1990 bounder turning gene on and off i hear buzz sound

Is the hum at the breakers and not anywhere else? try cycling the breakers 4 or 5 times with all 120 volt power disconnected. It may be the main breaker, or loose connections in the breaker box, or the transfer switch. If you are not comfortable with 120 volt AC, get some guidance from someone you may know. Things are tight to get to the transfer switch, if you have one.