OS x mountain lion dosen't detect external projector

Doesn't seem to work after downloading Display Menu and connecting it to a data projector. It just freezes and the little round circle rotates until you pull out the dongle. Prior to installing Display Menu, the whole screen would go white, so there is a slight improvement in that we can see the desktop, but other than that - no hope yet.

I thought I might just weigh in to this thread with some vaguely interesting info.

I just upgraded my old MBP (snow leopard) to the new MBP Retina (mountain lion). My old MBP worked perfect with my ACER data projector, first time every time.

Then yesterday I took the new MBP to a lecture and when I tried connecting the data projector to the MPB (via the old DVI miniport I'd been successfully using on the old MBP) all that projected onto the wall was the "solar system screensaver" image. I couldn't see what was on my MBP screen, which at the time was just the Finder screen. I tried looking at Google Chrome, iTunes and a powerpoint presentation (using Office For Mac) - nothing but the solar system. I assumed there was a problem with the new mountain lion software and after reading through many different threads have seen solutions regarding using a genuine Apple miniport (which I am already), or at least a "newer" one which may be more compatible with the thunderbolt connection, or downloading the Display Menu App, or going into System Preferences/Displays.

After much cursing Apple for making my life ****, I eventually stumbled upon the fact that the powerpoint presentation was working the whole time, but now (for some reason) it appears the presentation only displays via the data projector once I switch Powerpoint into "Slideshow" - then it displayed fine. I'm assuming it is some new way of allowing me to work on my computer without the audience seeing what I'm doing, and then I can turn on "slideshow" and then they can see the presentation. So it seems I don't have a problem after all.

Admittedly I haven't tried displaying the general screen (finder / internet etc) but I have now also downloaded the Display Menu App (free) and can see that this does solve my problem anyway, and can view anything via the data projector with this app working.

Hope this helps people.

My MacPro will not recognise or detect my Dell u2711 monitor.

I would just like to record my thanks to Luis Poza for suggesting Display Menu, a free utility on the App Store: http://itunes.apple.com/us/app/id549083868

This allowed me to investigate my problem properly.

My problem started when I bought a second hand MacPro to update my older MacPro.

This newer machine is a 2010 MacPro5,1 / 6-Core Intel Xeon, 2.66 GHz / Mountain Lion 10.8.4 / ATI Radeon HD 5870 1024 MB graphics with DVI and 2 mini display ports.

Having set it up on a HP monitor without problems, I thought it would be very easy to plug in my Dell u2711 monitor using the same 'mini display to display port' cable.

Wrong. Nothing - not an electronic sausage, just a blank screen.

Lots of checking of various forum threads, but nothing seemed to work.

Did all the obvious things, the Dell monitor worked perfectly on my old 2008 MacPro (10.8.4) using a Dual DVI cable. This time, I was trying to use the display port using a cable that worked on another MacPro with a similar screen and also on my HP monitor.

Plug in my old HP screen and all is well again, but plug in the Dell at the same time - blank screen on both.

Swopping monitors and doing a restart (Ctrl-cmd-eject) still left me with blank screens, only a full shutdown and restart seemed to restore the HP monitor.

Reset NVRAM, SMC, reboot, swop cables, tried a very old Dell monitor and that didn't work either.

Then I downloaded & tried the Display Menu app. Set up was by using the HP monitor, chose a resolution like 1280x800, and plugged in the Dell along side the HP screen. The screen of the HP monitor immediately cleared, leaving me with just the desktop background image, and the Display Preferences dialogue box.

Woke up the Dell from the power save mode and suddenly I had the desktop revealed. I was able to switch to mirror mode using the Display Menu app.

Unplugged the HP monitor and the Dell continued to work OK. Yeah!

This was not the end of the story however. When the computer was woken from sleep, the Dell again showed a blank screen.

More checking of threads. On a Dell forum I found two suggestions. Set the DDC/CI option to DISABLE, and also unplug the Dell from the mains and reconnect. Other suggestions were that the display port option could be temperamental, and a DVI cable more stable.

Did all that, and changed back to the DVI cable, and this has finally given me the solution.

I will look out for a better quality display port cable, and see if that will work, but for the time being I have it fixed.

HTH

Hi everyone,

Just to let everyone know what FINALLY worked for me:

reset the SMC.

you can follow the process here:

http://support.apple.com/kb/HT3964

can't believe it was this easy.

why on earth would they hide "detect" by forcing you to hold down the option key? it's not like the screen is cluttered with options and i suppose if you're looking in system preferences, you're in there for a reason.

i would never have guessed i had to hold down the option key, but i guess i'm going to be trying that everywhere from now on.

mende1 wrote:

It hasn't disappeared. Open System Preferences > Display, hold Option key and press Detect display at the bottom

COULD NOT FIND AN ANSWER ANYWHERE ONLINE! THIS SOLVED MY ISSUE!!! Thank you!!!