iMac 2012 27" with latest Catalina + 27" Apple Thunderbolt Display wont work!

[Kaos13]

Hello everyone!

I hope someone can link me or let me know or guide me in this crazy thing I have with my iMac!
Basically, I got a Thunderbolt Display from work and wont work with my iMac 2012, but was working with iMac 2014 and MacMini 2011 without issues.

I bring it home, I connect it to my 2012 iMac >> NOTHING happens...
I really can not find a solution more than getting super annoyed of this strange things no one in Apple can help with either... And loosing so much time for this stupid thing.. But I like to solve issues, and I have it deep at the moment... 😅😅

I am trying when receiving today or tomorrow a Mini Display to Mini display cable, as 50EUR for a Thunderbolt2 to Thunderbolt2 cable I think is crazy when it should be working straight with he glued cable in the Apple monitor...
I connect the Thunderbolt cable glued to the Monitor to the iMac, and nothing happens... I really do not get it...
What I know, is that 3-4 years ago, when I updated to Catalina from Mojave, I lost my 30inch monitor connected to the iMac.. I was working with a simple HDMI(Monitor) to MiniDisplay cable(MiniDP iMac). I updated, and this Dell 30inch monitor, stop working forever with my iMac...
I get very furious and looing many hours till I needed to drop the towel... Lets see if is not the same case with an Apple damn monitor...

- I did the basic by reseting PRAM on the iMac and is the latest supported Catalina already.
- I plugged in the Wall, in case is the plastic surge, which I read can be the issue too.
- And I repeat the monitor was working fine in 2 other devices newer, and older.

So not sure if I am missing something or or not, but is really strange an update fvked the iMac thunderbolt port, but seems is not sending or receiving as it should... Or I dont know anymore, but I dropped the towel with a DELL monitor years ago.. I tried 3-4 ways to connect it: Not detected anymore on the iMac. The same than now.

I hope someone with experience in this can help me with this mess please.. Thanks in advance and kind regards!

 

[PsychoSync]

Ok i read your post maybe 2 days ago and did not reply as i just didn't know what to suggest. But today i thought of some basic troubleshooting you could try.

Maybe something went wrong with the upgrade to Catalina? I would try to install Mojave on an external drive or connect the hard drive from another Mac that has a MacOS version supported by your iMac (10.8.2 upto 10.15) and try to boot from that to see if the external monitor works.

The Thunderbolt ports can be used for both pci lanes and Displayport monitors.

Dumb question: you tried both ports?

Do you have any dongles that convert mDP to hdmi or dvi or vga? Try them with a known tested monitor.

Other than that i really have no idea.

 

[Bigwaff]

Check your firmware version -

About EFI and SMC firmware updates for Intel-based Mac computers - Apple Support

This article lists firmware updates available as standalone installers for Intel-based Mac computers.

support.apple.com

If it isn't the latest version, you will need to boot Mac OS 10.9.5 Mavericks to install the firmware.

 

[Kaos13]

Thank you very much to both for your support!

Check your firmware version -

About EFI and SMC firmware updates for Intel-based Mac computers - Apple Support

This article lists firmware updates available as standalone installers for Intel-based Mac computers.

support.apple.com

If it isn't the latest version, you will need to boot Mac OS 10.9.5 Mavericks to install the firmware.

I will try this yes, will see and I will report it here.

Ok i read your post maybe 2 days ago and did not reply as i just didn't know what to suggest. But today i thought of some basic troubleshooting you could try.

Maybe something went wrong with the upgrade to Catalina? I would try to install Mojave on an external drive or connect the hard drive from another Mac that has a MacOS version supported by your iMac (10.8.2 upto 10.15) and try to boot from that to see if the external monitor works.

The Thunderbolt ports can be used for both pci lanes and Displayport monitors.

Dumb question: you tried both ports?

Do you have any dongles that convert mDP to hdmi or dvi or vga? Try them with a known tested monitor.

Other than that i really have no idea.

I really do not know, I will try the firmware update when I arrive home today, and I check it.
It might be that, because I can not get it. Is nto working with my macbook either..
I tried with my Macbook Pro 2018 (x4 Thunderbolt 3) and not working at al the monitor...

Tested Options:
- Apple Monitor Thunderbolt Cable >> iMac 2012 (NOT WORKING)
- iMac 2012 << 4K MiniDP to HDMI adapter << 4K HDMI to 4K MiniDP Cable >> Monitor (NOT WORKING)

- (Macbook Pro 2018) << USB-C to Mini Display port Cable >> Monitor (NOT WORKING)
- (Macbook Pro 2018) << USB-C to 2x HDMI 4K adapter << 4K HDMI to MiniDP Cable >> Monitor (NOT WORKING)

I received a cable today, I will get the Apple one just to close options, and Ill try it tomorrow.
To be tested:
iMac << 4k MiniDP to MiniDP Cable >> Monitor
iMac << Apple Thunderbolt 2 to Thunderbolt 2 Cable >> Monitor

I will leave the updates and will see if we find a solution making sense, as I am getting really paranoid with this thing on the iMac not working since that old update..

 

[PsychoSync]

I have an Apple Cinema Display, a 23" i think. It has a mDP connector as well as the usb cable and magsafe charger. The mDP connector is (probably) broken inside. If i just plug the monitor and don't take real good care to make sure there is no pressure on the cable it doesn't turn on. Maybe you have the same problem i have.

Try plugging in the monitor, grab the cable near the connector and place it straight so there is absolutely no stress on the cable. Try pushing it in holding the cable about one inch away from the connector.

If you also have a broken connector you'll either have to just live with it like i do, as long as i don't touch the cable it is stable. Or you can buy the whole cable from eBay. There are guides on how to replace it.

 

[Kaos13]

If you also have a broken connector you'll either have to just live with it like i do, as long as i don't touch the cable it is stable. Or you can buy the whole cable from eBay. There are guides on how to replace it.

Thank you very much for your tips! 😌
Unfortunately, I had a look on that too (And the iMac connector itself). I can already confirm is the iMac, and the damn Catalina update, and yesterday I read looking further that I am not the only one, and I just think is a really frustrating and annoying "small" hardware problem... (https://discussions.apple.com/thread/250724828?answerId=251591734022&page=4)

1- I tried @Bigwaff option, which sound a possible one, to make the ports alive again, but with Mavericks, was reporting "Your Computer does not need this firmware update". (The monitor did not work on the runned Mavericks External SSD on the iMac 2012 neither.)

2- I tried the same Monitor again in an iMac 2014 21,5" with Big Sur, and is simply working perfectly fine (From where I took it from) with the linked Thunderbird to the Monitor. 0 problems when connecting to the 2014 iMac...

3- NO SINGLE connection option is working. Is simply NOT WORKING...
iMac > Monitor or Monitor > iMac not working in any direction. With any adapter, with any cable.

I will need to just drop the towel again, and I feel really frustrated with this.. Really annoying..
But hey, I leave it in here in case someone find or report something extra on a possible solution..
I was even thinking in downgrading to Mojave but > I dont want to mess around the music software I have, which I had problems with many going to Catalina too.. Due transition from 32bit to 64bit.
Second option (which I might be doing) is to install Big Sur Patched, in case its solving the hardware itself, then I downgrade afterwords to be in a legit MacOS, and maybe this is solving the damn issue...

Anyway, I really appreciate your help in here @PsychoSync and @Bigwaff
Kind Regards!