F. Clara, R. McCarthy and R. Weiss
We used the capacitance bridge circuit to establish the wiring of the ETMY. We found (as Keita had guessed)
that the common bias line was connected to cable 1 and not cable 3. The capacitance change between the bias trace
and the individual quadrant control traces was measured as the recoil mass and the test mass pendulated 
driven by the ground noise. The seismic system and all suspension damping was turned off during the
measurement. The accompanying figure shows the voltage spectrum at the output of the lock-in amplifier
for each quadrant. The number at the right is the amplitude of the pendulum peak for each quadrant. The smaller
value for the capacitance change between cable 1 and 5 is somewhat worrisome. If this measurement needs to be repeated
to validate a difference in the force/voltage^2 ratio for the quadrants, it would be best to deliberately apply a force
to the penultimate mass at the resonance frequency of the pendulation rather than to rely on the ground noise. The
peak measured in all the quadrants is at 0.4297 Hz