Jenne, Kara, Stefan, Keita, Peter, Shiela, Rich

Results summary:  With the 3 OMC cables removed from their respective rack mounted chassis (QPD, DCPD, PZT), there are no connections between any two cable shields, and none of the shields are connected to chamber ground.  This agrees with the wiring diagrams so far.

As relates to the OMC Air-to-Vacuum cabling, it is established that the QPD cable shield is tied to rack ground when the DCPD cable is plugged into the split whitening via the squeezer 3.125mHz pickoff chassis.  There must be some connection between the QPD shield and a "Ground" wire in the DCPD wiring chain. Remember, the QPD shield is NOT connected to the DCPD shield, NOR is it connected to the PZT shield as verified by direct measurement.

Attached is a new revised cartoon plan that shows the results of the initial measurements, and plans for a new set of measurements to get to the (next) bottom of this matter.  

What is not clear is how the QPD shield gets grounded by plugging in the DCPD cable to its rack mounted chassis.