Rui, yes your reference to the previous thread indicated pretty clearly that a ground loop wasn't involved. The same answer as to what caused the problem that was given there would apply here. As to how easy the fix would be, although I have no knowledge of the AX500A, presumably the rectifier and capacitors are standard parts which are readily available. Still, someone with the necessary diagnostic equipment to determine exactly what needed to be replaced wouldn't likely charge less than about $100 for parts and labor.
