Work on 2021.7.13

Investigation of F1 stepping motor ground fault.

To identify the F1 stepping motor cable, I removed the feedthrough (Port4) once. After that, I found a short circuit where the cable was fixed to the IP structure. (See photo: the sheathing was damaged in the area circled in red.  The ground fault was at the point indicated by the arrow.)

I took temporary measures to insulate the cable and tried to run the stepping motor. The motor was trying to move, and I could see vibration in the LVDT signal, but I could not change the keystone height. There seems to be a lot of mechanical resistance.

Where the cable is fixed in a similar way at the IP, additional measures should be taken to maintain the insulation. We will continue with the cable insulation and motor drive checks tomorrow.

======
Resistance of F1 stepping motor (measured from feedthrough)
Pin 1-6, 9.0[ohm]
Pin 2-7, 9.2[ohm].
======