Re: Soekris boxes are not silent

[Frank Schuhmann]

Hello Jan and list.

> -----Original Message-----
> From: soekris-tech-bounces@... [mailto:soekris-tech-
> bounces@...] On Behalf Of Jan Ceuleers
> Sent: Sunday, June 10, 2012 8:15 AM
> To: Soekris-tech@...
> Subject: [Soekris] Soekris boxen are not silent
>
> What's causing it? I thought it was the CPU but given that the 4801s and the
5501 have
> a different CPU (OK so they're both Geodes) I was thinking perhaps not?

Were these boxes brand new or did you buy them "used"?
Are this "hissing" was occurring since the first days, you was using the boxes?
If it was not so, perhaps a capacitor was damaged during the long time using,
with the increasing throughput of your internet account!
Or you were inserting some spare parts and they are high power consuming?

My personally tip is really, to pointing this "problem" to the capacitors on the
boards, under high load they start this "hissing" in my opinion.
I would not swear on this, but I´ll guess it seems, that is nearly coming to
this point or it is related to the near region of the capacitors.
Only two ways are going to solve this out;
The first choice, you will change the box, perhaps to something like a net6501,
because it can handle better the higher load.
Or you are able to solder some newer, with better quality.

This is perhaps interesting for you; I mean who is producing noise suppressing
capacitors,
if this will not be a known problem for the industry companies?  ;)
Only as an example, please don´t buy these once!!!!!
"http://img.directindustry.com/images_di/photo-m2/noise-suppression-capacitors-2
24759.jpg"

Perhaps you´ll get better tip by Soren or Soekris support team,
for finding a better solution, or better capacitors that is much more compatible
to your both soekris boards.


I hope this was helping you a little bit.



____________________

Kind regards and my best wishes

Frank Schuhmann






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[Jan Ceuleers]

On 06/10/2012 10:17 AM, Frank Schuhmann wrote:
> Hello Jan and list.

Hi Frank, thanks for your reply.

> Were these boxes brand new or did you buy them "used"?
> Are this "hissing" was occurring since the first days, you was using the boxes?

I bought all my boxes straight from Soekris Europe in the course of the
past few years, and they have all exhibited this behaviour from day 1.
It is not getting worse (except indeed perhaps with network traffic). I
have to add though that only my 5501 is still in use; I occasionally
break out the 4801s if I need them for a project.

The hissing is louder if the network traffic involves the wireless card
than if it doesn't (Atheros AR922X), but there is also hissing for
purely wired network traffic.

> The first choice, you will change the box, perhaps to something like a net6501,
> because it can handle better the higher load.

The box really is not overloaded. It acts as a broadband router (Eth to
home network, PPPoE to VDSL modem, firewall, wireless AP). I guess that
the fastest the box ever has to go is if I wirelessly download something
to my laptop that is hosted on the home network, at something like 20
Mbit/s.

> Or you are able to solder some newer, with better quality.
>
> This is perhaps interesting for you; I mean who is producing noise suppressing
> capacitors,
> if this will not be a known problem for the industry companies?  ;)
> Only as an example, please don´t buy these once!!!!!
> "http://img.directindustry.com/images_di/photo-m2/noise-suppression-capacitors-2
> 24759.jpg"

Don't they mean another kind of noise here?

Thanks, Jan
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[Frank Schuhmann]

Hi again Jan.

> -----Original Message-----
> From: soekris-tech-bounces@... [mailto:soekris-tech-
> bounces@...] On Behalf Of Jan Ceuleers
> Sent: Sunday, June 10, 2012 11:06 AM
> To: soekris-tech@...
> Subject: Re: [Soekris] Soekris boxes are not silent

I don´t really know what the producers of the capacitors mean with low noise
suppression, but in normal times this caps don´t do piping or hissing.
The questions about new or used boxes were related to the point, that someone
was smashing his boxes and then he was selling those!
But ok perhaps you are right, but if this is only pointed to the use of the wifi
card, it can perhaps also be the OS based driver or the wifi card itself!
Or if you are using a hdd inside the hdd motor is driving faster and together
with the higher use of the wifi card together it does the "hissing"!!
But the "hissing" should be coming from exactly one or more "parts" inside of
your box and in normal cases, only in my opinion, this will be the
done by the capacitors! In sorter words if I am not be able to explain those
technical related things very good and clear, related to my not so
well formed English, but the usual suspects in this cases are often or mostly:
1. The capacitors or called also "Solid Caps"
2. The on the board placed chokes or " Icy Choke"
3. The soldered Hi-c Caps

Or in shorter words to the whole assemble or group of this parts, but I must
fairly say I can also be wrong at this point.

Ok this is only my opinion and can surely vary in this case from the named above
parts.



____________________

Kind regards and my best wishes

Frank Schuhmann







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[Jan Ceuleers]

On 06/10/2012 11:45 AM, Frank Schuhmann wrote:
> I don´t really know what the producers of the capacitors mean with low noise
> suppression, but in normal times this caps don´t do piping or hissing.

Right. Well I mean acoustic noise, and I suspect your kind is the following:

http://en.wikipedia.org/wiki/Decoupling_capacitor

And as I said, the issue is not limited to my use of the wireless card.
I did not say, but the issue occurs with multiple different makes of
wireless card.

Thanks, Jan
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[Stanislav Meduna]

On 10.06.2012 11:05, Jan Ceuleers wrote:

> The hissing is louder if the network traffic involves the wireless card
> than if it doesn't (Atheros AR922X), but there is also hissing for
> purely wired network traffic.

99% of the time the hissing comes from some inductance in a power supply
circuit, changing sound as the power needs (both absolute and structure)
change. Depending on mechanical tolerances the same part can be louder
or quiter.

There is not much one can do about it. If the surface of the winding
is accessible one can try to tighten a sewing thread around it. There
are also impregnating solutions, but I doubt they can be reasonably
used on parts already soldered in the board.

Regards
--
                                       Stano
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[Brendan Minish]

Identify the component(s) that are noisy. these will generally be
ceramic caps.

Once you have found them, encase them in hot melt glue or a rubber
mastic compound. This will greatly reduce noise levels  



On Sun, 2012-06-10 at 14:34 +0200, Stanislav Meduna wrote:

> On 10.06.2012 11:05, Jan Ceuleers wrote:
>
> > The hissing is louder if the network traffic involves the wireless card
> > than if it doesn't (Atheros AR922X), but there is also hissing for
> > purely wired network traffic.
>
> 99% of the time the hissing comes from some inductance in a power supply
> circuit, changing sound as the power needs (both absolute and structure)
> change. Depending on mechanical tolerances the same part can be louder
> or quiter.
>
> There is not much one can do about it. If the surface of the winding
> is accessible one can try to tighten a sewing thread around it. There
> are also impregnating solutions, but I doubt they can be reasonably
> used on parts already soldered in the board.
>
> Regards

--
73
Brendan EI6IZ

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