LCD Monitor problem

Okay... now I'm going to scream...

I started looking at the monitor again today after work, couldn't figure out any more about it. Then about an hour later went back to try a few more things... and it just worked when I turned it on.

I literally didn't do anything that should've changed anything about it. This is after not working at work for a month or so. I just took it when they gave up and were throwing it out.

I hate electronics :)

Well, I'm happy to say that now the monitor appears to be working mostly correctly.

It won't come back from sleep mode, but turning it off and back on brings it back.

Also there's a slight darkening of the picture at three corners, but nothing that's going to bother me. (unless someone has an idea of what that would be and it's an easy fix). I suspect it was more than likely somehow caused by me during the inspection/repair process. Who knows.

Anyway, thanks for the tips/help.

Sounds like the CCFL backlights are marginal and starting to fail. It's common for backlight inverter modules to shut down when they detect an incorrect load, such as bad lamps, so perhaps that is where your problem lies.

Dave

My 15 inch HP lcd monitor has a red tint to the screen...any adjustments or trouble shooting hints please......thanks

Possibly a bad VGA cable of bad ccfl lamps.

I'd bet on VGA cable.

- Mike

Thank you Mike....that gives me a start....I don't know how they generate the color on these.....I'd like to get a how to repair book on these....not to many guys know anything about them.....thanks again

Well there isn't much to most LCD monitors from my experience.. I've just started reparing them recently and most problems are related to bad capacitors or bad lamps.

The reason you don't find much info on them is there isn't nearly the amount of components inside one compared to a CRT monitor. Usually all they have in them is an inverter board wich powers the flurescent lamps in the lcd panel and a control board which handles video signal processing..

- Mike

Is there any books out on the repair in general?? and the lamps I can google and see what they look like .....thanks again

Thus spake lurk:

Your CCFL lamp has reached "end-of-life". They go pink when they are old.

jkl lamps.com has lamps and some links to articles showing how to do this. It's pretty straightforward, but not for the faint-of-heart.

Good luck,

Here are some links to help you out..

This appears to be a quite long article, but has no pictures which makes it not so good.

The stright bulb on this page looks like your typical ccfl lamp.

You can buy ccfl lamps at

Yet another article..

Just google LCD backlight or CCFL backlight.

You can somtimes find free service manuals for whatever monitor your working on at

One word of caution if your changing ccfl lamps.. They BREAK VERY EASY if your not careful.

- Mike

Mike, speaking of parts, have you found a source for inverter transformers capable of supporting 2 19" lamps? I'm guessing the transformers will have to be rated at about 14 to 16 watts to handle the bigger lamps. Digikey has inverter transformers but they seem to stock only the smaller ones which are good for screens up to 15". Thanks, Dave

I picked up a used Micron AP150T at our town's recycling center. It cost me nothing, so there is no loss if I can't figure out what's wrong.

When I hook it up to a computer, all works just fine. Then the picture starts tearing horizontally after a few moments of on time. When I hit the Function key, the function block pops up and looks perfectly fine while the picture behind it is tearing.

So I assume that the sync signal from the computer is somehow being lost. It does the same with two different computers, so the computer output is not the problem; the computer outputs are fine with other monitors.

Any ideas? Is there a know problem with this unit syncing to the VGA signal?

Al

Does it always happen after the same time period? Also when you don't allow time to cool down? Perhaps it's simply a connection somewhere which gets interrupted when the monitor warms up.

Do you have a scope? If so, you could track the input sync signals in the circuit, and find out where it gets mixed up. If all VGA signal enters the ADC correctly, then the fault will be a bit more difficult to find...

Bad electrolytic capacitors are fairly common and can cause any number of strange symptoms. That's where I'd look first, the surface mount sort used in flat panels tend to be especially troublesome.

OK, I'll do the check with the 'scope. And the time of the start of the tearing does vary with the interval between startups; something must be temperature sensitive.

Al

That does not rule out capacitor based problems. I've repaired several mainboards which had leaky capacitors, which worked fine as soon as they were warm. It's the opposite to what you're experiencing, but it illustrates that caps are temperature senstive.

ere

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If this is a crt monitor, there could be a high-voltage arc that is not high enough to be seen or heard, but is generating "noise" that is being picked up by some other circuit. A scope would be invaluable.

Capacitors are very temperature sensitive, more so than any other part I can think of, aside from those meant to react to temperature.

Judging by the subject, I would say it is not a CRT :)