LG monitor going off and on every few seconds

Just got a new PC with windows 7. ATI radeon 5850, 4 gigs ram, AMD phenom triple core.

A couple days ago, the monitor (21" LG flatron, about a year old) starts going off for a second then coming back on, then maybe 15 seconds later off again. Sometimes more frequently, sometimes less. I unplugged the dvi cable from the monitor and back of PC, and now it won’t even come on again. The power lights work.

So, I switched out this monitor for my 7 year old 19" viewsonic. The viewsonic works fine. No problems, so it’s not the computer.

I connected the LG monitor to my second computer and it now also works fine. Stays on.

What could the problem be?

It sounds like you have a dead monitor. Do you have another computer you can try it on?

Sync. Check the settings for frequency and resolution you are attempting to display at, specifically if it’s recognized as a generic plug and play.

Flashing in and out is the attempt to sync signal.

EDIT: You may even have an auto-sync button on the monitor that will attempt to resync with the PC, but chances are you are over-driving either the signal refresh or display size.

I shut down the computer, hooked up the LG again, and now it’s been fine. I checked the refresh rate and I have ‘30 hz’ and ‘60 hz’ options. I seem to remember it was on 60 before, but now it’s on 30 after a reboot. Maybe it didn’t like 60. I’ll leave it on 30 and see if it happens again. It does show as ‘generic pnp’ under monitor settings.

I do have an ‘auto set’ button on the monitor. Don’t know if that’s the same thing. I did try that while the problem was occuring, but it didn’t fix it.

Sounds like a winner spatzi. That can sometimes happen using the generic driver as well, so I would keep an eye on what the settings are and possibly check to see if LG has a more specific driver for your OS.

We used to have this happen on huge old tube monitors when engineers tried to drive them at higher refresh or resolution than they were geared for. The monitor will continually attempt to sync from the signal, but in most cases never will.

sometimes one of the buttons on the bezel may be shot, happened to a samsung.

30hz is pretty low, but if you don’t have any eye strain or the screen doesn’t flicker to you, I wouldn’t worry about it. A lot of people (like me) can’t look at anything less than 60hz without headaches or flicker.

What’s bizarre is that I just tried out the ‘60 hertz’ setting and the resolution dropped down to 1280x720 from 1650x1050. I can only get the native res of 1650 by using the 30 hertz (interlaced) setting. Is this normal?

That doesn’t sound normal. Windows 7 could be recognizing the monitor incorrectly, in which case you’re going to have to find a workaround either in the driver you are using, or find out why Windows isn’t driving your specific monitor with the generic driver.

Ok that was weird …

yes, this is a really old post but hear me out.

Also have an old LG monitor that worked fine until I plugged it into an old windows 7 desktop (only 4gb ram but i5 so worth playing about) - blink blink blink, at about five second intervals (steady).

Tried the auto button as suggested above, didn’t work. Had briefly seen a mention of opening task manager somewhere else so tried that, didn’t work. In between blinks, was trying to close the task manager and try something else (don’t know what lol) and hit the maximise button instead.

Got full screen - and the blinking immediately slowed, then, after about 30 seconds, stopped !!

Obviously a soft not hardware problem, will try and install drivers and see if that fixes things. But as a workround, try alt+ctrl+del, then (in between blinks) double click on the top task manager bar to maximise.

Might not work for everyone but another approach to try.

Ok so this is an even later response but it might save someone some pain. I had a dual screen setup with two trusty 25EA63 full HD LG monitors. One started blinking one/off every second, meaning totally unusable. After ignoring it, it would sometimes sort itself out and stop the flicker. Once it stopped it was good until de-powered. I thought it was the laptop (my PC - an Asus N56V, and also very trusty). I figured the video output was on the blink, but then when I switched the monitors around only the one had the issue. Eventually I found the power block was bust. Replaced it and voila, no more blink. I happened to have twin monitors so the power supply test was easy - you might have more of an issue but do get it tested if you can. Ebay has tons of power supply units.

Thank you very much!
You did save me some pain. I troubleshot this issue with my LG 22MP65 monitors and I completely haven’t thought about the power block being the culprit.