W241D (W240D) flickering Problem

[tom66]

Re: W241D (W240D) flickering Problem

I may have a spare main board for the W240D available (from a cracked screen W240D), if all else fails. PM me if you are interested. Mine used a Samsung panel.

[xSharkyx]

Re: W241D (W240D) flickering Problem

I may have a spare main board for the W240D available (from a cracked screen W240D), if all else fails. PM me if you are interested. Mine used a Samsung panel.

Hallo,

what would the main board and the shipping to Germany cost ? (If the main board is still available )

Thx

[Yetanfou]

Re: W241D (W240D) flickering Problem

I got one of these monitors for free because it had the jitterbug. In this case it was caused by a faulty - ie temperature-sensitive - 1.8V regulator on the main board. The diagnosis was rather easy: wait 'till the monitor starts jumping, spray some cooling spray (I used electronic cleaner (Isopropyl Alcohol) spray as I do not have 'real' freezing spray) on the suspected component and observe. It stopped jumping around for a bit. The opposite of this method also works: turn the thing on when it is totally cold, the image should be fine. Now point a hot air wand or another well-directed source of heat at the suspected component, the image should start jumping around.

I used an AP1048K18L-13 as replacement. For good measure I also replaced the 3.3V regulator with a TS1084CM-3.3. Farnell managed to butcher my order by shipping me two 3.3V regulators, one of them in a bag marked '1.8V' (which should have contained 2 1.8V regulators, look at the label on the bag) so CHECK YOUR COMPONENTS BEFORE YOU MOUNT THEM! Farnell is not exactly a fly-by-night operation, but mistakes happen. You don't want to end up soldering a 3.3V regulator on an 1.8V bus...

I also replaced all secondary PS capacitors for good measure, some of them have a stated life span of ~2000 hours at 105°C which probably means they're on their last legs by the time these monitors start showing these problems, ie. after 2.5-3 years of use. I used Panasonic FR series as replacements. For less than 10 € in parts I now have a monitor which theoretically should last another few thousand hours...

[retiredcaps]

Re: W241D (W240D) flickering Problem

I also replaced all secondary PS capacitors for good measure, some of them have a stated life span of ~2000 hours at 105°C which probably means they're on their last legs by the time these monitors start showing these problems, ie. after 2.5-3 years of use.

Each 10C increase halves the life. Conversely, each 10C decrease doubles the life.

I don't have an IR temperature gun to measure the inside of a LCD, but my guess is it runs around 55C.

https://www.badcaps.net/forum/showpo...30&postcount=7

[Yetanfou]

Re: W241D (W240D) flickering Problem

As to the temperature around those capacitors I can only guess, but - given that these monitors seem to fail because of insufficient cooling - it is probably higher than 55°C but a lot lower than 105°C. The total parts expenditure for replacing the secondary side capacitors lies somewhere around 5-6 € when bought in smaller quantities, much lower when bought in bulk. Given that the device is in a disassembled state to replace the regulators, replacing those capacitors is not that much more work. The monitor would certainly have worked without replacing them but I see this as a rather cheap and easy insurance against having this thing on my bench again within a foreseeable time frame. The original capacitors now live in the spare parts drawers, waiting to be tested and possibly reused in some or other project of lesser importance.

Completely unrelated: that 'Smilies' frame to the right of the editor is *incredibly* annoying... luckily I can zap it using the 'Remove this object' add-on. I have not gone through the profile settings yet so I don't know if it can be disabled.

[Leontius]

Re: W241D (W240D) flickering Problem

I got one of these monitors for free because it had the jitterbug. In this case it was caused by a faulty - ie temperature-sensitive - 1.8V regulator on the main board. The diagnosis was rather easy: wait 'till the monitor starts jumping, spray some cooling spray (I used electronic cleaner (Isopropyl Alcohol) spray as I do not have 'real' freezing spray) on the suspected component and observe. It stopped jumping around for a bit. The opposite of this method also works: turn the thing on when it is totally cold, the image should be fine. Now point a hot air wand or another well-directed source of heat at the suspected component, the image should start jumping around.

I used an AP1048K18L-13 as replacement. For good measure I also replaced the 3.3V regulator with a TS1084CM-3.3. Farnell managed to butcher my order by shipping me two 3.3V regulators, one of them in a bag marked '1.8V' (which should have contained 2 1.8V regulators, look at the label on the bag) so CHECK YOUR COMPONENTS BEFORE YOU MOUNT THEM! Farnell is not exactly a fly-by-night operation, but mistakes happen. You don't want to end up soldering a 3.3V regulator on an 1.8V bus...

I also replaced all secondary PS capacitors for good measure, some of them have a stated life span of ~2000 hours at 105°C which probably means they're on their last legs by the time these monitors start showing these problems, ie. after 2.5-3 years of use. I used Panasonic FR series as replacements. For less than 10 € in parts I now have a monitor which theoretically should last another few thousand hours...

I did precisely what you described and the screen is still flickering, so I suppose that replacing the PS capacitors and voltage regulators doesn't fix the cause of the problem. Using cooling spray to cool the brand-new regulators does work indeed, but it is very inconvenient because it has to be done every few mninutes. The problem is, WHY are the regulators overheating, and I don't have any foggish idea how to answert this question and how to fix it...

So, if somebody did really fix the problem in some other way than replacing the power supply capacitors and 1.8/3.3 V reulators on the mainboard, or has some other idea what may be causing the problem, please help

[Rtech]

Re: W241D (W240D) flickering Problem

Ensure you have the refressh rate set propely,also try varying the brightness etc and see if that make any difference.

[Leontius]

Re: W241D (W240D) flickering Problem

Changing the brightness does not have any effect. Refresh rate is set properly. It's the kind of flickering you can see here: https://www.youtube.com/watch?v=yfGphxARFY4

[budm]

Re: W241D (W240D) flickering Problem

Leon, That is the LCD panel problem.
Does the screen has separate T-CON board?

[Leontius]

Re: W241D (W240D) flickering Problem

Leon, That is the LCD panel problem.
Does the screen has separate T-CON board?

Yes, I think it has. That is, it has some kind of board under metal screening with a ribbon cable connected to the panel.
https://*************/a/img594/7880/l7tm.jpg
The hidden letters on the metal screen are "LTM240M2".

So, when I unscrew this board, what should I look for?

[budm]

Re: W241D (W240D) flickering Problem

Try re-seating all the cables on that T-CON board, but I think it is the LCD panel itself that is bad.

[Leontius]

Re: W241D (W240D) flickering Problem

I have detached and reattached the ribbon cable, no effect.

I don't see how this problem may be panel related given that the monitor works perfectly for an hour after turning it on, and spraying voltage regulators or the GENESIS chip with a cooling spray effects in a minute (or so) of perfect display without flickering.

[budm]

Re: W241D (W240D) flickering Problem

I expect bad regulator with bad voltage will cause the problem on the whole screen, not just at the bottom part of the screen, but then I am learning new possibility of the cause every day.

[Leontius]

Re: W241D (W240D) flickering Problem

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

[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.

[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

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

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.

[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.

[nnname]

Re: W241D (W240D) flickering Problem

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