My sony xbr-75x850c 4k tv will randomly turn off. It will turn back on but then turn off at a random time again. Sleep = OFF, ECO Mode = OFF, Timers = OFF. I think this is a hardware issue

SOURCE: Samsung LE32R87BD-Turns itself on

Hey Devaman, like you I have just upgraded the software and disabled all of the timers, but most importantly I have disabled the "update whilst on stanby" option from the SETUP menu. It now seems to behave...
One more comment, I was very dishappointed by Samsung lack of interest, they never bothered to reply to my email, which I think is extremely rude... but then, am I surprised? :¬)
Peace

SOURCE: My Samsung HLP6163 tuns off randomly all evening

if you are able to simply turn it back on, then the problem is probably the lamp door cover switch. unplug the set, remove the lampdoor cover. the switch will be in the lower left of the opening. put the door back on while making sure that the switch lever goes down NOT UP. some of these sets came through with the switch up. it works for a while but then the little arm starts to warp and it causes your problem

SOURCE: Sony lcd projection tv repeatedly turning on & off

There are 2 primary things that can cause this problem - a bad TEMP sensor that is sensing too much heat, OR, a lamp that is going bad, which sometimes causes excessive heat before it dies. Either way, the set will shut itself off, and you can turn it back on in about 5 min or so, and it will work OK....for another period of time before it shuts off again.

You need a good TV Tech with the Sony Service Codes for your set, to come out & check your set. The Service Codes will tell him the exact problem you are having, and how many hours your set has been running. Most of the time a new bulb solves this problem, (if youe set is at least 3 years old).

SOURCE: Sony KV-34HS420 Random Shut downs

normally this is because of a failed capacitor or two that is located on the power supply board. replacing the power board in this unit will fix this issue.

SOURCE: TV shutting off randomly

it looks like a faulty mains board. you need to upgrade the tv software with the latest update. if the tv is not accepting the upgrade then it can be a crook mains board.
hope it helps! please rate my comments :D