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Entry  Fri Jul 5 23:28:52 2019, rana, kruthi, Summary, SUS, ETMX unstuck by shaking the stack 
    Reply  Tue Jul 9 08:33:31 2019, gautam, Summary, SUS, ETMX PIT bias voltage changed by ~1V 
Message ID: 14736     Entry time: Tue Jul 9 08:33:31 2019     In reply to: 14730
Author: gautam 
Type: Summary 
Category: SUS 
Subject: ETMX PIT bias voltage changed by ~1V 

After this activity, the DC bias voltage required on ETMX to restore good X arm cavity alignment has changed by ~1.3 V. Assuming a full actuation range of 30 mrad for +/- 10 V, this implies that the pitch alignment of the stack has changed by ~2 mrad? Or maybe the suspension wires shifted in the standoff grooves by a small amount? This is ~x10 larger than the typical change imparted while working on the table, e.g. during a vent.

Main point is that this kind of range requirement should probably be factored in when thinking about the high-voltage coil driver actuation.

Quote:

We unstuck ETMX by shaking the stack. Most effective was to apply large periodic human sized force to the north STACIS mounts.

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