2nd monitor not recognized suddenly after sleep following el capitan update

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2nd monitor not recognized suddenly after sleep following el capitan update

iMac 27 inch 2014 model with 512 GB SSD; apple cinema display attached as second monitor in use for split screen. Worked great for two years; after El Capitan upgrade also worked until I tried shut down; system hung and when I returned (after I left for a weekend thinking it had shut down) ; it went to sleep mode and now 2nd monitor is not recognized and is black; power is fine and monitor seems to be functioning otherwise. Tried system reboot and unplugging, re-plugging in monitor and did NVRAM/PRAM and SMC resets with no luck. Suggestions?

Posted on Apr 6, 2016 4:34 AM

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Answer 1

AppleJoe

Community Manager

Apr 7, 2016 1:36 PM in response to Nano-rick

Hi Nano-rick,

Thanks for using the Apple Support Communities!

I understand from your post that your external Apple Cinema Display is not displaying any image when connected to your Mac. To continue troubleshooting this situation, I recommend reading over and working through the suggested steps from the following article.

Get help with video issues on external displays connected to your Mac - Apple Support

Best!

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