LG 42LT777H Service Manual page 20

Power-Up Boot Fail Trouble Shooting guide
Check P2401 All
Voltage Level (3.5V, 12V, 24V)
Y
Check Q2407 output Voltage(12V)
Y
Check LVDS Cable
Y
Check LCD Module
Control board
No OSD Trouble Shooting guide
Check P2401 All
Voltage Level (3.5V, 12V, 24V)
Y
Check IC8701 RESET and
UPDATE pin
Y
Check X8700 Clock
32.768KHz
Y
Check IC8701 IIC
Communication status
Y
Check IR input state of IC8701
57pin
Y
Re-download PTC Micom
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Only for training and service purposes
TROUBLESHOOTING
N
Check power connector and
RL_ON signal OK ?
N
Check Q2407 application circuit
Or replace Q2407
N
Replace Cable
N
Check power connector and
RL_ON signal OK ?
N
Check switch SW8700, SW8701
N
Check X8700 application circuit
or Replace X8700
N
Check IIC line or replace IC8701
N
Check IR board
N
Replace Power Board
N
Replace Power Board
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LGE Internal Use Only