aLIGO LHO Logbook

H1 ISC

corey.gray@LIGO.ORG - posted 14:45, Thursday 17 July 2014 - last comment - 16:59, Thursday 17 July 2014(12813)

Cable Ground Loop Fixed on EX TMS

(Corey, Filiberto)

Keita walked us through a ground loop he noticed on the TMS (the cable which goes to 4 [of 6] BOSEMs on the TMS). I went in chamber and Filiberto went to the air-side of the flange for this cable.

Filiberto first confirmed that there was indeed a short.
I then disconnected the Seismically Responsible (SR) Cable from the BOSEM cable to try and narrow down to the culprit and luckily we were able to see that it was the SR Cable (this cable goes from a Cable Bracket on the Optics table and then up around the ISI Stages upstairs and then off to the Chamber Flange.
Didn't find anything on the Optics Table side.
Started to unscrew the cable from flange, and before removing Filiberto noted that the short was gone.
Completely removed the cable to make sure the slot-head screws were screwed in tight and were not causing the short (they were fine)
Reinstalled the cable by pushing it in completely (no short observed). Then started screwing in the cable (no short observed, at first). Then a short was observed when the the set screws were screwed more.
So, I simply engaged these screws enough to keep the connector on the flange and called it good.
Ground Loop eliminated.

Comments related to this report

filiberto.clara@LIGO.ORG - 14:55, Thursday 17 July 2014 (12814)

Link

The air side cable we disconnected this morning is H1:SUS_TMONX-1.
We also disconnected H1:SUS_TMONX-4 and found no short.
Both cables are on Feedthru E6 subflange 7.

keita.kawabe@LIGO.ORG - 16:59, Thursday 17 July 2014 (12821)

Link

This is the same as one of the failure modes found in HAM6.

https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=12348

Scroll down to "annoying cable and connector problem" in the above alog. Also look at the picture in that same alog.