On Thu, 09 Feb 2012 10:12:31 -0800, Austen wrote:

Sorry, FWIW, for the benefit of onlookers who dont know this unit, it
has TWO usb ports: One for power in the back and a separate data-only
port to plug it into the computer at the side. It buzzes until the side
usb port is connected to a computer, - it gives a splash-screen and then
as soon as the connection is recognised, the buzzing stops.

Only caught a few of the posts in this thread, so if I'm too far off base
I apologise. Many of the cheap power supplies are half-wave (rectified
one way only instead of through a bridge. They rely on a capacitor to
modify the intermittent "DC" to a (sort of) constant voltage. It may be
that the design of the Nuvi has this capacitor within the body of the
unit, so that if this capacitor has gone down, the smoothing will be non-
existent. If the buzz is mains frequency this would support the
hypothesis. If you can find a good quality full wave power supply, and
this eliminates or markedly reduces the buzz, it would (almost) prove the
case.

Keith