Samsung S22A350H - 4-3. When the screen is blank (Analog)

4-4
4. Troubleshooting
4-3. When the screen is blank (Analog)
Symptom - Even though the LED power turns on, the screen is blank when connecting the VGA cable.
Major checkpoints
- 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 Main board.
Diagnostics
CN400
X401
IC400
Yes
Yes
Check the signal cables and
their connections.
Check and replace the circuits
related to X401.
No
① Is X401 oscillating correctly?
② Do the RGB inputs appear at R106,
R110, and R113?
Check the R106, R110, and
R113 input terminals.
No
Yes
Check the circuits related to
IC400.
Check the circuits related to
CN400.
Check the +5V_Panel signal
and the BL_EN signal.
No
No
No
Do the ③ Hsync and ④ Vsync
waveforms appear at pins 38, 39 of
IC400, respectively?
Yes
Yes
Yes
Do output signals appear at pins 8 to 30
of CN400?
Is DC 5V measured at pins 1, 2, and 3
of the CN400?
Check and replace the panel.
Caution Make sure to disconnect the power before working on the Main board.