[Takahashi, Lucia, Eleonora]

Today we notice that Geophones and LVDT signals have a strange behavior. Suspecting some stange electronic issue in the boards, we went at Y-End station to do some checks.

Here a summary of what was done:

1) LVDT signal were fine

2) we recovered geophone signal by switching off the IP stepper motors

3) we found that the IP coil driver had  low actuation gain. We recovered it by simply switching them off and on.

The current position of the IP after the pumping down recovery and when all loops are open is:

L = -250 micron

T = -25 micron

Y = -100 microrad

As reported in klog 8446, this position is a bit different from the one recorded during the previouse alignement (L,T,Y=0,0,0). We tried to replace the old position by using the stepper motors, but we coudn`t do this because H1 motor was not working properly (maybe close to the mechanical limit).

We tried also to steer the IP with the DC controls closed to the old position and adjusted the BF Y position to recover the old alignement,  but while doing this, a steep line at 240 Hz appears and IP H1 coil got close to saturation (17000 counts).  

Usually this proble could be soved centering the IP with the motors, but at the moment they are not working.

Tomorrow we will try to recover it by changing the IP tilt base.