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Last updated: 31 December 2010
This page is for user comments and information specific to the Meade ETX-90RA (originally known as the "ETX Astro"). Comments on accessories and feedback items appropriate to other ETX, DSX, and DS models are posted on other pages. If you have any comments, suggestions, questions or answers to questions posed here, e-mail them to me for posting. Please use an appropriate Subject Line on your message per the Site Email Etiquette. Thanks. Remember, tips described on this site may invalidate the warranty on your telescope or accessories. Neither the submitter nor myself are responsible for any damage caused by using any contributed tips.

Subject:	Lithium Grease
Sent:	Tuesday, December 28, 2010 00:36:09
From:	George Layburn (
After all those 3 way emails, you two guys are obviously awesome. Mike I
haven't done anything yet, and if you remember me I am the guy who asked
for advice on the Microstar II, Maybe Dr Clay knows the answer to that

Dr Clay, the Microstar II, you familiar with that thing? I have a
question for you about it. I wont ask it now. Are you familiar with it?
Mike the question is for you, I do this both the Microstar II problem,
my wife the mechanical engineer is going to look into the the best lube
for the plastic hubs.  ( What is the deal on the Lithium Grease, I keep
seeing that mentioned)

I have a first generation ETX remember not the computerized version. The
mictostar II sticks when trying to raise the scope. That's insignificant
compared to this issue of that secondary mirror baffle fix.

But these two fixes should I document everything pictures and all, step
by step. And post it on your awesome site after it's done and all works
well. "Hopefully" Should I do that? I will do a great lab report.

My wife will do the grammar check, before I post it.  :-)

All goes well, and I have a fully functional ETX-90 again, maybe I can
give a I did that and it worked, you can do it too advice article.

You know for the few people that still use the original ETX-90.

Mike here: Lithium grease is frequently mentioned as the preferred grease for the ETX lubrication.


Works for me, solves that problem.

Subject:	ETX 90
Sent:	Saturday, December 25, 2010 14:02:21
From:	Clemente Cuevas (
I recently received a used ETX 90 (not the autoguided).
I like the little scope. 
Can someone tell me the dimension of the 3 legs?
I am going to purchase some threaded stock and cut them to length 

Mike here: I'll measure mine and let you know. Once I find them.

Found them. The two non-adjustable legs are 23.1 cm long, not counting the bolt that threads into the ETX base. The adjustable leg is also 23.1 cm when set for 42.5 degrees of latitude. When set for 27.5 degrees of latitude, the leg is 42.3 cm. However, the scale is not divided into equal increments. Tell me your latitude and I'll measure that.


Thanks I live in Orlando, FL lat 28.31
Again Thanks

Mike here: That would be approximately 41 cm. Be certain to allow for some adjustment of the leg; the scale is not that precise.
Subject:	ETX Question
Sent:	Tuesday, December 21, 2010 23:49:04
From:	George Layburn (
Big fan of your ETX page for years now. I have the Microstar II added to
it, as best as memory serves it used to work great but it has been a few
years since I last used it and I decided to tune it up and use it again.

I have a problem with the Dec. motion when raising the scope. Lowering
is no problem, but raising it sticks the motor spins but no movement on
the Dec. Knob. I have taken apart the tube fork mounts even greased all
of the moving parts in the hubs.

It used to work fine as I recall, do you think now being an older scope,
would you recommend scraping/sanding the internal arm that rides on the
Dec, bolt might fix the problem?

I would greatly appreciate your advice.

Thanks in Advance

George Layburn
Clay, NY.
Mike here: If you turn the DEC knob manually, can you feel any resistance? If so, then the problem is likely with the shaft. However, if you don't feel any resistance, then the problem could be with the rubber O-rings; they could either have stretched or become slick and so slip on the metal knob. I have a similar problem on my ETX-90RA. The O-rings slip. One of these days I plan to replace them.


Thank you for your response to my question, I don't have any resistance
on the threaded shaft. I did grease the hubs that holds the scope, I
think that may have been too much. I cleaned everything up and used just
plain oil, I hope that fixes it. I am still working on that.

But I have another question and then I will leave you alone. On the
Microstar II their are the potentiometers for setting the speed of the

The adjustment for the R.A. motor does changing that alter the actual
"tracking speed" as when following an object, or does that alter the
Fast Forward/Rewind speed.

I don't want to alter the "tracking speed" it works perfect. But if I
can speed up the searching speed that would be neat, I am hesitant to
touch that adjustment.

Is the tracking speed independent of that potentiometer?

I hope I phrased my question correctly.

Thank You In advance, and I will leave you alone. I bet you get lots of

George Layburn

P.S. Again love the web page, totally rocks. Crying shame that
Scopetronix went out of business. Love the Microstar II, and the Zoom
eyepeice. among other things I bought from them.
Mike here: The "pot" on the handcontroller controls the focusing speed. Tracking speed is not affected.


No, I am talking about the pots on the printed circuit board mounted
inside the base of the scope. Their are two one for the R.A. motor one
for the Dec motor. I wasn't talking about the hand controller.
Mike here: The RA pots "might" affect the tracking speed. The DEC one won't. Someplace I have the documentation that came with the Microstar II+ but after all my moves, I'm not certain where it is.
After checking my closet, I found the Microstar II+ manual. There are two pots: one for adjusting the DEC slewing speed, and the other for adjusting the RA tracking speed. The RA speed pot should normally be in the factory setting.


Hey, Thanks a lot for checking it out. I think I am just going to leave
that circuit board alone, if it ain't broke don't fix it. Right!

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