Samsung QLED GQ50Q67TGU turns on and off

[Batata]

Hello everybody,

my TV has a problem. It keeps turning on and off. The speakers are still working, and I hooked up the TV to my PC, and it recognizes it as a Samsung device. I am able to get a stable backlight when I disconnect the cable(I believe it is called the LVDS cable) that connects the left lower board (which is connected to the "main board") and the right lower board. I have tried a taping method I saw on YouTube, where the CLK cables are taped off. In fact, I proceeded to figure out which pin I have to tape off in order to get a stable backlight. It doesn't matter what I tape off, as soon as the 3.3V (I think pin 15) are connected to the right board I get the boot loop. By taping off the 3.3V line, I managed to get a glimpse at the working panel. I saw the QLED picture, but it slowly faded by loosing pixel and lines started forming, and I was left with the backlight. I checked all capacitor and resistors on the lower board for shorts, but I couldn't find anything.

I hope I described the problem well enough that someone can help.I spent 2 nights trying to get something out of the TV, but the fading QLED is the only thing I managed so far.I am curious at what you guys have to say about it and if you can help me.

Best regards

Bartol

P.S. That wasn't the only time I got anything. I also got a short post by disconnecting the PWM BLU lines from the power supply. The picture there was good, but short, since the TV just turned off and back on again. This however happened only once, and I haven't managed to recreate that event.

[EazyBone]

Lines and such is clear indication panel is dead. I would throw it away. Looks like you did a good amount of research to fix already. These 50 inch TVs are garbage.

[Batata]

Thank you for your answer. My search however continues. I just looked at the mainboard and noticed around ten shorted capacitors. Could this be due to my experimenting with the tape? And do you know where i could get the values of those capcitors? I am more and more confused by this TV. I am pretty sure i never checked the mainboard capacitors. But it is so weird that there are so many

[Diah]

Thank you for your answer. My search however continues. I just looked at the mainboard and noticed around ten shorted capacitors. Could this be due to my experimenting with the tape? And do you know where i could get the values of those capcitors? I am more and more confused by this TV. I am pretty sure i never checked the mainboard capacitors. But it is so weird that there are so many

No way... you are doing wrong... one clear photo better than 100 words... show please yours whole the back and yours mainboards

[Batata]

https://www.dropbox.com/scl/fi/81pii...=3a7xxqo4&dl=0
https://www.dropbox.com/scl/fi/st3xn...=ym0bjw1s&dl=0

I am sorry. I am just now realizing those were probably resistors. Still, the resistance is really low, I am reading 0.0-0.1Ohm. My Voltmeter can't give a more accurate reading than that. Is it worth it looking into it? I am kinda new to this, and thought smd resistors are usually labeled.

[lotas]

And these are not even resistors, but chokes, and they always have low resistance.

[Batata]

But there are also some with high resistance?

[Batata]

Anyway, could someone explain to me what the problem with the 3.3V line is. My guess there is a short in the panel to the ground and the short triggers the circuit protection. Is there a way to find out where the short is and somewhat get the picture. I put so much time into this, and it feels so disappointing not getting out of it. I would be happy if I just got a picture regardless of the quality, so I can sell the main board and the power supply with good consciousness and throw the panel out the window at the next party :p (last part is obviously a joke).

[Diah]

But there are also some with high resistance?

connect this 2 points together.... and then on the Panel buffer boards you have links and right ribbon cable disconnect one a time check there are no reboot and to see which side of the screen defect.

[Batata]

Yes, the backlight works with the "extension" to the right buffer board disconnected. But I am still only getting backlight and no picture whatsoever...

[Diah]

Yes, the backlight works with the "extension" to the right buffer board disconnected. But I am still only getting backlight and no picture whatsoever...

post photo here... of yours panel buffer boards left and right... dont use external site,, you can upload here

[Batata]

Sry for the speakers standing in the way.

[Diah]

Sry for the speakers standing in the way.

did you put the jumper i asked you between the 2 point?
did you remove the masking you did before?
post close photo of the last 10 cm at the end of the panel buffer boards which you disconnected..

[Batata]

Really appreciate the help. I can't pick which side I connect the motherboard with. The main ribbon leads to the left side, and a smaller (U-shaped) ribbon cable leads to the right side. By connecting the 2 points, it doesn't matter if the small ribbon is connected or not, the TV keeps turning on and off. Without the 2 points connected, the small ribbon has to be detached to keep the TV on. No more masking tape anywhere. (Probably irrelevant, the small ribbon has up to 3 Ohms on some wires. I don't know how this would affect anything, but maybe someone does...)

[Davi.p]

hi, you have private message.. check out

[Batata]

Update: by taping off(sheer luck) i got a completly white screen meaning most of the pixels are still good. I'm 99% percent sure I saw few dead pixels. I'll post wich pins I masked of next and wich ones are Maske off in case it can help someone.

Also there are some vertical lines visable but i think it is due to more pins disconnected than neccessary. The Tv is refreshing in vertical lines basically.

++the chips heatsing on the mainboard is getting very hot. Dont know what the temperature there is supposed to be but could be the potential problem

[Diah]

why you are happy so much... scrap it if you don't see image ... white screen are different story.

[EazyBone]

Agreed. 🗑️

[Batata]

Short Update: I didn't stop, because I am doing it for fun more than any other reason. I noticed that, by taping of the VGH pin to the right buffer board I get a constant QLED picture on boot up, but the TV still turns off(I got a milisecond of half the regular TV home screen once). Other than that, no new discoveries I don't really know where else if could look. Does someone know what kind of resistance I should get after the small resistors next to the testing points towards the end of the boards? I will try contacting Samsung for some kind of schematics if they can provide it.