MDM Trouble Report for 2011 Nov 5

Telescope: 2.4m
Observer(s): Julie Skinner (Dartmouth College)
Instrument: ccds

Problem(s) Encountered:
I opened and tried to slew to a bright star near zenith.  The telescope
then slewed all the way over to the northern hard limit.  I backed it
out of the hard limit and set it near the zenith manually with the 
hand paddle.  I reset the encoders after making sure I was at the zenith
on the tilt sensors.  Then, I tried to slew to a different bright star
near the zenith.  It again slewed far to the north --this time going past
the hard limit to a dangerous position.  I tried to back it out and
called the 1.3m observer to help.  This did not work, so I called Bob
and he came up to the mountain.  Bob had to release the brake on the
telescope to sit it upright.  At this point, when the telescope was near
the zenith, the tcs computer thought it was at -71 in dec.  We tried moving
the telescope with the hand paddle north and south.  The telescope would
actually move in both directions, but the tcs would only read
that it was moving south.  Anytime we tried to move north the tcs would
not increment.  Bob tried a different dec encoder and a different
dec encoder buffer box, but those gave the same results.  He then tested
an intermediate circuit board and came to the conclusion that it was a failed
integrated circuit.  He replaced the ic and the problem seems to be solved.
He left around 12:30am mst.


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Submitted on 2011 Nov 6 [5:53:34]