Apple LED Cinema Display Brightness Control

Having problems with the brightness control on an external LED Cinema Display?

I'm posting this purely as a potential service for anyone who might be Googling for a solution to the same LED Cinema Display screen brightness problem I wrestled with last week.

When setting up a non-Thunderbolt Apple 27" LED Cinema Display as a secondary monitor for an iMac (mine is a 27" iMac 11,3, 2.8 GHz Intel Core i5, mid-2010), there can be a problem controlling brightness on the secondary monitor. There is no physical brightness control on the 27" LED Cinema Display, and when you connect the secondary monitor through the Mini DisplayPort, although everything else seems to work fine, there is no virtual brightness control for the second monitor in the System Prefs—>Displays panels either, regardless of how you have the monitors arranged.

The solution
With help from several experts, I tried about half a dozen possible solutions over several days. It stumped a number of Apple experts, to the point that the AppleCare Tech Support Supervisor was about to submit a help ticket to the Apple engineers in Cupertino. The solution is that, although the external monitor works in every other way with just the Mini DisplayPort cable connected, to restore the brightness control you ALSO have to connect the USB cable. (This also activates the USB ports on the external monitor, so it has that additional benefit.) The Brightness slider then magically shows up in the appropriate control panel.

Hope this helps someone out there at some point.

Mike

Original contents copyright 2012 by Michael C. Johnston and/or the bylined author. All Rights Reserved. Links in this post may be to our affiliates; sales through affiliate links may benefit this site.

(To see all the comments, click on the "Comments" link below.)
Featured Comments from:

Scott: "Further, if you want fine control over brightness, as when profiling, and one 'block' is too much, push the Shift & Option keys as you push the brightness key and the levels go up and down in one quarter stops."

Patrick Perez: "So it has come to this: Mike Johnston is providing computer tech support/advice. I think I just saw a pale horse ride by. I kid! Thanks for another great year of reading here on TOP to Mike and his band of contributors, as well as the wonderful group that adds so much in the only comment section I regularly read on the web."

Mike replies: To your first point, I admit that that seems improbable, and, on the face of it, suspicious. But even I am capable of absorbing the relevant details in the direct wake of first person experience!

Comments

[Fazal Majid]

That is the case even if the display is primary, not secondary. For whatever reason, Apple does display control over USB instead of DDC.

[Peter silvia]

This helped me. Thank you Mike!

[Dean Johnston]

Hiya!

> if you want fine control...push the Shift & Option keys

Brilliant! (pun intended). Works for volume too.

Thanks.

[David Anderson]

Does holding ctrl-F1 or ctrl-F2 not adjust the brightness on the other display?

[No. Just the main display. --Mike]

[DavidB]

The need for a USB cable has existed for many generations of the Apple display. My 20" Apple Cinema Display (purchased new in 2006) requires USB to control brightness.

[Curious, then, that a full-time independent Apple tech/repairman, two Apple phone tech support people, and one tech support supervisor with seven years' experience still didn't know it.... --Mike]