User profile for user: tim9909
tim9909 Author
User level: Level 1
8 points

How to force Mac mini to re-find external monitor?

I have a Mac mini and a laptop sharing a Samsung monitor. The Mini attaches to the HDMI port and the the laptop attaches to the VGA port. Often when I switch from laptop to Mini, the Mini cannot find the monitor. I can go back to the laptop and Share Screen to access the Mini, so I was hoping there was a command to force the Mini to search for the monitor. I have tried:

  • opening Display settings and fiddle around including option key to get find monitor button
  • put to sleep and re-wake with keyboard
  • unplugging monitor and plugging back in

The only thing that works reliably is to shut the Mini down and power it back up. Then it will always find the monitor during the progress bar start up phase. Any other suggestions? I can do command line if there are low level system commands.

Posted on May 21, 2020 9:03 AM

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User profile for user: den.thed
den.thed
User level: Level 10
94,640 points

May 21, 2020 4:13 PM in response to tim9909

tim9909 wrote:

It's a Samsung SyncMaster Px2370, Mac mini is about 9 months old, model 8,1. I don't have another HDMI cable handy to try. I have heard that can make a difference.

Thanks for the info and sorry for not getting back to you sooner.

I would try a different HDMI cable first and then if that doesn't help, move to using a USB-C to HDMI adapter.

see > https://www.apple.com/shop/product/HKQ22ZM/A/belkin-usb-c-to-hdmi-adapter

Doesn't seem like the PRAM would be an issue since it generally works. I would say about 1 out of 5 times when I switch to laptop, it won't find the Mini when I switch back. The SyncMaster will try the HDMI for about 10 seconds and then go back to Analog. If I switch to HDMI a 2nd time, it will often find it, but if it fails that second time, it will never succeed without powering down.

Yea' sounds like maybe the connection from the HDMI is getting lost when the Mac Mini is asleep and the Samsung is on VGA. I would also check to see if there is a way in the Samsung Menu to manually switch and lock it onto the HDMI input.

The fact that it always works when the Mini powers up makes me think there might be some init sequence that I could trigger manually, from the laptop using Share Screen. But power cycle is actually not that painful.

Personally I prefer to let my Mac Mini's sleep for weeks at a time instead of restarting them multiple times a day, because I feel that is it a lot easier on the hardware.

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User profile for user: tim9909
tim9909 Author
User level: Level 1
8 points

May 21, 2020 1:56 PM in response to den.thed

It's a Samsung SyncMaster Px2370, Mac mini is about 9 months old, model 8,1. I don't have another HDMI cable handy to try. I have heard that can make a difference.


Doesn't seem like the PRAM would be an issue since it generally works. I would say about 1 out of 5 times when I switch to laptop, it won't find the Mini when I switch back. The SyncMaster will try the HDMI for about 10 seconds and then go back to Analog. If I switch to HDMI a 2nd time, it will often find it, but if it fails that second time, it will never succeed without powering down.


The fact that it always works when the Mini powers up makes me think there might be some init sequence that I could trigger manually, from the laptop using Share Screen. But power cycle is actually not that painful.


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How to force Mac mini to re-find external monitor?

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