The upgraded CMS Preshower high voltage system

In March 2012 the high voltage system of the silicon-sensor-based CMS Preshower detector underwent a significant upgrade. In order to increase the granularity of the bias distribution lines, the number of power supplies was doubled and fully configurable distribution boards were developed and installed. These new boards provide much improved flexibility in the powering, necessary to cope with the expected evolution of the 4288 silicon sensors with radiation damage. They also provide measurement of the ~2200 bias-voltage lines that go to the detector, enabling fast identification/diagnosis of any anomalous currents and providing detailed knowledge of the sensor current evolution over time.