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Re: [nslu2-general] Re: NSLU is making high frequency noise

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  • Oz-in-DFW
    Most likely noting is really wrong. What you are hearing is almost the windings or the core halves contracting as the current through the part cycles. This
    Message 1 of 7 , Nov 6, 2009
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      Most likely noting is really wrong. What you are hearing is almost the
      windings or the core halves contracting as the current through the
      part cycles. This is probably just due to the fact that the glue that
      holds the core halves together wasn't applied too thoroughly or it was
      wound somewhat loosely, though there is a slim chance it's indicating
      hight current. The coil is probably electrically fine, though it might
      fail early if the windings are moving and scrubbing their insulation off.

      From what you described and hints from the picture this is probably part
      of a small on board switching power supply that is used to generate
      another supply voltage.

      You might be able to quiet it down by running some really thn lacquer
      into it, but you're just as likely to dissolve insulation and short it
      out. This will probably kill the switch transistor and other parts
      around it.

      I wonder if others are missing C31, C14 and C17? There are a lot of
      unstuffed parts on this board. I guess they are used for option
      selection or alternate parts. Now I need to look at some of mine.

      Nicely done pic BTW.

      doberanbookings wrote:
      >
      >
      > Well.. thanks for the suggestions. I guess, i have found the source of
      > the whine.
      > I'm pretty sure it's one of the coils, like Hendrik said. When i touch
      > the L2 coil with a screwdriver, the sound goes absolutely insane..
      > So now i wonder, is the coil bad, or could something be causing this
      > instead?
      >
      > http://www.nslu2-linux.org/wiki/uploads/NSLU2-board-front-hires.jpg
      > <http://www.nslu2-linux.org/wiki/uploads/NSLU2-board-front-hires.jpg>
      > L2 is on the left center (marked 220 on top)
      > What are these things for?
      >
      > __._
      >
      >

      --
      mailto:oz@...
      Oz
      POB 93167
      Southlake, TX 76092 (Near DFW Airport)
    • Henrik Fransson
      Hi again, This coil is probably a part of a DC/DC step down converter, to generate a lower voltage than 5V. It could be a mechanical fault on the coil, that
      Message 2 of 7 , Nov 8, 2009
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        Hi again,

        This coil is probably a part of a DC/DC step down converter, to generate a
        lower voltage than 5V.
        It could be a mechanical fault on the coil, that makes it vibrate when the
        DC/DC converter is running chopped DC current through it.

        Maybe try add a small droplet of glue if you find any part of the coil that
        is responsible for the noise.

        Is your NSLU working normally except for the noise?

        /Henrik


        _____

        Från: nslu2-general@yahoogroups.com [mailto:nslu2-general@yahoogroups.com]
        För doberanbookings
        Skickat: den 5 november 2009 22:54
        Till: nslu2-general@yahoogroups.com
        Ämne: [nslu2-general] Re: NSLU is making high frequency noise




        Well.. thanks for the suggestions. I guess, i have found the source of the
        whine.
        I'm pretty sure it's one of the coils, like Hendrik said. When i touch the
        L2 coil with a screwdriver, the sound goes absolutely insane..
        So now i wonder, is the coil bad, or could something be causing this
        instead?

        http://www.nslu2-
        <http://www.nslu2-linux.org/wiki/uploads/NSLU2-board-front-hires.jpg>
        linux.org/wiki/uploads/NSLU2-board-front-hires.jpg
        L2 is on the left center (marked 220 on top)
        What are these things for?






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