Dome motion failure (motors)

Thursday, June 29, 2023 6:16 AM

Problem(s) Encountered:

Again, the dome worked for the first couple of targets and, this time, refused to move in response to a slew.  It did not make the same noise as before - I don't remember what noise it made.  I disabled the auto-dome and tried using the paddle, but the dome still would not move. 

The slit is centered near 102 degrees azimuth.  For the rest of the night I observed objects as they passed through the observable part of the sky, so managed to work through the night, but most of the targets were not the highest 

The emergency cable plug is awkwardly placed near the unused secondary, and I didn't feel I could plug it in safely, so I left the dome open. There is zero likelihood of rain, but the sun will be falling on the telescope.  The mirror cover and dark hatch are closed, and the dewar is full.


Quite the frustrating problem.  Initially thought it was associated with the north motor mount but it appears that the issue mayt be caused by running two motors off a single controller.  If the motors are not perfectly synchronized, they may begin to fight each other and result in failure.  The better solution would be to modify the system so each dome motor had a dedicated controller, with a third controller to gate them through.  The cheaper/faster solution is to simply remove the south motor, running dome rotations through the single north motor.  Testing indicates there is more than adequate hp for this and that the dome is balanced enough to make this a non-issue.  Torque settings were adjusted in the controller parameters for running off the single motor and things have been good ever since.