Question Monitor turns off when video input is present


Golden Member
Mar 21, 2007
We have a monitor at work that started turning off randomly and now will not stay powered up when there is a signal being sent to the monitor. If I unplug the video cable and just leave power connected and the monitor turned on it will stay powered up and display the prompt that there is no signal. As soon as I plug in the cable, either HDMI or VGA, the monitor will start turning off and back on again. You can visibly see the power LED turn off and on with the display. My first thought is that perhaps the power supply is bad. Unfortunately, it's 19V and the plug is a size that I don't seem to have on hand to test if that's the problem (those barrels should be standard!!! :mad:) I checked the voltage on the power supply and it shows 19V without any load on it.

Anybody seen something like this before? Is it the panel? I don't really want to spend any money buying a new power supply if the panel is bad.


Diamond Member
Aug 11, 2001
Yeah when I suspect a power supply, if I'm going to buy a new one anyway, I'll pop the PSU open and look for burst capacitors or other signs of a fault. If it's sealed shut without screws or latches in the housing, that may require a vise or c-lamp or chisel or saw, etc depending on what's available.

Another alternative is hook a scope up to the power feed to see if it's going crazy when the load increases like it would have been with the monitor change of state when it got an input.

Hopefully at $15 you got a good deal on a major brand PSU instead of a generic which may have a lot shorter lifespan than the original. Than again depending on the age of the monitor, a generic might still last long enough.