Dell U3014T moving vertical bar - Page 1
Forum section: electronics / repair

author: james_s
author_rank: Super Contributor
timestamp: February 11, 2018, 09:44:52 pm
content: I'm not a novice when it comes to repairing equipment but I've never seen a symptom quite like this monitor has. It's a Dell 4k monitor which contains a LG LM300WQ6 panel. When powered on there is a slightly flickering white band which slowly scrolls back and forth across the screen. It has one of those annoying capacitive touch button strips that relies on the OSD so I'm not entirely sure what mode it's in but the buttons do seem to respond and occasionally the picture changes to a narrower band down the right-most edge, I assume that's where the OSD appears. Looking inside I see no obvious faults, voltages look reasonable everywhere I checked, unlike the other monitors I have it uses two LVDS cables between the interface and T-con boards so I can't do any swapping for testing purposes. I did some searching and came across a couple of posts from people with exactly the same symptom but no indication of a solution being found.Any opinions on this? I suspect it's either a bad T-con board or a bad interface board, the former seems to be reasonably available but I don't want to throw money at it without having a reasonable idea of where the fault lies. Looks like a nice monitor if I can get it working.

author: KhronX
author_rank: Frequent Contributor
timestamp: February 12, 2018, 01:03:20 am
content: Could that white bar be a "stretched" no-signal prompt? Kinda looks like the rows aren't being driven, for whatever reason.

author: james_s
author_rank: Super Contributor
timestamp: February 12, 2018, 01:08:10 am
content: It could be, the monitor was given to me in this state so I don't know how it behaved when it was working. If I loosen one of the ribbons from the T-con board to the panel I can get blocks on the screen that don't stretch all the way down the vertical axis so I'm reasonably confident that the panel itself is ok.I'd love to find one of these with a cracked panel or even a board to swap for testing purposes. I have a few universal LCD drivers but none that can drive a 4k panel and no compatible LVDS cables.

author: KhronX
author_rank: Frequent Contributor
timestamp: February 12, 2018, 01:50:43 pm
content: Well, assuming it's no more than $20-30 or so, i might be willing to spring for a known-good Tcon board and swap it out, especially if you can return it in case it doesn't fix the issue..

author: Armadillo
author_rank: Super Contributor
timestamp: February 12, 2018, 02:14:27 pm
content: Such T-con board is not replaceable even if you have a TAB, I won't try.Most of the time, its faulty panel.IMHO, Salvage the parts.

author: wraper
author_rank: Unknown
timestamp: February 12, 2018, 02:54:46 pm
content: Quote from: Armadillo on February 12, 2018, 02:14:27 pmApparently you have not ever seen 30" monitor LCD panel.

author: Armadillo
author_rank: Super Contributor
timestamp: February 12, 2018, 03:03:54 pm
content: Quote from: wraper on February 12, 2018, 02:54:46 pmDon't talk nonsense and maybe it would be more constructive for you to tell how 30" LCD panel looks like and advise How to change the Tcon board rather than being absolutely rude.

author: KhronX
author_rank: Frequent Contributor
timestamp: February 12, 2018, 03:11:01 pm
content: Quote from: james_s on February 12, 2018, 01:08:10 amQuote from: Armadillo on February 12, 2018, 03:03:54 pmWho's being rude here?Usually replacing the Tcon is a matter of dealing with a couple screws and a couple ribbon cables.

author: Armadillo
author_rank: Super Contributor
timestamp: February 12, 2018, 03:22:52 pm
content: Can James confirm whether the COFs are bonded to the Tcon board?

author: wraper
author_rank: Unknown
timestamp: February 12, 2018, 03:24:30 pm
content: Quote from: Armadillo on February 12, 2018, 03:03:54 pmMust be impossible to replace.

author: wraper
author_rank: Unknown
timestamp: February 12, 2018, 03:26:43 pm
content: Quote from: Armadillo on February 12, 2018, 03:22:52 pmIf you ever seen 30" panel, you would not ask such question.

author: grifftech
author_rank: Frequent Contributor
timestamp: February 12, 2018, 03:27:49 pm
content: Connect it to a computer

author: Armadillo
author_rank: Super Contributor
timestamp: February 12, 2018, 03:36:52 pm
content: Quote from: wraper on February 12, 2018, 03:26:43 pmI may have not. But please direct your energy into resolving OP problems than continue on your 30" panel. Be Constructive!

author: wraper
author_rank: Unknown
timestamp: February 12, 2018, 03:42:41 pm
content: Quote from: Armadillo on February 12, 2018, 03:36:52 pmYou basically suggested to destroy/throw away $1000 monitor without knowing a thing about it. FYI T-CON was always a separate board for both LG and Samsung 30" panels.

author: KhronX
author_rank: Frequent Contributor
timestamp: February 12, 2018, 03:44:20 pm
content: Quote from: Armadillo on February 12, 2018, 02:14:27 pmQuote from: Armadillo on February 12, 2018, 03:36:52 pmRight...

author: Armadillo
author_rank: Super Contributor
timestamp: February 12, 2018, 03:51:33 pm
content: Quote from: wraper on February 12, 2018, 03:42:41 pmHey, thanks for the info. I may have been bewildered by the COFs distribution.So on with helping OP to save the $1000.BTW, when I say "IMHO" is an opinion and not a assertion. An opinion to salvage the parts but not "destroy/throw away". Please do not exaggerate the worst of things like a kid.I may be wrong about the Tcon being bonded but I did qualify in my assumption of the TAB and it is not the core of the subject problem here.So we look you up to solve the problem and save the $1000 for OP.

author: Armadillo
author_rank: Super Contributor
timestamp: February 12, 2018, 04:16:21 pm
content: Quote from: wraper on February 12, 2018, 03:42:41 pmSo you know a great many things but I have not seen any diagnosis or solution offered by you.Can you confirm whether you are suggesting to change the Tcon board or something?

author: wraper
author_rank: Unknown
timestamp: February 12, 2018, 04:22:27 pm
content: Quote from: Armadillo on February 12, 2018, 04:16:21 pmIt depends on qualification of OP. First I would check power voltages as a general thing. If possible, presence of signals on inputs and outputs of T-CON. But IMO this looks like a good chance for T-CON being bad.

author: james_s
author_rank: Super Contributor
timestamp: February 12, 2018, 08:11:18 pm
content: Wow, I didn't mean to start an argument here.I have connected it to a computer and it made no difference, as I mentioned though the user interface relies on the OSD and I never saw this monitor in a working state so I can't tell what input is selected and whatnot. I can randomly stab buttons and hope for the best but even the buttons are unlabeled. Either way something is clearly broken.The T-con board is trivial to replace, it's held in by a few screws, two big FPC cables to the panel and two LVDS cables to the interface board. I have checked voltages and didn't find anything unreasonable however without any service literature I can only speculate. I did find a datasheet for the panel but I don't have any reasonable way of capturing the signals from the LVDS interface to analyze them in any meaningful way. Since the T-con board is considered part of the panel assembly the datasheet doesn't even describe precisely what it does.I may have to just replace the T-con board and see if that fixes it, I hate to buy parts and then find out the problem is something else. Most sellers won't take returns on something like that for obvious reasons, too many unscrupulous people who will try to return the defective one or damage the new one and then send it back as defective. My whole group was laid off recently so I've postponed any non-essential expenses for the time being.

author: Rasz
author_rank: Super Contributor
timestamp: February 13, 2018, 07:15:35 am
content: Quote from: james_s on February 12, 2018, 08:11:18 pmDell monitors have standardized OSD. I can confirm turned on with nothing plugged in monitor will display 'walking' "no device connected, will go to sleep in 5 minutes" message window = control board(scaler) is most likely working, problem is in the LCD signaling, either tcon or vertical drivers on the edge of the panel.

author: gjvc
author_rank: Newbie
timestamp: October 07, 2020, 12:18:45 am
content: I'm having the same problem on my Dell U3014. I've replaced the timing controller board, but same result.People are seemingly very quick to say "ah yes, the panel is dead." That may very well be true, but what I would like to know iswhat has actually failed. :-)Did you get this resolved in the end? I would very much like to know if it's worth attempting to source a replacement panel for the unit.

author: wraper
author_rank: Unknown
timestamp: October 07, 2020, 12:34:34 am
content: Quote from: gjvc on October 07, 2020, 12:18:45 amSome driver IC on flex cable within the panel. Which of course is impossible to replace.QuoteFor your monitor it's not economical. Nowadays you can get a better brand new monitor for less money than replacement panel for this.

author: james_s
author_rank: Super Contributor
timestamp: October 07, 2020, 04:12:59 am
content: I ended up scrapping it eventually. I don't know 100% that the problem was in the panel but it seemed likely enough and I had no real use for the monitor anyway. Too many projects and not enough time.