Lucia, Yoshinori with remote help of Takahashi-san, Okutomi-san, ..

= ITMX =

== Summay ==
the driver channel was not working and that is why we could not actuate F3-GAS FR yesterday. However, by using a standalone stepping motor driver, we could compensate the height by 0.5mm. We may still have to compensate the height by 3mm more somehow.

== What we did ==
-- Based on klog#8865, we checked the situation of stepping motor driver for F3-GAS-filter, and found that the driver (especially for the channel) was not working properly [1].
  -- However, we also found something strange:
    -- Even though the driver worked properly first, once the F3-GAS stepping motor was connected to the driver, the driver (connected channel) stopped working, i.e., the motor started jittering. If we cycle the power supply on the chassis, the 'daed' driver channel starts working properly though.
    -- The above happened even when the F3-GAS cable was connected to the channel (w/o injecting steps).
    -- This issue is to be solved.

-- Then we tried to use another stepping motor driver, the standalone driver;
  -- We confirmed that this driver was able to actuate the F3-GAS stepping motor properly somehow.
  -- We found that we could push down the keystone by only 0.5mm at F3 even though the wanted was 3.5mm [2].
  -- The amount was:

    -- The compensated height was ~2.1mm, including F2 and BF adjustment. We will still have to compensate about 3mm more somehow.


-- Since basically I did not have any other good idea to compensate the height mismatch, and since we wanted to know the current height mismatch, we asked the commissioners to align the optics for the height check.
  -- The options would be:
    -- to jack up the IP,
    -- to push the LVDTs toward outside the linear range.


[1] I brought/connected a stepping motor for a test to a channel of the driver, and checked if the motor moves smoothly or not.
[2] Based on klog#8865, we should push ITMX down by 3.5mm more since we compensated ~1.6mm by F2 and BF-GAS.