Blank Screen

August 25, 2008 at 07:14:25
Specs: XP Pro, 3GP4 2G DDR
I have just picked up a used Flat Screen monitor. When first turned on all if fine but after about two mins the screen goes blank and stays blank. If I switch the monitor off for a few moments then on again the screen is ok. After another few moments the screen will shut down again. The power light stays on. Any ideas? Could this be a capacitor? There is a large cap 68mf @ 450V. Or a thermal problem? Mick (UK)

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August 25, 2008 at 14:17:04
Your info is not clear enough.

Is it a flat screen CRT monitor, or an LCD display?

Is this when it's plugged into a computer video port when the computer is running, or when it's plugged into a computer video port when the computer is NOT running, or when the monitor is not plugged into a video port?

Is it going blank as in all white, or as in all black?

If it's going black, if it's an LCD monitor, and this is when it's plugged into a running computer's working video port (if you have more than one and one is built into the mboard, the output from the port built into the mboard is probably disabled) the same things that can afflict the LCD display on a laptop can apply to an LCD monitor.
For some info about replacing a voltage inverter or backlight, and what some typical symptoms are, see response 5 in this:

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August 26, 2008 at 02:55:12
Many thanks for your reply. Sorry for not giving the type of flat screen. It is an LCD flat screen. It is plugged in to the VGA outlet on the mobo. Computer running. Everything is normal for a while(about two mins) then the screen goes Black, as in turned off. I can leave it switched on (monitor) for a short while (about 1 min) then switch off (monitor) and then on again and all will be fine again for about 1 or 2 mins, then it goes black again. The computer is running all this time.I have tried it on another PC with the same result.
Thanks for the link, will look now. Kind regards, Mick. (UK)

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August 26, 2008 at 08:28:27
It can commonly be one of, or both of, two things that could cause your symptoms....
- the backlight is nearing the end of it's life and the voltage inverter is okay but is detecting there is something wrong with the backlight and is switching itself into a lesser voltage mode after a few minutes to protect itself - in that case before that happens you often have already been seeing a tint to the display sometimes for a while - when the screen goes black if you turn the brightness all the way up, you can often make out very dim images some of the time, but not all the of the time, depending on what is being displayed - e.g. you may be able to make out the Windows logo when Windows first loads but not the desktop.

- the voltage inverter is defective - in that case, when it goes black you see no image at any time regardless of the brightness setting. However, some voltage inverters may switch themselves off rather than going into a lesser voltage mode when the backlight is dying.

If you still have a CRT monitor, I advise you to use it until it's image is no longer good enough.

Many people believe an LCD display will be usable longer than a CRT display, but that's not necessarily true. Some brands of LCD displays are warranteed for only one year regarding the backlight, though for better brands that's often three years. I've had CRT displays, which commonly had a 3 year warranty, that lasted as long as ten years. We frequently hear about LCD displays that have developed symptoms like yours in much less time than that.
Even recent LCD displays are not as good as the later CRT displays.
LCD displays cannot display rapid motion as well as a CRT display, and they always have a "native" or "optimal" resolution they look best set to - when set to other resolutions they don't look as good and text is often not as clear in those other resolutions. CRT displays are equally clear in any resolution they can be set to.

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August 26, 2008 at 13:55:46
Many thanks for your in depth reply. I think I will take your advice and continue to use my CRT monitor which always shows a very clear picture, it's a bit bulky on my workshop bench but has always given great service. Best regrds, Mick.

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