View Full Version : [SOLVED] Screen brightness set to zero at each bootup of 13.10-64 on a HP Pavilion dv4 Noteboo

December 21st, 2013, 09:46 PM
New complete installation of 13.10-64 Desktop release on a HP Pavilion dv4 Notebook PC (WA684UA#ABA). During boot, the purple Ubuntu screen shows for a moment, then goes black. Machine boots up correctly, but the screen brightness must be turned up (alt-F8) before anything can be seen. Once brightened, it runs fine until the next boot cycle. Same scenario then repeats. No additional drivers being used.

How to fix??


After searching around I may have found a fix for this:


Post #2: says; I found this workaround (from bug #35223 (https://bugs.launchpad.net/bugs/35223), comment #51):"[...] If I put
echo 2 > /sys/class/backlight/acpi_video0/brightness
in /etc/rc.local (before exit 0) it seems to work."
Indeed it works; I just changed 2 to 1, as 1 gives a low but acceptable brightness level on this lapto

After testing it I will mark solved if it works.


I have tested and the results are good.

Yes, that does work for me, and of course it "sticks", since it is a change to etc/rc.local.
echo 2 I've changed to echo 20, which sets brightness to 100% it appears, what kind of number base is that????????

marking this solved.

December 22nd, 2013, 03:17 AM
have you tried any of these commands ?


December 22nd, 2013, 07:05 AM
Thank you raja, as you will notice in my original post (edited), it's fixed.