Amplifier Hum


Hi, I have a Parasound HCA 2200 II that has started to make a humming noise. The noise is coming from the amp itself not the speakers. It just started doing this but still seems to function fine. Previously it was dead silent. The amp has about 3 years of use on it. My question: Is it time to sent to Parasound for a tune-up or is there somthing I can check myself? (the amp is not under warranty as I'm not the original owner) Any help would be greatly appreciated.
Thanks
skeevay
Could be your furnace, dimmers, microwave oven, etc.. You may want to look at some of the other threads here about hum. Here's a few about amplifier transformer hum:

http://forum.audiogon.com/cgi-bin/fr.pl?htech&1014100392&openusid&zzStehno&4&&

http://forum.audiogon.com/cgi-bin/fr.pl?htech&1013875690&openusid&zzStehno&4&&

http://forum.audiogon.com/cgi-bin/fr.pl?ddgtl&1012613085&openusid&zzStehno&4&&
.......could also be as a result of changes in your local power supply. My McCormack DNA2 amp hums occasionally (fairly loudly), and after long conversations with Steve McCormack (the amps designer), and upgrade to Rev. A, we have concluded that the hum is caused by variations in local power supply-- nothing we can do about it except to complain to the power company. I did, they replaced the transformer I'm on, and the amp still hums occasionally. Good Luck. Craig
The problem could also be that over time with heating and cooling cycles, something such as the transformer mounting has loosen up so check that all screws are tight.