Previous 1 2 3 Next 124 Replies Latest reply: Feb 22, 2014 7:25 AM by geoffreyfrommatthews
davidexcom Level 1 (0 points)

Hi firts of all excuse my english because Im from Spain.


I use a Belkin Mini Displayport to HDMI converter (same as Kanex, Dr. Bott) to play XBOX 360.

But after 10.6.8 update when put the target 2 (cmd+F2) the brightness of my iMac is super max

I was going to melt my eyes and I can not change, it is like F1 and F2 will not work now, but F10 and F11 (volume buttons) are still working.


Any ideas?

Any way back to 10.6.7?THANKS



  • Carson Jones Level 1 (65 points)

    We're seeing this as well at our studio.  DON"T update if you're using dual displays with one display connected via HDMI (Nvidia 4000).  Just got off the phone with Apple tech and they have absolutely no idea what's happening - even after 1/2 hr of troubleshooting. 


    I'm at a total loss to understand how something as simple as maintaining display connections breaks after an update.

  • a brody Level 9 (65,743 points)

    Often F-keys are disabled, because of Keyboard preferences in Apple menu -> System Preferences -> Keyboard with a simple checkbox that asks if you wish to use fn keys with the F-key.  Try the Fn key with the F-key and see if that improves matters.  If not, display issues can often arise from an update because something messes up in NVRAM or PRAM.  Here are the instructions to do that:


  • davidexcom Level 1 (0 points)

    Thanks, I try the 2 things but nothing works.

    Its imposible go back to 10.6.7?

  • Carson Jones Level 1 (65 points)

    Not certain why fn keys would affect an HDMI connection.  Seems like a bit of a disconnect there.


    In our case we're using the Nvidia 4000 and the display connected via HDMI simply isn't recognised by the OS since this last update when used as a second display.  Used to work flawlessly and since the update it doesn't at all.


    When the only diplay plugged in is the HDMI display the computer fires up and the display works.  This tells me the hardware is fine and the OS has broken the connection.  Apple tech agreed although they have no specific idea as to what's causing it or how to fix it or when we can expect a fix.  We ran the usual spectrum of Apple troubleshooting, including resetting the pram.  Still not working.

  • davidexcom Level 1 (0 points)

    I do not know really have changed the minidisplaypor connection sotware, but the F keys of volume if it works, the problem is that the brightness can be lowered while taking the image oftarget 2 on in my case and in yours is something diferent.


    It's obviously a software problem

  • a brody Level 9 (65,743 points)

    Backup your data first at least twice if it hasn't been already*:



    Find the 10.6 discs that installed 10.6 on your system.


    Apply the 10.6.7 combo updater:



    Apply the font update



    And if that fails, erase and install 10.6 using the same installation disc, apply the 10.6.7 combo and font update, and use the Migration Assistant to import your data from the clone backup.

  • a brody Level 9 (65,743 points)

    Fn keys don't affect HDMI, but they do affect how F-keys operate if the Keyboard settings are switched.  Sometimes system settings reset to default when updates are performed.

  • Rich The Limey Level 1 (0 points)

    This is also happening on my system where I am running a 27" iMac as an external display for a Lenovo laptop. They are connected using DisplayPort to mini DisplayPort.

    Every since the 10.6.8 update the external display mode is like staring at the sun. I'm getting quite a nice tan from it though.


    Is this problem under investigation?


    I really don't want to have to go to all the hassle or reinstalling 10.6.7.  I wish OSX had restore points like Windows does.

  • davidexcom Level 1 (0 points)

    finally I cant be solved in any way.

    I had to return to 10.6.7
    I hope Lion dont have this huge failure.

  • Rich The Limey Level 1 (0 points)

    This is ridiculous. Did anybody at Apple actually QA test this 10.6.8 update??  Perhaps it was the same team that QA tested the iPhone4 before its initial release.


    Based on the number of issues I've heard of with 10.6.8 perhaps Apple should revoke it entirely to reduce any further suffering.

  • citan Level 1 (0 points)

    Same problem here: MacBook Pro and iMac 27" used as external screen (connected via Belkin Mini DisplayPort cable). SMC reset didn't help, key bindings for brighhtness are fine (and work when iMac was not connected to MacBook).

  • webdevbrian Level 1 (0 points)

    I can also confirm this is an issue with my setup as well (27'' iMac as an external, 15'' MBP as primary).  I use to be able to adjust the brightness of the iMac just fine CMD+ f1 & f2, but it looks like the most recent OSX update broke this somehow.


    Really hoping this gets a fix ... this iMac is so bright my eyes are bleeing!

  • davidexcom Level 1 (0 points)

    I'm update again to 10.6.8 and my eyes are burning.

    Please Apple fix this. I'm afraid that Lion remains the same

  • bhirt Level 1 (0 points)

    Same problem here.   macbook pro (thunderbolt) plugged into iMac 27" with a mini-display port cable.   My eyes are burning from the brightness, there has to be some sort of solution.   I used to be able to change the brightness, but now I cant.

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