On Sun, 22 Feb 2009 13:23:49 -0800 (PST), Boris Epstein
wrote:

Hello all,

This printer we've got (a Phaser 8560N) is perfectly functional but
keeps making continuous humming noise. We know it is not normal as we
have 2 other printers of the same model that do not make the noise.

Has anyone experienced this? Any idea what may be causing it?

Thanks for any and all help.

Boris.

Does continuous mean even in a lower power (sleep) mode,
and/or also when it is fully on, but not printing anything
at the moment?

Could it be a fan worn out? How old, how many pages
(roughly) are on the printer? If a worn fan is possible,
see if you can locate the fan intake or exhaust on the side,
and stick a plastic drinking straw barely in against the
blades to see if slowing the fan or stopping it entirely
causes a change in the noise. Note also that if the printer
is very well engineered it is possible that causing the fan
to stop could cause the printer to turn off, so you might
then have to disconnect AC power for a few minutes and
reconnect to reset it.