Anamaria, Robert

Richard asked me to check if pulling the power supply grounds this morning had affected the CS IO chassis fan peaks in DARM. It can be difficult to make comparisons because, when the fan frequency is moving more, it appears lower in averaged spectra and coherence. But, as far as I could tell, the ground work at the CS this morning didn't  seem to reduce the peaks.  Based on the coherence and peaks in the figure (I checked other harmonics as well), I would say that the highest priority locations for putting IO chassis fans on separate power supplies are still CS and EX ISC/ASC/LSC. Normally, as in the figure, the EX ISC chassis is the worst, but, as Anamaria pointed out, the CS peaks were way worse on March 14.  I have not see the EY chassis fans in DARM....