Apple Thunderbolt Display won't wake up unless I unplug LG display first.

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Level 1

127 points

Apple Thunderbolt Display won't wake up unless I unplug LG display first.

Hi - I have two monitors:

1) 27" Apple Thunderbolt Display

2) 27" LG UltraFine Display 5K

Whenever I wake my 2016 MacBook Pro, my LG display wakes up fine, but my Apple Thunderbolt Display does not. Black screen.

BUT - if I unplug the LG's cable to the Macbook, THEN the Apple Display wakes up - then I plug the LG back in and all screens are now active.

As a secondary impact, doing this also causes my computer to "forget" the arrangement of the screens so like a game of musical chairs, my apps and wallpapers all move to different displays (sometimes the apps are even hidden - with only the smallest upper left corner of the app appearing in the bottom right of the display. Very annoying.

So multiple times a day I have to go through this routine of unplugging the LG and re-arranging and sizing all my app windows.

It's been over a year that I've been quietly dealing with this and I really wish there was something I could do to fix it.

I can't be the only person going through this. Has anyone solved it?

I've checked and all my firmware and software is up to date.

MacBook Pro with Touch Bar

Posted on Feb 6, 2019 7:01 AM

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Answer 1

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DonH49

Level 6

16,704 points

Feb 7, 2019 5:51 AM in response to Joel Pro

You have 4 thunderbolt -C ports. I assume you are using the proper dongle for the LG and the Apple display. Connect each directly not in some hub or daisy chained or other externals. I'm assuming you are not daisy chaining. I also assume you are not having other externals daisy chaining. I'm also assuming you have the two displays separated to a thunderbolt bus and ports associated. I'll also assume you cease unplugging the displays while they are live powered on.

This is enough information for you to try and make it work. Good luck. The 5k is the culprit, it demands lots of power from those thunderbolt -C buses and port.

Lastly it does make a difference which display is connected to which port , so experiment around but not live unplug.

Thought of another, since you have been live unplugging and you have had black screen then do a pram zap and an SMC reset. If you stop the live unplugging but continue to have arrangement issues, ie losing the arrangement and or a black screen then SMC reset will need to happen so much so that maybe you need to dump that 5k display.

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Answer 2

Joel Pro Author

Level 1

127 points

Feb 7, 2019 7:53 AM in response to DonH49

The LG connects directly to the Macbook via a Thunderbolt 3 cable.

However, the Apple monitor connects via a Thunderbolt 1-to-Thunderbolt 3 adapter.

I did NOT know that port choice could have an effect! I thought the C ports were agnostic. I'm going to play with that.

Also I DID have two external HDDs daisy-chained to the Apple monitor. I have now disconnected those.

SO now I ONLY have my Ethernet cable connected to the Apple Monitor because I do not have an adapter for that.

Let's see if this solves the problem. If not I'll try connecting to different ports.

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Answer 3

Joel Pro Author

Level 1

127 points

Feb 25, 2019 4:03 AM in response to DonH49

"Lastly it does make a difference which display is connected to which port , so experiment around but not live unplug."

That did it.

I changed ports several times (over the course of days to verify the stability of the arrangements), but finally found a port arrangement that resulted in both screens waking automatically.

The first port change resulted in the opposite situation - still only one screen woke - but it was the OTHER screen. So I felt some encouragement. A couple more tries and found a setup that allowed both to wake.

I'm glad this seems resolved, but which port one plugs into really shouldn't matter.

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Answer 4

Joel Pro Author

Level 1

127 points

Feb 7, 2019 4:45 AM in response to Joel Pro

Anybody have a thought on this? Would be a huge help!

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Apple Thunderbolt Display won't wake up unless I unplug LG display first.

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