Dell laptop DC power jack pinout

Discussion in 'Dell' started by Al T., Sep 17, 2005.

  1. Al T.

    Al T. Guest

    I'm attempting to wire in a different DC power jack (the original broke
    and direct replacements are not available except by purchasing a new
    motherboard) on an Inspiron 8600 and thought that it would be a rather
    straight forward project. The size N coaxial power jacks available at
    Radio Shack will fit nicely in the chassis in place of the original. As
    I was determining voltages and polarity of the power plug I was
    surprised to find a second voltage present. I have voltages of
    approximately 8VDC and 20VDC present with one common lead. On the plug
    end the 8 volts is from the center pin to center barrel and 20 volts
    from center barrel to outer sleeve (which I assumed was just an RF
    shield). Can any one enlighten me what's going on with the second
    voltage? Any one care to share their story of a successful resolution
    to a broken power connector on this model (third party replacement jacks
    are available for other models)?

    By the way, I've heard the same jack is found on Inspiron 5150, 8500,
    500m, 600m, and Latitude D500,
    D600, D800.

    Al T
    Spokane, WA
    Al T., Sep 17, 2005
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  2. You've discovered the third power supply connector for modern Dell
    laptops. This third lead is used for communications between the power
    supply and the laptop, so that the laptop can ensure it's got a valid,
    legal, OEM Dell power supply, and what it's power capacity is.

    I have no idea what the communications protocol between the two is,
    but I know Dell laptops will reduce charging current (and extend
    charge time) when operated with 65W instead of 90W power supplies,
    will refuse to charge if operated from a non Dell supply, etc.

    Let us know if you find out anything else!
    William P. N. Smith, Sep 18, 2005
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  3. Al T.

    Al T. Guest

    Thanks for the reply, William. Now I have conflicting stories as to
    whether or not it will charge with the center pin broken or not
    connected. I read a post of an instance on an 800D where the center pin
    completely broke off and yet the AC adapter continued to function,
    albeit with "Unrecognized Power Adapter" messages. I also had a reply
    this evening on a Dell sponsored forum that one can disable such
    messages in the BIOS 'Adapter Warnings: Enable/Disable' option. Leading
    me to hope that I can get by without tying in that odd pin and just
    using the 20 volts. As a last resort I can always hardwire the adapter
    to the MB or use an ungainly external 3 lead connector wired to the MB
    but of course would rather not. Guess I'll try the coaxial connector
    without the center pin and see if it'll work since it fits so well and
    looks like it belongs there. I'll drop a note with the end results but
    it may be a couple of weeks before it gets reassembled and tested.

    Al T.
    Al T., Sep 18, 2005
  4. Let us know how it works, and if it will charge the battery in that
    state. IME it will operate, but refuse to charge the battery with a
    non-Dell supply.
    William P. N. Smith, Sep 18, 2005
  5. Al T.

    Tweek Guest

    Tweek, Sep 19, 2005
  6. Al T.

    Guest Guest

    Thanks for all of the input guys, I ended up ordering the connector
    conversion kit from as Tweek
    suggested. If your vision is as bad as mine and you're kind of ham
    fisted and don't have access to a decent microscope, save yourself some
    time and order a few extra pins at the time you place your order. It
    took me 3 attempts before I felt good enough with the results to clamp
    the connector housing together. I think I could do the next one on the
    first try now though.

    Anyway, I ended up with mixed results. The system now works fine as long
    as the AC adapter is connected, but it still spits out error messages
    about the AC adapter and will not charge. I imagine that the AC adapter
    ID circuitry is screwed up on the adapter or MB yet. So now I've got a
    non-standard connector on both the MB and AC adapter.

    As William alluded to, the thing just refuses to charge without that
    signal present. Curses and a pox upon Dell for not supplying a hardware
    kludge or BIOS workaround. It is my son-in-laws laptop and I suspect
    that he's going just leave things as they are, it'll only work when
    plugged in to AC. I did mention that he may not be able to update his
    BIOS in that state and I got the impression that he was just pleased
    that he didn't end up with an expensive doorstop.

    Al T. in Spokane
    Guest, Oct 11, 2005
  7. Al T.

    miltw Guest

    I think that I might have clue about the "second voltage" thing.

    My Inspiron 8500 was not recharging its battery (no light on the right
    hinge LED's). It worked fine on AC.

    When you go to page 5 of the BIOS it was displaying something negative
    in the AC adapter but when I borrowed my brothers AC adapter, the
    battery charge came on and the BIOS displays a big "90Watt" on page 5.

    Ordered a new adapter this afternoon and now maybe I'll be able to
    avoid that "change the connector" kluge that I have been reading about.

    I guess that second circuit is how the adapter identifies itself to the
    miltw, Oct 12, 2005
  8. So, are you going to reverse engineer the dead brick to determine what
    the third pin is, or do you want to send it to me for analysis? 8*)
    William P. N. Smith, Oct 12, 2005
  9. Al T.


    May 12, 2007
    Likes Received:
    RE: Power Jack

    For what it's worth, power jacks are available. I have an xps m170 and found my jack on Ebay for about ten dollars.

    It cost four times more when I just did a Google search.

    The original jack went wonky (it wasn't obviously loose, but inside of the jack, it was pushed back and that created a big problem).

    It was hellish getting the old jack out, but I persisted and prevailed. Soldering the new jack into the motherboard was pretty straightforward.

    I hope this helps.

    I'm not 100% sure about that third lead, but remember that you're also charging the battery when you plug the laptop into AC...anyone else know for sure?
    Last edited: May 12, 2007
    nurse4kitties, May 12, 2007
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