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Phone Charger Cord Repair

  1. Dec 12, 2009 #1
    I sat the leg of my chair directly on my phone charger cord and severed it in two.

    Now I need to know what polarity the part that plugs into the phone is supposed to be.

    It's a small, flattened kind of plug, sort of like a mini USB plug.

    Is there an engineering convention that dictates the outside terminal (the obvious flattened metal can thingy) is always one polarity or the other? I'm afraid if I hook it up incorrectly I could fry something inside the phone.
  2. jcsd
  3. Dec 12, 2009 #2


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    If you mean a barrel connector (concentric DC plug thing that you often find on 'wall wart' DC supplies), you can probably read it off of the label on the supply itself:

    This probably isn't the case, but if you cut through the two wires of the cord, you may be able to identify which wire should be wirenutted / soldered / crimped to which, based on colour, or the presence of markings along the length of the wire (often the negative wire will have white dashes along the entire length of the wire).
  4. Dec 12, 2009 #3

    Yes, upon close inspection the white dashes you mention are in evidence! They're faint and were easy to miss in the confusion of light reflections off the shiny black plastic untill I looked close up.

    Thanks very much, MATLABdude!
  5. Dec 12, 2009 #4


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    Who knew? Being pedantic occasionally ends up being useful! :tongue2:
  6. Dec 12, 2009 #5
    Indeed! Within 20 minutes of your post my phone was plugged in and delivering the message "Phone is charging".
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