what to repair on TV with bootloop with artifacts

Nagby · February 22, 2022

Hi, the TV model is : Samsung UE49MU6405U

It was given to me because it wasn't working, but when I received it, everything worked fine.

Although, one sign of misbehavior was when my fridge compressor turned off, 80% of the time, the TV would shut off for a seconde or two.

I could use this TV with this behavior for around 2 month

One day when this happened, I got those artifacts when it got back on :

turning off and back on the TV wasn't enough, I had to unplug it's power and plug it back in to get a normal display.

But since 1 week (2 weeks after the video) I can't get past the boot screen, and just turns on and off with subtle artifacts :

That's really how it looks, not because the picture is from the side : right part of the logo is fine, left looks more like blue lines + sometimes a white bar at the bottom appear with the same artifact (where the TV menu usually appeared).

When openning the TV, I couldn't see any damaged components or badly plugged connectors.

I tryed buying a replacement power supply for 50€ (brown PCB) but the problem is still here.

I tryed unplugging each components separatlety (power button, wifi antena, speakers, backlight, LCD panel)

the TV start normally (backlight stays on for more than 10sec) when either of the 2 LCD panel cables are removed. (but no image on the screen when only 1 LCD cable is plugged in)

I saw this video

And found that on both LCD PCBs i get no resitance to ground on the "IBC" test pads.

But I don't know if that necessarily means there is a short (maybe IBC should be connected to ground?)

So would you try the method in the video to power the short to see what heats up and replace those components or try buying a replacement motherboard for 100€?

Thank you.

Needfuldoer · February 22, 2022

This might sound kind of out there, but try pressing on the HDMI ports while the TV is on. There are a couple Samsung TVs that have weird grounding issues that can manifest as screen corruption.

Nagby · February 23, 2022

I tryed it on the HDMI 1 at least pushing toward the TV and away with no different result.

but as the TV stays on (doesn't reboot) when the LCD panel is disconnected, i think the problem is there instead.

when I have time with someone to help, i will try to power the IBC pad with a lab power supply, slowly increasing the amperage while looking at the PCB with a tiny thermal camera (8x8 pixels, but could be enough to spot an area that heats up)

amtays · February 29

On 2/23/2022 at 11:55 AM, Nagby said:

I tryed it on the HDMI 1 at least pushing toward the TV and away with no different result.

but as the TV stays on (doesn't reboot) when the LCD panel is disconnected, i think the problem is there instead.

when I have time with someone to help, i will try to power the IBC pad with a lab power supply, slowly increasing the amperage while looking at the PCB with a tiny thermal camera (8x8 pixels, but could be enough to spot an area that heats up)

Hey Nagby, did you ever figure out what was wrong?

I have a QE50Q60TAUXXC that is suffering similar problems, and I was hoping you might have some solutions.