What may cause LCD monitor show image for a moment and then go standby

Electrolytic capacitors in the power supply are a good possibility.

I think "Electrolytic capacitors in the power supply" should be step three, after "Turn it off and back on again" and "Is it definitely plugged in."

These three things will fix almost every computer problem :-)

PS - In the instant case, I think it probably *is* electrolytic capacitors in the power supply. I'm sure they've turned it off and on several times, and if it wasn't plugged in they wouldn't see the flash of the loading screen.

Most LCD monitors allow entry to configuration menus, even with no input connected, some by dedicated buttons on the bezel and others by holding the power button. Do those work?

At least on my Dell monitors the LED is blue on startup and yellow on standby.

Power supplies are a common villain, but if you've got an LED at all there's at least some power....

hth,

bob prohaska

yep, I suggested this too at first, but it doesn't react to buttons (except power), hence the suspicion it turns off any image immediately (which is confirmed by quick blink of some picture on power up).

As about blue / orange LED - thanks for hint, perhaps we'll figure out what is what. It is blue when no video cable is attached and turns orange on connecting VGA. But then after startup it again turns blue. We'll see...

Not anwering its own buttons seems like a bad sign. I imagine you've tried any inputs other than VGA, but if not that'd be my next step.

I've got four Dell monitors, the newest is over ten years old. All use yellow LEDs for standby mode.

The behavior you describe is consistent with the monitor not seeing a signal, though I'd expect to wait for at least a few mminutes before closing up shop.

Good luck,

bob prohaska

Dear Friends, as a follow-up of the story, I'm glad to tell that repair was successful, even though not without curious minor incident :)

The girl, my friend, opened the case and eventually got to the power supply board (as usually, the larger one). I explained her your suggestion about search for faulty capacitors and when she sent along the photo, we easily identified a couple bloating ones 220uF * 35v.

Thus I guided her to the local components shop and she replaced them according to my instructions - though as it was her very first experience of handling soldering iron, and my instructions were given remotely - there were minor damages to the traces etc. Thus the thing even stopped blinking as before. Today she brought the "patient" to me and after some puzzling we were able to identify tiny scratch and repair the broken trace. Works like a miracle now, thus the hint about capacitors was 100% exact.

Here come five images:

- two bloating capacitors identified

- they are replaced

- slightly damaged traces repaired

- one last thin trace connected with wire (in lacquer isolation)

- the thing works

She expresses great thanks to everyone and says this was extremely interesting experience :)

Glad to be of assistance.