Alternator repairs are one of those things that I take to a rebuild shop for. You can usually find them in the automotive section of your phone book. I usually look for alternator, generator and starter rebuilding shops. Many electric motor repair shops can also do it. There's a lot that can be done wrong if you haven't been trained to work on modern alternators. If you go to a shop and pay them like $80 (sometimes less), they'll rebuild it for you and they'll stand behind their work. They have a lot more experience than I do when it comes to this, and it keeps me from having to buy any tools. I can't get the parts for it for 1/2 the cost they can, anyway. But Honda alternators might be a lot simpler than my Mitsubishi's alternator is... even though a Honda's alternator in most cases is made by Mitsubishi.

My Honda's alternator has been doing the same thing since I installed a stereo. Mine doesn't make noise when everything electrical is off, it does when I turn all that stuff on, and when the bass hits, my idle speed even drops. I don't think there's anything really wrong with it, mine's just 13 years old.