Today, Dan Hoak and I finished checking all the cabling associated with H2 ETMY.  The summary is:

1.  All cables (SUS, ISC, SEI) going to the vacuum system, and inside the vacuum system, are now properly functioning with respect to grounding and shielding.  This statement refers to in-vacuum and in-air cables with respect to shields only (not internal pin functions which have been largely exonerated by subsystem checkout).

2.  There are two L4C cables (L4C-2 and L4C-3) that show an in-vacuum short from shield to ground.  We believe this is due to the strain relief screw not being tightened down yet.  This is not a cable flaw by itself as the screw is supposed to be tightened, and will be tightened at final install time (per Jim), it's just something to put on the final checklist.

3.  Every shield associated with the ring heater drive cables is grounded at end closest to the ring heater.  This is due to the way the metal collet that terminates the shield is attached to the structure.  This does not present a problem to any other neighboring subsystem in terms of noise, but may have implications on the 60 Hz content of the ring heater drive spectrum.  A design change is needed to fix this problem if it is deemed worth fixing (I don't have a sense as to whether it is possible to pickup enough energy into a heater connection to actually move an optic or conversely to radiate enough energy from the ring heater drive to bother another subsystem.  My instinct is it's not a huge deal).

4.  I noticed that the RTD used to sense local ring heater temperature is not attached to anything.  It just floats near the ring heater on the end of a length of wire.  It would seem better if that sensor were attached somewhere to make the readings more meaningful and repeatable.

Here are some details of measurements taken today on ISC, SUS, and SEI cables:

1.  The SUS cables going to the chamber from the satellite boxes were disconnected from each satellite box and a resistance check was performed from the backshell to ground.  All connections are free from ground contact.

2.  The same SUS cables were then checked to see if pin 13 of each connector was connected to the cable shield as it is supposed to be.  Two cables were found (SUS-1 and SUS-19) without a connection.  We later found out that this was due to poor workmanship on the cable construction as can be seen from the attached photos.  The SUS cable shield connection is made by pinching a short piece of wire precariously between the two halves of the backshell.  This is not a reliable connection.  The ISC cable has a soldered connection from the backshell to the cable shield rendering it far more reliable over time.  We fixed the SUS cable problems by better positioning the shield wire connection between the two halves of the backshell, but it calls into question the reliability of the shield connection for this type of cable.

3. Verified that all cables incident upon the air side vacuum feedthroughs have no connection between the backshell and shield.  A connection here would ground the cable shields once they plug into the vacuum feedthroughs, it would not be apparent until the mock feedthroughs are removed because the mock feedthrough uses a short length of unshielded ribbon cable to achieve the needed mirroring of the pinout.  

4.  For all SUS and ISC cables, we verified that once the airside cable is disconnected, the inside vacuum shields are isolated from ground.  The SEI cables were similarly verified yesterday to be satisfactory with the exception of L4C-2 and L4C-3 as previously noted.