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Reports until 12:32, Sunday 09 July 2023
H1 SEI
jim.warner@LIGO.ORG - posted 12:32, Sunday 09 July 2023 - last comment - 11:31, Monday 10 July 2023(71181)
ITMX ISI oscillation from coil drivers

I came in to investigate the ITMX ISI troubles. Seems like the problem was (is?) an issue with the ISI coil drivers, which is a new one for me.

What I tried so far this morning:

1. Killing all requested drives in the model, turned off masterswitch.

2. Checked rack, all of the chassis seemed to be in a normal state, no missing lights.

3. Power cycled ISI interface chassis, T240 chassis. No change.

4. Turned off all the coil drivers. Boom, oscillation goes away. See attached trend. L4Cs go to 0 when I turn off ISI interface chassis, but come back  in oscillating state. The ring down is when I powered off the coil drivers.

5. Turned each coil driver one at a time to see if it comes back. All quiet, but there is a kick each time a chassis gets turned on. Must be some offset somewhere in the electronics? Model is still requesting 0. I haven't seen that before, worth doing some more testing.

6. Turned on damping loops, everything is still quiet.

7-? Start bringing ISI back. Get sidetracked by blend settings not being INIT'd in SDF....

Images attached to this report
Comments related to this report
david.barker@LIGO.ORG - 08:52, Monday 10 July 2023 (71195)

Sunday morning ISI ITMX problem started around 06:00:50 PDT. I checked the MAINS_DQ channels around that time, did not see any AC power issues.

jeffrey.kissel@LIGO.ORG - 11:31, Monday 10 July 2023 (71204)CDS
Opened and closed FRS Ticket 28481. Marked as 18 hours of observing lost, for now, since IFO wasn't back to observing until late late Sunday night, see LHO:71186.
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