-Up Boot Fail Trouble Shooting guide
Check P2401 All
Voltage Level (3.5V, 12V, 24V)
Y
N
Check Q2407 output Voltage(12V)
Y
Check LVDS Cable
Y
Check LCD Module
Control board
Check power connector and
RL_ON signal OK ?
N
Replace Power Board
Check Q2407 application circuit
Or replace Q2407
N
Replace Cable
N
No OSD Trouble Shooting guide
Check P2401 All
Voltage Level (3.5V, 12V, 24V)
Y
N
Check IC8700 RESET pin
Y
Check X8701 Clock
10MHz
Y
Check IC8700 IIC
Communication status
Y
Check IR input state of IC8700
13pin
Y
Re-download NEC Micom
Check power connector and
RL_ON signal OK ?
N
Replace Power Board
Check switch SW8700,
N
Check X8701 application circuit
or Replace X8701
Check IIC line or replace IC8700
Check IR board
N
N
N
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Analog RF Video Trouble Shooting guide
Check RF cable & signal
Y
Check TU6500 Pin8
(Video output)
Y
Check tuner 5V power R6513
Y
Check tuner 3.3V power L6502
Y
Check tuner 1.8V power IC6501
2pin : 1.8V
Y
Check MTK LVDS output
Replace Tuner.
N
Check IC2404
Replace L6502
Replace IC6501
N
N
N
Replace IC105
N
Replace IC2404
N
Y
Digital RF Trouble Shooting guide
Check RF cable & signal
Check tuner 5V power R6513
Y
Check IIC Signal
TU6500 Pin#3,4
Y
Check TS Signal
TU6500 Pin#17,18,19,27
Y
Check X100
and application circuit
Check IC2404
Replace TU6500
Replace TU6500
N
N
N
Replace IC105
N
Replace IC2404
N
Y
Replace X100
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AV Video Trouble Shooting guide
Check input signal format.
Is it supported?
Y
Check AC cable for damage
For damage or open conductor
Y
Check JK1100
Can you see the normal waveform?
Y
Check the input of MTK(IC105).
Measure waveform at C616 because it’s more easy to check.
Can you see the normal waveform?
Y
This board has big problem because Main chip (MTK) have some troubles.
After checking thoroughly all path once again, You should decide to replace MTK or not.
Replace JK1100
N
HDMI Video Trouble Shooting guide
Check input signal format.
Is it supported?
Y
Check AC cable for damage
For damage or open conductor
Y
Check JK3301/JK3302/JK3303
Can you see the normal waveform?
Y
Check HDCP key NVRAM(IC100)
Power & I2C signal
Y
Check the input of MTK(IC105).
Measure waveform at R3314, R3315, R3328, R3329, R3308, R3309 because it’s more easy to check.
Can you see the normal waveform?
Y
This board has big problem because Main chip (MTK) have some troubles.
After checking thoroughly all path once again, You should decide to replace MTK or not.
Replace JK3301, JK3302, JK3303
N
Replace IC100
N
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RGB-PC Video Trouble Shooting guide
Check input signal format.
Is it supported?
Y
Check AC cable for damage
For damage or open conductor
Y
Check JK3603
Can you see the normal waveform?
Y
Check the input of MTK(IC105).
Measure waveform at R323, R324 because it’s more easy to check.
Can you see the normal waveform?
Y
This board has big problem because Main chip (MTK) have some troubles.
After checking thoroughly all path once again, You should decide to replace MTK or not.
Replace JK3603
N
Analog RF Audio Trouble Shooting guide
Check RF cable & signal
Check TU6500 Pin6
(SIF output)
Y
Check Audio AMP output
L5402,L5403,L5404,L5405
Y
Check IC5400
Y
Check C352
(SIF signal to IC105)
Replace Tuner
N
Replace L5402,L5403,L5404,L5405
Replace IC5400
N
N
Replace IC105
Y
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