Re: [linux-audio-user] noise from USB printer

Dave Phillips wrote:
> Hi Mark :
>
>> Ground loop problem? As a test only, what happens if you unplug power
>> on the printer, or turn the printer off?
>
> Same noise. It stops if I pull either the power or the USB cable.
Is the noise only present when printing, or also when the printer is idle?

>
>> If it is a ground loop issue - I did hear of this recently with a USB
>> hard drive I think - then possibly it's a cable issue or maybe you
>> could stuck a USB hub in the middle to break the loop? (Just
>> guessing!) ;-)
>
> I tried sticking a hub between the machine and the printer, it didn't
> reduce the noise at all. :(
That isn't very surprising as the ground will just be connected through.

What you can do to test whether it is a ground loop is interrupting the
ground connection of the power plug (e.g. by wrapping some
non-conductive tape around the pin). If the noise stops, you have a
ground loop. Don't use this as a solution to your ground loop however,
as it is probably against regulations and is also pretty unsafe
regarding electric shocks.

If it is a ground loop, it is pretty difficult to solve. It's badly
designed hardware. You could try to plug your printer into the same
power outlet as the machine.

Greets,

Pieter
Received on Sat Jul 22 16:15:04 2006