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Subject: "Repaired" LX-200 Pointing Accuracy
From: Allen Ginzburg
Reply To: mapug@shore.net
Date: Wed Feb 07 11:38:56 1996

The sky finally cleared long enough for me to test my 10" LX-200 (v 3.34)
after it came back from Meade following repair. Although everything
functions, the pointing accuracy is way off now. I tried all the alignment
options including known and unknown site and got similar results. Aligning
on Procyon and Aldebaran (on either side of Orion), the scope couldn't
get Betelgeuse or Rigel into the field of view of a 26mm eyepiece. I
then centered on Rigel, did a sync and tried for Betelgeuse only 19 degrees
away. It still couldn't get Belelgeuse into the FOV. It looks like the
error was mostly (if not all) in azimuth. I had similar results when
trying to goto Castor. I also tried centering Rigel, syncing, slewing
far away from it and then doing a goto back to Rigel. It always came back
exactly in the center. I had been using the scope for over a year before
I sent it to Meade so am familiar with it's operation and I don't think it's
cockpit error. Before the repair I was consistently getting pointing
accuracy over the whole sky of 10 arcminutes or so, and 2 to 3 arcminutes
when going between sync'd objects that were close to each other. The errors
now look like 10 to 15 minutes on nearby objects and 30 to 60 minutes on far
off ones. All these tests were done in alt-az mode.

I am suspecting that the RA encoder is consistently dropping one or more
ticks per revolution. Has anyone had this kind of problem with their LX-200
and what did the ultimate cause turn out to be? I have a call into John
Piper at Meade but thought I would consult the group's experience to help
him out.

Any suggestions would be appreciated.

Thanks,

Allen
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Allen Ginzburg
SCO x7737