9 
3 
2 screen goes black but still running
Mac 27" late 2009 (EMC 2374)
Mine is a late 2009 27" iMac running Sierra. Screen goes black like it's energy saver black screen. (except I disabled that, and the screensaver, etc) I know the computer is working except for the black screen because I am able to remote desktop in and everything is normal (except for the imac's screen)
It seems to come back if I sleep the computer (remote desktop / apple menu / sleep) and then click the mouse. The screen comes back on like nothing was amiss.
I tried an app: antisleep from the appstore but it's still happening.
I tried smcFanControl to crank up the cooling. Still happening.
I of course did all the usual pram, disk error checks, update OS, etc. Didn't help.
Seems a lot of people over the years have had this issue, but I've not seen one definitive answer. Just happened again while I was writing this... Still had remote desktop going on my laptop. No change on it. just a black screen on the iMac. Sleep and mouseclick brought it back... Weird. Also extremely annoying!
boot in recover partition or usb install os x
if your screen keep going black probably your backlight is gone
由 lapo 完成的
The screen comes back perfectly if I sleep the computer and then wake it up. If it was the backlight wouldn't it be black all the time? I'll look closely tonight after dark as others have suggested.
I also tried a plugging an external display in using the mini display port and a vga cable I had. When the imac screen goes black, the external screen is left switched on, completely unaffected.
由 mark 完成的
What OS X are you running?
由 mayer 完成的