"Andrew Rossmann" wrote in message
.net...
I have a weird question. I recently bought a second Linksys BEFSX41
VPN router to test out some new firmware before deploying it elsewhere.
I noticed that when it was on, there was a very audible buzzy/hissing-
like noise coming from it. I ended up opening it up and tracing it to
two chokes on the 12VDC input line. They look like Fig D in the
following link:
http://www.jwmiller.com/pdf2/FB2000.pdf

By moving them around, I could sort-of make the noise worse or better,
but couldn't eliminate it. As a temporary workaround, I simply shorted
them out with a solder bridge on the solder-side of the board.


these days manufacturers do not include parts that are not needed.

On the other router, you can barely hear the hissing only when your
ear is pretty much presed up against it.

My question is: What is causing the hissing, and why is it doing it on
DC? Any fixes to stop the hissing without losing the EMI suppression?

glue the ferrite in place. a little glob of RTV silicon caulk should work.



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