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Precision M6800 - Low Display Brightness on Sierra 10.12.6


cc333
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Hi,

 

Just got an M6800 (excellent machine, by the way!), and I've successfully installed macOS Sierra on it.

 

Other than built-in audio, everything seemed to be working okay under 10.12.0 (including the Expresscard slot).

 

However, when I updated to 10.12.6, the brightness of the internal display seems to be stuck at 50%, and I can't change it. The brightness slider is useless, as it has only two positions: 50% on and 100% off).

 

I installed the brightness fix bootpack for the m6800, but it hasn't helped.

 

Switchable graphics is off, and the Graphics card is Nvidia K3100M.

 

Any help would be greatly appreciated.

 

Thanks!

 

c

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I figured it out!

 

Apparently, all I had to do was install the AppleBacklight.kext and AppleBacklightExpert.kext from Sierra 10.12.0, and everything's working fine again! I have full brightness, and I can adjust it to any level at will.

 

So, for anyone with this problem, rather than go through a bunch of rigamarole to patch your DSDTs and adding extra kexts that may or may not work, simply installing older versions of these two kexts appears to the problem quite nicely (at least with the Precision M6800; your mileage may vary with other models).

 

c

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