When I tried to raise the anode voltage in cathode bias mode on May 23 evening, I found the target or tube shorted to HV common. Investigations in the faraday cage today showed the same. I removed all the new electronics (resistors, gemovs, etc) from the power supply to no effect, so I disconnected the TGHT supply and pushed it away from the busbars. There was still a short. David Frank and I then went down to the pit and disconnected everything to measure the module. The module itself showed no short, and the bus bars in the chase for TGHT showed no short, though the ones for TBHT still showed the short.

David and Frank reconnected the module and I disconnected the TBHT supply in the faraday cage, then I found no shorts to TGHT/TBHT. When I reconnected everything there were still no shorts. There must have been a short in the TBHT line in the faraday cage, and another short in the TGHT line in either the faraday cage or on the module top. Both these shorts got resolved by taking everything apart. Still not sure how it happened.

Next I found I could not raise the anode voltage above 230V, it looked like it was current limiting but since the current limit was high, I figured it had something to do with the new electronics installed. I disconnected them all the in cage and that solved the problem, and then reconnecting the gemovs that go from the PSU terminals to HV common caused the problem again, so I left those disconnected.