Thunderbolt II Monitor Not Working (MBP, Tahoe)

[scarletphire]

I have an older (Apple) 27" TB2 monitor (not the gen 1 that ran via mini display port, mine has a power cord and a separate TB cable coming out of it) with a BRAND NEW certified/Apple TB>USBC adapter. I replaced the adapter after upgrading to Tahoe thinking it was that. I have used this monitor since its release with all operating systems up until now. I had/have it plugged directly into my macbook pro (m1). I bought a selfpowered TB docking station and tried it that way. It is not working with Tahoe. I have done all the usual things-tried to detect displays, used terminal to clear monitor/display profiles, ran first aid on all disks, started in safe mode (just to triple check) - NOTHING. I really, really like this monitor/don't want to drop $2500 on the new one. It feels silly an OS upgrade would cause this to stop working. Any ideas?

 

[Bigwaff]

I have an older TB2 monitor (not the gen 1 that ran via mini display port, mine has a power cord and a separate TB cable coming out of it) with a BRAND NEW certified/Apple TB>USBC adapter.

You have an Apple 27" Thunderbolt Display or some other brand?

 

[scarletphire]

You have an Apple 27" Thunderbolt Display or some other brand?

yes, the apple 27"

 

[Bigwaff]

yes, the apple 27"

I have had many of this model over the years. Over time, the built-in Thunderbolt cable gets finicky. For several, I have had to resort to using a separate TB2 cable instead of the built-in cable. Just plug the separate cable into the TB2 port on the back and into the Apple TB2>TB3 adapter. While I haven't been brave enough to upgrade to macOS 26 Tahoe yet, I currently use one of my TBD in this configuration with M1 Max MBP w/out issues. One last troubleshooting step perhaps.

 

[scarletphire]

thanks, looks like I'll need to buy a TB cable and try that. I DO NOT recommend upgrading to Tahoe, not only for this reason, but tbh, bc I find it super ugly and a step backwards...

 

[joevt]

I have an older (Apple) 27" TB2 monitor (not the gen 1 that ran via mini display port, mine has a power cord and a separate TB cable coming out of it) with a BRAND NEW certified/Apple TB>USBC adapter. I replaced the adapter after upgrading to Tahoe thinking it was that. I have used this monitor since its release with all operating systems up until now. I had/have it plugged directly into my macbook pro (m1). I bought a selfpowered TB docking station and tried it that way. It is not working with Tahoe. I have done all the usual things-tried to detect displays, used terminal to clear monitor/display profiles, ran first aid on all disks, started in safe mode (just to triple check) - NOTHING. I really, really like this monitor/don't want to drop $2500 on the new one. It feels silly an OS upgrade would cause this to stop working. Any ideas?

The Apple 27" Thunderbolt Display actually uses Thunderbolt 1. I don't think that matters though. It just means any Thunderbolt device connected to it will be limited to < 10 Gb/s.

Do you have another Mac to test the display?

Do you have a backup of the earlier macOS version that you can boot to make sure the display still works?

What TB docking station did you try? Do you have any other Thunderbolt devices you can connect the display to?