can't change screen brightness after OS upgrade on XPS 17 (l702x)

Hi everyone,
I received my new XP 17 notebook with just the right configuration I wanted (4 memory slots etc.) and upgraded to Win7 ultimate.
The problem right now is I can't change the screen brightness by using Fn+F4 or Fn+F5 keys anymore. I installed all the drivers I can find (including Dell OS support utility, Dell quickset, latest NVidia drivers etc).
When I press Fn+F4/F5, I see the on screen display of brightness control with the slider which moves up & down but brightness doesn't change.
This is not a hardware problem as I can go into Nvidia control panel and select "use nvidia ..." to control brightness and move the slider to change brightness.
It is definitely a software/driver issue but I can't figure out what it is. Any ideas?

Also is there any software on PC which does automatic brightness control depending on lighting conditions? This would need an ambient light sensor I guess.

 

Others have mentioned this before, I think you need to upgrade your BIOS.

 

But it used to work before I upgraded win7. Also I am running the latest bios which Dell has on its website.
By the way, do you have a reference to the other post?

 

I just wanted to give an update. I fixed my problem by installing the latest NVidia graphics driver. It seems for 3d you need both A08 BIOS and the latest graphics drivers. Dell support page says you need A07 video drivers which don't exist on their web site (goes only to A05) so I downloaded the latest from Nvidia directly.

 

Hi there, just registered to say this thread helped me fix the same problem. I tried updating the videocard drivers on the 555m GT to the latest on the nvidia website but after getting a black screen for 10 minutes I had to reset. After that the brightness keys didn't work and the sliders didn't work in the power options.

How I fixed it was going into Dell's website and downloading the latest BIOS update (A08). For this model of laptop you can go here: Drivers & Downloads

During installation of the BIOS the laptop will make a bunch of scary loud beeps, just ignore it. The Dell technician on the phone wasn't sure why it beeped so much but it all installed successfully.

After that all brightness configuration worked perfectly again. Not sure if I'll try installing the latest nvidia drivers again for a while. Thanks heaps Kalm for that info, saved me having dell try to replace the screen, which was going to be his next option!

 

Hi,

I have the same notebook(L702x) and the same problem with the brightness adjustment (works via nvidia panel but not from keyboard shortcuts Fn-F4/F5).

I followed your advices without success: downgraded BIOS to A08 version and upgraded nvidia to the latest driver (270.61).

Is there any other hints?
Thanks.

 

I was able to fix this by applying both the newest BIOS (currently A10) and the newest nVidia drivers (currently 270.61).

Be warned: the BIOS update sounds scary, as the system beeps constantly for several seconds, and the nVidia driver installation caused my screen to go blank. I could hear the sounds of being logged out of Windows, but nothing happened. I pressed the power button to force it to turn off, and after booting into Safe Mode (just to make sure nothing had actually been hosed) and then rebooting into regular Windows, everything has been fine and working as it should.

 

I've installed the A12 BIOS version and the latest NVIDIA driver (280.26) without seeing any improvements. The brightness problem still persists.

 

Some laptop graphic controllers won't be able to change brightness unless you use the supplied driver from XX manufacturer. This was true for my Dell Latitude 13.

 

Well BIOS A08 I think is the one that fixed this issue, and it was really only with the 120Hz screens iirc. Try using the latest Dell graphics driver (so run driver sweeper in safe mode to kill the current NVidia drivers and then install the Dell one). You might have better luck then.