[Halld-cpp] [New Logentry] HV wire chamber channel 1 malfunctions

zihlmann at jlab.org zihlmann at jlab.org
Thu Apr 14 09:20:03 EDT 2022

Logentry Text:
The HV channel for chamber 1 of the FMWPC is broken.
when swapping HV channel 1 and channel 2 at the breakout box I can ramp up chamber 1 with no trip (this is HV channel 2). but chamber 2 which is in that
case connected to HV channel 1 will trip.
So there is clearly something wrong with HV channel 1 either
a) the HV channel itself on the board
b) inside the breakout box
c) the cable from the HV module to the breakout box

Also what is noticed is that when turning off a HV channel on the gui (looking at the "show all HV") the button turns to "red" with the lable "on" indicating
that the chamber HV is off. However the readback is still showing HV of 300V and very slowly ramping down. It takes several minutes for the HV
to completely reach 0V. There must be somewhere some quite large capacitance in the system. I would not expect the readout side to have capacitors
that large for the capacitive coupling of the readout.


This is a plain text email for clients that cannot display HTML.  The full logentry can be found online at https://logbooks.jlab.org/entry/3991089
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