Systems and methods for setting up grid voltage for a tandem pin charging device for charging a photoreceptor in a xerographic printing machine. A charge-generating emitter ratio of a first charging unit is determined and a first grid voltage is set based on the charge-generating emitter ratio of the first charging unit. A charge-generating emitter ratio of a offset voltage is then determined and a second grid voltage is set, based on the determined charge-generating emitter ratio of the offset voltage. A final voltage of a photoreceptor is then compared with a final target voltage.