An example system includes a power supply. The power supply is electrically coupled to an electrode, a developer roller, and a cleaner roller. The system also includes a controller. The controller is to instruct the power supply to reduce, at a first time, a magnitude of an electrode voltage supplied to the electrode. The controller also is to instruct the power supply to set, at a second time, a developer roller voltage and a cleaner roller voltage each to about a wet null voltage.