The current FSS servo we are using is labeled D980536 Rev. C on the PCB, but the schematic that matches the PCB more is D980536-D (there are minor corrections).

The schematic is posted below.

I'm checking If the board will match the schematic or not. Then its transfer function (TF) will be calculated by simulink, and compared with the result from measurement. 

The correction will be added soon.