These two components are the most likely ones to be at fault if your Atari isnt working.
Microwave Oven High Voltage Capacitor Power Fuse High Voltage Diode Maintenance
Bi Cal Microwave HV High Voltage Capacitor 0.90 uF CH85 Parts Replacement
Microwave Oven High Voltage Capacitor CH85 21113 2100V /
Microwave Oven High Voltage Capacitor Bicai CH85 21105 2100V AC / SM086
Samsung CM1919, Samsung CM1929 High voltage capacitor 1.10µF 2100v
Microwave Oven H.V. High Voltage Capacitor CH85-21100 2100VAC+Power Fuse & Diode