RA motion failure (mechanically seized... sort of) x2

Sunday, February 4, 2024 7:19 AM

Problem(s) Encountered:

Odd behavior with RA drive when switching targets and end of night failure. When trying to slew to a new target we noticed that the telescope slowly overshoots in RA (sometimes to the point of concern in altitude) and then reaches a limit and quickly returns to the commanded RA value. At one point we tried to switch targets and got stuck in a weird orientation with the RA drive slowly drifting. This was initially fixed by setting the track rates to zero and returning to zenith, then restarting the slew. When we went to close for the night and slew to zenith we encountered the same issue. This time we could not successfully restart the RA drive. The telescope is currently stored at the correct DEC but stuck at an RA a little over 1 hour off (zenith dist ~ 23 deg).


Found a bolt that was binding up on the RA drive assembly.  This was related to the work done previously when the assembly seized due to a bearing walking out on one of the pulley wheels.