Last updated: 31 October 2003

ETX-90RA RA lock/DEC cross coupling fix and DEC slow motion control improvement

Sent:	Wednesday, October 29, 2003 15:26:44
From: (George Hofmann)
I think I solved one problem and partially solved the other. The DEC
adjuster stickiness appears to be caused by one of the knobs on the
adjuster shaft not being mounted square on the shaft. You can see it
wobble as you turn the shaft. Both knobs rub the fork arm fairly
tightly, I guess to provide a little friction by design (I'll give them
credit although it is probably not due). I put a little WD-40 on the bad
knob and that seemed to ease the stickiness a little, although I can
still feel the uneveness. At least it's tolerable.

The problem in the RA axis, which manifests itself as a declination
change when the RA lock knob is tightened, is fixed. I took the base
apart and found that there is a Z-shaped bracket whose edge fits into a
groove in the side of the main spur gear.The lock is just underneath it.
The lock pushes up against the spur gear forcing the groove edge to push
against the bracket thus clamping the spur gear between the lock and the
bracket. There was a lot of slop between the bracket and the groove
edge. I took the bracket off, bent it slightly in a vice. I also
slightly tightened the single sorry screw that fastens the base to the
fork mount. Now there is essentially no noticeable declination change
when locking the RA.

I don't see either of these fixes on the Mighty ETX site, so you might
post it.

George Hofmann
Edgewood, WA
"where it's always cloudy"

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