I too am having the same exact problem! I have a Samsung - 75" Class - LED - NU8000 Series (UN75NU8000FXZA). I purchased it from Best Buy (at Sanford, Florida) around November of 2018. Everything was fine except around December 2018/January 2019, my TV said that there was a firmware update. I updated and noticed the problem. This is what happens:
If the TV hasn't been on for a while (20 minutes or more) and I press the power button, you hear the TV turning on but still get a black picture. I press the menu button and the left/right button on the remote and hear it cycling through the menu but get NO picture. HOWEVER, if I turn off the TV and turn it back on - it works. The TV will continue to work (turning off and on) as long as it hasn't been turned off in a while. If I turn off the TV for about 20 minutes (or more) and try it again, the same problem happens.
Here are a few things I have done: I checked to see if there was any more firmware updates. There were none. I reset the TV to factory defaults - same problem. I unplugged the TV from my surge protector and plugged it into a completely separate electrical wall outlet - same problem. I've unplugged ALL HDMI cables - waitied 20 minutes - and get the same problem.
Again, this only happens on the initial boot / start up of the TV. If you immediately turn the TV off and then back on, it will work.
Thinking it was a bad TV, I returned the TV back to Best Buy (at a completely separate Best Buy - this time at Daytona Beach, Florida). I set it all up and downloaded and installed the latest firmware. I turned off the TV for a while and turned it back on AND THE SAME EXACT PROBLEM HAPPENS!!! HOW?! I even reset the second TV back to factory defaults and did all the same troubleshooting steps as above and nothing has changed.
Below is a recording showing precisely what is happening:
Again, for reference, it is a Samsung UN75NU8000. The software/firmware is the latest: T-KTM2AKUC-1202.3, BT-S
Could it be the firmware?! If it's something internal and needs to be serviced/fixed, how is it possible that it's happening on two different Samsung UN75NU8000 TVs that were purchased from two different places?! What are the odds?! What are my next steps?
The software is up to date, it happened once over this past weekend, but this time I believe it was due to the kids playing with the remote, and shutting OFF the TV. I'm continuing to monitor the TV.
I was having the same issue with my 65 inch. I actually had Samsung contact me on the phone and they had me reset my TV and turn off all the ECO setting in the TV. Since I have done that I have not noticed the screen going black yet. It has been 2 days since i did this adjustment.
I too am having trouble with blackouts on my TV I can hear just fine but I can't see anything .. happens with the Cable TV on and when I have my HDMI cable attached from my laptop .. can someone please help me out .. my tv is older so it doesn't have the smart hub etc.. so the solutions that were above don't apply for me..and even if they did the screen doesn't stay long enough for me to do anything (I'm from Canada)