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AdV-SBE (EIB-SAS commissioning)
bulten - 16:28 Saturday 09 December 2023 (62688) Print this report
EIB SAS balancing
The actuator horizontal 0 for the EIB-SAS was above 7 V and gave orange alarm. I tried to remedy that now, since there was a slot in the commissioning with the beam unlocked.
As I suspected, (see report 62368) the stepper motors pulled the bench to the endswitch; that is because they have not been used since the power failure in November. Unfortunately, the
horizontal microsprings are al very close towards the end; the Ty rotation of the bench is out of reach of the microsprings. I reduced the actuation of horizontal actuator 0 from
7 to 5.5 Volt, but that could only be reached by having higher voltages (3 on actuator 2 and 4.5 on actuator 1).

The only way to get the zero set point in range of the bench is by re-doing the cabling that pulls on the external injection bench and introduces torsion. This operation has been tried
already twice (last report logbook 60754); at that time we could reduce the Ty offset from -1500 to -600 microrad and the actuator voltage close to zero.
However, that was the furthers that the cables on top of the bench could be pulled.

I propose to continue running in the current condition; the actuator voltages are somewhat high but the noise on the bench is so high that the actuator noise plays zero role.
I think that we could rebalance the bench by shifting countermass weights of maybe by mechanically changing the tilt stabilization a bit; this is however a delicate operation and
would require my presence (or Alessandro); I prefer to do such an intervention at a moment that we can simultaneously fix the SQB2 and SIB2 stuck fishing-rods on filter0.
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