Trouble connecting M1 Mini to 27” Thunderbolt display

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Level 1

8 points

Trouble connecting M1 Mini to 27” Thunderbolt display

My Apple 24” cinema display finally died, and I liked the solid feel and style of an Apple monitor, so I got a used 27” Thunderbolt display (and later found out I needed to get a (Apple) Thunderbolt 3-to-2 adapter, which Apple says will allow this combination to work).

And it did, perfectly, for a day. When I came back to it the next morning, it was dark and wouldn’t come back on. I hard-rebooted the Mini via the power button, and plugged and replugged the monitor without success. But then some time later, boom, it came back on by itself, seemingly.

I went to the Mini’s “Displays” preferences, and deselected options about *if the mouse pointer went beyond the edge of the (TB) display screen it would show up on other Macs that were close* (?) (sounds like trouble; don’t need that anyway) and used the display and Mini successfully for the rest of the day.

Next morning, now it’s dark again, and nothing helps. (The monitor looks dead - is there supposed to be any power light?)

To recap: Genuine Apple TB3 to TB2 adapter, with the male USB-C style connector end plugged into M1 Mini, and the Apple 27” TB monitor’s mini-displayport-style TB2 connector plugged into the corresponding female end of the adapter. (Yes, I’m *sure* this is a Thunderbolt display - with a TB port, USB ports, and an ethernet port and a Firewire 800 port (!) on the back).

And it works (or *worked*) fine, while it did. How can I even tell that the monitor’s not just dead? (Unfortunately, I don’t have access to a Macbook Pro with a TB display-out port to test it with).

Any suggestions?

Mac mini, macOS 13.6

Posted on Aug 1, 2024 2:38 PM

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Answer 1

pdq2 Author

Level 1

8 points

Aug 1, 2024 3:00 PM in response to pdq2

Huh. After going over to the Wikipedia page, it turns out my wife’s MacBook Air (13”, early 2014) supports this monitor. Did TB 2 really go back that far? Apparently so!

So I plugged the display into the Air, and the monitor came alive. Seems to work fine. So, presumably, it’s some weirdness with either the M1 Mini or the TB3-to-TB2 adapter.

Someone, somewhere had suggested checking the firmware version of the TB display. It’s 26.2. I have no idea how that would be updated anyway.

But my wife already has an external monitor (an old, tiny Dell) that she’s happy with, and this monitor was bought for the M1 Mini downstairs. Why is it being weird with that?

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Answer 2

pdq2 Author

Level 1

8 points

Aug 8, 2024 6:18 AM in response to tbirdvet

Yeah - so, I’d heard that possibility. But since the octopus cable worked perfectly with my wife’s MacBook, I was rather skeptical. Still, I ordered one ($20 for a genuine Apple one - not too bad, but still seemed kind of outrageous, and I was prepared to return it).

My latest post on my problems seems to have not made it to this thread. In short, I had arranged a Genius Bar appointment to show them this display worked perfectly with the MacBook, but didn’t work with my M1 Mini. And in gathering all this hardware together that morning, I tried it again, and boom! The display suddenly worked with the Mini!

Well, for awhile. After a bit, it started going black suddenly again, like sudden shutdown, or sudden sleep that it wouldn’t wake up from. Rebooting would bring it back for awhile, but for shorter and shorter periods before it went black again.

By then, the TB2 cable had arrived, and I skeptically tried it. And the combo has been working since (a couple days now).

Doesn’t make a lot of sense to me. Octopus cable works perfectly with the MacBook, but not with the M1. But so far, the separate TB2 cable (plus the TB3-to-TB2 adapter) bypassing the octopus cable works perfectly with the M1 Mini.

Keeping my fingers crossed.

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Answer 3

Aug 11, 2024 7:18 PM in response to pdq2

pdq2 wrote:

Yeah - so, I’d heard that possibility. But since the octopus cable worked perfectly with my wife’s MacBook, I was rather skeptical. Still, I ordered one ($20 for a genuine Apple one - not too bad, but still seemed kind of outrageous, and I was prepared to return it).

…

Doesn’t make a lot of sense to me. Octopus cable works perfectly with the MacBook, but not with the M1. But so far, the separate TB2 cable (plus the TB3-to-TB2 adapter) bypassing the octopus cable works perfectly with the M1 Mini.

Another poster who seems to know a lot about displays has written that recent versions of macOS are not tolerant of display transmission errors. As in, they don't want to see any. If they see any errors, they may intentionally shut down a the display, or reduce the resolution of the video signal.

If the hydra cable on that display was a bit "flaky", it seems possible that the old Mac wasn't doing anything about the transmission errors it caused, and the new Mac was – thus explaining the observed behavior.

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Answer 4

tbirdvet

Level 6

14,411 points

Aug 6, 2024 4:59 PM in response to pdq2

Could be a bad all in one (octopus) cable. You can try getting a TB cable and connecting directly to one of the TB ports on the display bypassing the all in one cable.

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