DELL U2311H 2 second issue but works after some try´s

[schnub]

First of all please excuse my bad grammar

One of my DELL U2311H got the following issue:

Push the on button and the screen turns on and shows an image. After a few seconds it turns black and only the blue Power LED is on.

That´s the "2 seconds to black" issue i guess.



But the miracle is that when i try switching on and off a few times, the monitor switches on and the display flickers for a short time (10 seconds or so) and then the monitor works fine till i switch it off.

maybe thats an indecator for this and that to be defect?

could it be bad caps or inverter?

i didn´t open the monitor yet to look for bad caps.

regards schnub

[momaka]

Open it, take pictures, and post them here.

It is more likely a capacitor issue since you can eventually make the monitor work when it warms up. But we will see with the pictures, of course.

[schnub]

ok :P then i´ll strip down the monitor to show some pix

[schnub]

So finally i made some pictures

please klick *here*

hope pictures say more than 1000 words.

i didn´t saw any blown cap´s from my pov all looks fine. but i think also a cap could be altered and not fully working.

i wrote down the specs of every cap i found so maybe i replace every cap that´s on there. do i need DC caps or normal ones?

shouldn´t be that hard to solder?

do ya think the power board is the one that failes or the logic board?

best regards

schnub

[kaboom]

(Not so) Elite, and lelon= change em. "FDAI" on the signal board- change them too.

Nothing on the power board has failed, yet; just those craps are making it act up.

[momaka]

Yup, those Elite and Lelon caps could be up to no good without showing any signs of it at all.

My suggestion is to replace all of the electrolytic capacitors on the power supply board (except for the big Elite 450V cap - those high voltage caps on the input rarely fail when there is no APFC, which there isn't on your power board). Also make sure to replace the two small caps too - I'm taking about C613 and the other small cap directly below it. One of these could be the PSU start-up caps, which is rather important.

As for the logic board - generally the caps on it rarely cause an issue, even if they are of an inferior brand. But changing them is never a bad idea. Plus, if you are already ordering caps for the power board and paying shipping, ordering a few more small caps will not cost you that much more.

[kaboom]

Originally Posted by momaka

As for the logic board - generally the caps on it rarely cause an issue, even if they are of an inferior brand. But changing them is never a bad idea. Plus, if you are already ordering caps for the power board and paying shipping, ordering a few more small caps will not cost you that much more.

I'll add to this- I should've mentioned this in my above post. Sometimes, the heavy ground planes in those logic boards is too much for underpowered soldering irons. What works well for soldering the power board may be borderline on the logic/signal board. But it won't hurt to list/order new caps for it, even if just recapping the power board for the time being.

Those black/gold lelons look really cheep- almost like low-end, worse than usual (ha!) OSTs. Without the "dimpled" vent stamp, of course. Those are quite likely (beyond?) junk.

[schnub]

First, thanks for the answers!

Nice to know that DELL uses those cheap caps

I will order all caps except the big one and re-solder all of them

Panasonic caps should be fine?

i´ll keep you guys informed if it worked. this weekend i should get this done.

[momaka]

Originally Posted by schnub

Panasonic caps should be fine?

If you get FC, FK, FR, and FM series - YES. Here is a bigger list of caps that are generally suitable for power supplies and monitors:

Manufacturer................................Series
Nichicon ................................ PW, PM, PS, PJ, PV, HE, HD, HW
United Chemicon (UCC) ............ KY, KYA, KYB, KZE, LXV, LXY, LXZ, KZH, KZM
Panasonic .............................. FC, FK, HFQ (old stock only), FR, FM
Samxon ................................. RS
Rubycon ................................ YXJ, YXG, ZL, ZLJ, ZLK

[schnub]

i got the FC Series of Panasonic should arrive here tomorrow.

i also got a heatable desoldering pump which should make things pretty easy i didn´t think that it would be hard without but im kinda lazy guy ^^ and the pump wasn´t that pricy.

i´ll let you know on the weekend if it worked or not

[schnub]

so... soldering done, changed all the caps from the power supply except the big one. all solderings are good, contact wise.

but... no change

maybe it needs less on and off switch cycles to turn the monitor finally on, but that´s not a big change didn´t try that so often.

maybe is the backlight flickering (bright, a little bit darker, bright and so on, for about 10secs) after the monitor finally stay on the issue?

or should i change the caps on the logic board too?

[budm]

It sounds like you need test lamps to narrow down the problem:
http://www.badcaps.net/forum/showthread.php?t=19987

[momaka]

Originally Posted by schnub

so... soldering done, changed all the caps from the power supply except the big one. all solderings are good, contact wise.

but... no change
...
or should i change the caps on the logic board too?

Yes, change them first.

It could indeed be the lamps, as budm suggested. But it could also be those small caps on the video/logic board, which is why I suggested you get replacements for those as well. Some monitors (like the Hanns-G HG281D) are notorious for this issue.

If that doesn't work, then at least we know all cap-related (potential) problems should be eliminated and what you have left is likely either an inverter or lamp issue.

[schnub]

hi guy´s

today i totally messed up the monitor

at least i know the "solution" or the error.

i had turned down the brightness to 60 or so and the monitor stays on every time. that worked for 3 days or so.

now i wanted to check if its the case at 100% brightness and yip 3 seconds to black and doesnt stay on.

i tryd to reset with holding 5 seconds the power button with everything unplugged but no change.

(((

maybe its the inverter transformer ?

[stj]

more like worn tubes.

[budm]

Worn out lamps.

[stj]

lamps or led kit.
http://stores.ebay.com/lcd-led-parts