I purchased a Yamaha PSR 290 keyboard a while back-$180. I like it.
For the price I thought it was a bargain. The worst sounds on it sound
no worse than the best early eighties synth strings, and the best
voices sound good enough to use on a pro recording. Anyway, It
generates a bit of hum. For some reason this hum is absent when I'm
simply listening to the keyboard through headphones, but when I plug it
back into my external soundcard (through the headphone out--the only
out on the keyboard) the hum reapears. I'm using my computer both as
the midi controller and the DAW--perhaps there's a feedback loop of
some type there, or simply thourgh the AC connection, which is your
standard cheapo radioshack 3-12 volt multi adapter with no ground prong
on the transformer. I'm thinking about taking off the cover of the
keyboard, finding a screw, wrapping a bit of wire around it, and
splicing the other end into the ground lead of a three prong plug. The
plug would otherwise be unnattached. That is, no AC current will be
flowing throw it from the outlet.
Is this a good way to tackle this issue? Is it safe?