AP 1200DA Problem


Brian McFarland
 

Hello everybody,

I recently purchased a used 1200DA mount that had the QMD + DSC encoder upgrade, and it has a problem that I'm wondering if anyone out there has experienced. The RA axis is very stiff while under load (and only while under load). When loaded with a scope that weighs about 75 lbs plus balancing counterweights, the RA axis is so stiff it's difficult to find balance, and the motor repeatedly stalls. This stiffness is present even when the worm/motor assembly is removed, so the clutch and worm-to-gear mesh aren't even part of the equation. When unloaded (no scope or weights), it rotates pretty freely, although not completely free-wheeling - there's still a small amount of resistance even with the worm removed. The rotation feels smooth, not rough. The dec axis behave normally.

My first inclination is to suspect a bearing problem, but this doesn't seem like a typical bearing failure mode.

Any insight greatly appreciated!

Brian

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