現在のバージョン作成者： Paul Clark

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編集者： Paul Clark

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オリジナル投稿者： Paul Clark

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I may have hacked a solution to the iMac screen, specifically I think the iMac 2011, going dark or just black!

'''Problem:'''

I have an iMac 2011 someone donated to me because the screen went dark after brightness of 3 or 4. I’ve used it a long time, but recently its screen just failed to turn on. Tried PRAM, SMC, even fresh copy of High Sierra using an external drive. Nothing.

'''Potential Hack for others to try, or learn from.'''

So I got out my older iMac 2009. I use the iMacs for 2nd monitors, using their Target Display capability. I plugged in a DisplayPort cable from the iMac 2009 to my MacBook Pro 2014. Everything is working fine, just using the older iMac. I keep wondering about solving the black screen on the iMac 2011.

So I then shut down the iMac 2009, unplug cables. Get the iMac 2011 up on the desk, plug in the cables, including the DisplayPort to the Macbook, and WOW, up powering up the iMac, the screen came back alive!!! And once the iMac

'''Please update this community if you test this and find it works, doesn’t or any other information to consider. Here are the steps that worked for me.'''

Specifics to what I did, not sure what steps could be modified, clarified, or removed, but this is what I did. Posting hoping this leads to a good hack for others to revive older iMacs. Please test and comment for others to learn more.

# Had '''iMac 2009''' with DisplayPort only capability, connected to a '''MacBook Pro 2014''' with TB2 capability, '''using a DisplayPort cable'''.
# '''iMac 2009  was being used in Target Display to the MacBook Pro.'''
# Shut down the iMac 2009, disconnected all cables (Power, keyboard, mouse, DisplayPort)
# Left the MacBook running with DisplayPort Cable plugged in and was connected to iMac in TargetDisplay mode when the iMac shutdown.
# '''Put iMac 2011 where iMac 2009 was,''' connected all the same cables.
# Powered on iMac 2011…. And….
# '''SCREEN TURNED ON !!!'''  Somehow, the dead screen was on, and able to go to FULL brightness, not turning off after 3 or 4 in brightness. It has stayed at full brightness for a couple hours now.
# Thoughts: My gut has always said this would need a hardware fix, but somehow these steps triggered the screen’s power to work correctly. I think it will stay on until some odd event triggers the old behavior. For now, these steps worked to revive the iMac 2011 screen.
# Observations for consideration:
** Somehow the displayport cable, with the MacBook looking for the iMac 2009 in Target Mode, triggered the iMac 2011 screen to come on.
** MacBook was expecting an iMac to be connected via TargetDisplay mode over the Dip
** Once the iMac screen was working fine, the Target mode would not (does not)  work with DisplayPort cable. But it was the DisplayPort cable that seemed to trigger the screen in the 2011’s Thundebolt 2 port.
** Once the screen was working, I replaced the DisplayPort cable with a TB2 cable, and then TargetMode worked fine, and at full brightness.
** Q: Did the DisplayPort cable, between two TB2 machines, cause some electrical signal, pulse, that reset the video board, power board, on the iMac? Or some “loss” of signal expected? I don’t know, but it seems this is what happened.
** This issue seems to behardware related. I was never able to solve this with any software solution, or PRAM, SMC reset. Even tried a freshly installed High Sierra using external USB hard drive.
** I hope this “hack” will help others.
** My iMac 2011 is working great at full brightness again. If it goes dark, I’ll post here again.
# Outcome:  I now have an iMac 2011 who’s display was dead, and revived like its new.

Hardware used:

MacBook Pro 2014 i7 / Big Sur (TB2 compatible)

iMac 2009 27” i7 / High Sierra (DisplayPort only)

iMac 2011 27” i7 / High Sierra (TB2 compatible)

Cables: Thunderbolt 2, DisplayPort.

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