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
