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MOUNT CARE AND ALIGNMENT
Your 1200GTO is a precision instrument with very accurate worm and wheel adjustments. Please be careful if you place the
mount on a flat surface, i.e. the ground or trunk of your car. The gear alignment may be affected if the R.A. and Dec.
motor/gear box assemblies sustain undue lateral force. This is true of any fine instrument. We suggest that you transport
and store the mount in a case or in a well-padded box.
Mount Maintenance
Under normal operating conditions, minimal maintenance is required. Every 12 months the clutch knobs (4 for Dec. and 4
for R.A.) should be removed and 1 or 2 drops of light oil (3 in 1 household oil) should be put in the exposed hole. If the R.A.
and Dec. axes are attached together for a long time in outside
conditions (i.e. in a permanent observatory) then the mating
surfaces should be lightly oiled or greased - if you expect to get them apart again after 10 years.
Tips and support
For additional information regarding the 1200GTO, refer to the Technical Support Section of our website. We also
encourage you to participate in the ap-gto user group. The members of this group are very knowledgeable about the
operation of their mounts, CCD imaging and other related issues. The staff of Astro-Physics also participates and you will
find a wealth of information in the archives. To find the group, link from User Groups in the sidebar of our website.
We encourage you to submit your technical support questions directly to Astro-Physics by phone or e-mail: support@astro-
physics.com.
TROUBLESHOOTING
The troubleshooting issues below relate to the mechanical or electrical function of the mount. Additional troubleshooting
questions are in the GTO Keypad manual. Please refer to them.
The declination (or RA) axis is fairly tight even with the declination clutch knobs fully loosened.
Under each clutch knob is a Delrin plug with a tiny hole in it. This plug acts as the clutch material and when pressure is
applied via the knob, it presses against the worm wheel hub to couple the Dec axis to the underlying worm wheel (so it can
turn when the worm turns). When these clutch knobs are pressed too tight for long periods of time, the Delrin plugs tend to
splay outward and expand into the sides of the threaded hole. Then, they will not retract when you loosen the clutch knob
pressure, and what you have is sort of a permanent friction of the Delrin material against the worm hub.
It is quite easy to fix this. Simply remove the clutch knobs, then remove the Delrin plugs. If you have a 4-40 tap handy, you
can try to thread it into the hole in the middle of the clutch plug. Then, simply pull it out with the tap. Alternatively, you can
borrow or purchase a modified screw driver from Astro-Physics to remove the plugs.
Once out of the hole, you can either sand the outside down with a bit of emery paper until it goes smoothly into the threaded
hole in the Dec axis, or call Astro-Physics, and we can send you 4 new ones (or 8, if both axes are involved). Replacement
with new ones is the preferred solution, however sanding them down may get you up and running quickly.
Remember that the clutch plugs do not have to be tightened heavily with a hex key in order to be effective. Over tightening
will cause this problem. If replacing the clutch plugs does not resolve your problem, please call Astro-Physics for
assistance.
The LED on the GTO Control Box changes from red to yellow and the motors stop or go out completely (for
mounts shipped after 02-25-00).
1. The motors are overloaded, probably due to an unbalanced load on your mount.
Rebalance your telescope, and then press one of the N-S-E-W buttons to reset the keypad. Re-enter the last
object on your keypad and the scope will slew to the correct position. Even though your motors had stopped, the
logic in the control box retained the scope position in memory. As long as you didn’t change the pointing position of
the scope, you are still calibrated.
If the scope was moved during re-balancing, simply enter a nearby bright star on the hand controller, press GOTO
and allow the mount to finish slewing. You can then move the scope manually or with the N-S-E-W buttons to
center the star in the eyepiece, and press the #9 RECAL button. This will recalibrate the mount.
Additional explanation
: The GTO drive circuit includes logic for overload protection to prevent burning out the
Summary of Contents for GTOCP3
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