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Blank external display M1 iMac

iMac 14M2LL/A


I just received a refurbished 24” M1 iMac yesterday and I used an Apple USB-C multi-port adapter and HDMI cable to connect a LG external display.  The computer sees the display and it is shown in the display preferences, but it’s blank.


I have used that same monitor with my 2017 MacBook air with no issues. (the display is only about 3 weeks old).

What I've done so far:

  • Upgraded the iMac from OS 11 to 12.1, no help.
  • Swapped HDMI cables, no help.
  • Swapped USB-C multi-port adapters, no help.
  • Swapped the USB-C ports on the iMac and the HDMI ports on the display, no help.
  • Turned the display on and off and unplugged it and plugged it back in, no help.
  • Re-booted the iMac, no help.
  • Used the USB-C multi-port adapter to connect to a TV and the TV displays the desktop.
  • Plugged the adapter into our 2019 MacBook air and the LG display worked.


Any suggestions?

iMac 24″, macOS 12.1

Posted on Jan 22, 2022 4:10 AM

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Posted on Jan 22, 2022 4:22 AM

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Blank external display M1 iMac

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