MacBook Pro 2017 screen flickers when NOT connected to an external display

Question

Level 1

8 points

MacBook Pro 2017 screen flickers when NOT connected to an external display

Hi ,

I have a weird issue. When my Mac is connected to an external display it works fine. But if it is disconnect it flickers (it looks like switching on and off).

OS Sierra 10.12.6

No flicketing in Safe mode.

Resetting NVRAM and SMC doesn't do anything.

P.s. Another change is that when connected to an exteral display closing the Mac sends it to sleep, while when it worked normally closing would make all open windows move to the exteral display and it kept working.

Any ideas how to fix this?

Thank you.

Posted on Jun 17, 2018 8:01 PM

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Answer 1

sterling r

Community Specialist

Jun 19, 2018 2:47 PM in response to MurphyCooper

Hello, MurphyCooper.

Welcome to Apple Support Communities.

It's my understanding that your MacBook Pro screen flickers when it's not connected to an external display. You've done an excellent step by testing this issue in using safe mode. Since it doesn't occur in safe mode it could be possible something else is causing the issue. As mentioned in this article you should attempt to rule out incompatible login items: Use safe mode to isolate issues with your Mac

If an issue doesn't happen in safe mode

If an issue doesn't happen when your Mac is started in safe mode, try restarting without pressing any keys.

If the issue comes back, you might have incompatible login items.

If the issue doesn't come back, it was probably caused by a cache or directory issue with your startup disk, which safe mode fixed.

There are some steps listed in the Incompatible login items article that can help you narrow it down. As far as closing the lid, does this seem to have an issue in safe mode? You can also test to see if this happens on a test user account: How to test an issue in another user account on your Mac

Let me know if this helps.

Cheers!

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Answer 2

Jun 21, 2018 1:08 PM in response to MurphyCooper

When you run an external display that is not Mirroring, you can designate which is the "Primary" display by moving the tiny Icon of the menu bar to a different display than the default, (which starts as the Internal display).

The Mac does not care, internal, external, it treats them all the same.

.

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Answer 3

MurphyCooper Author

Level 1

8 points

Jun 21, 2018 12:47 PM in response to sterling r

Thank you for your response, Sterling.

The issue comes back after a normal restart.

It is not the Incompatible login items. I removed all the login items and the issue is still there.

The screen flickers continuously even on the login window before I even log in as one of the users.

It feels like the MacBook Pro believes that the second display is a required part of the system and desperately trying to reconnect to it.

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Answer 4

MurphyCooper Author

Level 1

8 points

Jun 21, 2018 1:00 PM in response to Grant Bennet-Alder

Thank you for your question, Grant.

I remove the cable at the MacBook Pro itself. It is USB-C to VGA adapter, which I unplug to disconnect from the external display.

It looks like MacBook Pro doesn't treat the external display as external. Normally, if you close the laptop it collects all the windows on the external display. This one goes to sleep. It is not an external display to it. It thinks it is a required part of itself.

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Answer 5

Jul 5, 2018 10:34 AM in response to MurphyCooper

¿Can you reproduce the problem reliably ?

Anything you can reproduce, the guys at the Genius bar can fix.

I have had them massaging areas on the bottom of a MacBook brought in for service. When I asked, "Why are you doing that?"

They said, "That is where there sometimes is a common loose connection on this model. If you put pressure on it there, and the screen breaks up, it is loose and needs to be re-connected properly."

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Answer 6

MurphyCooper Author

Level 1

8 points

Jul 5, 2018 11:26 AM in response to Grant Bennet-Alder

It can reproduce the problem. The Mac is unusable - it blinks all the time.

I agree with you and also think that something got loose because the problem sometimes comes back or does away after I carry it in the backpack. Any software issue must have been resolved with OS High Sierra update.

My appointment at the Genius bar is today. We'll see if they can resolve it.

Thank you.

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