External display connected via HDMI and USB-C adapter to iMac suddenly does not work

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External display connected via HDMI and USB-C adapter to iMac suddenly does not work

I've had an external monitor connected to iMac via HDMI and USB-C adapter for several months. It functions as an extended display. Somehow the display went blank about 2-3 days ago and it seems the iMac now does not detect the external display.

I have tried using 2 other HDMI cables and another USB-C adapter, and the external display remains undetected.

Can anyone suggest how to troubleshoot and fix this, please? Thanks.

iMac

Posted on Sep 25, 2022 2:48 AM

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Answer 1

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den.thed

Level 10

82,528 points

Sep 25, 2022 10:18 AM in response to gaius777

Try resetting the iMac’s SMC and NVRAM.

see> Reset the SMC of your Mac - Apple Support

and > Reset NVRAM on your Mac - Apple Support

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Answer 2

gaius777 Author

Level 1

4 points

Sep 25, 2022 6:12 PM in response to den.thed

Thank you, den.thed!

Resetting the SMC worked.

I did the following from the link you provided:

"If your Mac isn't a notebook computer, follow these steps:

1. Shut down your Mac, then unplug the power cord.
2. Wait 15 seconds, then plug the power cord back in.
3. Wait 5 seconds, then press the power button to turn on your Mac."

The external display is back in service... appreciate the advice.

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