My dad's computer uses two monitors, and the second one is still detected by the computer. Windows is set to extend the desktop, and I can move windows into the area where that monitor should be. However, the screen itself stays black. When I power-cycle the monitor, it briefly shows the desktop for a fraction of a second before going dark again. It used to start working after pressing the power button, then required unplugging and reconnecting it, but now it no longer comes back on despite repeatedly checking the cables and power. What could be failing, and is there anything else I can test?
3 Answers
A failing backlight or its driver board is a common symptom when a monitor briefly displays an image and then goes black. Shine a bright flashlight very close to the screen while the computer is sending an image; if you can see a faint desktop, the panel is still working and the backlight has failed. If you cannot see any image, the power circuitry, controller board, or panel may be defective instead.
At this point, software troubleshooting is unlikely to help. The gradual progression from working after a power-cycle to only flashing briefly and then staying black points to an aging monitor component, possibly a power supply or internal capacitor. Repair may require opening the monitor and soldering, which is usually not worthwhile unless it is a valuable model. Testing it with another computer or replacing it is the safest way to confirm the diagnosis.
Since the computer detects the display and you can move windows onto it, this probably isn’t a Windows display-setting problem. The brief flash suggests the monitor is receiving a signal but shutting down internally. Try a different video cable, a different port on the computer, and another power outlet if possible. If the monitor behaves the same way with another device, the monitor itself is likely failing.
I tried the flashlight test and couldn’t see a faint image, so it may be something other than the backlight.