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External Display Not Always Detecting Imac Input

Hello,


I have an HP 22cwa Display and an Imac 2012 on High Sierra. The secondary display is connected via HDMI to mini DV and almost every other day when I wake up the Imac it either fails to wake up the secondary display, or the display wakes up and searches for a signal but fails. I've noticed that sometimes it helps to try to run the mouse towards the secondary display, but that doesn't always work. I've also noticed in the past that I have to initiate sleep from the iMac display and not the secondary display, otherwise the secondary display will absolutely not wake up.


The work around I have to do to get the display to recognize the signal is a combination of turning the display on and off a bunch of times and inserting the mini DV cable over and over again.


Thank You,

Nikolai

iMac 21.5", macOS 10.13

Posted on Jul 23, 2019 3:26 PM

Reply
Question marked as Top-ranking reply

Posted on Jul 23, 2019 3:43 PM

I would recommend resetting the SMC 2-3 times back to back with NO external peripherals connected. Also, please reset the NVRAM. After you have done the resets, please re-test. If the problem persists, chances are high it is the cabling you are using.


https://support.apple.com/en-us/HT201295


https://support.apple.com/en-us/HT204063

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2 replies
Question marked as Top-ranking reply

Jul 23, 2019 3:43 PM in response to nikolai1989

I would recommend resetting the SMC 2-3 times back to back with NO external peripherals connected. Also, please reset the NVRAM. After you have done the resets, please re-test. If the problem persists, chances are high it is the cabling you are using.


https://support.apple.com/en-us/HT201295


https://support.apple.com/en-us/HT204063

External Display Not Always Detecting Imac Input

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