We're checking the grounding of things in HAM2. IM4_TRANS QPD, ISS array QPD and all 8 ISS array PDs are fine.

IM4_TRANS and ISS array QPD:

Disconnected the DB25 cable from the transimpedance amp (ISC R4 slot 31) and measured the resistance between the pins and the chamber ground. (Ground potential for the chamber and the racks are significantly different, so we connected one cable directly to the chamber and measured the resistance between that cable and the pins.) 

All pins are isolated from the chamber. pin13 is tied to the shielding.

ISS array PDs:

Disconnected two DB25 cables from the second loop chassis (D1600229) in the PSL rack and measured the resistance between the pins and the chamber ground. Same caveat about chamber VS rack ground.

All pins are isolated from the chamber. Pin 13 is not connected to the shielding. This is fine, as this is a special cable made to convert four pairs of coax cables (total 8 coax) into DB25. Shielding of 8 coax is connected to pin14 through pin21 which are tied to the ground inside the second loop chassis. Pin13 is also connected to the ground inside the chassis. See D1600321.

Fil is done with SUS, some issues were found and he'll work with Rahul to try to fix them. He will also test picomotor grounding later.