An electrostatographic printing machine has a liquid toner supply chain incorporating at least a toner supply device (10), a metering roller (21) and a development member (31) and an image carrying member (41). An electrostatic charging device (33) acts onto the development member to impress an electrostatic charge onto the development member and to induce a voltage thereon with respect to a machine electrical common earth potential. The toner supply roller, the metering roller and the developer member are each electrically connected to the machine electrical common earth potential (37) via a respective voltage regulating or controlling means (25, 27, 35) to regulate or control induced voltages on each of the toner supply roller, the metering roller and the developer member.