A compact dunnage conversion machine (20) includes a converging chute (74) with a restricted inlet (120), a powered feed assembly (76) with a sealed gearbox (160), a plurality of interchangeable power supplies (200,202), and a restricted outlet chute (100). The converter can convert a sheet stock material into dunnage for use in packaging one or more objects in a container. The restricted inlet and outlet make it more difficult for foreign objects to enter the converter and disrupt the conversion process. The sealed gearbox interposed between the driving elements of the feed assembly and an electric motor facilitates maintenance and repair of the feed assembly, while also protecting the gears therein. Finally, the power supplies provide electrical power to the motor and can include an electrical storage device, such as a battery (212), or an alternating-current-to-direct-current converter (214) which is connectable to a source of electricity for supplying that electricity to the motor in an acceptable form.