Tim, There are two potential causes of what you describe. First some background. When I decided to design the ServoCAT I needed a DSC to 'talk to' ... and as it turns out the Sky Commander had a serial data protocol already in place. However, and this is not meant as a slam on the Sky Commander -? my experience as a design engineer for decades working around serial comms included the expectation that there is always at least a minimal error checking capability in that serial data - the Sky Commander had none. So - the ServoCAT doesn't know if what it 'sees' is good data or just garbage but it has to assume its good and try to interpret it. This can mean if it isn't working correctly, that the data is bogus - it could be interpreted as a command to run 3X the normal rate - in one direction and the next sample 10X in the opposite.?
So - with that... there are two ways it can screw up. One is that indeed the serial comms is corrupted and the data is bogus. You can easily determine if this is the case by simply unplugging the serial cable ("DSC" on Gen2/3, "SC" on Gen1) from the front of the ServoCAT. If the movements stop - if you can control the motors using the handpad or hand controller going both directions and seeing it decelerate and stop when you let go of a button - then it is indeed this issue. Note this can be with any of the 3 DSC's: Sky Commander, Argo Navis, or Nexus as again the serial protocol I put in was that of the Sky Commander. What can cause it to fault? The serial cable is often several feet long - our standard cable was either 7' (gray) or 9' (black)... and that is long enough to pick up energy from a nearby lightning event - nearby, depending on the magnitude of the event, can be miles away. This can damage the serial chip in one end or the other - or both ends.?
The other way it? can screw up is if you unplug that DSC cable and it is still uncontrollable - it is within the ServoCAT. The ServoCAT is not seeing the motor encoder. When this happens you cannot control it with the hand controller! The motor simply takes off at a high rate of speed and can reverse on its own. This can be a bad connection and often is. But it might be a bad motor encoder. I designed in protection for the motor encoder in Gen2+ ... so it's pretty rare for it to be the motor encoder in those.?
Do the test above - contact Bill with the results and he'll go from there to get you back in good shape. It is repairable without much fuss.?
Gary Myers
StellarCAT/ServoCAT - retired
