No Dvi Video - Samsung 820DXn Service Manual

4. Troubleshooting

4-4. No DVI Video

Symptom The LED power turns on but the screen is blank when the DVI cable is connected.
-
Check the DVI cable connections.
-
Check whether the LVDS cable is connected correctly to the panel.
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Major
checkpoints
Check whether the lamp connector of the panel is connected correctly to the IP board.
-
Check the circuit related DVI input and scaler operation.
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Diagnostics
Caution Make sure to disconnect the power before working on the IP board.
4-6
Does the LED light up when turn on
the power?
Yes
Does 5 V appear at Pin 14 and 16 of
CN101 DVI port?
Yes
Does the wave form as the figure
appear at R116(DVI_SCL) ⑦ and
R120(DVI_SDA) ⑧?
Yes
Does the signal appear at RA105(R),
RA101(G) and RA103(B)?
Yes
Does the TX** signal appear at Pin 14
and 15 of CN403?
Yes
Check the cable between the main
board and panel
and replace the LCD panel.
CN403
RA103,101,105
R116, 120
CN101
Main Board Front
No
No
No
No
No
Check the power port.
Check the cable connection.
Replace the main board.
IC105 is abnormal. Replace
the main board.
The Scaler (IC408) is
abnormal.Replace the main
board.