Setting wrong refresh rate for external display on Mac mini - black screen! (+ Solution)

Question

Setting wrong refresh rate for external display on Mac mini - black screen! (+ Solution)

Hello,

I post this to help other facing the same issue I had.

I accidentally changed the refresh rate of my attached external display of my Mac mini 2014 from 60Hz to 24Hz. Right after that, I got a black screen and a popup came up on my older Philips screen saying that I'm using the wrong refresh rate and have to switch back to 60Hz. I wasn't able to do this, Esc didn't work to switch back to 60Hz, maybe cause I lost the focus in my panic ;)

I tried different solutions after google-ing to reset NVRAM with cmd+option+P+R or boot into safe mode with shift key but every action leads again to the black screen.

Attaching a second screen suddenly brought back both displays, but detaching the second monitor again just brought back my issue. I think, the Mac is saving different set ups with different attached screens separately and not by device itself.

Here now my advice to solve the problem: use a second screen again, install google remote desktop and setup your Mac as a remote device, leave chrome browser open! Now detach your second screen - black screen again. Now use another device with google chrome and remotely connect to your Mac. You can now open System Preferences -> Display and switch back the wrong refresh rate. and tataaaaa - fixed!

Good luck

Posted on Nov 17, 2021 2:38 PM

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Answer 1

Nov 18, 2021 12:28 PM in response to WESTCOASTHOPKINS

I tell you again that nothing of the reset/safe mode procedures worked for me. My problem is already fixed using google Remote Desktop as I mentioned. This thread is for those who encounter the same problem and how to resolve it with this workaround. Thanks

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Answer 2

Nov 18, 2021 6:55 AM in response to MichaelScherf

I did the exact same thing. I wound up installing VNC to remote in and fix it. That was quite the learning experience!

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Answer 3

Nov 17, 2021 3:36 PM in response to MichaelScherf

A simpler solution would have been to to a PRAM/NVRAM reset, that will resolve the issue and/or do a SAFE mode boot. One might also need to do a SMC reset as well.

Glad you solved it though.

Cheers,

Anthony

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Answer 4

Nov 18, 2021 5:15 AM in response to WESTCOASTHOPKINS

As I wrote in my post, I already tried this NVRAM reset with cmd+option+P+R at start, the Mac did a reboot afterward but nothing was reset. I don’t know why this was not working, I tried it several times. The safe mode also did not work, after switching on and immediately pressing and holding shift, the Mac did not start into safe mode, right after the apple symbol appeared, the monitor switched back to 24Hz and the error message appeared again.

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Answer 5

Nov 18, 2021 5:54 AM in response to MichaelScherf

Hi MichaelScherf,

So the reboot into Safe mode and/or resetting of PRAM/NVRAM should have set the monitor settings back to none and allowed the Mac to boot with the monitor working. The only thought left is, turn your Mac off fully and then, turn your monitor on and check through the settings to see if you can reset them to factory default.

Assuming you can do that, reboot the Mac into SAFE mode (reboot, hold down the Shift key until you are at the user login screen) and go into System Preferences > Display and set it back to the Default settings. Reboot into normal mode and see if you can login.

Do you have a 2nd monitor you and temporarily use to connect to your Mac and boot with?

If not, you're going to have to contact Apple Support.

That said, good luck with resolving this.

Cheers,

Anthony

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Setting wrong refresh rate for external display on Mac mini - black screen! (+ Solution)

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