VIXEN DD1 CONTROLLER CIRCUITS
Some time ago I noticed the motor performance had dropped for the declination motor on my vixen DD1 controller.This is controlling a vixen great polaris dx mount.The symptoms were such as if one of the phases of the stepping motor was not being switched by the integrated circuit that drives it.On investigation with an oscilloscope it showed that one of the chip driver stages was faulty.Looking at the driver chips on the circuit board both of them had glued on heatsinks so their identification numbers could not be read.On top of that the circuits to the two halves ie the declination half and the right ascension half appeared to be different so that meant that the driver chips were different for each motor.I then decided to spend a few hours reverse engineering the circuit the results are in jpeg form below.Most of this circuit should be correct but I could not identify the right ascension driver chip, however the declination driver chip I sourced for a few pence UK.This fixed the problem.The circuits are available for anyone who wishes to use them for repair or modification to their controller.As an example it should be obvious to any one wanting to attach a guider as to how you can modify the circuit to do this.
