Aug 11 16:40:49 rotse3a schierd: Error reported on RA Axis:
Aug 11 16:40:49 rotse3a schierd: @RecentFaults Axis 1 Encoder Failure 8/11/2002, 15:45:12.767;
What exactly does this mean? When confronted with the problem, Alan Schier quipped ``Well, it sounds like the Axis 1 encoder failed.'' It should be noted that axis 1 is the RA axis, and axis 2 is the Dec axis.
There are two possible problems. There could be some dirt on the encoder tape, causing the encoder head to lose track of the tape. The solution here is to clean the encoders as well as possible.
Alternatively, the encoder head could be slightly misaligned, so that the head loses contact with the tape at a certain point. This misalignment might be very small, and the range over which contact is lost might be very small as well. The solution is to very gently and carefully re-align the encoder head. This might take some time (over an hour), but it is time well spent.