NSLU is making high frequency noise

[doberanbookings]

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!

[Ingo Flaschberger]

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 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@..., "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 check. Changing amplitude/pitch with varying would make sense in that
case.
 
Regards
Henrik Fransson
 

  _____  

Från: nslu2-general@... [mailto:nslu2-general@...]
För Ingo Flaschberger
Skickat: den 2 november 2009 14:56
Till: nslu2-general@...
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 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?