Dell U2518D strobing/flashing with vertical lines

[atticus_]

Hi all,

I dumpster dived a 1440p Dell U2518D screen the other day and figured I'd take a crack at fixing whatever issues it may have. I powered it up to find that even with no signal input the screen flashes rapidly when turned on and has vertical lines across it. I disassembled the monitor and took pictures of the 3 circuit boards inside it along the way.

The three circuit boards are labeled "power board l6256-1m", "LED Driver BD L6257-1". and "Interface Board L6127-1". if anyone has schematics for any of them it would be much appreciated if that could lead to knowing what voltages should be where.

I couldn't find any obvious visual signs of damage (anything burned or brown, bulging capacitors) when inspecting the components on the board, but took many pictures of the boards in case anyone could see something I couldn't.

STROBING LIGHT WARNING:
I made an album on google photos, as well as a video of the problematic behavior of the monitor. - if you have any issues with strobing images or flashing, be aware that the problem displayed in the video is quite striking.


I have a multimeter and a soldering iron, and am willing to test voltages and such, but not sure where to start with that. Please let me know if you have any suggestions of what the issue might be, or if you need any additional photos of any particular area.

I have attached a few of the pictures. The rest, and the video (which I was unable to upload here directly), are in the linked album at full resolution.
Apologies if the link goes against forum policy - I wasn't sure how else to show the video.

[mikey5791]

Re: Dell U2518D strobing/flashing with vertical lines

Could be some component failure from your power board.
1.Have you checked all your diodes are not shorted, esp those at PD301 to PD304.
2. Also see what sort of component is hiding under the two heat sink. Check to see if those are shorted.
3. Use your multimeter to detect any dc output from CN501.
4. After power on about 10 minutes use your finger test to feel for any heated component. (Be aware not to touch anything on the primary hot side- you might get electric shock!)