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

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  • Ingo Flaschberger
    Hi, ... yes, broken caps can be responsible for this noise. try to replace all big electrolytic capacitor. Kind regards, Ingo Flaschberger
    Message 1 of 7 , Nov 2, 2009
      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
    • scott_645
      Hi, Could it be the beeper? I purchased a NOS NSLU2 off ebay, and it works fine except for a high pitch noise that like yours varies by what is plugged into
      Message 2 of 7 , Nov 2, 2009
        Hi,

        Could it be the beeper? I purchased a NOS NSLU2 off ebay, and it works fine except for a high pitch noise that like yours varies by what is plugged into the NSLU. I have concluded by pressing on various components while the NSLU2 was operating that in my case at least, it is the beeper.

        Regards,
        Scott

        --- In nslu2-general@yahoogroups.com, "doberanbookings" <doberanbookings@...> wrote:
        >
        > 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?
        >
        > Thanks!
        >
      • 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 3 of 7 , Nov 2, 2009
          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 4 of 7 , Nov 5, 2009
            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 5 of 7 , Nov 6, 2009
              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 6 of 7 , Nov 8, 2009
                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]
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