Thunderbolt Screens Randomly go Blank with Mac Mini (2023) M2 Pro

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Level 1

23 points

Thunderbolt Screens Randomly go Blank with Mac Mini (2023) M2 Pro

I have two Thunderbolt 2 Screens attached to a Mac Mini (2023) with M2 Pro. One Thunderbolt screen is attached (chained) to the other, and the other is connected directly to the Mac Mini using a Thunderbolt 2 to Thunderbolt 3 adapter. At random times, both screens will simultaneously go blank without any warning. When the screens go blank, I notice that it disconnects from my scanner. All I have to do to get both screens to come back on is to press the spacebar on my keyboard and enter my screenlock password. Sometimes I go minutes, sometimes weeks, and sometimes months between these incidents. I can't identify any consistent event or pattern. Today it happened four times within just a few minutes and then it hasn't happened again for the past several hours.

I've seen a prior thread that suggests that the problem could be caused by a sleep setting. My Energy Saver settings show that shows that I have turned off automatic sleeping when the display is off. It doesn't seem like a sleep setting to me since it sometimes occurs while I am typing or using an app on my computer.

Any ideas about how to prevent these random events?

Mac mini (M2 Pro, 2023)

Posted on Jan 2, 2025 09:22 PM

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Answer 1

samtenor

Level 4

2,074 points

Jan 3, 2025 01:01 PM in response to rmblood

Have you tried to connect them "reversed" daisy chain. - the cheapest way to finger few things:

If the first TB Display connected to the Mac Mini M2 Pro is having issues - the chain reaction would lead to the second one go black. By re-arranging the TB display, to see if you can duplicate the scenario.

My personal experience - these TB displays have some weak spots:

a. The Octupus cable - especially the TB connector

b. The Logic Board - usually it cause the USB devices (such as speaker, webcam or external devices) "disappeared."

By re-arranging Daisy-Chain to rule out the original connected to the Mac Mini might have issues.

2.You can try to connect both monitor individually to see if they both act the same way -- that means, you have to buy another adapter, OR - connect 1 TB display at a time - to see if you can duplicate the "black out" problem.

Good Luck

Best

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Answer 2

rmblood Author

Level 1

23 points

Jan 2, 2025 10:26 PM in response to hcsitas

Thanks. My Mac Mini is missing the 2nd and 3rd options shown in your screen shot, but I have set the others as you have suggested. I'll see how it works.

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Answer 3

Jan 3, 2025 05:56 PM in response to rmblood

I've read that modern versions of macOS don't like to see display transmission errors – and will cut resolution, or even signal, if they see any.

The permanently-attached "hydra" cables on those old Thunderbolt Displays can be a weak spot. I'd venture to guess that a flaky cable that "worked" (well enough) with an old Mac might cause the symptoms you describe if used with a new one.

A workaround for a bad or flaky cable is to run a Thunderbolt 1/2 cable into a Thunderbolt Display's Thunderbolt daisy-chaining port.

Note that if you intend to daisy-chain two Thunderbolt Displays, the one that you plug into the Apple TB3-to-TB2 adapter needs to have a good "hydra" cable (so that it's daisy-chaining port will be available for daisy-chaining … and not tied up by this workaround).

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