problem? magnetron humms after cycle completes stops when door opens.will boil water if placed in unit and no time or funtions pressed. humming stopped for a week after placing a cup of water and temp probe in water and programing for a temp of 150 degs. now nothing seems to resovle the problem. blew a house fuse when trying micro/conv combo. checked hivoltage diode,hi capcitor & magnetron omhs seems ok. is there a way to check smartboard self dianostic check? pressing 7-8 keypad displays 48. any help much appreciated.

Thanks For The Info On Problem, Smartboard Is Pricey. Can I Return This If Not The Problem. Or Can It Be Sent Somewhere To Be Checked Out. I Hate To Be A Replacement Mechanic. I Already Believe That The Power Relay Has Caused The Malfunction, If This Is What Regulates The Duty Cycle Between Microwave & Convection Heat. How Best To Check This Out?