Frage: iMac 27" mid 2010 - backlight random switch off
I installed 10.13.4 on my iMac 27" mid 2010 and discover a bug that the backlight switches off at random.
First I thought that my iMac was gone and that I have the graphic card problem that many users had. But than I saw that the display is still showing windows and only the backlight switched off. The backlight lights up as soon as you reboot.
Than I found a user at youtube that discovered that you can get the backlight back to work without rebooting.
When the backlight goes off just
1. Type "CMD-SHIFT-EJECT" - shortcut for switching off backlight (thou it is already off)
2. wait 2-3 seconds
3. press any key and backlight switches back on :-) until it goes off again :-(
If you set higher backlight levels it switches off in a shorter time, if you set the level less than 50% the backlight stays on (at least for a much longer time period)
I still thought of a hardware error until I discovered that this only happens with High Sierra. I tried with 10.6.8 and 10.12.6 - no problem.
So this looks like a new bug in High Sierra but do not mix it with graphic cards bug or half lighted displays. This looks to me like a software bug.
Every hint is welcome
iMac, macOS High Sierra (10.13.4)