That IS the best way to isolate the component to see if it will work on it's own. We do this on a regular basis for refers to see if the control boards are bad, or if they have a bad cooling unit by taking the heating elements out of the control board and plugging them directly to a KNOWN working 120VAC circuit. It would work for a micro as well.
Lew Farber...RVIA Certified Master Tech...ABYC Certified Master Marine Electrician
SOLAR TECH ENERGY SYSTEMS, INC.
AM SOLAR ...MAGNUM…VICTRON ENERGY...LITHIUM & LIFELINE BATTERIES…MARINE REFRIGERATION