LG Microwave Inverter Board Assembly AJJ75478302 16.50 x 12.50 x 6.00 Genuine OEM. This is a Genuine OEM LG part. This inverter board assembly (part number AJJ75478302) is for microwaves. Inverter board assembly AJJ75478302 regulates power to the magnetron. The assembly includes the inverter board, inverter board housing, wire harn... - LG Microwave Inverter Board Assembly AJJ75478302 16.50 x 12.50 x 6.00 Genuine OEM.