jim.warner@LIGO.ORG - posted 15:01, Monday 14 September 2026 - last comment - 11:20, Tuesday 15 September 2026(91892)
HAM2 dead cps after whitening measurement
I unplugged some cables to an interface chassis in the CER this afternoon to do some CPS whitening measurements. Not sure what has happened, but when I plugged everything back in, the corner 2 cps didn't come back alive, and are sitting at ~0 cts. I have to leave early today, so I'm out of time to diagnose, but hopefully I can fix this tomorrow morning when I get back on site. This means HAM2 won't be able to isolate, until the corner 2 CPS are working again.
It turns out, the cabling at the HAM2 rack is kind of confusing and I was inadvertently swapping the cables for corner2 and corner1&3. Apparently when we had to swap cables around during install to make room for the PSL, we plugged the cable marked CPS2 into interface chassis 1 and vice versa. Confusingly, we did not do this swap with the power cables, so power cable 1 is coupled with CPS cable 2. Fil says he thinks we can probably straighten this out at the chamber, but we are running out of time today, so we will come back to this. FRS is : https://services1.ligo-la.caltech.edu/FRS/show_bug.cgi?id=39086