Led Cinema Display brightness control not working after upgraded to macOS Monterey

Here's a 3rd party fix! If it can't detect the brightness or contrast then put it as 50 and 50, it works perfectly with my 24"! https://lunar.fyi/

lunar.fyi fixes it

OMG. I just found the solution to this. There is an app called Luna Pro that fixes this issue!

I'm using monterey 12.4 and a cinema display 27'' 2010.

The only way I managed to fix was doing what I send here.

After I changed the brightness ddc max to 255, moved the brightness down and up the monitor reached its maximum brightness.

Update...

Shut down, checked all the connections and restarted. Bingo! Cinema HD is back up and a little brighter than before, around 85%-90% brightness, I'm guessing.

I'm guessing because nothing controls it anymore, not the Display Preferences, nor MonitorControl where it no longer appears at all.

I'm stumped!

But as a general conclusion, connecting to an older machine with an older OS does seem to enable better brightness, albeit with no actual control. For me, anyway.

Update to the last update (03.10.2022)

I have been away from my Mac Studio for a couple of months but there seems to be a general improvement with the Cinema Display brightness issue since my return.

Full brightness is still not achieved but comes on at around 80% - 90% at startup.

If the Mac falls asleep, the Cinema Display brightness tend to drop after waking.

Over prolonged use, the monitor might flicker on and off until it goes off completely. This may be due to overheating, or to a faulty power unit. Detaching power and allowing the monitor or power unit time to cool off seems to remedy the problem, anyway.

Also, updating to macOS Monterey 12.6 may have helped stabilise the brightness overall. The Cinema Display still has no brightness control in the Displays Preference setting, however.

Obsolete. ? These display still work very well.

Anyway let's scrap good products to make even more money. And continue to ruin the planet.

(and also not pay income back to the nation they grew in and from btw)

Luckily there still good will people. Thanks for MonitorControl.app

see leoluzacmp's post.

I have a 30" Cinema Display, connected to a new Mac Studio running Monterey 12.4 via a DVI - USB C adaptor.

Displays control panel took a moment to adapt to the addition of a new external monitor but the brightness was good (and had been good when previously connected to a 2014 iMac). Following a restart however, the brightness has stuck at around 50%. Displays control panel offers no Brightness control. I have installed Lunar, Monitor Control and Brightness Slider, with no luck whatsoever.

Each of those additional controls (recommended here and on MacRumors by users experiencing similar problems) shows Cinema Display Brightness at 100%. Monitor Control and Brightness Slider do enable further dimming (to -50%) but Lunar has no effect whatsoever. Changing brightness via the F1 and F2 keys works as normal on the new Studio Display but shows a lock under the Cinema Display on-screen brightness display.

Is there any way of unlocking the Cinema Display fixed at 50%?

Install either MonitorControl or lunar.fyi, that should fix it. It'd be good if it was native tho

Obsolete products are not tested with current OS and resolution is not guaranteed.

Check out HT201624 - Obtaining service for your Apple product after an expired warranty

https://support.apple.com/en-us/HT201624

Hitting my head on the desk with this issue as well. Can you “downgrade” the OS to Big Sur if it came pre-loaded with Monterey? Got our fam a brand new Mac mini for Christmas, as I had an extra 27” Cinema Display from my studio. Made sense to me, right? This display is gorgeous.

After finding out the hard way that thunderbolt 2 to thunderbolt 4 adapters don’t work… finally got the MDP - TBolt4 in the mail today. Display and audio now work, but the brightness is definitely an issue. Photo/Video editing and working/editing in any DAW is going to suck at 50% brightness.

Maybe I’ll try the third-party app? Any info as this progresses will be great though. Thanks for posting!

Same problem this was a bug / omission in the build of macOS Monterey. Apple please restore this service. I have a brand new Mac-mini and I would like to use my Apple LED Cinema Display 27 in. properly see image below.

I just got a Mac Studio and connected my trusty LED Cinema Display. I guess I didn't notice the lack of brightness controls in Monterey until now. It's unacceptable Apple would drop something as simple as a brightness control. The Cinema Display is my secondary monitor, and I can accept the current brightness. If I need to change it I'll try the third-party utilities.