DCLCD DCL9A 19" LCD screen touchy when warm

[dood]

Got this LCD screen in from a remote user who complained that it would shut off every so often. I hooked it up to my machine, and it worked fine for about 4 weeks. Then, suddenly, I couldn't get it to stay on. The screen goes dark, but the power light stays on solid as if it were still operating.

Opened it up and found that it was full of Elite caps on the power supply board. None of them were visibly bad, but I decided to replace them all with panny FM's. After doing that, it still has the issue. What I've noticed is this:

Once the screen is warmed up, if you give the desk a good jolt (or set your coffee cup down), the screen will shut off. When it's cold, this isn't an issue. But once it warms up it'll do it every time.

I went through and resoldered all the connections for the transformers, as there's one that's making a hissing noise. Didn't seem to help. Should I assume that these transformers are just shot, and try to find replacements? It's a single-sided board and is nice and easy to solder on

[Rainbow]

Re: DCLCD DCL9A 19" LCD screen touchy when warm

Look for bad solder joints.

[dood]

Re: DCLCD DCL9A 19" LCD screen touchy when warm

I did... and resoldered everything that looked iffy... still no luck!

[garfield2000]

Re: DCLCD DCL9A 19" LCD screen touchy when warm

it's a bad solder joint. use a magnifying glass to locate that bad joint. as the unit warms up it heats the bad joint causing intermittant problems

[dood]

Re: DCLCD DCL9A 19" LCD screen touchy when warm

I still have this LCD, and am still trying to repair it. I opened it back up and resoldered EVERY joint on both boards. Still, hte problem remains. It worked for a while, then shut itself off. I still think it's one of the transformers (the one that's hissing), because after it shuts off, it's silent. Now I just need to try to figure out which one I need....

[tvtech]

Re: DCLCD DCL9A 19" LCD screen touchy when warm

Its a solder joint,prolly an SMD resistor or transistor on the inverter board,a bad transformer doesn't act like that,there either good or bad.

[Krankshaft]

Re: DCLCD DCL9A 19" LCD screen touchy when warm

Make sure your monitor is plugged into a video source during this test.

When the monitor shuts down and the green light remains on try shining a flashlight on the LCD do you see an image?

If so then the power supply portion that supplies the mainboard is functioning.

If you resoldered every part on the board and the board or its traces aren't broken anywhere. Then there is only one remaining option.

You have a thermally intermittant component if the screen still shows an image when you use a flashlight the issue is on the inverter side of the power board.

There is only one way I know of to track down these components.

When the monitor shuts down and starts acting up blast the suspected component with freeze spray and see if the monitor stops shutting down.

If so replace that component.

Here is a site that sells the spray:

http://www.allelectronics.com/cgi-bi...0_OZ_CAN_.html

This stuff is also good for coaxing intermittant solder joints out in the open as well but since you have already exhausted that option a thermally intermittant component is the only other thing I can think of.

[gonzo0815]

Re: DCLCD DCL9A 19" LCD screen touchy when warm

I have seen a similar issue, it turned to be out a bad solder joint on one of the video IC. Another possibility could be that one of the connectors is not well seated. I have had such an issue with a monitor, the connector was not seated well, but i overlooked it, as it was held by the original factory glue.

[Sixmark]

Re: DCLCD DCL9A 19" LCD screen touchy when warm

I know this post was from a long time ago, however I happen to be working on one at the moment. I did notice that the OP made no mention of checking the caps on the inverter board, only resoldering joints. This is the 3rd one I have had in here now that had a problem with the caps on the inverter board, 2 had a flashing power light and one was a steady light, however the 470uF caps on the inverter board turned out to be the issue with all 3 units.......odd, yes I know but this is life in the world of electronics.