James Paulson's roll off roof observatory at the Sunridge Observatory site, taken in the summer of 1986, housing a 10 inch f/5 Cave Astrola Newtonian reflector telescope

Wednesday, October 7, 2009

Adjusting my LXD75 Mount

Meade's little medium duty LXD75 GoTo mount is a nice little mount, but it's not without it's idiosyncrasies. Tonight, after reading about it on the net, I decided to tackle the little bit of lash in the Right Ascension axis. I removed the motor assembly by removing the 3 hex headed screws. I finally located the 3rd screw which is found right above the latitude adjuster coming into the assembly from the backside. Once inside, it exposes an aluminum gear and an adjustment with a collet and locking nut to check side to side play on the worm, as well as 3 adjusting screws to position the worm closer to the worm gear, I did a slight adjustment on these 3 screws, 2 outside first and then the middle one, checking for the tightness of the gear by rotating the worm assembly and checking for play. If you over tighten the worm you will have issues with motor's jamming so one must be careful with this. It only takes a very small adjustment to make it right.

I then set the scope up outside and proceeded to polar align it and I am still a bit off. Also I should have done a few other things which I didn't do but will. I need to do a reset, calibrate motors and train drives since I have changed all of the lash adjustments, but that will wait for another night with more time. The moon was coming up a bit after 9 PM and I thought I would get in some DSO's before then, so I checked out M31 and M13 and found the accuracy to be acceptable, all things considered. A more accurate polar alignment and a drive calibration will fix things more than adequately. I also tested the high precision feature in the mount and found it to be perfectly acceptable, and only a little annoying to have to constantly center an alignment star. I adjusted and used my red dot finder for the first time this evening and it worked out alright.

Honestly I can't imagine what this mount would be like with a larger OTA and some accessories on it, I think it performs best when it's not overloaded at all.

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