Alexa, Dan, Sheila
We found the BS ISI ST2 watchdog was tripping when the DRMI was acquiring lock; big transients in the MICH control signal would show up in the ST2 GS13s and saturate the inputs. After some dataviewer'ing, we found that these transients are always there, but today they were large enough to hit the watchdog threshold. We suspected the GS13 gains had changed, and conlog said that yesterday the 'Gain' filter (FM4) on the BS ISI GS13INF filter banks was turned on. (We suspect that someone turned these off during the SEI work today?) We turned them back on; the problem seems to be fixed.
None of the other BSC chambers have these filters on, but it looks like we need them for the BS, for now.
We tripped the ISI even while DRMI was locking (and luckily did not break the lock). We compared the length signal to the BS between today and yesterday, and concluded the LSC signals were not very different and were not the culprit.