I have a un65mu8000 with these same issues, have tried a reset 3 times , had the cable company come and check all wires and connections. Finally had Samsung authorized technician come out ,they eventually changed the one connect, then the “ mother board” ?? Still the same problem.waiting on a return call to see what next.
I actually thought that I was alone in this issue as well. I purchased a Samsung UN65JS8500 TV in July of 2015. It worke 100% well until probably sometime in late 2017/early 2018. I no longer remember the precise date. Maybe it corresponds with the latest Firmware version's release. <shrug>.
My television model is connected via HDMI to a [One-connect?] box which in turn is connected to a TiVO that receives a cable signal via Verizon FIOS. TiVO works perfectly fine.
In any case, what happens with me is that the TV is turned on, sound and audio works fine for about 60-90 seconds then the screen goes black along with audio. To recover, all I do is hit the Source button on the Samsung TV remote and re-select the relevant HDMI source input and then the TV works great aftterwards until it is powered down.
Now I do have one interesting note. I noticed that after I came back from a 3 week vacation recently, that when I first turned on the TV, this problem did not exist! So clearly it seems that if the TV is powered off for some extended period of time, this issue goes away. I was ecstatic but then about 1-2 weeks later the problem re-appeared.
Based on my "life experience" and all the items on this thread, I am 100% convinced that there is a bug in the Samsung firmware for this category of its TV sets whether Samsung wants to admit it or not. The moderator responses of "Call a service Technician" is quite frankly insulting and idiotic. It literally makes no sense given the number of reports of this issue and the varying types of models impacted. I am sure that the problem is not necessarily a 2 week fix but it would be helpful to customers if at least they indicated they were investigating the issue. My guess is that the company hopes that folks will simply buy newer model TVs and the problem will go away that way.
All that being said... this is far from the worst problem that could happen to a TV set. It's more of a nuisance as it disrupt ones viewing experiencing. It's comparable to when people used to have to start their cars via a hand crank. I mean, sure the car starts eventually but who the heck wants to go through that hassle????
I will say this. It is quite likely that after years of being a loyal Samsung customer from a TV perspective that I will end up making LG the next model that I purchase.
Still working ok after 10 days now. Again, all i did was reset the smart hub and it cleared all settings. The tv settings remain the same. I didn't sign in for a few days but now I signed in to the hub and it still works ok and it has not switched to another source. Or maybe, It was the samsung rain dance i did with my martini, I don't know-but its working.
With all do respect your problem on your tv that was fixed by resetting the smart hub seems different than the one people are experiencing here. I have reset the smart hub and the tv several times and it doesn’t fix a thing. A lot of people seem to have done the same if not more. So resetting the smart hub is no miracle fix is what I’m saying.