aLIGO LHO Logbook

H1 SUS

betsy.weaver@LIGO.ORG - posted 16:17, Tuesday 10 June 2014 - last comment - 09:57, Wednesday 11 June 2014(12292)

H1 ITMx Monolithic installed - another ESD cable issue

This morning, we used the Genie "duct jack", the install arm, elevator, and 5-axis table to install the newly assembled ITMx Monolithic lower suspension into the chamber and mate it to it's upper structure. All went as expected. We then proceeded to start reconnecting wire segments and cabling. When we mated up the lowest stage of the ESD cable, we had a small hiccup. One of the 5 pin receptacles had fallen into the connector back shell on the end that is soldered directly to the CP. With some care, we were able to gently fish it back out and push it into place with the wire which had been tugging on the other end of the pin receptacle. We expanded the receptacle such that it seemed to hold itself in place better. As well, all 5 receptacle "houses" were twisted such that they seemed to seat better in the connector. We then connected this female connector to it's upper male cable counterpart and it "seemed" like it the connection seated properly. We have no way of visually knowing though. WE NEED TO CHECK THIS AT THE FEEDTHRU, OR SOMETHING.

Comments related to this report

betsy.weaver@LIGO.ORG - 16:26, Tuesday 10 June 2014 (12296)

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Picture of connector with "slipped" receptacle (furthest left, shown missing in black hole):

Images attached to this comment

betsy.weaver@LIGO.ORG - 16:31, Tuesday 10 June 2014 (12297)

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Forgot to mention, we also suspended the entire QUAD.

jeffrey.kissel@LIGO.ORG - 16:34, Tuesday 10 June 2014 (12298)CDS, SYS

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Just trying to figure out what Betsy's talking about (before Betsy subsequently posted a picture herself), I showed Gary and Margot my picture from much earlier in the install (right after it came out of the storage container, basically, from the collection in LHO aLOG 12286). Gary said immediately "Look! You can see it's not there even that early in the day!" I attach the picture, with the missing pin circled.

Non-image files attached to this comment

2014-06-10_ESD_PinMissing.pdf

rich.abbott@LIGO.ORG - 17:09, Tuesday 10 June 2014 (12300)

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This is bad.  The center pin of each coaxial connector is supposed to be held fixed by a PEEK cylinder specifically designed for this purpose.  If the center pin fell through once, it is likely to do it again.  I would do two things before buttoning things up:

1.  Take the connector apart and see what's really going on.  There may (albeit unlikely) be a way to immobilize the center conductor by hook or by crook.
2.  After whatever mitigation you are able to do, I would suggest cleaning a bit of wire and literally shorting across adjacent terminals on top of the CP (if that's even physically possible) while someone outside the vacuum chamber verifies connectivity from the airside.

It may be (I just can't remember) that there's some hope that the center pin can be snapped into place with tweezers after disassembling the connector.  That would be really good if it were true.

betsy.weaver@LIGO.ORG - 09:57, Wednesday 11 June 2014 (12309)

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Further detail of my first alog above:

When we discovered the problem in-chamber, we (Gary, Travis and I) already disassembled the connector very carefully, pulled the receptacle through, and attempted to "immobilize" it as Rich suggests in his alogged point 1. We also attempted to "snap the pin into place" as he also suggested in the alog. We plugged the 2 connectors together, so unplugging them now will likely break it again. We need to move on to test 2. as per his alog (and as per Rich McCarthy in many verbal convos on testing all of them where we can). We'll plan to do this today.