No Pc(D-Sub) Video - Samsung 400UX-2 Service Manual

4. Troubleshooting

4-3. No PC(D-SUB) Video

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Symptom Though the LED power turns on, the screen is blank when connecting the VGA cable.
-
Check the D-sub cable connections.
Major
-
Check whether the LVDS cable is connected correctly to the panel.
checkpoints
-
Check whether the lamp connector of the panel is connected correctly to the SMPS board.
Diagnostics
Does the LED light up when turn on
Does 5V appear at Pin 10 of CN101
Does the waveform as the figure at Pin
6 ( H-sync) 4 and Pin 8 (V-sync) 5 of
Check the cable between the main
board and panel and replace the LCD
Caution Make sure to disconnect the power before working on the SMPS board.
4-4
the power?
YES
D-Sub?
YES
IC304 appear?
YES
Is TX** signal sent to Pin 3, 4 of
FT604, FT609?
YES
panel.
FT604 FT609
IC304
CN101
No
Check the power port.
No
Check the cable connection.
No
The Scaler(IC304) is
No
The Scaler(IC303) is
abnormal. Replace the main
abnormal.
board