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I have an Acer Aspire one 5742 laptop. I installed Linux Ubuntu 12.10 on it. I have one problem with it. no matter how I press the Fn+ or Fn+ keys I cannot adjust the Screen Brightness. It is at its maximum brightness and this drains the laptop battery. I did some googling and found out that you needed to change some settings in the grub file but I don't know exactly what to do. Can anyone help me?

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closed as off-topic by To Do, Jane, Jorge Castro, Mikołaj Bartnicki, Eric Carvalho Aug 7 at 23:11

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1  
try,Fn+ right arrow or Fn+ left arrow –  Shaharil Ahmad Oct 21 '13 at 6:45
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Ubuntu 12.10 has reached end of life. Please use a supported version of Ubuntu like 14.04 LTS. –  To Do Aug 6 at 21:10
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@ToDo this question was asked a year ago 12.10 was still supported then. –  Warren Hill Aug 7 at 11:14
    
Sorry didn't notice. –  To Do Aug 7 at 17:33

4 Answers 4

Reading here it says KeyTouch may fix the problem, as it has done for other Acer Aspire models.

Otherwise there are the commands below that can fix via the process you described. In the terminal type:

    sudo gedit /etc/default/grub

you will find a line like this:

    GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

change this line to (making sure to keep the quotation marks):

    GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"

Save the file and then in the terminal type:

    sudo update-grub

Then it should be fixed.

Hope this helps. :)

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First let us check yiour VGA device code

lspci | grep VGA

The device code looks like 00:03.0 for example.

To set brightness

sudo setpci -s '00:03.0' F4.B='xy'

where 00:03.0 is your VGA device code && xy is hexadecimal value of your screen brightness varies between 00 and FF.


Another Method

first know the output name

xrandr -q

for example my output name is DVI-I-2

The brightness can be changed like this:

xrandr --output DVI-I-2 --brightness 1
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Well, I have a notebook Acer aspire 5742, and I had the same problem after installing Windows. The problem was with the drivers, specifically the VGA Intel video card driver was missing. I downloaded it from here! So may be the problem is not with the OS but the missing drivers!
Do you have Windows installed or only Ubuntu? I installed Windows, then necessary drivers and then I installed Ubuntu alongside Windows. And brightness control works well.

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I have a 4830t and the screen looked awful. I had to manual adjust the rgb gamma and the contrast. Now it looks a lot better.

I create a simple script to adjust it at boot:

#!/bin/bash
xgamma -rgamma .8  
xgamma -bgamma .6  
xgamma -ggamma .7  
xcalib -contrast .88  

exit 0

You can adjust the color and contrast to fit your taste.

I hope this helps.

You can also adjust the brightness with xcalib.

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