richard.mccarthy@LIGO.ORG - posted 15:55, Tuesday 13 May 2014 - last comment - 16:57, Tuesday 13 May 2014(11860)
ETMy ESD drive
Spent some time driving each segment of the ESD individually with UL being week and UR, LR not Really being seen. LL and DC making the most movement as seen on the oplev. Trying to make some sense out of the unit put offsets on various combinations of ESD segments trying to get a decent yaw or pitch movement. This would help with the swapped cable theory. I would apply a 125K offset to two segment then make the offset -125k. Again not much luck. Attached are a couple of the plots first being individual drives. Second LL and DC together then sign flip. Ran every combination of paring this is just representative of responses. With UR,LR the response was not as dramatic.
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Richard you might set up the bridge capacitance circuit and note the change in capacitance as you drive the PUM mass magnetically at the pendulation frequency. It will help in determining if you have open or shorted connections and, from the spectrum, if the mirror is touching something.