Loading ...
Sorry, an error occurred while loading the content.

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

Expand Messages
  • Henrik Fransson
    Hi, It could also be a coil or choke that causes the sound if there are any DC/DC converters inside the NSLU? I don t have the schematics at hand right now to
    Message 1 of 7 , Nov 2, 2009
    • 0 Attachment
      Hi,

      It could also be a coil or choke that causes the sound if there are any
      DC/DC converters inside the NSLU? I don't have the schematics at hand right
      now to check. Changing amplitude/pitch with varying would make sense in that
      case.

      Regards
      Henrik Fransson


      _____

      Från: nslu2-general@yahoogroups.com [mailto:nslu2-general@yahoogroups.com]
      För Ingo Flaschberger
      Skickat: den 2 november 2009 14:56
      Till: nslu2-general@yahoogroups.com
      Ämne: Re: [nslu2-general] NSLU is making high frequency noise




      Hi,

      > I just bought an aftermarket nslu, and turns out, it makes a bad high
      pitched whine. It gets worse, when i connect the lan cable,
      > and even worse when there's 2 usb drives connected.
      > When under load, the frequency seems to be constantly changing, so when
      listening closely, it sounds like smth is creaking inside..
      > As much as i have tried to hear it, i just can't figure out, which
      internal component actually produces it.
      > It can't be the power supply's fault, since it makes the same noise when
      powered only by usb-hdd (from powered hub).
      >
      > As far as i have read, nslu's should be dead silent, right?
      >
      > According to power switching schematic's from nslu2-linux.org, C160 and
      168 caps are actually responsible for removing the high
      > freq's.
      > Maybe i should try to replace these?
      > Any more ideas?

      yes, broken caps can be responsible for this noise.
      try to replace all "big" electrolytic capacitor.

      Kind regards,
      Ingo Flaschberger






      [Non-text portions of this message have been removed]
    • doberanbookings
      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
      Message 2 of 7 , Nov 5, 2009
      • 0 Attachment
        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
        L2 is on the left center (marked 220 on top)
        What are these things for?
      • 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 3 of 7 , Nov 6, 2009
        • 0 Attachment
          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 4 of 7 , Nov 8, 2009
          • 0 Attachment
            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?






            [Non-text portions of this message have been removed]
          Your message has been successfully submitted and would be delivered to recipients shortly.