Disassembly Pictures for NexStar GT Azimuth
In chapter 12 of the NexStar User's Guide I describe how to disassemble,
reassemble and adjust the NexStar GT mount. I included as many
pictures as was practical for a book, but thought additional pictures would
be useful. Note that the book describes more detail; these pictures
are meant to supplement.
Caution! The very real possibility exists during the procedures
described here that you may damage something. Also, disassembly may void
your warranty and you should consider returning your telescope for warranty
work rather than attempting adjustments on your own. After the warranty has
expired you should consider the possibility that you will cause costly
damage when working on your scope. While I consider the following procedures
reasonably safe, not everyone should approach an expensive piece of
equipment with a screwdriver in their hand.
Click any of the pictures below for a larger version.
||In this view of the bottom of the GT
base, we can see the bar that holds the base to the tripod and the nut
securing the bottom of the azimuth axis.
||After removing the bar and the nut, I
have laid out all the parts in order. Note the red fiber disk.
The surface of this disk, as well as the area of the large gear that
the disk mates to, must be free of grease.
||When reassembling the base, first you
will replace the large washer, then the lock washer and finally the
||This view shows the large gear removed
from the top half of the base. Note the large white nylon washer
that provides the bearing surface between the gear and the top of the
base. Also note the 3 white nylon disks that provide the bearing
surface between the top and bottom of the base. They must be
replaced in the recesses on the top of the base prior to reassembly.
||This view of the top of the base shows
the nut securing the top of the azimuth axis. The top cover of
the base is removed by prying up gently at the two openings just above
the orange ring (not shown here).
||When reassembling the top of the base,
first you will replace the plastic washer, then the flat washer, then
the cone-shaped washer (large side down) and finally the nut.
To correctly adjust the tightness of the nuts, first tighten the
bottom nut as much as you like. This nut simply allows the mount
to slip at the point of the red disk, should you need to move the
mount by hand (during storage). In practice, we never move the
mount by hand. Next tighten the top nut just to the point where
the fork arm no longer rocks back and forth. Too tight on the
top nut and the mount may not move freely, tracking will suffer and
battery life will be shortened. Apply power to the mount and
ensure free movement for 360 degrees. Adjust the top nut again
See The NexStar User's Guide for
more details on adjustments, cleaning and lubrication of the axis.