428      iPhone_iPad_Mac_apple

Black Screen

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.

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.

thanks did this already. i do not see anything with the flashlight.

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.

最後更新：2017-09-03 23:30:06

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