Samsung C24FG70, flickering on half the screen.

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Repair guides for displays (or monitors) for computers or other devices with video output.

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Valentin @delfyr

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Postato: 10 dic 2023

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Samsung C24FG70, flickering on half the screen.

hello, I purchased a Samsung C24FG70, and the screen displays flickering on half of the screen.

To be more precise, when the screen is 144hz half of the screen is displayed. But when I reduce the hertz (120hz, 60hz), the whole screen crackles.

(Screen with 60hz) :

also, the screen menus are not a display problem, it is just what windows displays. It seems to be a frequency problem, but I bought a displayport 1.2 cable.

If anyone has a solution, that would be wonderful!

This is what happens when I switch to 144hz :

I think we have the culprit of our problem... as we can see it seems that 2 screws of the support were screwed too much, and it reached the motherboard.

I'm not sure if it's really serious on the left side. But on the right side it completely broke a small chip, called K7? (maybe K72).

Does anyone know if I can find this chip somewhere? or if I have to buy a motherboard, knowing that it will cost me almost as much as a new screen...

@oldturkey03 Today I tried to make the first connection, to master the technique. But I had a problem. I managed to make the copper visible, and I tried putting tin on it.

After putting the tin on the lower part of the connection, I tried to put the 0.1 mm copper wire. But when lifting the soldering iron with the tin, the copper wire clings to the tin on the iron, instead of soldering to the card. I don't know if the problem comes from the fact that I potentially put the tin wrong on my copper wire, or on the traces?

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@oldturkey03 Okay, tomorrow I'll open the screen and send you this, hoping we can find a solution.

10 dic 2023 da Valentin

@oldturkey03 It seems that the problem comes from a screw that is too tight. I included photos in the original post.

11 dic 2023 da Valentin

@oldturkey03 Hello, so I've been trying for 3 days, and I can't. My copper wire refuses to solder to the copper of the PCB, even though I put tin on it. And when I put my copper wire on it and I place the tin with the soldering iron on the wire, the wire comes up with the tin. Sometimes I can hold it in place, but the wire sticks to the flux, but doesn't solder. I have the impression that by dint of putting flux in my different tests the card becomes sticky, and I wonder if that's why it doesn't hold. However, I regularly use isoprophylic alcohol, but it remains sticky. Do you have any advice?

18 dic 2023 da Valentin

@delfyr yeah it's not going to look pretty. maybe a bit to much heat so it lifts the traces. That is the toughest part, to hot the traces lift not enough heat and it wont stick. It does not look to bad, It might be that the wire needs more heat then the traces. You could always try solder lugs somthing like this and some low melt point solder

18 dic 2023 da oldturkey03

@delfyr get an old bored from something and try it out. Get the feel for it. See what temps, solder and definitely FLUX, will work for you. Develop your own technique is just as important as the right material

18 dic 2023 da oldturkey03

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@oldturkey03 Okay, tomorrow I'll open the screen and send you this, hoping we can find a solution. — Valentin
@oldturkey03 It seems that the problem comes from a screw that is too tight. I included photos in the original post. — Valentin
@oldturkey03 Hello, so I've been trying for 3 days, and I can't. My copper wire refuses to solder to the copper of the PCB, even though I put tin on it. And when I put my copper wire on it and I place the tin with the soldering iron on the wire, the wire comes up with the tin. Sometimes I can hold it in place, but the wire sticks to the flux, but doesn't solder. I have the impression that by dint of putting flux in my different tests the card becomes sticky, and I wonder if that's why it doesn't hold. However, I regularly use isoprophylic alcohol, but it remains sticky. Do you have any advice? — Valentin
@delfyr yeah it's not going to look pretty. maybe a bit to much heat so it lifts the traces. That is the toughest part, to hot the traces lift not enough heat and it wont stick. It does not look to bad, It might be that the wire needs more heat then the traces. You could always try solder lugs somthing like this and some low melt point solder — oldturkey03
@delfyr get an old bored from something and try it out. Get the feel for it. See what temps, solder and definitely FLUX, will work for you. Develop your own technique is just as important as the right material — oldturkey03

oldturkey03 @oldturkey03 Rep: 783,8k 1,1k 894 2,3k · Answer 1 · 2023-12-10T20:13:54-07:00

@delfyr since this is exactly half of the screen, this will be an issue with the monitor. It is time to open it up and check your boards. It is possible that this is a GPU error but it can also be a data error. I am convinced that there is not a setting that will turn your Left hand side (while looking at the monitor) This is most likely a panel error. Post some pictures of your boards as well as how they are organized in the back of this monitor.

@delfyr it most certainly is part of the problem. The bigger issue will be the destroyed traces. Unless you have the tools and the skills to solder jumpers on those traces, you are most likely looking at purchasing a new board. Can yours be fixed? Yes, but it needs some excellent craftsmanship.

@delfyr okay that is a good question. Let's start with the what do you need to do. The green stuff on top of those traces has to come off. That is a tricky part. IT is just a thin layer so you need to be carefully scrape it away. I used to use a scalpel for this. Available at places like Amazon, Tractor supply etc. So you need to be very gentle with that. Of course you can get a small rotary tool to help you with that.

So remove that layer to expose the copper. Then get a piece of enameled jumper wire. Something Like 0.1mm or thereabouts will work. Tin the ends of the wire and tin the exposed copper of the broken trace. Then solder the jumper into place. No, you do not need to follow the original contour. Just make sure you are on the right trace. I prefer to start and end teh jumper a short distance away from the damage area. Once the jumper is soldered in place, apply a UV solder mask to ensure it is somewhat insulated. There are also pad strip available that you can use instead on the wire. I just prefer the wire.

Shopping list

Soldering station

Solder (I prefer a 60/40 solder)

Flux (Amtech NC-559 is my preference)

jumper wire (If you have some thin wired cable you can use the strands from that. I use an old LVDS cable for that)

UV solder mask

UV light

and the above tools to remove the old solder mask.

As with any board level work, make sure you have good light and some sort of magnifying source.

I am sure there is a thing or two which I forgot to mention but this should get you there. If you have never done that, be prepared to practice. To much heat may just lift the rest of the traces :-) not enough heat will only "stick" the jumper on without being properly connected. It'll fall back off :-)

Practice, Practice, Practice

@delfyr That is correct. If nothing else, you could even bypass that whole area and go to the next straight run (Extend your line to the next straight end) Something like this

@oldturkey03 It seems that the problem comes from a screw that is too tight. I included photos in the original post. — Valentin
@delfyr no doubt! By now tightening that screw, is what has destroyed those traces. Just replacing the single component is not going to repair that board. — oldturkey03
@oldturkey03 Do you think that the screws could have destroyed the traces deep enough to create the problem? The problem is that the only motherboard I found costs almost the same price as the screen :x — Valentin
Maybe it's time to learn something new about soldering, and learn how to fix it, since the board is probably ruined anyway :') — Valentin
@delfyr absolutely. Time to get acquainted with the soldering iron and a good magnifying source :-) — oldturkey03

jayeff @jayeff Rep: 450,9k 11 367 1,4k · Answer 2 · 2023-12-10T18:58:55-07:00

jayeff @jayeff

Rep: 450,9k

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367

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Postato: 10 dic 2023

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Hi @delfyr,

Have you checked the display when using Windows in safe mode or when viewing the BIOS menus of the PC?

Just wondering if it is a driver problem as when Windows is in safe mode or when looking at the BIOS menus only generic vga drivers are installed and not GPU hardware specific drivers

If it is OK in safe mode (or BIOS) is a separate GPU card used?

If a separate GPU card then does the PC also have integrated graphics on the motherboard i.e. CPU with graphics capability?

If it has try that. It could be a faulty GPU card or a video driver problem

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I tried, but the screen has the same problem from the bios.

As for the GPU, the drivers are up to date, and I even tried on another computer which has another graphics card, but the problem remains the same.

I also tried connecting it to a console and the problem is the same. It seems that it comes from the screen which is not capable of displaying an image under a certain number of Hz

10 dic 2023 da Valentin

@delfyr

Can you try using a HDMI cable?

10 dic 2023 da jayeff

yes I tried with an HDMI cable, but the HDMI does not go up to 144hz, so the image crackles entirely. I was only able to get half the image with a DisplayPort cable and at 144hz.

10 dic 2023 da Valentin

@delfyr

144MHz should work on HDMI if HDMI is V1.3 or higher.

It seems like the signal processor on the mainboard in the monitor is faulty.

The menus are stored in another chip on another part of the mainboard. Seeing the monitor menus OK means the mainboard → display is OK but not the signal processor on the mainboard.

Not sure what is contained in this software install link for the model as it is a .exe file and I don't have your model monitor.

If you want to try it, scan the file for viruses etc first before opening it.

Otherwise if that doesn't help, if the monitor is new get it repaired/replaced under warranty.

10 dic 2023 da jayeff

@jayeff Unfortunately I already downloaded the driver from the same link, and it didn't work. And I don't have a warranty with the screen... If the problem really comes from the processor, is it possible to analyze it to find out if it's really the fault? and is it possible to replace it easily?

10 dic 2023 da Valentin

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