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User name `stevensm
Log entry time 13:07:01 on February26,2000
Entry number 34555
Followups:
keyword=no control of electron dipole
The electron dipole power supply stopped responding to the controls. We discovered it after a cryo control failure resulted in the dipole tripping on low helium level. The cryo IOC was reset normally, and helium levels returned to normal, but the electron dipole power supply would not restart by remote control. We entered the hall in a controlled access, and observed this new failure mode of the electron dipole power supply. There were no faults on the power supply except for the M3-M4 overtemp warning. All other indications were nominal. Attempting to start the power supply resulted in no response from the control screen. Normally, when the "on" button is pressed in the power supply control window, a "starting" appears next to the on/off status display. This did not happen. The "starting" never appeared. I put the power supply into local mode, and started it normally. At that point, I assumed that the problem was external to the power supply. My next step was to push the "electron magnet controls VME reset" button. But this action did not correct the problem. We then cycled all power to the dipole power supply. This action corrected the problem. I suspect that the standard bus computer which is the interface between the power supply and the spectrometer controls was locked up.