CF-52 Mk 1 brightness stops at 50%

Question

I used the acpi_osi= trick to make Xubuntu 14.04 work with my newly acquired CF-52 Mk 1 Toughbook. Among other things, this enabled it to control the LCD backlight brightness. This mostly works fine, but at 50%, the backlight brightness stops increasing.

These laptops are notorious for failing CCFL backlights. However, I am not experiencing flaring/flashing on startup, dimming over time, or inconsistent brightness. Is it possible that I have either limited the brightness to 50% somewhere without realizing it?

Thanks.

score 0 · Answer 1 · answered Mar 03 '16 at 22:30

0

Download xblacklight from Ubuntu software store.

Xbacklight is used to adjust the backlight brightness where supported. It finds all outputs on the X server supporting backlight brightness control and changes them all in the same way.

   -get   Print out the current backlight brightness of each  output  with
          such a control. The brightness is represented as a percentage of
          the maximum brightness supported.

   -set percent
          Sets each backlight brightness to the specified level.

   -inc percent
          Increases brightness by the specified amount.

   -dec percent
          Decreases brightness by the specified amount.

   -help  Print out a summary of the usage and exit.

   -time milliseconds
          Length of time to spend fading the backlight between old and new
          value.  Default is 200.

   -steps number
          Number of steps to take while fading. Default is 20.

answered Mar 03 '16 at 22:30

DesertGhost1776

23

XBackLight produces no change between 50.0% and 75.0% or 100.0%, just like the Fn-key or GUI controls. – Leonora Tindall Mar 04 '16 at 03:52
Are you on Ubuntu or Xubuntu? – DesertGhost1776 Mar 04 '16 at 04:55
Xubuntu, as stated in my question. – Leonora Tindall Mar 04 '16 at 15:37
Are you on the latest version? I opened up my terminal and used commands with xbacklight and it worked for me. Did you install xbacklight from terminal or the USC? – DesertGhost1776 Mar 04 '16 at 18:47
Have you tried this:
1. sudo nano /etc/rc.local
2. add this line to the file (substitute X with the desired level of brightness):
echo X > /sys/class/backlight/intel_backlight/brightness
– DesertGhost1776 Mar 04 '16 at 18:49
They are talking about it on here in another script. Check it out. [http://askubuntu.com/questions/739654/xbacklight-is-not-working-ubuntu-14-04-lts] – DesertGhost1776 Mar 04 '16 at 18:50
Or try this one. [http://askubuntu.com/questions/615974/brightness-setting-not-working-on-xubuntu-15-04-vivid-vervet] – DesertGhost1776 Mar 04 '16 at 18:54
Or this [http://askubuntu.com/questions/287572/unable-to-adjust-brightness-in-ubuntu-xubuntu-lubuntu13-04] – DesertGhost1776 Mar 04 '16 at 18:55
The problem is not that XBackLight doesn't work, it's that changing the brightness with ANY tool only works up to 50%. – Leonora Tindall Mar 05 '16 at 21:00

CF-52 Mk 1 brightness stops at 50%

1 Answers1