ETX-90RA AND ETX-90EC USER FEEDBACK Last updated: 9 March 2001

This page is for user comments and information specific to the Meade ETX-90RA (originally known as the "ETX Astro") and the ETX-90EC. Comments on accessories and feedback items appropriate to other ETX 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 and I'll post them. Please use an appropriate Subject Line on your message. Thanks.

Subject:	Another night with my beloved ETX 90EC
Sent:	Wednesday, March 7, 2001 19:50:04
From:	tims@charter.net (Tim Sheets)
Well, it's been many months since I have had the opportunity to use my
ETX, but tonight, it wasn't too cold (42f) and the sky was beautiful.
It's getting late so I don't go through the motions of aligning and
such.  Orion, glittering in the sky was beckoning.  After 6 months with
my new ETX, after having had a 8" Meade Starfinder EQ, I can honestly
say, I would take the ETX anyday.  Don't get me wrong, the 8" mini
lightbucket produced some beautiful sites.  But, even as a fairly
seasoned star hopper, the mechanics of of the eq mount, with no
electronic controls, made finding anything a challenge. With the ETX,
all you need to know is approximately where something is, and the
slewing controls make getting there an easy task.  Of course, the
Autostar makes finding things as easy as toasting bread.

M42, the jewel of the winter sky.  I only have 96x capability right now
and it was still gorgeous, under moonlit skies.  Of course, Jupiter's
bands were bright and beautiful, and Saturn (with Titan), my favorites,
were amazing.

I know most of the conversation on Mike's great site here has been
technical of late, but for those of you simply wanting to know how us
ETX owners feel about our scopes.  There is absolutely nothing in the
price range that can compare.

Tim

Subject:	ETX90EC question...
Sent:	Wednesday, March 7, 2001 18:10:10
From:	abcuellar@hotmail.com (abcuellar)
Hi,my name is Adrian,I'm eleven.I'm trying to buy an ETX90EC. The
problem is that it's going to be hard to get $600,so I really want to be
sure if it's worth the time and effort. The question is if I could ask
you (or anyone who reads this message) COULD YOU BE SO KIND to take a
picture with your ETX90 plain ? I mean with no addaptation (cept for the
T-adapter), the way i'll recieve it from the store. I want to know if
without any addaptation I can see Jupiter's clouds,Saturn rings etc.like
it said in MEADE'S site.

Please answer me
ADRIAN CUELLAR

Subject:	ETX-90RA on a DS mount
Sent:	Wednesday, March 7, 2001 09:07:49
From:	bpowell@one.net (Brent Powell)
First of all, thanks for having your site; I check it daily.  It's clear
you put a lot of work into it and there's lots of great information on
it.  I wish I had seen more of it before I bought a DS-70EC/AT for my
son.  I'd definitely have tried harder to find an ETX-90 in my price
range!

Thanks to the info on your site and on the Meade-DS Yahoo group, I've
gotten the darned thing to work as it should!

Now that we've been able to use it a few nights, I know that I should
have forked over the extra money for a 90mm objective.  I'm watching
e-bay and Astromart for an ETX-90 to buy, EC or RA.

Which brings me to my question.  I saw (I think it was on your site)
where someone had mounted their ETX-90RA on a DS-90 Mount so that he
could use the Autostar with it.  Now I can't find it on your site.  Can
you point me in the right direction?

Thanks again for all your help.

Brent Powell

Subject:	ETX90: Problem with Electronics Controller
Sent:	Sunday, March 4, 2001 23:47:09
From:	pakdee.m@usa.net (PAKDEE MAKEJUMROEN)
Thanks for the excellent information of ETX on your website.

I just buy new ETX-90EC a couple of days. Have the same problem as
MrPhatOne@aol.com. My scope seem to randomly have the problem with the
moving up & down with electronic controller. Sometime didn't even hear
the motor moving sound. Once I try to recycle power sometime work
sometime doesn't. I'm sure it not the DEC knob issue that you mention in
your mail. I wonder if this problem is known problem as you post on your
website "Random Slewing Problem with DS and ETX Drives" announcement
from Meade. How I can solve this problem

Thanks,
Pakdee

Subject:	Re: Trunion Slop Adjustment Question
Sent:	Sunday, March 4, 2001 13:50:23
From:	sherrodc@ipa.net (Clay Sherrod)
To:	Bill
Yes!  You've got the part identified that needs the Teflon tape; keep in
mind that Teflon tape is very difficult to work with and does not want
to stick.  CLEAN the tapered trunion first with mineral spirits and rub
vigorously to remove all grease; then very tightly wrap the tape.....it
is the stretching of the tape as you wrap that results in a firm grip. 
A couple of wraps should do it.  THEN, spread a generous amount of
Lithium grease with your fingers over the tape and work it around (being
careful to not dislodge the tape) evenly.

When you replace the arms into the fork, you will note that they are
very tight; this is okay.  Just work them back and forth (rotate) as
long as necessary; eventually the tape will "seat" and the OTA support
arm will rotate very freely.  Be sure when you reassemble and place the
setting circles back on to LUBRICATE behind the setting circle where it
rubs against the plastic (you will see a wear line of the inside of the
setting circles). Otherwise, you will get bothersome binding when
slewing.

Good luck....let me know how it comes out!

Clay Sherrod
-----Original Message-----
>I'd like to thank you for your ETX tune-up articles, they are very helpful.
>
>I have an ETX 90 - EC.
>
>Regarding adding the wraps of Teflon tape around the trunions, it looks like
>I have to remove the OTA so that I can do this, right?
>
>Thanks again,
>
>Bill

Subject:	Thanks! Re: ETX 90 loose gear assembly??
Sent:	Thursday, March 1, 2001 22:22:45
From:	Bryan
To:	sherrodc@ipa.net (Clay Sherrod)
Thanks for the info!  I appreciate it.   I fixed most of what was
happening.  It was the plastic gear assembly that was messing up.  The
one with the plastic white gears and the drive motor.   What I did was:

Take the whole danmed thing apart.  (I'm a regular mr. fixit  hehe)

Wash and degrease everything.  Though they used so much grease on there
I scraped a bunch off to re-use

The pins in the gears did not sit tightly in the grooves, so I used some
white paper and KwikBond glue to add some extra plastic to the grooves.
(Similar to glassing a surfboard...thats where I got the idea)

The pins were also not installed correctly from the factory.  One side
has a flat spot that fits into a matching flat groove.  One of the pins
was put in backwards.

Put all of the gears back together and greased them liberally.

Noticed the motor was not braced tightly at all, so I used some nylon
washers as braces wedged along each side of the motor.

All this (along with the cleaning/tightening described in your
article; did notice my clutch plate/nut didn't have any metal nubs to
grind off though) got rid of most of the delay in the RA drive system. 
The remaining delay can be taken up with the dec % thing in the new
Autostar software.

The lifting problem is still persisting though.  I put everything down
and went to the garage and installed an exhaust system on my Mustang to
give me time to think about the problem...

The large nut that holds the RA drive system to the rest of the
telescope has a plastic washer that seems to wiggle a bit.  If I tighten
this nut too much the scope is difficult to move.  If its too loose it
seems to lift when the RA drive is activated.

I thought about removing the plastic washer and just using a good amount
of grease instead.  What do you think?


Thanks again for your help and great articles.

-bryan

----- Original Message -----
From: "Clay Sherrod" (sherrodc@ipa.net)
> Bryan - there are two (2) gear assemblies in the RA drive which you might be
> talking about, both of which are causing both problems (the delayed star in
> Azimuth (RA) and the upward motion in ALT (DEC)).  You need to specify WHICH
> gear assembly is moving:
>
> 1)  in the very middle of the inside of the base is a larger, flat "drive
> gear" which is engaged with a cylindrical "worm driver" gear.  This assembly
> has been known to come loose;
>
> 2) the second drive gear assembly is the series of very small white
(nylon)
> relay gears that transfer the motion (and reduce it) from the motor to #1)
> above.
>
> I suspect that, from what you are describing, it is the main gear/clutch
> assembly that is LOOSE from the turntable of the telescope.  Go to Mike's
> TECH TIPS and pull up the "ETX Tune UP" article and then to the "ETX-125EC
> Right Ascension lock Fix."  In the latter post, you will see a photo of the
> drive gear and clutch plate removed from the large shaft that moves the
> scope; it is connected with a 1-1/2" nut and steel shaft.  It sounds like
> that nut is loose on your ETX 90.  Every time you apply torque (push the
> buttons in RA), the turning worm driver "lifts" the drive gear in the
> direction the gears are turning if this nut is loose.
>
> I doubt it is the numerous small gear assembly; but if it is, tell me
> exactly how it moves relative to the large drive gear.
>
> My "Enhancement Guide", Part 1 under the Tech Tips tells about working on
> the clutch plate and the main drive gear.  Getting the clutch plate OFF is
> tricky, but it is described; if the scope is still under warranty, I would
> ask for a new one.  The movement of the main gears can cause a lot of
> unnecessary and premature wear on the entire gear train (not to mention your
> nerves!)
>
> Tightening the three screws indicates that we are talking about the main
> drive system as I suspected.  Those three screws will not affect the
> looseness, except to jam the worm driver too tight against the drive gear
> (hence the grinding).
>
> The uplifting in declination is a "false" impression.  What indeed is
> happening is that the ENTIRE TELESCOPE turntable (which holds and rotates
> the fork arms) is LIFTING as you torque the drive gear.....when the drive
> gear activates and pushes against the drive shaft (that big steel shaft that
> the 1-1/2" nut holds tight), it literally lifts the scope.  What you see is
> what appears to be DECLINATION movement, when in reality it is not.....your
> declination is NOT moving.
>
> You CAN fix this yourself.   But I would NOT use it until it is fixed.  If
> it is not under warranty, certainly try to use the helpful guides I have
> mentioned in conjunction with my "Enhancement" Part 1.  It should step you
> through it completely.  If you do NOT want to try yourself, and if the scope
> is out of warranty, I would be happy to fix it for you but you would, of
> course, have to ship the scope to me via UPS.
>
> Good luck....getting in there and working on it is not as hard as it might
> appear;  THE MAIN CAUTION that I always express to self-helpers on the ETX
> is the WIRING and ELECTRONICS.  They are VERY fragile.
>
> I hope this helps....I know it is not good news, but you have a loose drive
> shaft and it most definitely needs immediate attention!
>
> Let me know if I can help further.
>
> Clay Sherrod
> Arkansas Sky Observatory

Bryan - it sounds like you licked the problem.  Normally these things,
as you have seen CAN be fixed if you are willing to get in there and do
it; you methods sound good, particularly shimming the motor as well as
the reversed pins.  Glad it worked.

Regarding the RA axis and the loose nylon nut.  Leave the nut in, it
smooths out the power transfer in the RA train, making tracking and GO
TO smoother and more efficient. HOWEVER, the RA axis is SUPPOSED TO BE
TIGHT.  That is where the "lifting" is coming from; when you apply
torque in RA (i.e., slew or move) the power is transfer through the path
of least resistence, in this case a loose fitting to lift the scope's
turntable.

Snug down on the nut as I suggested until you have some tightness; most
ETX scopes demonstrate significant resistence in RA when attempting to
move when unclamped; this is pretty much what you WANT.  However, again
do not overtighten.  My ETX 125 is very, very tight, as though my clutch
is engaged all the time; having experience with other clutch mechanisms
in more complex drives, this worried me at first, but now that I
understand the very simple - and effective - clutch design for the ETX,
mine is as tight as can be and works just great.  So, tighten the RA (do
this by trial and error...stop when it begins to tightly bind) until the
nylon washer is snug and DOES NOT MOVE under the leverage of a
screwdriver placed against it.

I hope you did not remove "too" much of the play in the white nylon gear
train; they are supposed to be a bit "relaxed" in their motion so as not
to put accessive torque onto the small driving motor; backlash or
looseness in that assembly usually cannot transfer past the main drive
gear/clutch assembly.

You're off to a good start...keep me posted!

Clay Sherrod

Subject:	ETX 90
Sent:	Thursday, March 1, 2001 06:31:42
From:	spsblw@mail1.hofstra.edu (Barbara Warburton)
Hi: I bought my husband an ETX 90 Meade Telescope for Christmas last
year. We have never operated a telescope before and we are having a
little difficulty with it. We are having problems using the manual that
came with the book. We also have the tripod and the Autostar. We would
like to be able to view things in more detail. I saw the tutorial on
aligning the Autostar. Will this get us started. Are there any basic
easy instructions for us to use so that we can fully learn and enjoy
this telescope. I also bought a blue and yellow filter, a Barlow lens
and also another lens recommended to my by the store where I purchased
it. We have taken the telescope out during the summer months and viewed
the moon. However we did not have the other lenses at that time. We
would really like to view things like the moon, stars etc. in more
detail. Can you give us some pointers on what to begin with first since
we are novices at the telescope.

Thank you,
Barbara Warburton
spsblw@hofstra.edu

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