Reports until 12:38, Tuesday 25 August 2015
H1 SUS (ISC, SUS, SYS)
richard.mccarthy@LIGO.ORG - posted 12:38, Tuesday 25 August 2015 - last comment - 09:09, Wednesday 26 August 2015(20865)
PRM M3 LL coil investigation
Following up on Evan's investigation into the glitches from LL coil on the PRM M3.   I tried to monitor the output with a scope attached.  I was not looking for very big signals as the the noisemon indicated roughly 30mV signal and it has some gain associated with it. So I connected to scope probes to the LL coil drive signal and looked at it on a scope with a trigger set fairly low.(10s of milivolts).  I also looked at UL just for comparison.   I was able to get the signal to trigger on some events  on LL that were not seen at as high a level on UL.  This was with the DAC both connected and disconnected with small offset (20 counts) applied and a large offset (20,000 counts) applied.  After a couple of hours of investigation I decided there were some glitches present and seemed to be from the coil driver not the DAC.  I also looked at the DAC input to the coil driver and did not see the glitches.  In the end I swapped out the coil driver.  I am not 100% certain this will fix the problem as it was difficult to verify the glitches were present at all times.

Comments related to this report
filiberto.clara@LIGO.ORG - 09:09, Wednesday 26 August 2015 (20914)
Unit removed S1100045.
Unit installed S1100025.