WP 13577

Sheila reported the EY ESD bias was not responding. Readback monitor shows output ~200V regardless of requested voltage. I checked the HV and LV power supplies. Both were powered on. One thing to note, the current draw on the positive 430 and negative 430 power supplies were not the same. I went out to the VEA and verified connections near the flange. The shrink tubing used to isolate the SHV connectors from the cable tray were not installed. I reinstalled them. I verified led lights on both the HV and LV ESD drivers. Both look fine. I enabled and disabled the HV outputs on the UK HV driver and heard the relays switching. Next, I powered cycled the chassis by removing the ±18V with the HV outputs disabled. I disconnected the first two SHV cables (Bias and one of the quadrants). To test the remote enable, Louis enabled the outputs from the control room. The bias slowly ramped down to -430V. First Quadrant went to 140V. High voltage disabled. SHV cables reconnected and repeated to drive the outputs. Louis confirmed the bias readback monitor is responding.

F. Clara, L Dartez