Doug Lane

SQL Server Entertainer

When Your MacBook Won’t Detect a Projector

by

Experiencing a major technological disaster is a rite of passage among presenters. At SQL Saturday in Madison, I had my first presentation laptop failure. Surprisingly, it happened with my MacBook Air. (I’ve had two MacBooks with zero problems, versus three HPs with a combined twelve hardware failures.)
 
With ten minutes to go before my presentation, I could not get the laptop to recognize the projector. I checked and re-checked the cable, the DisplayPort<->VGA adapter, restarted both projector and laptop. A few other speakers tried to help, as did the room monitor. Five minutes into my session time, I plugged in a copy I had on a USB drive to the room’s PC and began my presentation. Not long after, the IT person in charge that day took my laptop to another room to see if he could get signal there. He couldn’t. I continued on, blowing past the three VM-based demos I had lined up. Fortunately, the presentation went well enough without the demos.

"If it were an HDMI connection, I would have found it hours ago."
Last week, I finally took the laptop down to the Apple Store and got some answers. What happened? In short, the chunk of memory that stores information about display connections became corrupt. With about sixty seconds of work, the guy at the Genius Bar got it to recognize both Apple and generic VGA monitors. Here’s what he did to clear the memory.
 
First, he reset what he called the Power Management Unit (PMU) using these steps:
  1. Shut down the computer.
  2. Connect it to AC power.
  3. Press the left shift + command + option + power button.
Second, he reset the Parameter RAM (PRAM) on the computer using these steps:
  1. Shut down the computer.
  2. Press the power button to turn on the computer.
  3. Immediately, before the gray screen appears, press and hold command + option + P + R. Hold the keys down until the machine restarts and you hear the second startup sound.
If your MacBook ever refuses to recognize a projector or VGA connection and you’ve tried everything you can think of, try resetting the PRAM. It may save you from having to dismember your presentation at the last minute.
 
You can find a little more about PRAM here:

http://docs.info.apple.com/article.html?path=Mac/10.6/en/26871.html

Comments

  1. Kourtney says

    Thank you! I am a teacher and one day my computer just wouldn’t recognize the projector for my promethean board! I have tried everything (so I thought) with no success. Thank you! My students are excited to have the board back up and running!

    • Doug Lane says

      As far as I know, these steps only clear out video memory, so you won’t lose anything else like system settings or files. I’ve done it a few times both on my machine and others without any adverse effects. The guy at the Genius Bar didn’t seem concerned about any side effects either.

  4. Clare Kelly says

    Yey, found this on google and it worked!!!!! Thanks so much!!! I never post comments but im well happy

  7. Nerisha says

    HI Doug thanks for this super useful post. I have been experiencing the same problem which is a nightmare when running training workshops for clients. I tried both the resets and it didn’t work. Tried a software update install, still no joy. The iStore guys say that it might be the graphics card but the rest of my machine is working fine so I am not convinced that I need to buy a whole new machine again yet or spend so much to fix the graphics card. Could it really be the graphics card and do you have any other trouble-shooting tips? Thank you.

  8. Jared says

    Thanks so much for this. It worked. However, when I disconnect my mac from my projector and reconnect it, I am forced to go through the process all over again. Any suggestions? thx

  9. RelievedTeacher says

    I also never leave comments on threads. I am also a teacher, and was at my wit’s end, as was my IT department. This solution worked – I was a bit taken aback to be honest. Thank you!!

  10. Makiko Love says

    Thank you! I am not sure what it had happened. But it led me to a screen where I can change setting to mirror screen. After that it went back to normal. Strange, but it worked! Thank you for posting this.

  11. aylin says

    Hi
    I did this solution but is not working till now, My Mac connected with mini display cable to my HDMI device, I work with about 1 year ago but at one night after updating something it didn’t work anyway, Now I don’t know what can I do? It’s my nightmare I need my Mac in my classrooms….

  12. Padre Andrés says

    My MBA wouldn’t talk to either of our projectors for weeks. I reset the PMU and PRAM as you said and that did it (first I thought I could skip the PMU reset and jump right to PRAM reset, but I couldn’t – no use in trying to cut corners). Thank you!

Trackbacks

  2. […] I’m the person who looks up the DIY guide to installing new memory cards in my laptop, and resets my PRAM when the projector doesn’t seem to be communicating with my […]