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Can't change brightness on external 27" cinema display

Hi,


I can't change the brightness of my 27" cinema display. I have no brightness fader on the settings. I have tried it with my MacBook Pro (Sow Leopard) and my MacBook Air (Lion). On both devices the same problem.


The display is too dark and I would like to brighten it up.


I have searched the forum and tried several things without luck.

The USB cable is plugged in.


Any help is highly appreciated.


Thanks,

OBE2011

Cinema Tools, Mac OS X (10.7.2)

Posted on Dec 4, 2011 1:04 PM

Reply
Question marked as Best reply

Posted on Jan 11, 2012 12:00 AM

Plug in the USB tentacle that comes out of the display, crazy but that is needed in order for the System Preferences to enable the Brightness slider. I know, it took me about 2 hours of drilling through doucmentation to find this.


http://support.apple.com/kb/HT4293


Additional Information

This software updates the System Preferences pane where you can change Ambient Light Sensor settings. Enable the option "Automatically adjust brightness as ambient light changes" to turn the ambient light sensor on and off. Use the slider to adjust the brightness level.

User uploaded file

Note: You must have the cinema display's USB cable connected directly to your Mac to access this functionality.

10 replies
Question marked as Best reply

Jan 11, 2012 12:00 AM in response to OBE2011

Plug in the USB tentacle that comes out of the display, crazy but that is needed in order for the System Preferences to enable the Brightness slider. I know, it took me about 2 hours of drilling through doucmentation to find this.


http://support.apple.com/kb/HT4293


Additional Information

This software updates the System Preferences pane where you can change Ambient Light Sensor settings. Enable the option "Automatically adjust brightness as ambient light changes" to turn the ambient light sensor on and off. Use the slider to adjust the brightness level.

User uploaded file

Note: You must have the cinema display's USB cable connected directly to your Mac to access this functionality.

Nov 6, 2012 5:20 AM in response to Nick F-J

Thanks Nick F-J! This is what solved my problem. I recently had my LED 27" Cinema Display repaired. They replaced the logic board. However, they apparently didn't know or forgot to reset the EIDID. Using the link you provided to download the EDID_Reset_Tool.dmg and following the instructions solved the problem.


Since I am running Mountain Lion 10.8.2, I had to do one extra thing and that is to use the Ctl-Click and Open on the program since it was not identified as a APP downloaded from the App Store (a new "safety" feature in Mountain Lion but they forgot to update all of their own software to be). Doing this allowed me to run the APP.

Feb 13, 2013 7:46 AM in response to dlisanto

Dear dlisanto,


No, you don't need to specify any software. Just hold down the control modifier key and click on the file. A popup menu should show up and then select "Open", not "Open With". If you do select "Open With", then select the default, which is DiskImageMounter. You should see "EDID Reset Tool" appear mounted on your desktop or under "Devices" in a finder window.

Can't change brightness on external 27" cinema display

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