External display randomly turns black / goes to sleep.

Kenny Millar wrote:

@den.thed Thanks for the helpful reply.

The HDMI adapter is an ULT-WIIQ from Amazon

The monitor is a Phillips 21" can't remember the exact model at the moment.

Both work well on a PC I have - with no issues at all.

The main HDMI Output from the mac mini never has an issue either.

I will try replacing the HDMI Adapter.

I'm not finding that adapter by the ULT-WIIQ reference at Amazon.

I would test one of the following adapters listed at BestBuy.

https://www.bestbuy.com/site/insignia-usb-c-to-hdmi-adapter-black/6473497.p?

https://www.bestbuy.com/site/best-buy-essentials-usb-c-to-hdmi-adapter-white/6458562.p?

FWIW I'm using the Insignia adapter on one of my Mac mini dual display setups.

Another option, is to spring for the more expensive Apple adapter.

https://www.apple.com/shop/product/MUF82AM/A/usb-c-digital-av-multiport-adapter?

https://www.bestbuy.com/site/apple-usb-type-c-digital-av-multiport-adapter-white/5596800.p?

Kenny Millar wrote:

Using an M2 Mac Mini. With one monitor on the HDMI port, and a second on a thunderbolt-4 to HDMI adapter.

The 2nd display is set up as "Use as separate display", so not using screen-mirroring.

At random intervals macOS will put the thunderbolt display to sleep (or turns it black).

No amount of mouse-movement or anything else will bring the display back on. To get it back on I put the whole machine to "sleep" for a moment and wake it back up. Both displays will now work again perfectly for some time.

The random amount of time can be anything from a few minutes to about 1-hour.

This sounds more like a faulty adapter, cable or weak connection than a sleep issue.

If it is the display on the TB/USB-C to HDMI adapter, then I would test a different TB/USB-C to HDMI adapter.

usb-c to hdmi adapter

If it is the display on the Mac mini's HDMI port, then I would test a short premium certified HDMI cable.

For more focused and accurate help, please post

the make and model of both displays

the brand of the USB-C to HDMI adapter

plus the brand and length of both HDMI cables

OK that cable adapter should work fine.

What other devices and drives do you have plugged into the M2 Mac mini's TB/USB-C ports...?

If that adapter cable is plugged into a Hub or Dock, try plugging it directly into the Mac mini TB/USB-C port.

If that doesn't help, test that adapter cable plugged directly into the M2 Mac mini's others TB/USB-C port with a minimal amount of devices plugged into the other TB/USB-C port.

Nice! Now shut everything and pull the power cable before bringing everything back up again.

There’s no need for sleep - it gets you nothing but trouble. So, disable it and save yourself a ton of aggravation. As already mentioned, for power savings, let the monitors switch off on timer. It’s different from Sleeping - unrelated entirely.

Try these settings Wake up a remote Mac mini - Apple Community exactly as shown, might fix.

You're welcome.

Good. Is the Hub self-powered or buss powered...?

Yea' could be one or the combination of those device drawing too much power.

You have to experiment with different things, including using a wall charger to charge the iPhone.

Turn “Wake” off - that should do it as far as the settings link is concerned.

??? You don’t need sleep for syncing. Disable sleep entirely for normal operation or shut for long absences. As for the displays, set to turn off on timer.

We agree to agree on the sleep issue problem..... 😉

However the OP states that only the one display on the adapter randomly blacks-out, which leads me to believe that this is a different problem.

At random intervals macOS will put the thunderbolt display to sleep (or turns it black).

No amount of mouse-movement or anything else will bring the display back on. To get it back on I put the whole machine to "sleep" for a moment and wake it back up. Both displays will now work again perfectly for some time.

The random amount of time can be anything from a few minutes to about 1-hour.

“It's OK on here to post irrelevant replies, but it is not OK to call someone out for it.”

We can agree on that 😁

By the way, Sleep used to be “normal” pre-2018, but now it’s totally…irrelevant (and aggravating, as you’re finding out). All the best!