Summary
Per Gautam's request, I've checked the coil resistances and inductances.
- PRM/BS/SRM coils were tested.
- All the PRM coils look well-matched in terms of the inductance. Also, I didn't find a significant difference from BS coils.
- Pin 1 of the feedthru connectors is shorted to the vacuum chamber.
- A discovery was that: The SRM DSUB pinouts are mirrored compared to the other suspensions.
Method
A DSUB25 breakout was directly connected to the flange (Attachment 1).
The impedance meter was nulled every time the measurement range and type (R or L) were changed.
Result
|
Feedthru connector: PRM1
Pin1 - flange: R = 0.8Ω
Pin11-23 / R = 1.79Ω / L=3.21mH
Pin 7-19 / R = 1.82Ω / L=3.22mH
Pin 3-15 / R = 1.71Ω / L=3.20mH
|
Feedthru connector: BS1
Pin1 - flange: R = 0.5Ω
Pin11-23 / R = 1.78Ω / L=3.26mH
Pin 7-19 / R = 1.63Ω / L=3.30mH
Pin 3-15 / R = 1.61Ω / L=3.29mH
|
Feedthru connector: SRM1
Pin1 - flange: R = 0.5Ω
Pin11-24 / R = 18.1Ω / L=3.22mH
Pin 7-20 / R = 18.8Ω / L=3.25mH
Pin 3-16 / R = 20.3Ω / L=3.25mH
|
|
Feedthru connector: PRM2
Pin1 - flange: R = 0.6Ω
Pin11-23 / R = 1.82Ω / L=3.20mH
Pin 7-19 / R = 1.53Ω / L=3.20mH
Pin 3-15 / R = N/A
|
Feedthru connector: BS2
Pin1 - flange: R = 0.6Ω
Pin11-23 / R = 1.46Ω / L=3.27mH
Pin 7-19 / R = 1.54Ω / L=3.24mH
Pin 3-15 / R = N/A
|
Feedthru connector: SRM2
Pin1 - flange: R = 0.7Ω
Pin11-24 / R = N/A
Pin 7-20 / R = 18.5Ω / L=3.21mH
Pin 3-16 / R = 19.1Ω / L=3.25mH
|
Observation
The SRM pinouts seem mirrored compared to the others. In fact, these two connectors are equipped with mirror cables (although they are unshielded ribbons) (Attachment 2).
The SRM sus is located on the ITMY table. There is a long in vacuum DSUB25 cable between the ITMY and BS tables. I suspect that the cable mirrors the pinout and this needs to be corrected by the in-air mirror cables.
I went around the lab and did not find any other suspensions which have the mirror cable.
WIth the BHD configuration, we will move the feedthru for the SRM to the one on the ITMY chamber. So I believe the situation is going to be improved.
|