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I have just purchased an HDMI screen. I can attach this screen to my 2014 Macbook Pro with no difficulty. When I try to attach to the 27" 2018 iMac using a USB C to HDMI adapter, it recognises that there is a screen attached but it sends no data to the screen. How can I troubleshoot this? Is it a hardware problem or a firmware problem?
I succeeded by disconnecting the HDMI powering down the computer, unplugging the computer power for 10 seconds, reconnecting the HDMI, then powering on the computer. the screen came on without problems
You can restart in Safe Mode and then re-attempt, otherwise it is likely the USB C-HDMI adapter you are using.
Note: I am running OS Catalina
My 2018 iMac will not connect to an HDMI screen using a USB C to HDMI adapter. How can I troubleshoot this?
