From the blog "Samurai Appliance Repair Man's Blog"
Electrically speaking, microwave ovens have two sections: low voltage and high voltage. The low voltage section consists of the door switches, start button, control panel, turntable motor, cooling fan, stirrer motor, and some miscellaneous switches. The high voltage section consists of the transformer (which steps 120vac line voltage in residential units and 240vac in some commercial units up to 2,000+ volts), the high voltage rectifier (diode), and the charging capacitor (which together with