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 Sat Aug 5 11:04:07 2017, gautam, Update, SUS, MC1 glitches return 
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 Wed Aug 9 15:15:47 2017, gautam, Update, SUS, MC1 glitches return
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Thu Aug 10 21:01:43 2017, gautam, Update, SUS, MC1 glitches debugging
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Fri Aug 11 12:32:46 2017, gautam, Update, SUS, MC1 glitches debugging
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Fri Aug 11 17:36:47 2017, gautam, Update, SUS, MC1 <--> MC3
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Sat Aug 12 14:09:36 2017, gautam, Update, SUS, Glitches stay on MC1
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Sat Aug 12 22:35:22 2017, rana, Update, SUS, Glitches stay on MC1
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Sun Aug 13 01:35:09 2017, Koji, Update, SUS, Glitches stay on MC1
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Mon Aug 14 20:01:38 2017, gautam, Update, SUS, Glitches stay on MC1
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Wed Aug 16 19:50:17 2017, gautam, Update, SUS, MC1 <--> MC3 switched back
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Thu Aug 17 11:17:49 2017, gautam, Update, SUS, MC1 <--> MC3 switched back
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Thu Aug 17 17:33:01 2017, gautam, Update, SUS, MC1 <--> MC3 switched back
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Message ID: 13195
Entry time: Fri Aug 11 12:32:46 2017
In reply to: 13187
Reply to this: 13196
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| Author: |
gautam |
| Type: |
Update |
| Category: |
SUS |
| Subject: |
MC1 glitches debugging |
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Attachment #1: Free swinging sensor spectra. I havent done any peak fitting but the locations of the resonances seem consistent with where we expect them to be.
The MC_REFL spot appears to not have shifted significantly (so slow bias voltages are probably not to blame). Now I have to look at trend data to see if there is any evidence of glitching.
I'm not sure I understand the input matrix though - the matrix elements would have me believe that the sensing of POS in UL is ~5x stronger than in UR and LL, but the peak heights don't back that up.
Attachment #3: Second trend over 5hours (since frame writing was re-enabled this morning). Note that MC1 is still free-swinging but there is no evidence of steps of ~30cts which have been observed some days ago. Also, from my observations yesterday, MC1 glitched multiple times over a few hours timescale. More data will have to be looked at, but as things stand, Hypothesis #3 below looks the best.
| Quote: |
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Some possible scenarios (assuming the free swinging spectra look alright and the various resonances are where we expect them to be):
- With the watchdog shutdown, the PIT/YAW bias voltages still goto the coil (low-passed by 4 poles @1Hz). So if the glitching happens in this path, we should see it in both the shadow sensors and the DC spot positions on the WFS.
- If the glitching happens in the shadow sensor readout electronics/cabling, we should see it in the shadow sensor channels, but NOT in the DC spot positions on the WFS (as the watchdog is shutdown, so there should be no actuation to the coils based on OSEM signals).
- If we don't see any glitches in WFS spot positions or shadow sensors, then it is indicative of the problem being in the coil driver board / dewhitening board/anti-aliasing board.
- I am discounting the problem being in the Satellite box, as we have switched around the MC1 satellite box multiple times - the glitches remain on MC1 and don't follow a Satellite Box. Of course there is the possibility that the cabling from 1X5/1X6 to the Satellite box is bad.
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