How does the MBP control the Magsafe power supply?

Discussion in 'MacBook Pro' started by WorryWort79, Jan 18, 2014.

  1. WorryWort79 macrumors newbie

    Joined:
    Jan 17, 2014
    Location:
    Tampa Area
    #1
    I have repaired a Magsafe power cord at the Magsafe but the magsafe won't charge the MPB! I understand the center pin is the control pin but I can't understand how the MPB can control the Magsafe with only two wires going to the unit!
    I have checked the power at pins 1 and 5 and see about +3.5 V as referenced to pins 2 and 4. I can see no connection between pin 3 and the Magsafe!
    I hope someone on this Forum can explain the control function.
    Thanks
     
  2. klamathvx macrumors newbie

    Joined:
    Jun 19, 2009
    Location:
    Philly
    #2
    This blog post has a pretty good explanation towards the end of how the charger and the computer handshake when plugged in.
     
  3. WorryWort79 thread starter macrumors newbie

    Joined:
    Jan 17, 2014
    Location:
    Tampa Area
    #3
    Thanks for the link klamathvx,
    This is the answer I have been looking for!
     

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