Toughbook CF-30 screen brightness

[nyscan00]

I have a tough book CF-30 that has been having a screen brightness issue. After trying all the normal steps to increase the brightness ( control panel .. display etc ) I have installed new LCD screen and have found no difference in the brightness. Just to double check all settings I went into bios and confirmed the internal LCD is selected and set to high brightness. I then went into conceal mode and turned off the LCD back light and then back on to confirm that works. Next I checked all display and video settings to confirm all has the most current drivers.
One thing I find very interesting is that when I go into control panel and try to adjust the display with the slider button nothing happens... even if I try to decrease the brightness it always remains at the same dim level. Since this is a different LCD i can assume that the physical screen is not the issue

The computer is running Windows 7 Ultimate 32Bit

Does this computer have a photocell that could be stuck? or temp sensor possibly not working? I have tried several computer forums and cant find a solid solution to this issue. If anyone has any advice or has seen something like this I would greatly appreciate the help!
Thank You

 

[poltergeisty]

I'm only guessing, but either it's Windows its self or the inverter.

 

[poltergeisty]

Have another idea. To rule out the OS or hardware, burn a copy of DSL (Damn Small Linux) on CD or use Rufus and write it to a thumb drive and boot it. If you still have a display problem then you know it's hardware related. Possibly the GPU or maybe the inverter though I have my doubts about that. Just make sure you don't accidentally install DSL to your hard drive. If you want to make sure that doesn't happen just disconnect a power cable or data cable from the hard drive/s. Though, I'm not sure if DSL will even offer and install option. It's been years since I used it.