Screen Brightness...

[quackquack]

Hi,

I cannot change my screen brightness at all in Ubuntu. i could not do it in gutsy and i have just upgraded to 8.04 and i still can't change my screen brightness. I have tried using the function keys which shows the bar which is supposed to control the brightness, and i can move it up and down with the function keys fine but it doesn't change the screen brightness at all. I have also tried clicking lower my screen brightness when on battery power in power manager and unplugging the laptop and the bar moves down but again the brightness does not change.

It is probably something i am doing wrong, but is there a way to fix this?

Thanks in advance.

[lecter255]

i don't think you are doing anything wrong. in 7.10, i could adjust my laptop's backlight. i can't in 8.04. i use a hp dv2000 with a nvidia graphics card. I can't adjust my screen's brightness at all. when it's plugged in it's bright, when it's not, it's dim. i have heard that there are settings in bios that ubuntu set permanently that caused this, but i don't know how to get into bios.

[Danielkida]

I have a toshiba satellite and report the same problem, the bar slides up and down when i press they keys to adjust the brightness but nothing happens. The display also shows that the brightness has changed when using battery power but nothing has happened. It didn't work in gutsy and still doesn't work now in hardy

[pivot@pivpoint.no]

Bump!

I have a HP Compaq 8710w og Hardy Heron. Bars are moving, but no effect

[Morty007]

What if you have a desktop? How do you adjust the brightness then? Same thing?

[konungursvia]

You could try altering the desktop gamma in terminal.... [also, if you love linux, there are companies that try harder than HP to make it work].

[quackquack]

so its not just me that has this then?

isn't there some sort of magic thing i can do with the terminal to make it work?

lol

[quackquack]

oh and i should probably say

the laptop is a toshiba equium l40 - 10x

[rlc2]

I have a Dell 1420N with the same dim screen issue.
It worked fine under gutsy, but after upgrading to hardy using the update manager app, the first time I resume the laptop after suspending it I lose the ability to change the display brightness. With the Gnome brightness control running I can move the slider to any position to no effect, and the brightness control keys on the keyboard pop up the brightness meter but have no other effect. The xgamma command didn't help either.

After editing various startup scripts in /etc/resume.d, I finally found a workaround, though it's not pretty. It looks like the gnome resume code fails to run the 'vbetool post' command properly. Disabling the Gnome resume scripts and using the system scripts instead resolved the brightness problem but that interferes with the Gnome power management controls. So here's what I do about it (I only have this dell laptop, so this hasn't been tested on any other brand or model):

* Use the "Ctrl-Alt F1" key combination to get to a virtual console after the system starts up from a cold boot (on my system none of the virtual consoles are visible after waking up the laptop).

* Keep a root console running in this terminal by running the following:

$ sudo su -

and enter your user password. Press "Alt F7" to get back to the window manager.

* whenever you wake the laptop, use the "Ctrl-Alt F1" key combination. Your screen will turn black. Carefully type:

vbetool post

and press ENTER.

* The "Alt F7" key combination should return you to the window manager, and at this point the brightness controls should work again.

* Alternatively, instead of using a virtual console, you can simply open up a terminal under Gnome and run:

sudo vbetool post

and enter your user password.
Warning: this can produce disturbing video artifacts. "Ctrl-Alt F1" followed by "Alt F7" should clean up the screen afterwards.

Hopefully this work-around explanation will also be helpful for whomever maintains the gnome power manglement packages, so all of this will no longer be necessary ..

[quackquack]

thankyou for your post

i tried your solution and it caused my screen to flash different colours rapidly (almost causing me a seizure lol ) and i tried all run modes including ctrl alt f1 and ctrl alt f7 and nothing happened. i had to restart my computer.i tried again and it went black and i used ctrl alt f1 then ctrl alt f7 and it went back to normal, however the brightness control still did the same (bar moves up and down but brightness doesnt change). I tried a third time and it did the flashy thing and i couldnt get it out of it again .

are there any other solutions? ill try anything lol.