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spagester Author

Level 1

8 points

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

Top-ranking reply

Smilin-Brian

Level 9

56,179 points

Posted on Jan 22, 2022 4:22 AM

▷ Follow this helpful guide here. 

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Blank external display M1 iMac

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