A customer replaceable unit installable in a printing apparatus comprises a component requiring high voltage electric power for operation, a low voltage power input, and that cooperates with the low voltage power input in order to transform low voltage electric power from the low voltage power input into high voltage electric power for use by the component. The customer replaceable unit may also include a low voltage signal input, and the high voltage power supply unit controls output of the high voltage electric power in response to signals received at the low voltage signal input. The signals received at the low voltage signal input are independent of a type of the component in the customer replaceable unit, and the high voltage power supply unit provides an appropriate high voltage for the type of the component, thereby allowing modification of the type of component without having to provide a different low voltage signal.