W241D (W240D) flickering Problem

[Stefan Payne]

Re: W241D (W240D) flickering Problem

Oh, nice to see that someone else has the same problems with this screen I have.

The main problem here is the lack of airflow and thus some kind of overheating problems.
If you take a look at the white plastic thing on the back, you know what I mean.

prad tested it and you can't really see what I mean...

I 'fixed' the problem with my W241 by removing the white plastic thing on the back. Now it does not flicker anymore. And well, I don't really use it anymore...


PS: Power Consumption is somewhere between 40 and 120W with this thing...

[Leontius]

Re: W241D (W240D) flickering Problem

Yes, you're obviously right. These are surface mount electrolytic capacitors. Sorry for the confusion.

[selldoor]

Re: W241D (W240D) flickering Problem

I'm confused now. I thought that 100 should be read as 10 x 10^0 pF = 10 pF?

Maybe the confusion is that they have been described as ceramic caps.
I believe they are surface mount electrolytic caps. The notation/marking you are using is the one used on ceramic caps and my understanding is that the 100
is in fact 100uf - the same as on an ordinary through hole electrolytic cap .

[luismcv]

Re: W241D (W240D) flickering Problem

I'm confused now. I thought that 100 should be read as 10 x 10^0 pF = 10 pF?

[Leontius]

Re: W241D (W240D) flickering Problem

Did you mean ceramic? 10pF electrolytic ones don't seem to be easy to find. Or am I reading incorrectly their value and they aren't 10pF?

The creamic ones ("100 16V H86", it must stand for 100μF 16V) were replaced with electrolytic Jamicon 216C2(M) 105 ℃ 100 μF 50 V. To be honest, I don't know wheter the Jamicons are Low-ESR or not.

After a few weeks I can say that the monitor works all the time with closed case and there are no problems any more, even when the weather is very hot (>30℃ outside without air conditioning, no problems).

A line flickering ??
Is it a single pixel line ? horizontal or vertical ?

Something like this, but it usually starts with single line and then goes on.
https://www.youtube.com/watch?v=c33qWjzYtfk

[bammbammfran]

Re: W241D (W240D) flickering Problem

A line flickering ??
Is it a single pixel line ? horizontal or vertical ?

[luismcv]

Re: W241D (W240D) flickering Problem

They can be replaced with electrolytic ones. Worked for me.

Did you mean ceramic? 10pF electrolytic ones don't seem to be easy to find. Or am I reading incorrectly their value and they aren't 10pF?

[Leontius]

Re: W241D (W240D) flickering Problem

Try replacing the two capacitors marked with yellow circles on this picture:



They can be replaced with electrolytic ones. Worked for me.

[HaHe]

Re: W241D (W240D) flickering Problem

Just to confirm what "konecma" said in his post...
I had the line flickering going on for some time now and it got worse and worse. So finally I took the Monitor apart and did an ESR check on the caps. I did not google beforehand so I wasn't aware that this seems to be quite a common problem with this monitor. The fact that the problem got worse over time and also got worse after prolonged use clearly pointed to something like a caps issue - therefor the ESR check. However the "usual suspects" - the caps on the powerboard surprised my quite a bit.
The ESR values of all caps were excellent and after desoldering some of them to also measure their actual capacity these values also proofed to be a lot better than I expected after a few years of heavy use.... - So the caps on the power-board certainly were not the culprit.
Just short of giving up I decided to check the ESR of the SMD Caps on the logic/interface board and ...- surprise ! - A few of them had really bad ESR values (at least compared to the others with the same capacity value right next to them). However desoldering these proofed quite a bit of work but I finally succeded with a hot air reflow station. I replaced those caps (I had no fitting SMD caps available arround so I used standard low-esr ones), put everything back together and ... the Monitor has been up and running now for almost 20 hours without any jittering ...
It used to be hard to find ESR testers but nowadays there are quite a few available. If you don't have one available just replace all larger values caps (>= 47µf). The only problem that I can forsee is the desoldering. The solder pads can be easily ripped off from the pcb and the layers of the pcb are quite good heatsinks so desoldering takes a bit of work.

[konecma]

Re: W241D (W240D) flickering Problem

Hello,
i have thist LCD W241D and i had similar problem - flicekring
3monts ago i was install pasive cooling system, fand monitor was OK aprox for 1 month
after this month same problem

1.5 month ago i was recaps w241d power board no effect
i was recaps lcd driver board and LCD is OK for this time.
regulator ICs temp before recaps was aprox 60C now is 33C

So i belive that recaps can solved flicekring problem

[luismcv]

Re: W241D (W240D) flickering Problem

...going back to topic.. anyone already got a solution for the flickering problem on the W241D problem ?!

Not a proper solution, but as I mentioned earlier in the thread I kind of solved my issue of overheating by attaching an old heatsink to the graphic chip and leaving the monitor's plastic back cover removed. You could try with only one of those things, although in my case I need both; only removing the cover wasn't enough and I also tried to put the cover back and despite the heatsink, the flickering came back.

Lowering the brightness setting can also help to reduce the temperature.

And I read somewhere that someone had also "solved" his problem by installing a small fan in the cover to force ventilation, but personally I prefer to avoid the possible noise.

[storexxm]

Re: W241D (W240D) flickering Problem

...going back to topic.. anyone already got a solution for the flickering problem on the W241D problem ?!

[Glorfindal]

Re: W241D (W240D) flickering Problem

Sorry for hijacking this thread (new member cant make my own yet ) I have a problem with screen not coming on all the time when turned on, sometimes the red light comes on and other times it goes blue but I get the 3 coloured bars across screen changing to all white then all black, to rectify this if I turn the moniter on/off a few times I get it to start working, I've had the moniter apart and there doesn't seem to be any blown capacitors, is there a way to check them whilst still attached to board or do I have to remove them?


thanks in advance for any ideas and once again sorry for hijacking thread.

[nnname]

Re: W241D (W240D) flickering Problem

Talking about ripple, can you say the overheating problem could be possibly caused by bad capacitors?

[luismcv]

Re: W241D (W240D) flickering Problem

I have remeasured both regulators' outputs, this time paying more attention and writing down the numbers

Reg 1: 3.27V, around 30 mV ripple peak-to-peak most of the time, although sometimes it can reach 50mv.
Reg 2: 1.75V, similar 30 mV ripple. This one seems more stable.

What has a 0.2-ish V ripple is the 5V input of the first regulator (which I guess, comes directly from the PSU). This is probably what made me mix up the orders of magnitude.

[luismcv]

Re: W241D (W240D) flickering Problem

Hmmm, I most probably misread the amplitude and didn't think it over and check it again :/. It actually makes sense, because 0.25V out of 1.8V would have been quite obvious in the wave shape, and it wasn't.

When I get some spare minutes I'll open the monitor again and recheck.

[budm]

Re: W241D (W240D) flickering Problem

The AC ripple at the output of the regulator should be 20~30mV range, if the swing is like 0.25V that means the DC output will vary by that much.

[luismcv]

Re: W241D (W240D) flickering Problem

I've been having this same issue for some time, but it wasn't so bad, just a few shakes every few minutes when the monitor had been on for some hours. But in the last couple of days it went crazy; with some graphic patterns the screen wouldn't stop shaking. And that's how I found this forum.

My findings are the same: if I cool down either the regulators or the graphics chip, the shaking stops.

I checked all pins of the regulators with an oscilloscope as suggested here, but I couldn't see any differences between cold and warm. The outputs are a bit noisy (approx. 0.20-0.25V of amplitude), but I don't know if that's within their expected tolerances.

In any case, I've "solved" the problem by attaching the heatsink of the processor of an old router to the graphics chip and leaving, at least for now, the plastic back cover of the monitor removed. So far it's been working fine for quite a few hours, even without the random shake I used to experience. If if carries on working fine for some days, I might try to put the cover back.

One thing that has surprised me is how clean the inside was despite close to 5 years of almost daily use, which I think says a lot about the poor ventilation it has.

[budm]

Re: W241D (W240D) flickering Problem

Then what voltage output of the regulator when it it is warm and when it is cool? May have to look and see if it is oscillating which can be due to bad filter caps.

[Leontius]

Re: W241D (W240D) flickering Problem

Flickering is proportional to temperature, the warmer the regulators are, the bigger part of the screen flickers.