My dad's computer uses two monitors, and Windows still detects the second one as an extended display. I can move windows into the area where the monitor should be, but the screen itself stays black. When I turn the monitor off and back on, it briefly shows the desktop for a fraction of a second before going dark again. I've tried power-cycling it and unplugging and reconnecting the cable, but the problem has gradually worsened. At first, switching the power button fixed it, then I had to unplug it, and now it remains black. What could be causing this, and is there anything else I can test?
3 Answers
Since the computer detects the monitor and you can move windows onto it, this probably isn’t a Windows display-mode problem. The brief flash followed by a black screen points more toward a hardware issue inside the monitor, such as the backlight, its driver circuit, or the power board. Try shining a bright phone flashlight closely at the screen while a window is on that monitor. If you can see a very faint image, the backlight has likely failed. If there’s no image at all, the monitor’s power or display electronics may be failing.
You can verify the display settings with Windows + P and make sure Extend is selected, but the fact that the screen briefly shows the desktop makes that unlikely to be the cause. Updating graphics drivers would be reasonable for display-detection problems, but it won’t usually fix a monitor that powers on for a moment and then shuts its picture off. The next useful test is swapping the cable and testing the monitor with another device.
It’s still worth ruling out the simple external causes before replacing the monitor. Try a different video cable, a different port on the computer, and a different power cable if one is available. You can also connect the monitor to another computer or game console. If it behaves the same way there, the monitor itself is almost certainly failing. Repairing an older inexpensive monitor usually costs more effort than replacing it, especially if the fault is on the power or driver board.
I tried the flashlight test but couldn’t see any faint image, so it doesn’t seem to be just the backlight.