Problems with 2012 11" Macbook Air and external projector

Originator:dave.addey
Number:rdar://11861539 Date Originated:12 July 2012
Status:Open Resolved:
Product:Hardware Product Version:Model no: A1495
Classification:Serious Bug Reproducible:Always
 
Summary: Connecting my Mid-2012 11" Macbook Air to an external projector using a Mini Displayport to VGA Adaptor results in distorted and unusable video on the projector

Steps to Reproduce: Connect an external projector to the VGA port of a Mini Displayport to VGA Adaptor (http://store.apple.com/uk/product/MB572Z/A). Connect the adaptor to the Thunderbolt port of a Mid-2012 11" Macbook Air.

Expected Results: The projector appears as a second screen for the Mac.

Actual Results: The projector is detected as a second screen, and the Mac's monitor setup changes as if it is supporting two screens, but the projector displays a black screen with a few distorted vertical lines on it.

Regression: This problem does not occur on an earlier (2011) 11" Macbook Air. The 2012 MBA was set up as a restore from the 2011 MBA, and so the setup is essentially identical apart from the change in hardware.

Notes:

I have installed the MacBook Air (Mid 2012) Software Update 1.0 (http://support.apple.com/kb/DL1551), both via Software Update, and also as a download directly from the kb page, and rebooted the Mac, with no difference in output on the projector.

This behaviour has been seen with two projectors: one in a conference hall (sadly I don't know the make or model), and on an Hitachi Illumina PJ-TX10.

Comments

Workaround

An update: if the Displayport adaptor and VGA monitor are connected to the MacBook Air before it is booted up, then the MBA works with the projector with no problems. Unplugging and reconnecting the Displayport adapter / projector also works fine under these circumstances. However, if you boot up the MBA, and then connect the adaptor / projector, the projector does not work correctly, and displays the symptoms described in my original report.

One further detail: after a day of using the MBA with an Apple 27" Thunderbolt display, during which time it had been rebooted with the Thunderbolt display connected, I took it home and connected it to the same projector used for my other testing. It correctly detected the projector with no problems. So it looks as though the presence of some form of display on the Thunderbolt port at boot time may be significant.

By dave.addey at July 15, 2012, 8:23 p.m. (reply...)

Video of the problem

Here's a video of what I saw on both projectors:

http://daveaddey.com/postfiles/macbook_air_to_vga_projector.m4v

By dave.addey at July 12, 2012, 8:28 p.m. (reply...)

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