Last updated: 31 December 2004
Sent: Sunday, December 26, 2004 08:22:40 From: email@example.com (firstname.lastname@example.org) My father-in-law bought an ETX-60AT over a year ago, and hardly used it. Yesterday, I found it in a closet, and thought it would be nice for my two girls to use. Unfortunately, the horizontal / azimuth motor doesn't seem to engage -- just makes some (not unpleasant) noises. The vertical / altitude motor works fine with the Autostar. I popped the lower cover off, and it looks to me like the horizontal lock / clutch simply doesn't engage tightly enough for the motor to turn the 'scope. Since it's out of warranty, I thought I'd give it a try to fix it myself. However, it's not too obvious to me how to get access to the motor, nor to adjust the clutch./ Must I remove the horizontyal lock lever? 'Cause the screws under the little rubber feet appear to only hold the internal metal plate / weight in place. Any tips / help on disassembly are appreciated. --AndrewMike here: It could be that the locking lever needs a slight adjustment. See the FAQ page on the ETX Site for info on doing that. Let me know if that fixes the problem.
Thanks -- that looks promising. Now I gotta go find the Allen wrench! Any idea what size it is if I can't find the original? 1/16? --Andrew
Found the Allen key -- cute, how they do the horizontal locking via a simple hex-head bolt. Anyway, that had no effect. I.e. doesn't matter how tightly the horizontal lock is set -- won't turn, but motor is running. I suspect something inside is loose / has follen off ... Regards, --AndrewMike here: Rats. Well, time to dig deeper. See the article "ETX-60AT Tuneup" on the Helpful Information: Telescope Tech Tips page.
And an update:
Thanks for your help and website. It turns out that the plastic "tensioner spring" that pushes the horizontal motor's worm gear against the ring gear had broken, so the horizontal motor was no longer able to turn the base. So, after disassembling the unit (and note that the white plastic "nut" did not shear off as per the link you gave me -- I was able to simply unscrew it), I drilled and tapped (8-32) the center upright of the casting to accept a spring-loaded pin, VLIER P/N SSMD-51A. I also drilled a small access hole in the base (not shown) at the correct height so that I could adjust the pin for appropriate tension once everything was assembled. I've attached two pics to show the mod -- perhaps some of your website visitors may find them useful. The first pic shows the spring-loaded pin in its initial position -- I screwed it in a couple of turns once the base was attached, to achieve proper tension of the work gear against the ring gear.
Regards, ______________________________________ Andrew E. Kalman, Ph.D. email@example.com
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