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I'm running Ubuntu 12.04 on a MacBook air - everything works fine, apart from the fact that the screen dims after 60 seconds of activity. Is there any way to stop this?

My computer is on mains power. If I stop using the machine, after 30 seconds the keyboard backlight turns off (that's fine). After a minute, the screen dims by about 50% - this is annoying, especially when watching a video or reading a long page of text.

My "brightness and lock" settings seem fine:

enter image description here

I've tried

gsettings set org.gnome.settings-daemon.plugins.power idle-dim-time 600

But that doesn't make a difference - it still dims after 60 seconds, no matter what value I set it to.

I've also used gconf-editor but I don't appear to have /apps/gnome-power-manager/backlight

I'm not using Unity - just the standard Gnome desktop.

Is there any way to change this behaviour? I never want my screen to dim. I'm quite happy controlling it manually with the F1 and F2 keys.

EDIT

No - Caffeine doesn't work. The screen still dims.

No - changing the DPMS doesn't work.

No - Editing stuff in dconf doesn't work.

No - I don't have any other power manager software installed.

Terence Eden
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  • Couldn't be a BIOS setting like in Dell laptops? – user.dz Apr 09 '14 at 22:13
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    No. Macs don't have this. The behaviour doesn't happen when I'm booted into OSX. – Terence Eden Apr 10 '14 at 12:04
  • Are you using gnome or Unity or... Have you tried using any other environment? KDE, XFCE etc? (Not as a permanent replacement but to see what the problem might be). Will this occur if you boot the live CD and will this happen if you make a new installation? (you could install it on a USB) This could be useful information. – Xweque May 06 '14 at 09:24
  • have you tried caffeine as a temporary fix?? Install by typing sudo apt-get install caffeine in your terminal – Akisame May 06 '14 at 09:24
  • also I believe there was a bug in 12.04 where the system didn't save the checkbox. You could try to check and uncheck it. That used to fix the problem. If you're using the gnome shell you could try running: xset s off ; xset s noblank ; xset -dpms ;

    In a terminal

     – Akisame May 06 '14 at 09:26
  • That command doesn't work (even tried as sudo). I'm running Gnome and can't easily install another environment. – Terence Eden May 06 '14 at 09:39
  • Do you have any power-management softwares installed? Can you post the output of apt-cache search power | grep management? – jobin May 06 '14 at 12:59
  • See update - no power management installed. – Terence Eden May 07 '14 at 14:05
  • @TerenceEden did you already go through this answer? http://askubuntu.com/questions/171143/how-to-prevent-my-screen-from-either-dimming-or-the-screen-lock-starting-when-wa It should have a workaround if nothing else – No Time May 11 '14 at 00:03
  • @NoTime this is nothing to do with watching videos. Even turning the screensaver off completely fails to stop the screen from dimming. – Terence Eden May 12 '14 at 09:19
  • @TerenceEden I was looking further down the page of the linked answer, namely the lightsOn program, and the one that moves your mouse 1 pixel after a certain amount of time. It will not fix your problem necessarily (the lights on with modification may help though). It will possibly give you a work around, or a way to deal with the problem until you can find a permanent solution. – No Time May 12 '14 at 14:27
  • Did dschinn1001's answer solve your problem? If so, you should accept it in order to clarify that for future visitors to this question. – tparker Sep 07 '18 at 01:35
  • @tparker this question is 4 years old - I don't remember what worked. – Terence Eden Sep 07 '18 at 08:10

2 Answers2

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You could try using caffeine as a temporary fix. You can install caffeine by running the following command in your terminal (Ctrl+Alt+T)

sudo apt-get install caffeine

To find a fix you could do the following things:

Run the following command in your terminal:

xset -q

If you see the energy saving settings enabled (DPMS is enabled) you'll need to disable it.

You can do that by running:

xset s off
xset s noblank
xset -dpms

This should stop the screen from dimming. xset -dpms doesn't survive a reboot so you can add the command to either /etc/rc.local or to ~/.xprofile.

If this doesn't work of xset -q shows you that the energy saving options are disabled comment and I'll try the next method I know

check /org/gnome/settings-daemon/plugins/power with dconf-editor to check that idle-dim-time is set to 600 and that the "active" checkbox is checked if this does not work uncheck the "active" checkbox.
if that does not fix your problem you probably have a alternative powersaving program installed and if you can discover what that other program is I might be able to help you.

If you don't have any other energy saving software installed could you check if a live dvd has the same issue? If it doesn't you are most definitely running some energy saving option that doesn't come out of the box. If it does have the same issue, there is only one thing I can think of that might work.

Akisame
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  • +1 because I was just about to suggest the same thing about caffeine. Aside from perhaps being a temporary fix (and a useful little app anyway), whether it works or not would indicate whether it was the normal Ubuntu dim-on-inactivity at work, or some different problem. – Jon Hanna May 06 '14 at 09:47
  • Indeed, if that doesn't work it could be a powersaving setting from some program like laptop-mode-tools. As far as I know (I haven't used caffeine in a long time) caffeine doesn't work on that sort of stuff – Akisame May 06 '14 at 09:52
  • DPMS is disabled DPMS (Energy Star): Standby: 0 Suspend: 0 Off: 0 DPMS is Disabled – Terence Eden May 06 '14 at 11:56
  • Caffeine isn't available fo 12.04 and, furthermore, isn't suitable. I don't want to stop my screensaver - I want to stop the screen from dimming. – Terence Eden May 06 '14 at 12:01
  • Did you just disable DPMS or was it already disabled?? Caffeine is just a temporary fix to prevent that annoying dimming until a more suitable fix can be found. It can be installed on 12.04, you just need to add the repository sudo add-apt-repository ppa:caffeine-developers/ppaand update your system sudo apt-get update. After that you can install it with sudo apt-get install caffeine python-glade2 – Akisame May 06 '14 at 12:53
  • It's the same whether DPMS is enabled or disabled. I've installed Caffeine - but it does not stop the screen from dimming (yes, I have activated it!) – Terence Eden May 06 '14 at 13:03
  • btw. could you perhaps check /org/gnome/settings-daemon/plugins/power with dconf-editor. I want to check that the idle-dim-time is set to 600 as you said you did and you could change the idle-brightness. if both aren't working you're probably using another program to dim the screen besides the default powersaving programs. – Akisame May 06 '14 at 13:05
  • idle-dim-battery and idle-dim-ac are both unchecked. I've tried setting idle-brightness to 100 and checking the boxes but that hasn't made any difference. – Terence Eden May 06 '14 at 13:17
  • Terence - please do not have a conversation in comments - edit your question with what you have tried and extra results. Please tidy up by deleting your comments. Thanks. – fossfreedom May 06 '14 at 13:28
  • I did. It doesn't work. – Terence Eden May 11 '14 at 12:54
  • xset -dpms works for me on Mint 17 (i.e. ubuntu 14.04), xfce; thanks! This was watching a video with VLC, with AC unplugged. xset 0 0 0 did not work: it dimmed as usual after 45-ish seconds, then screen went black after about 2-3 minutes. – Darren Cook Dec 11 '14 at 20:23
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Installing xbacklight and then running xbacklight -set 7 and xbacklight -time 500 should work (OP has confirmed this)

sudo apt-get install xbacklight
fossfreedom
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dschinn1001
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