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My Samsung NP740 has been running Ubuntu fine for 18 months. I did an upgrade to 14.10 and the screen brightness controls stopped working correctly. I did a wipe and fresh install and I still have the same problem.

The symptom is that the brightness is now set automatically, regardless of setting it using the controls. In a bright room, it tries to turn up the brightness automatically, although it's very hit-and-miss. Conversely, in a darker place, it tries to turn the brightness down.

The brightness control has no effect until it's turned down to zero, when the display switches off entirely (and, fortunately, comes back on again when you reverse the process).

How do I switch back from automatic to manual brightness control?

1 Answer 1

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You can also use command line option to control brightness.

Steps:

  1. Open terminal using ctrl+alt+t.
  2. Type command "xrandr".
  3. It will display something like this:

enter image description here

4.You need to see (in the underlined part) which display is connected. (Here in my case it is LVDS1).

  1. Use following command to adjust brightness:

xrandr --output "your connected display name" --brightness "brightness value"

For example, in my case it'd be:

xrandr --output LVDS1 --brightness .75

enter image description here

Note: Brightness value should be less than 1. (Otherwise it will be too much brightness).

That's it. Hope this helps.

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    Good - this works quite well and allows some control over brightness. Is there a way to turn off automatic control (ambient light sensing)? I know the laptop's camera is being used because if I cover the camera lens, it dims the screen right down automatically.
    – Rick-777
    Nov 23, 2014 at 23:05

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