Q: 27'' LED Cinema Display flickers when powering MBP and dimmed down

Today I figured out that my Belkin extension cable is causing the flickering. I'm not sure if this extra 1m causes too much loss in the signal, if it's interferreing with something else or if it's internally damaged.. I've to buy a new cable to find out, but for now my problem is solved. Hopefully this might help others here to figure out what is causing flickering on these very sensitive Cinema Displays..

Hello all,

the two updates (EFI firmware for MacBook Air 2011) and Thunderbolt software update appear to have solved my flicker issue on my Apple Cinema Display (the mini DisplayPort from 2010).

About time.

S.

I have noticed the flicker happens most when time machine is backing up to a thunderbolt drive. If I turn the backup off (stop backing up) the flicker seems to slow down to nothing.

I have a 17-inch MBP, Early 2011

AMD Radeon HD 6750M 1024 MB graphics

27-inch (2560 x 1440)

AMD Radeon HD 6750M 1024 MB graphics

Two Promise Pegasus Thunderbolt drives

(the display is chained at the end of the drives)

I have tried all of the above. It doesn't matter what brightness setting I use nor does it matter if I unplug the laptop and run off battery. Same flickering occurs if I use the separate MBP power cable instead of the ACD power cable.

The one thing that helps is when I stop backing up to the larger Promise Pegasus drive. I've noticed that If I'm copying files to a thunderbolt drive that the display flickers too.

I will be going into the Apple Store today and will ask about this issue. If it seems that I need to bring in the display, my computer and the drives I will bring it all in order to find an answer.

I use this setup for video production and need it to work. When the display starts flickering It seems off more than on. I am dedicated to finding a solution and will check back here to post what I find.

--rchi

I'm pretty sure I updated with the (EFI firmware for MacBook Air 2011) and Thunderbolt software update but would you mind posting a link to those updates if you get a chance. I'm getting ready to go into the Apple Store now and can look for the updates later...

I've got a genius bar appointment today at 4pm. I'm going to bring in the whole set up including display and pegasus drives with my MBP to try to recreate the issue for the techs at the store.

We'll see how it goes. I'll report back what I find out.

As I was typing the message I could barely follow what was being typed it was flickering so bad.

---rchi

Sorry to necro an old thread but I just brought home a brand new MBP 15" Retina, thinking "I won't need to clutter my desk with a power brick because I have a 27" LED Cinema Display with a power connector."  The Cinema Display has a Magsafe 1, so I bought a Magsafe 1 to Magsafe 2 adapter.

After connecting it I am having precisely the same issue described by a majority of the people in this thread.  The display flickers when the following conditions are met:

1. Power appled to MBP via Cinema Display power connector

2. Cinema Display set to less than 50% brightness in control panel

Either unplugging the power connector or turning up the brightness alleviates the issue.  This looks like a power supply issue in the display - it's being mis-controlled.

Anyway, I'm wondering if there was ever a "fix" for this.  I updated the display's firmware a year or so ago when Apple released an update, so I think it's "current".

H.

If anyone has found a solution could they please let me know!!

If read through so many treads any nothing is working, I'd really appricate it!

I got mine fixed by changing the Belkin cable with an identical new one. See my previous post here. The first cable was brand new and it didn't seem to be broken, but the new cable somehow fixed the problem. The monitor seems to be pretty sensitive.. :/

Thanks for the quick reply Guido Paap, I'm going to try get another asap and try that!!

Like everyone else here, this has been bothering me for a long time, and like everyone else, I have tried all the combinations of re-installing, using separate power sources, visiting the Genius bar, covering my light sensor with tape and turning off auto-adjust, disabling graphics switching, etc. etc. all to no avail. I tried another Mac and had no trouble with the monitor, and tried another nearly identical display with my MBP and saw the flickering, so my guess is that the problem is somewhere in the MBP (or at least in the combo of the MBP and the Cinema display). In the end, I suspected I was doomed to just a new MacBook, and was upset enough to shop around for a nice Linux laptop at half the cost and a new display.

Then I came up with a fairly technical, but effective solution. In the daytime, I can often turn the brightness up enough so that the problem goes away. On cloudy days or in the evening, however, I use GeekTool.

I set up a Geeklet to display a black image at 50% opacity over the whole screen, and chose "Keep on top." This effectively darkens the screen, and allows me to turn up the brightness to over six bars even in the dark without burning my retinas. Of course it's a bit of a hassle when I switch resolutions and such, and some of the contextual menus are still a little bright, but it beats flickering/quavering by a country mile. If anyone is interested I can try and provide a writeup, but you would need to be a terminal junkie or advanced user to get it to work. Maybe someone can make an app to do the same thing - I bet we'd all pay a couple bucks for that :-)