Re: Samsung UN75HU8550 vertical smearing

I got back to troubleshooting this TV again after taking a break for a bit. I took off the outer metal frame to expose the flex ribbon cables that connect the driver boards on the back to the front lip of the panel. Once that was off it was very obvious the source of the heat along the top of the TV were the long Chip on Flex chips. The chips over the parts of the panel with the smearing got extremely hot while the others were just fairly warm.

By flexing the ribbon cable in different ways I was able to get the smudging to...

Re: Samsung UN75HU8550 vertical smearing

Well, the ground contacts on what I think are called the driver boards that have the tab connections all test out ok... They're around 0.2 to 0.3 ohms to the back panel.

So, I bolted everything back up and ran the TV for a little while and noticed that along the top of the TV the metal trim directly over the areas that distort get pretty dang hot. If I run my finger across the top of the TV it's cool where the picture is good and I can barely leave my finger where the picture is bad. Does anyone know what that indicates?

Re: Samsung UN75HU8550 vertical smearing

So I haven't been able to identify any bad tab bonds... one thing I did notice is that the distortion decreases when I just generally press down on the board (just the board, not the tabs specifically). Then I noticed that by pressing down the board it was increasing the contact between the conductive foam blocks under the board and the board's ground contacts. Directly connecting one of those contacts to ground pretty drastically improves the display... so now I'm wondering if it's a grounding issue or if that's just a red herring that's...

Re: Samsung UN75HU8550 vertical smearing

Welp, forging ahead. (sorry for the solo forum blogging, this just seems like the place for folks with problems like this so I'm just having at it)

I got the shielding off near the top of the tv that housed whatever boards bridge the cables from the t-con to the lcd panel (photo 1).

Powering it back up... pressing on those boards, specifically the cables that join the boards on either side (photo 2 & 3) reduces the display corruption by like 50%! Hurray! Lets just clean those connectors and inspect the solder...

Re: Samsung UN75HU8550 vertical smearing

I removed the rest of the back of the TV to expose where the ribbon cables from the t-con connect to the panel. I tried lightly pressing on the connectors, both on the panel and the t-con, and didn't see any change in the smearing on the screen....

I managed to score a free Samsung UN75HU8550! Unfortunately, the color is smearing vertically. The smears move with the picture and change related to other parts of the screen. It also smears on the settings menus, not just on input video.

So far I've gotten the main back panel off and did a visual inspection of the boards and reseated the cables connecting to the t-con and main board without any change.

If I flex the panel it does make the smearing slightly longer or shorter vertically depending on which way I flex it.

What should I try next? Based on the...

Re: New Members - please post your introductions here

I created this account to hopefully find some help with troubleshooting a Samsung LCD that's gone bad.