Chosen Solution
I recently started using my Macbook with an additional external screen. After a few weeks with this setup, connecting and disconnecting the external screen in between, the screen started flickering after I disconnected the external screen. The flickering only occurs when the screen is opened more than roughly 45 degrees and sometimes stops when fully tilted back. The issue is not the backlight! The screen itself just turns black for a few fractions of a second, turns back on for a few moments up to several seconds and then the whole things starts over again. Most peculiar is that it stops at any angle as soon as I have the external screen connected. An SMC and PRAM reset didn’t solve the problem. Booting in safe mode however does, but it happens again after leaving safe mode. Theoretically my Macbook qualifies for the “flexgate” repair, but an Apple employee told me on the phone they will only fix it if the backlight is faulty, which is not the case for me. Any input on how to fix this? This is so annoying, I can’t use the macbook without the external screen anymore. On the other hand I am quite happy with the macbook and would hate having to buy a new one, just because of this problem, as everything else on this machine is as good as new (after having the battery and top-case replaced for free not too long ago). Thank you! Update (02/06/2021) I attached Videos of my problem. Some of you might ask now how I know the backlight is working, as the flickering is so short. Well sometimes it is longer, for example when I‘m scrolling through a document. Then you can notice that the screen is actually still lit and „just“ turned black.
Update (02/07/2021) Here are the screenshots.
External screen connected
External screen disconnected
OK I get it! This looks like a power issue with the backlight logic. I’m wondering if the battery is causing this. Your display is likely offering power to your system so while its plugged in the power from the display is solving the problem. When you disconnect it the loss of power makes the system unstable. So… Lets see what CoconutBattery tells us take a snapshot of the apps main window and post it here for us to see. Do one with the display connected and a second when it is disconnected you’ll want to give it a bit of time between the to states so we get a clean capture. Update (02/07/2021) The flex cable issue makes sense! But, why does plugging in the external display stabilizes it? If it was the flex then plugging in or out of the external wouldn’t change the internal displays reaction. So what is different between the external being plugged in? Thats power! The USB plug carries power from the display to your system to charge it. When you’ve disconnected the external power connection your system is on battery. Which is why we started there. While I was expecting the original battery, as you have replaced it you pull that off the list. That only leaves the charging logic within the main logic board. Let’s see if Activity Monitor catches something, Open it up and monitor the Energy tab. I don’t think it will as its not very fast. A power meter might be able to see the power disruption like a MakerHawk USB-C Power Meter (6 digit resolution!) This is the most sensitive unit I have found. In the end you’ll need to find someone with the deeper skills to diagnose what SMD or chip on your logic board needs replacement or replace the logic board.
Mattes- Is your Macbook Pro still operating correctly? My screen just started doing this yesterday, also right after beginning to use an external monitor with it at work, and I haven’t found a solution for when I’m using the Macbook Pro when not connected to an external monitor. Any tips or ideas for anything that may have helped to solve your issue? Thanks!
Same prob as my daughter…. I’ve not checked this but this may help. Sounds interesting anyway - particularly the bit under the ‘answer’ about confusion between splitting the video signal. Please post success or otherwise…
