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Entry  Wed Jul 23 23:43:28 2014, ericq, Update, LSC, Locking efforts; Wrath of the Mode Cleaner 
    Reply  Tue Jul 29 16:41:54 2014, Koji, Update, LSC, MC servo MCservo.pdf
       Reply  Wed Jul 30 00:42:27 2014, Koji, Update, LSC, MC servo MCservo.pdf
       Reply  Wed Jul 30 22:01:24 2014, Koji, Update, LSC, MC servo 
Message ID: 10267     Entry time: Wed Jul 23 23:43:28 2014     Reply to this: 10285
Author: ericq 
Type: Update 
Category: LSC 
Subject: Locking efforts; Wrath of the Mode Cleaner 

 [Koji, ericq]

We were working on getting back into the locking groove tonight.

The POP2F and REFL3F demod angles needed some tuning to lock the PRC reliably. The green alignments were mostly fine, the X end PZT ASS works reasonably well. Suspensions, especially the ITMs, seemed to be drifting a fair deal; today was fairly hot out, I guess.

We only got to the point of attempting the SqrtInv handoff once (which failed because I forgot to check the filter bank offsets). This was because the Mode Cleaner refused to stay locked longer than ~5-10 minutes at a time. We adjusted the MC and FSS servo offsets by the usual means, but this didn't make a difference.

We discussed and decided that the time is right to roll up our sleeves and dig into the MC loop, and try to figure out why these intermittent times of unreliability keep cropping up. We will check out the servo board, and see if we can find the missing phase than Evan observed, as well as characterize the FSS/PZT crossover, and investigate what kind of conditions we may create that cause the PC to saturate.

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