UN7100 TV power cycles if both ribbon cables are connected

[Harbersbram]

Hey, 

We got a non functioning 65" un7100 for free and wanted to see if we could fix it. It fails to boot properly with the main board connected, so we replaced that. However, it seems the main board was/is fine, and something else is going on. 

If we disconnect one of the two big ribbon cables, it seems to boot properly, either works. But if both are connected simultaneously, it fails on boot.

Does anyone have a clue what could be wrong? Is it a failed panel?

 

[Anatoliy1]

If you are alternately disconnecting loops and the TV starts up with any one loop, then you need to check the power supply, it looks like it goes into protection mode when the panel is turned on. What exactly you need to check, it could be a faulty T-Con board (display control) or the power supply itself (this is more likely), ideally you need to look at the DC harmonics, maybe the capacitors are dry, but it may be easier to replace the power supply board.

[PastorSauce713]

I have the same issue with my 75nu8000. I saw a YouTube “hack” that called to disconnect the pin for the backlight control on the power that connects to main board (Pin#4 from the top; used a fine tipped tool to push it out of the prongs) This has allowed the tv to run longer without looping but probably because of reduced power consumption/switching from the backlights (They stay on even when the tv is turned off. You have to unplug 🤦‍♂️). Found your post today so I’ll try repairing the power board vs buying a new one. Thanks 😀