Currently Being ModeratedApr 29, 2012 9:21 AM (in response to sunny_1991)
One harmless thing to try is to reset the NVRAM:
Currently Being ModeratedApr 29, 2012 10:11 AM (in response to sunny_1991)
If the monitor has a USB cable, plug it in.
Currently Being ModeratedApr 30, 2012 11:30 PM (in response to sunny_1991)
The exact same thing has happened to me.
I am running a 27" Thunderbolt display off of a Mid-2011 MacBook Air.
Suddenly, last week, my brightness control keys on my external keyboard stopped affecting the brightness of the Thunderbolt display. The brightness keys on the MacBook Air, though, still affect the brightness of the laptop's screen.
I went into the Displays preference pane, and sure enough, the brightness slider has disappeared.
Have you been able to resolve this? (zapping PRAM, etc doesn't work.)
I'm wondering if this is a glitch that came with 10.7.3...
Anyone have any ideas? I have no way, now, to control the brightness of my Thunderbolt display. It is EXTREMELY frustrating.
Currently Being ModeratedApr 30, 2012 11:43 PM (in response to rudy_)
This resolved the issue:
(this is an Apple tool to reset the EDID after the LCD panel or logic board is replaced. My monitor, though, was never taken in for repair. The brightness controls went kablooey just sitting on my desk.)
Currently Being ModeratedMay 1, 2012 12:48 AM (in response to CT)
Thanks CT, I tried for resetting NVRAM. and it worked perfectly fyn. Brightness controls are back, and slider also. So Thanks A Lot for the help.
Currently Being ModeratedMay 1, 2012 12:50 AM (in response to Linc Davis)
Problem was in my internal Display. So no USB cable.
Currently Being ModeratedMay 1, 2012 12:53 AM (in response to rudy_)
There was problem in my internal display, with internal keyboard. So i think problem was little bit different. but anyways thanks for that tool (I have downloaded it.). In future, if i replace or anything happens in h/w. i will try to use that tool. Thanks.