Samsung SyncMaster LD190G, Service Manual

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4-4
4. Troubleshooting
4-3. When the screen is blank
Symptom - Even though the LED power turns on, the screen is blank when connecting the VGA cable.
Major checkpoints
- Even though the LED power turns on, the screen is blank when connecting the VGA cable.
- Check the D-sub cable connections.
- Check whether the LVDS cable is connected correctly to the panel.
- Check whether the lamp connector of the panel is connected correctly to the IP board.
Diagnostics
CN202
Main Board Front
IC202
X202
Yes
Check the signal cables and
their connections.
Yes
No
Check input part.
No Check IC202 and related
circuit.
No Check CN202 and related
circuit.
Do output signals appear at pins 8 to 30
of CN202?
No
There are DC 5V at Pin 1,2 and 3 of
CN202?
Do the
③
Hsync and
④
Vsync
waveforms appear at pins 32, 33 of
IC202, respectively?
②
Do the RGB inputs appear at R124,
R127, and R131?
①
Is X202 oscillating correctly?
Check and replace the panel.
No
Check and replace the circuits
related.
Yes
Yes
Yes
Check the +5V_Panel signal
and the BL_EN signal.
Yes
Caution Make sure to disconnect the power before working on the IP board.