I'm currently facing a little problem with our Yaesu controller. I have done all the calibration and the controller appears to be working fine. Unfortunately, it does so for short duration (a couple of hours maybe). After that, the azimuth control goes askew with an offset of around 15 degrees. Therefore I had to recalibrate it almost every time before I try to communicate with any satellite. Could you please provide advice in case you have encountered a problem like this before? I use GPredict and rotctld for all the control.
Sorry for the long overdue reply but you didn't tag your response with my ID so I didn't get notification of your response.
The control box azimuth reading and the computer azimuth reading share a common 6 volt feed from the rotor potentiometer circuit but each has their own calibration pot. If the control box meter reading is drifting from the computer reading after warm up, I would suspect that one or the other of the calibration pots is the problem. Try rotating both VR1 and VR3 back and forth several times through their complete range immediately after spraying with a contact cleaner. Then recalibrate both after they dry out.
After calibrating, leave the rotor azimuth in a fixed position. With a DVM, note the output voltage of the azimuth reading on the DIN connector of the rotor controller after you have successfully calibrated both pots. If the control box meter reading changes, you know that the problem is in that circuit. If the computer reading drifts after some time, re-check the DIN voltage reading. If that has not changed, then the problem is in your computer controller board, not in the rotor controller box. If it has changed, the problem is in the control box circuit that drives the external DIN connector.
Feel free to post your results after going through this troubleshooting exercise if you still haven't found the problem.