Whem I shut down my computer sometimes I get a black screen before it goes to login to my iMac. Does anyone else have this problem if ao how to fix it? i am using this version see below, this happens a few times and cannot just get to log in screen. I have unplug both ends of electric cord and held down power button for 40 sec. and then even left it off all nigth to see if it would fix it no luck. Any help would be much appreciated.
iMac, macOS Sierra (10.12.5), Please help asap
Try an NVRAM reset:
How to reset NVRAM on your Mac - Apple Support
Also, when you experience the black screen, shine a flashlight on your screen and see if you can see the login screen. If you can then it may be a backlight inverter.
Have you tried running Apple Hardware Test?
How to use Apple Hardware Test on your Mac - Apple Support
If AHT reports a problem, there usually is. However, even if AHT reports nothing there still may be a hardware issue. Apple stores have much more sensitive diagnostics they can run. So, I suggest making a Genius Bar appointment and bringing it in for a free diagnostic.
OK finally got done with the 1test and did the extended one as well nothing found. And still got black screen of death. Any other fixes but wil not be home to do it right away to get back to you but do appreciate anyone help in this matter.
Thank you macjack
thanks did this already. i do not see anything with the flashlight.
I will do this now will get back to you soon after test. Thanks
That's encouraging but not conclusive. I'd bring it in for further diagnostics.
Thanks for all your help but want to get this fixed. I apprecite all your help. If anyone else has anything else for me to try I will try it out.
Thank you all and machack
Did this and when shining flashlight see nothing? and now restarted it again and still comes up with black screen before wake up
Make an appointment at an Apple Store for a free diagnostic.
thanks will do
Black Screen
