WTF: iPhone held near MacBook shuts off screen

Discussion in 'iPhone Tips, Help and Troubleshooting' started by starakaj, Apr 19, 2010.

  1. starakaj macrumors newbie

    Apr 19, 2010
    Hi all. I was hoping someone could shed some light on a really strange phenomenon I've noticed. It seems like if you hold your iPhone in the right position over your MacBook Pro keyboard you can temporarily shut off the screen.

    I've got an iPhone 3Gs and I'm running 10.6 on a refurbished, 13' MacBook Pro. To get the effect (it doesn't seem to damage the computer but don't look at me if something goes wrong) first get out your MacBook and open it up. Next, grab your iPhone landscape style so that the home button is to your left with the screen facing you. Now you've got to position the phone over the keyboard. Actually, the sweet spot isn't over any of the keys: it's between the track pad and the headphone jack. The home button should be just below the headphone jack, and the top-left corner of the phone (which is on the top-right if you're holding the phone in landscape) should be just over the bottom-left corner of the spacebar. If all goes well you should see the screen flicker and go black. If it doesn't work right away try moving the phone around slowly.

    A couple more weird things: I tried running Caffeine to see if that changed anything but the phone still shuts off the display. Also, it doesn't seem to work with an iPod touch but it WILL work even if the phone is turned off.

    I did a quick google to see what piece of hardware might be affected and it looks like the phone is pretty much directly over the airport card. But why that would shut off the screen (and actually make the laptop totally unresponsive) is completely beyond me.

    Anyway, if someone could unravel this mystery it would be hugely appreciated.

  2. gorn macrumors member

    Jun 17, 2009
    Related, take a piece of metal and touch it to your MacBook's screen in the area that would touch the part of the bottom case you are referencing. Notice the metal is attracted to that part of the screen. There is a magnet in the screen and a sensor in the bottom case, this is the lid-is-shut detection. Your phone is similar enough to a magnet that it makes the computer sleep.
  3. mkrishnan Moderator emeritus


    Jan 9, 2004
    Grand Rapids, MI, USA
    Yeah, I also think you're tripping the Reed switch that is used to determine if the case is in the closed position. I don't think that Caffeine will stop it (not 100% sure; I don't use Caffeine, but I have used some other similar tools), because it's designed to keep the Mac awake with the lid closed, not to keep the screen on with the lid closed.
  4. darngooddesign macrumors G3

    Jul 4, 2007
    Atlanta, GA

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