No Dvi Video - Samsung 400UX-2 Service Manual

4. Troubleshooting

4-4. No DVI Video

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Symptom The LED power turns on but the screen is blank when the DVI cable is connected.
-
Check the DVI cable connections.
Major
-
Check whether the LVDS cable is connected correctly to the panel.
checkpoints
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Check whether the lamp connector of the panel is connected correctly to the SMPS board.
Diagnostics
Caution Make sure to disconnect the power before working on the SMPS board.
4-6
R308,R326,R329
R133,R135
Does the LED light up when turn on
the power?
Yes
Does 5V appear at Pin 14, 16 of
CN101 DVI port?
Yes
Does the waveform as shown in the
image appear at R133(DVI_SCL) 6
and R135(DVI_SDA) 7?
Yes
Does the TMDS signal appear at
R210 ~ R219?
Yes
Do signals appear at R332, R333
(red), R308, R326 (green), R330 and
R331 (blue)?
Yes
Does the TX** signal appear at Pin 14,
15 of CN603?
Yes
Check the cable between the main
board and panel
and replace the LCD panel.
CN603
R330,R331,R332,R333
IC205
IC302
R210~R219
CN101
No
No
Check the cable connection.
No
Check the IC205 and if it is
No
Check the IC302 and if it is
No
No
abnormal. Replace the main
Check the power port.
Replace the main board.
not normal, replace the IC.
not normal, replace the IC.
The Scaler (IC303) is
board.