Enzo, Terrence, Yoshinori,

= PR2 =

== Background ==
-- As reported in klog#8149, BF-LVDT-Vs signal was off from the MEDM screen. this issue was investigated

== after inspection ==
-- It was found that the channel of the LVDT board for BF-LVDT-V2 was broken:
  -- the LVDT coils were connected electrically according to a registance measurement.
  -- also, when the LVDT board channel was changed not to ch2 (origina one) but to ch4 (so far blank),  the suspension motion was observed, like the attachment.
    -- The red and green curves are the signals of V1 and V3 respectively, which were healthy. The blue one was the one when the cable was connected to ch2(original), the orange one was the one when the cable was connected to Ch4(blank so far). I note that the orange one was measured with a cicuit which had not been tuned yet and thus the gain was mutch different.


== Next ==
-- Somehow reproduce the tuned registance and phase of the LVDT board.
  -- The procedure would be: to set the same registance first, and then to tune the phas shifter so that the dc value becomes same value measured before when the suspension was healthy.