Apple TV causing TV to turn off

This is not so much a question as a "I found this so you don't have to".

We recently replaced our ancient Apple TV box with a new Apple TV HD, and connected it to our ancient LG Dumb TV which had served us so admirably for many years, but has no smart platform (necessitating the Apple TV box). It is still serving us admirably, in fact, but that's another arc in the story. With 3 HDMI devices and only 2 HDMI inputs on the The, we had bought an HDMI switch (with remote!) for easy switching between inputs and routed the cable receiver, Apple TV and DVD player all through that. This setup worked swimmingly for years. But with new security vulnerabilities becoming a daily news item and the ancient Apple TV box being unable to run the latest tvOS, it seemed prudent to replace it.

Shortly after we set up the new Apple TV HD (with the latest tvOS and the latest version of all of the apps we commonly use, huzzah!), we started having what appeared to be an intermittent problem with the TV suddenly turning itself off without warning or explanation. We could turn it back on again, and it would operate fine -- until it turned off again. Thinking our trusty LG was finally breathing its last, we replaced it with a new somewhat smart Samsung that was smart enough for us to watch, but not the other way around.

This did not fix the problem.

In other words, it was not the TV. Our brand new Samsung was doing the same thing as our old reliable LG. Which is now relegated to the second bedroom where it will pine for its glory days, getting only occasional use because cats don't have thumbs.

Next oldest item in the chain was the HDMI switch, which was a cheap one I'd found online, but had done the job for several years. This was replaced by a shiny new 5-port hub that was a significant (but very reasonable) upgrade.

This also did not solve the problem. But this wasn't immediately obvious because there were no hockey games for several days, so we were watching the Apple TV almost exclusively, and as long as the Apple TV was on (or definitively off), there wasn't a problem.

Thinking that the surge suppressor everything was plugged into was potentially the culprit, we swapped it out for a different one. Which also appeared to work for a while, because the actual root cause was able to disguise itself fin such a fiendishly clever way.

It took about 2 weeks, and a lot of trial and error, and false hope, but eventually one of us (not me) noticed that when the TV spontaneously powered down, the new Apple TV was also turning off.

AHA! Come, Watson! The game's afoot!

Normally it would have occurred to me to examine the thing that had changed as a root cause. But because of a weird convergence of circumstances, and the intermittent nature of the problem, it looks a month or more to even realize that there was a problem. By which time, the new Apple TV was no longer "new", and since there wasn't any obvious problem with it, and the other components were almost 10 years old, they got blamed.

There is an older thread from 2017 reporting the problem, but didn't really offer a solution, just a link to the support article If you can't control your TV or receiver with your Apple TV Remote - Apple Support (CA)

That's not the use case in the question (though it did give me a general idea where to look for the offending setting. Which I will detail in a response so that those who just want to skip to the end and not read my pithy commentary can do so and get the answer without the question.

Strange things started happening to my TV since first plugging in my new Apple TV a couple weeks ago, and while I didn’t immediately connect the dots, it quickly became apparent that the new device was the culprit. After a bit of digging and a lot of commonsense, I figured out my problems and how to fix them. As often, the solution was just at the click of a button.

The symptoms

The symptoms I experienced appeared to be completely random, and never seen before, as far as I was concerned. For example, the most annoying one was my Samsung TV suddenly displaying a “weak or no signal” error message while was watching cable. In that case, circling through the different inputs of my TV with its remote fixed the problem. It was a quick fix, but that was annoying nonetheless.

Another symptom I experienced was that my TV would magically turn itself on when AirPlaying music to my Apple TV. At that point, it became clear that the Apple TV was responsible for that mess.

Doing a little bit of digging about this problem online surfaced a bunch of similar issues from users who all have the 4th generation Apple TV. Some of the symptoms they experienced were their TV powering itself on and off, their receiver acting weird, and inability to change TV settings while Apple TV was on.

The cause

The cause of the problem is that Apple TV 4 is compatible with HDMI-CEC devices. Briefly, CEC, which stands for Consumer Electronics Control, is an HDMI feature that allows individual CEC-enabled devices to command and control each other without user intervention. There is much more to it than just that, but as far as we’re concerned today, this is what we’ll remember. Those of you interested in learning more about the topic can read the Wikipedia entry about HDMI-CEC.

The solutions

In my case, the problem was that I had turned on the Control TVs and Receivers option under Settings > Remotes and Devices. This setting was literally sending mixed signals to my receiver which would then pass these mixed signals on to my TV, causing my issues. This was also the reason why my TV would turn on when I AirPlayed music to Apple TV. In that case, Apple TV was just doing what I had set it to do.

Going to Settings > Remotes and Devices > and turning off Control TVs and Receivers fixed the issue. Of course, my Apple TV can’t control my other electronic devices anymore, but that is something I never wanted to begin with. On the flip side, the Apple TV remote is still capable of controlling the volume of my receiver, which in my case is just perfect.

Also read: How to control your TV or receiver volume using the Apple TV remote

While I can’t really pinpoint the true reason, it seems that for some users, turning off “Control TVs and Receivers” settings on Apple TV didn’t fix the issues entirely. Depending on your set up, you might have to disable HDMI-CEC directly from your TV settings. I know, digging around the terrible UI of a TV set is not something any of us enjoys doing, but sometimes it’s a necessary evil.

So power on your TV, grab its remote and look for HDMI-CEC settings in there, then turn them off. Note that most manufacturers come up with a different name for HDMI-CEC, so this is not what you might see on the screen. For example, the following manufacturers use these specific names for the feature: Anynet+ (Samsung), Aquos Link (Sharp), BRAVIA Link and BRAVIA Sync (Sony), SimpLink (LG), HDAVI Control, EZ-Sync, VIERA Link (Panasonic). You might want to look up how your TV maker branded HDMI-CEC with a quick Google search.

If you were having similar issues with your new Apple TV, I am hoping this will fix the problems. If not, let’s discuss further in the comments section below.

Can Apple TV power off my TV?

Why does my TV keep turning off out of nowhere?

Why does my Apple TV keep turning my TV on?