LG 32LT777H (CHASSIS:LA2FZ) Service Manual ▷ View online
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Analog RF Video Trouble Shooting guide
Check RF cable & signal
Y
Check TU8900 Pin5
(Video output)
Y
Check tuner 5V power R8953
Y
Check tuner 3.3V power L8904
Y
Check tuner 1.8V power IC8900
2pin : 1.8V
Y
Check MTK LVDS output
Replace Tuner.
N
Check IC2404
Replace L8904
Replace IC8900
N
N
N
Replace IC105
N
Replace IC2404
N
Y
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Digital RF Trouble Shooting guide
Check RF cable & signal
Check tuner 5V power R8953
Y
Check IIC Signal
TU8900 Pin#4,12
Y
Check DIF Signal
TU8900 Pin#6,14
Y
Check X100
and application circuit
Check IC2404
Replace TU8900
Replace TU8900
N
N
N
Replace IC105
N
Replace IC2404
N
Y
Replace X100
- 23 -
Composite Video Trouble Shooting guide
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 JK3800
Can you see the normal waveform?
Y
Check the input of MTK(IC105).
Measure waveform at C360 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 JK3800
N
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, R3308, R3309, R3328, R3329 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
Analog RF Audio 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
Check RF cable & signal
Check TU8900 Pin2
(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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