Dell U2412Mb

[Gabriel]

Got this from work today - Dell used only low quality foai,lelon and elite caps.

I got 2 foai 10uF that measures around 2.6 - 2.9 ohm measured on board, the rest of the same caps are all 2 ohms or below.
Even tought they measure higher ohm this might be a panel problem and not related to bad caps.

Will have a look tomorrow.

[bammbammfran]

Re: Dell U2412Mb

If that pixel line is the issue, that has nothing to do with the boards.
If you have a different issue, you should at least fill us in on what it is !

[AkumAone]

Re: Dell U2412Mb

Lelon RXW are low esr, high ripple, 105°C 5000-7000 hrs lifetime capacitors, which is pretty top spec for SMPS power supplies. Can`t tell the series of the Elite one, but it is usually pretty got as the main filter capacitor. Only the China Foai are "low quality", but 2.6 -2.9ohm for 10uF 25v general purpose capacitor is not too high.

[Gabriel]

Re: Dell U2412Mb

If that pixel line is the issue, that has nothing to do with the boards.
If you have a different issue, you should at least fill us in on what it is !

Yes just like I said it is most likely a panel only problem.

Lelon RXW are low esr, high ripple, 105°C 5000-7000 hrs lifetime capacitors, which is pretty top spec for SMPS power supplies. Can`t tell the series of the Elite one, but it is usually pretty got as the main filter capacitor. Only the China Foai are "low quality", but 2.6 -2.9ohm for 10uF 25v general purpose capacitor is not too high.

For me Lelon is not a brand known for making extraudenary top spec capacitors as I have replaced a few of them earlier, like another user here said about RXW ' They would technically work, but who knows for how long '

Elite as filter cap is usually good, sometimes they fail sometimes not.
Seem to remember a thread here about low quality filter caps failing, can't seem to find it.

[bammbammfran]

Re: Dell U2412Mb

that pixel line might be a loose contact where the ribbons are connected to the glass with heat activated conductive glue which can not easily be fixed.
If you remove the metal frame around the lcd panel and find the ribbon connection that is closest to that pixel line.
apply a little pressure to that ribbon from the front side in a few places and see if the line goes away.
If it does, you can install a pressure pad there between the ribbon and the metal frame and maybe get some more use out of it

[Gabriel]

Re: Dell U2412Mb

Ahh pressure pad, good idea.

[Gabriel]

Re: Dell U2412Mb

Took panel apart and put some pressure on the ribbon cables but the blue line did't go away - did it several times and more stripes were shown.

Did find the service menu.

Throwing it away.

[bammbammfran]

Re: Dell U2412Mb

if more showed up that easily then the glue had really loosened up over time.
the side on the green board can be soldered (major bitch to do) but the glass side connection can't

[Gabriel]

Re: Dell U2412Mb

I got another identical monitor from work today, this one turns on and operates as it should except that it does not show picture or on screen menu.

Backlight is on as normal, when I change resolution screen 'flickers' as normal, button work as normal ..but no picture.

Ideas ?

[kc8adu]

Re: Dell U2412Mb

the boards from the first can be assumed good.
take 2 and make 1

[Gabriel]

Re: Dell U2412Mb

Hehe well I used some parts from those boards so they are not working any more, I did swap over the flat flex cable but it did not work any better.

[Gabriel]

Re: Dell U2412Mb

About time I finish work on this monitor.

Replaced all caps on both boards and found a dead fairchild 278r12 ldo,replaced it and monitor is working.

If this ldo is dead monitor will still turn on with blue powerlight, backlight will work as normal and screen will 'ficker' when changing resolution on your computer. You will not see osd or picture, if this ldo is dead you will not have 12v on pin 3 (red wire) from psu to logic board.