With Yasui-san.

See SR2 notebook for notes: album SR2 Remedying work after O3.

Last week we finished assessing the health of the in-vacuum cables by measuring resistances, inductances and capacitances at the outer side of the flanges of the vacuum chambers. We had unexpected results and in this entry I report the reproducibility after a second (or third) measurement:

• SR2, IM-V3 OSEM, P3-3, pins 2-7:
  • Symptom: the measured resistance (24.5 Ohm)  is higher than the equivalent resistance in other OSEMs (~19 Ohm).
  • Reproducibility: we confirmed the initial assessment; during the measurement the value was not fluctuating.
  • Following steps: we should inspect inside of the chamber or try to find glitches in the actuation.
  • Difficulty: medium; the connecting points of the cable segments are accessible with relative ease.
• BS, F0 yaw stepper motor, P3-3, pins 2-7:
  • Symptom: the measured resistance (13.4 Ohm)  is higher than the equivalent resistance in SR3 (8.8 Ohm)
  • Reproducibility: we confirmed the assessment today in an initial measurement, but we found it's not stable.
  • Following step: open the chamber and check.
  • Difficulty: low; this motor and its cables are in the pre-isolator making them easily accessible.
  • Note: it seems SRM and SR2 F0 yaw stepper motors have a similar problem and we need to check.
• BS, F1 LVDT, P2-2:
  • Symptom: see klog entry 18191.
  • Reproducibility: we confimed by a third time there is a problem; some of the resistance values have changed since last week.
  • Following step: open the vacuum chamber and check.
  • Difficulty: possibly high becuase we don't have access to the F1 filter from the outside of the chamber.
• SRM, RM Coil TM-H1, P2-4:
  • Symptom: the coil has a connection to the chamber.
  • Reproducibility: reproducible and stable.
  • Following steps: medium; the connecting points of the cable segments are accessible with relative ease.
• SRM IP LVDTs: last week we also found that the primary and secondary coils are connected to each other's pins. We confirmed this situation today. These devices are at the pre-isolator and are easily accessible.