With Yasui-san.

See notebook notes in album PR3 Remedying Work.

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 assessment. The ones of concern have an asterisk:

• PR3, IM-V1 OSEM, P4-1, pins 2-7:
  • Symptom: the measured resistance (18.6 Ohm)  was higher than the equivalent resistance in other OSEMs (~15.8 Ohm).
  • Reproducibility: today we measured 15.9 Ohm and it was stable. It seems there's no problem.
• * PR3, BF-H3 LVDT, P2-3, pins 1-6:
  • Symptom: the measured resistance (21.6 Ohm)  is higher than the equivalent resistance in other BF LVDTs (~12.1 Ohm).
  • Reproducibility: We confirmed this value and it's stable.
  • Following step: we should open the chamber and take a look.
  • Difficulty: likely, medium, because although the cables are relatively accessible, cabling is messy.
• PR3, BF-V2 LVDT, P3-7, pins 2-7:
  • Symptom: the measured resistance (14.015 Ohm)  was higher than the equivalent resistance in other BF LVDTs (~12.1 Ohm).
  • Reproducibility: today we measured 12.5 Ohm and it was stable. It seems there's no problem.
• * PR3, BF-V3 LVDT, P2-1, pins 1-6:
  • Symptom: the measured resistance (14.1 Ohm)  is higher than the equivalent resistance in other BF LVDTs (~12.1 Ohm).
  • Reproducibility: We confirmed this value and it's stable.
  • Following step: we should open the chamber and take a look.
  • Difficulty: likely, medium, because although the cables are relatively accessible, cabling is messy.
• PR3 F1 stepper motor, P3-3:
  • Symptom: the resistances of both coils are higher than expected (14.5 Ohm vs. 8 Ohm).
  • Reproducibility: we measured 8.3 and 8.6 Ohm and these values are stable. It seems there's no problem.
• PRM, BF-H2 LVDT, P3-3, pins 2-7:
  • Symptom: the measured resistance (13.5 Ohm)  was higher than the equivalent resistance in other BF LVDTs (~12.1 Ohm).
  • Reproducibility: today we measured 12.8 Ohm and it was stable. It seems there's no problem. This value is the highest of this type of coil, with the second highest 12.6 Ohm.

After we changed the flip cable adapters in PR suspensions, we checked again the health of the cables by measuring capacitance, resistance and capacitance values. I compiled the results of the three suspensions in a single file to make comparison easy.

A more careful examination of the results will follow soon, but for now we can say that some cables of the PR3 Traverser may need to be checked again.

After changing the cable flip adapters, we checked the health of the connections in the three PR suspensions and found a few potential problems that we need to check:

• PR2 BF FR, pins 1-6, P1-7: the resistance is 9.7, which is higher than the values in other BF FRs in PR suspensions (8.8 Ohm maximum).
• PR3 BF V3, pins 1-6, P4-7: the resistance is 13.7 Ohm, which is slightly higher than 11.6 Ohm measured in other LVDTs (approximately).
• PR3 Traverser: there are several resistance values that are several Ohm higher than expected:
  • R1, P-2-2: pins 1-2, 1-3, 2-3, 2-6, 3-6, 3-7, 6-7.
  • R2, P4-2: pins 1-6, 2-6, 3-6, 6-7.

There are other observations that don't seem to be problems:

• The resistance values in the BF LVDTs tend to be larger than in the SF ones. Likely because the manufacturers are different.
• The capacitance values of the POP picomotors are larger than those of the picomotors used in the suspensions. Likely, this is related with the type and length of the cables rather than with a possible failure.

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