Macbook External Screen Question

Discussion in 'MacBook' started by djkyle65, Jan 18, 2009.

  1. djkyle65 macrumors newbie

    Jan 18, 2009
    Is there some setting that will allow me to run my external screen with my macbook without having the power adapter plugged in?

    If i just plug in my macbook without the adapter it flashes the screen for like 10 sec. and then turns off.

  2. WPB2 macrumors 6502a


    Jul 1, 2008
    Southeast, LA
    Are you talking about powering your external monitor off the macbook? If so no you can't do that, unless it will run off USB power which I doubt.
  3. djkyle65 thread starter macrumors newbie

    Jan 18, 2009
    No sorry guess it does sound confusing

    Ok i have a macbook with the mini dvi connected to my apple cinema display my macbook will only allow me to use the external display (macbook closed using the cinema display as the screen) with the macbooks power adapter plugged in .

    Does that help?
  4. rust.puppet macrumors regular

    Jul 18, 2008
    Ashtabula, OH
    um.... im not 100% sure but the apple cinema should come with a chord that plugs into the magsafe, usb and mini display port.... atleast i thought.
  5. djkyle65 thread starter macrumors newbie

    Jan 18, 2009
    Well its not just the cinemia display any computer dvi or vga connection that i connect the screen to.

    If the power adapter to the macbook is not plugged in the screen will not work
  6. WPB2 macrumors 6502a


    Jul 1, 2008
    Southeast, LA
    I have never been able to use my macbook with an external display "Closed". I leave it open and turn down the brightness to 0.
  7. eddy808 macrumors newbie

    Nov 14, 2008
    to use an external display with your macbook closed... just plug in an external mouse and wake up the computer with it when the lid is closed.
  8. scienide09 macrumors 65816


    May 5, 2007
    OP, according to this Apple support article, you're out of luck. Step 1 states that he AC power must be plugged in.

    I've never used my MB or my MBP with an external without having the computer plugged in to the outlet. I don't think you can.
  9. The Samurai macrumors 68000

    The Samurai

    Dec 29, 2007
    Funny, I was going to ask a similar question as to the OP.

    I have my Macbook connected with my Dell external display - and it only works properly when I have the Macbook connected to the mains. When its not connected to the mains, the external monitor will flicker and go into sleep. Strange.
  10. mlemonds macrumors 6502a


    Apr 9, 2008
    Lexington, KY
    try using insomniax too keep the computer from going to sleep.

    i guess you would have to run the dual display in mirror mode for this to work though as the main display would stay on too
  11. frogcat macrumors member

    Nov 9, 2007
    This happens to my 2.0 AlumBook as well!!

    I find this quite annoying as well! I don't see why its different because my girlfriend's Air can run my 20" Dell monitor without the power adapter plugged in.

    Can someone give us some answers?
  12. Demosthenes X macrumors 68000

    Demosthenes X

    Oct 21, 2008
    I can use my external without the MacBook plugged into AC, so it is possible. I didn't have to change any settings or anything, either.

    Try plugging the AC in, plugging in the monitor, then unplugging the AC, and see if the external stays on. Works for me.
  13. djkyle65 thread starter macrumors newbie

    Jan 18, 2009
    Yeah but thats what i hate about it having to unplug the ac just to get it to work. I think its stupid because it works in dual mode i just turn the brightness down. So its obviously not a power issues.

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