Q: Acrylic Cinema HD Display is usable but very dim

I have this exact same issue.  I didn't have this problem in Mountain Lion.  Apple needs to fix this.

I'm having the exact same issue. I have also tried the "Shades" app and it yielded the same results. This wasn't a problem until recently. The brightness keys on my Apple wireless keyboard stopped changing brightness a few months ago, but the display brightness was fine so I didn't care much. I am running Windows on a Bootcamp partition, however. Funny thing is that the display has always been more dim on the Windows side than the Mac side of the Computer. I'm hooked up to the display from my MacBook Pro 8,2 via mini display port to DVI adapter and then through the ADC adapter. I've seen that plugging in the USB has helped for some people losing control of brightness, but it hasn't halped me. Also, I'm running Mavericks.

Just ran into this today, myself. Using the ADC > DVI adapter, and connecting that adapter's USB plug into a hub that connects to one of the USB 3.0 ports on my new MacBook Pro 15" Retina display.* I've had this 24" acrylic Cinema Display for years, and it's worked fine until I set up Boot Camp with a Windows 8.1 partition.

The screen went dim on me while I was in Windows, so I assumed it was driver-related. Imagine my disgruntlement when I rebooted into Mavericks and saw it remained as dimmed. There is no slider for Brightness in the Display control panel. And whatever the "bright" icon on the lower left of the monitor itself is supposed to do doesn't seem to change anything.

Now that it's happening in both OS' I'm wondering if perhaps it's a hardware issue. I must have gotten this screen either late 2002 or early 2003. Is it possible that one of the backlight bulbs is out? Does this unit have more than one to go out?

*(EDITED: plugging the USB from the ADC adapter directly into one of the MBP's USB ports does not improve the dimming problem.)

Message was edited by: Alex Hare

In continuing my research on this topic, I found this article:

http://support.apple.com/kb/TS5198

Short version, the 23" Cinema HD is among one of several older "vintage" Apple displays that are no longer supported under Mavericks. No brightness control, and it's likely to not work reliably at all. I can't say why I was able to use it for as long as I did with no problems. I take all this to mean that the display itself works fine, but not with my new MBP Retina.

Though a tempting excuse to spend another grand on a 27" Apple Thunderbolt display, I opted for a $250 HDMI monitor from Fry's instead.

WOW This is such BS. To drop support is one thing.  To drop functionality is another.  And the idea that it is old technology unsupported by Mavericks is a load of crap.  This monitor was $3000 new.  I'm sure somebody's gonna chime in with a fix for this in Terminal.  Apple's losing a customer.

The useful line from the article is:

These displays were designed to work with older hardware that is incompatible with OS X Mavericks. To avoid incompatibility issues, use a newer display that includes a DVI, VGA, HDMI, Mini DisplayPort, or Thunderbolt connector with Mavericks.

I can't speak to the point about older hardware that's incompatible with Mavericks. I have an ADC to DVI adapter I picked up off eBay a couple years ago, and that seemed to work fine for about a week. The only changes to the rMPB I'm using that I know of were software related, as I'd had data and apps transferred over from an old drive, and set up Windows 8.1 in Boot Camp. Maybe I was just lucky it lasted as long as it did.

I did find a few Brightness apps in the Mac App store. Nothing that would set the brightness higher than 105%, though, which wasn't bright enough to make it useful.

I can concur that the brightness control is not available for me when the 23" Acrylic Cinema HD display is connected via a ADC to DVI adapter. I have tried using a DVI to MiniDisplay Port and DVI to HDMI adaptor on a 13" Retina MacBookPro running Mavericks.

However, I did find the available (default) brightness to be acceptable on the display I used

Found this solution (wish Apple told us prior Mavericks and CinDi's aren't compatible):  I have an older 23" Cinema Display, a G5 Quad Core and am running Mavericks, so no brightness controls available.  Screen went irreversably dim after using Windows 7 (Boot Camp, partioned hard drive).  Even when switched back to OSX, nothing worked to fix problem.  Fortunately, I also have a newer MacBook Pro still running Mountain Lion.  To get Cinema Display back up to desired brightness, I connected the Cinema Display to the MacBook Pro via Mini DisplayPort to DVI Adapter (and the USB plug), mirrored the two displays, and adjusted the brightness on Cinema Display through the MacBook Pro.  Then unplugged CinDi from MacBook Pro, and reconnected it to my G5.  Started the G5 ... and brightness is back.  If you can find someone (or have another computer) not running Mavericks, it may work for you as well.

NOTE:  Still cannot adjust brightness through G5, so set Cinema Display to your most desired level when re-establishing on other non-Mavericks computer.