iMac 27 2012 not detecting Thunderbolt display

[dosada]

Hello,

i am using a 2012 27 inch iMac, the first slimline model. Now i have purchased a second hand 2011 27 inch display to use as second monitor. No matter what i do i can't get the iMac ot find it. I have done the shut down, unplug, wait 5 minutes start up again things and also the nvram reset without any success. When i connect it to a 2012 macbook pro it instantly powers up. Any suggestions what else to try? Mac os is Mojave

 

[ferrarr]

Give the SMC reset a try, How to reset the System Management Controller (SMC) on your Mac - Apple Support.

 

[dosada]

Give the SMC reset a try, How to reset the System Management Controller (SMC) on your Mac - Apple Support.

I thought that's what i did with unplugging it and waiting? Or is there another way? This is what apple says

Follow these steps for iMac, Mac mini, Mac Pro, and Xserve.

Choose Apple menu > Shut Down.
After your Mac shuts down, unplug the power cord.
Wait 15 seconds.
Plug the power cord back in.
Wait 5 seconds, then press the power button again to turn on your Mac.

 

[IWT]

You sometimes have to do the SMC reset several times, dosada.

Don't know why, but most of us have found this to be the case.

May I ask if the "successful" 2012 MacBookPro is also running macOS Mojave?

Ian

 

[dosada]

You sometimes have to do the SMC reset several times, dosada.

Don't know why, but most of us have found this to be the case.

May I ask if the "successful" 2012 MacBookPro is also running macOS Mojave?

Ian

Yes, exactly the same OS version. Do you think installing High Sierra would help?

 

[chscag]

How are you trying to access the 2011 27" TB display from your 2012 27" iMac? What cables and/or adapters are you using?