Re: Tracking issues with AP900
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If I were having this problem, here is what I would probably do, in rough order...
1. Replace the ancient CP1 with a CP4, if possible. Get atmospheric refraction correction and a bunch of other new and cool functionalities.
2. Check RA axis backlash and axis balance. If your backlash has loosened up over time and the mount is very closely balanced and the worm lube is very dry, the scope could be "bouncing along in the backlash." Make the mount more imbalanced to "wrap up the backlash." This is usually more noticeable near the West and East horizons. Not so much close to the North or South horizons. Still worth checking.
3. Triple-check all of the optical train bits for something loose and flexing/sagging/shifting. Especially focusers and all set screws and lock screws.
4. Triple-check the polar alignment using the drift method in SharpCap.
5. Carefully re-lube both axis worm drive assemblies and carefully tune the worm mesh/backlash afterwards.
6. Always use on-axis or off-axis guiding, never piggyback guiding. Piggyback guiding only leads to tears. Especially with compound scopes with floating optical elements.
7. Check for loose or broken bolts and knobs on the mount and dovetail bars/brackets/saddles.
8. If this scope is accessible by multiple users, take NOTHING for granted. Check EVERYTHING. Especially the DEC axis disassembly/assembly dovetail lock knobs.
9. When in the Northern hemisphere and observing things near the Southern horizon, the OTA is tipped a considerable amount on its side from the DEC axis. A slightly-loose dovetail lock knob could wreak havoc. Not to mention putting the OTA and cameras in great jeopardy.
I hope this helps.
On Fri, Aug 7, 2020 at 10:08 AM Chanan Greenberg <chanan2009@...> wrote: