Score:1

Ubuntu 22.04 on Late 2012 iMac can't get display to turn off completely

aq flag

I have setup Ubuntu 22.04 recently on an old Late-2012 iMac, which I have setup to be a simple media server.

Everything is working well, but I can't seem to get the display to turn completely off. When the display powers off after inactivity, I can still see some backlighting, and it doesn't appear to be actually off.

I have followed the instructions here as well:

unable to power off macbook display w/ ubuntu server

and here:

https://www.reddit.com/r/linuxquestions/comments/fkql9a/turn_off_display_backlight_ubuntu_servermacbook/

If I run the command setterm —blank force, the screen does go black, but I can always still see some backlighting.

Any thoughts on how to get the iMac screen to complete turn off?

darth_epoxy avatar
nl flag
Macs have their own power control systems and Ubuntu has never really duplicated them. Since Macs went to an Intel chip this has imporoved but it is still hit and miss as to whether you will even have fan control for example. This might be worth a try. Type `xset -q` and note the last two lines. Then type `xset s off` (turns off screensaver) then type `xset -dpms` (turns off energy saving) this seems illogical but I reckon the DPMS clashes with the Mac chip power control.
Marloe avatar
aq flag
Gave it a try, and I still seem to see the backlight.
darth_epoxy avatar
nl flag
You can try this old one https://askubuntu.com/questions/253818/manually-turn-off-monitor but I am not sure how you would get it back on again without restarting.
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