Dell 2709W random colored lines/stuff

[elagil]

Hello,

I am trying to repair a Dell U2709W which once switched off with a buzzing sound and did not switch on again. When opening it up, I noticed a blown 250V/4A fuse on the power supply which I replaced.

Now the monitor switches on, backlight works perfectly, button presses are registered but I see strange colored bars (vertical) which change color, flicker in high frequencies and such things though no input is connected.
When I press a menu button I do see a menu on the screen behind the lines but it is barely readable.

What could it be? I already checked the connection to the display which seems to be in good shape.

Thank you in advance!

[elagil]

Re: Dell 2709W random colored lines/stuff

I now had the time to do some tests.

There is a board to which the panel is connected via two flat flex cables (T-Con-board?). I disconnected one of them and took some pictures of the monitor when powered on.

What I can see is, that half of the panel (the one which is not connected) is light grey while the other half shows a static striped image. That image changes with powering the monitor off and on again but not while powered on. I conclude that the panel is not broken but something that handles the signal.

I took a picture of the corner of the panel while the menu is being displayed. You might see that there is something on the monitor behind the stripes.

What could I do next in order to narrow down the possible reasons for the stripes?

Now some pictures. There is some alisasing in those actually:

[elagil]

Re: Dell 2709W random colored lines/stuff

Any idea what I could try next? I do have some equipment for testing (analog scope and multimeter) but I guess that will not help much.

[elagil]

Re: Dell 2709W random colored lines/stuff

Still trying things with this monitor...

I heated up the main board near the BGA-package, especially those CAPS and the image on the monitor changed considerably. Colors went completely towards green/blue, away from red. I even had some regions that went black and which showed the image of the "no signal" thing when it passed by. What can I conclude from that? Could it be worth replacing some of the caps?

I will soon attach pictures of the board but the caps still look decent.

[zwyczak]

Re: Dell 2709W random colored lines/stuff

welcome...

I have a similar problem.
Dell monitor 2709W. Initially, they were horizontal stripes, colorful beacons in several places on the screen. Currently, the entire screen filled with vertical stripes. Is my monitor is yet to recover?

Yours kb

[Ziggidy]

Re: Dell 2709W random colored lines/stuff

I am reviving this old thing to see if there was anyone else with this issue that has been able to resolve it? I have this EXACT issue on my 2709W!

I bought mine brand new back in I believe 2008, and it has probably less than 1000 of use on it. I moved not long after getting it, and haven't a proper desk setup since. Monitor has been stored in closets with other electronics that have NO issues. I pulled it out a few times to use it, and noticed that there was a red stripe on 6 inches of the right side. After being on for a while, warming up, the lines would go away. This was probably in 2015 or 2016 I believe. NOW, the ENTIRE monitor is covered in the lines, and don't go away.

I pulled it apart last night, checked out the boards I could, and haven't VISUALLY seen anything like bulging caps or burned up components. I put the shielding back on, plugged it in, sure enough red lines still there. I DID notice also there is a pretty bad smell coming off of it and lots of heat after plugging it in.


Is it dangerous to have it plugged in with the boards exposed? I don't know a TON about electricity, I know enough to not touch the caps while or after being powered on for some time.


There is another post for 2709W's, but that is a completely different problem, and I didn't want to post in the wrong thread.

https://www.badcaps.net/forum/showth...ighlight=2709w

[cip]

Re: Dell 2709W random colored lines/stuff

Any updates? I have the same problem.

[sci666]

Re: Dell 2709W random colored lines/stuff

Hi, would be interesting, i bought 2 of them beginning if this week, and they have both the SAME issue ... left AND right, about 6 cm from the border some vertical lines in black, blue, red, green, which dissappears about 15 minutes after powering on..... these are not visible when the picture is black (like on broken display where the defective line shines bright as the sun even the picture is black!!!) so what is the issue ? mainboard problems with heat or faulty caps ? or the ribbon cables ? i want to dissassemble one of them next weekend ...

by the way ,, how can i open the 2709w ? :-D

[img1]

Re: Dell 2709W random colored lines/stuff

Google for "COF issue" (COF = Chip On Film). Sadly not a DIY repairable thing, special equipment needed. I have 3 of these COF failed 2709Ws.