Last updated: 26 June 2002
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:	New ETX90RA
Sent:	Monday, June 24, 2002 14:42:56
From: (Arik Shafir)
I wanted to give everyone who reads the site a heads-up on a good deal. 
I just got my ETX 90RA from for $186.89.  If you look on the
site now, it says $249, but call them up and tell them you saw the
promotion last week and want the old price (it worked for me).

Unfortunately, the scope arrived with a broken tripod leg and a piece of
debris in the viewfinder.  When I called up Meade they were cool about
just replacing both parts, no questions asked.  Luckily I live about 15
minutes from Meade headquarters in Irvine.  Plus, who wants that 8x21mm
viewfinder anyway?

Thanks for the informative site.


Subject:	Something wrong??
Sent:	Tuesday, June 18, 2002 10:04:32
From: (Frank Lepisko)
Found your site while in the throes of my first scope purchase, in fact
, reviews and information here led me to choose My ETX -90RA. Great site
; Unfortunately I can't say I'm equally as enthusiastic with the RA. In
fact I am severly dissapointed with it.

I was prepared by a couple of months of research and binocular viewing
to not expect hubble-like images.  However;with the supplied 9mm
eyepiece Jupiter appears as a blurred/fuzzy disk ( like a pea held at
arms length) and  colored banding is barely discernable. I try to be
gentle and especially critical with the focus but to no avail.  I tried
some double stars the other night but the stars won't focus to a point
either.  Daytime terrestrial use in bright sunlight proves focus is only
just okay... but contrast is not what I would call razor sharp and

Now with your 1500 mile long screw driver... Could I be experiencing dew
formation or "poor viewing"?  Should I send it to meade for collimation?
 Should I give up and go back to my trusty bino's? Also I notice the ETX
On the sites' home page has an external  90 degree prism added,  is this
the "hot set up"? Thanks for any help or encouragement  you can offer on
this issue. I realize you can't look through my scope (also I haven't
seen any local star-parties to compare other views). Help,

Mike here: Right now Jupiter is very low in the atmosphere and so views of it will suffer from distortion by the Earth's atmosphere. However, you should be able to bring stars to essentially pinpoints when they are near the zenith. You didn't say whether this was a new or used ETX-90RA but see the Telescope Tech Tips page for information on collimation testing using a star or other objects. Try that to see if it needs collimation. You might also want to see the "Telescope Performance" section on the Observational Guides/References page (there is also a star test item there).
Subject:	ETX-90 Depth of Field
Sent:	Sunday, June 16, 2002 19:02:56
I have an ETX-90RA (Well two of them actually). I do not do much
terrestial viewing but recently did and noticed that both scopes are
sensitive to depth of field, ie objects in the background are not as
sharply focused as object in the foreground. I can focus on the
background and the foreground loses focus. I have tried 39X, 49X, 100X,
and 195X powers and can notice it at all powers. At 195X both scopes are
razor sharp, I continue to be amazed at the optics. It is not really an
issue for me, but rather I am wondering if this is a common aspect of
the Maksutov Design. Thank You

Mike here: Well, normally depth of field isn't an issue nor a design consideration with astronomical telescopes due to the distance of objects observed. But, just like with cameras, you could stop down the aperture, but only to a point due to the central obstruction.
Subject:	My ETX
Sent:	Wednesday, June 12, 2002 15:53:52
Hi all, I'm owner of a Meade ETX.
My problem? in the front lens, bonded to the mirror, there's a black
sleeve. On my ETX this bonding is going bad so the sleeve as partially
moved downward form the original position.  Doing that the glue has
contaminated the lens. I'm really angry for that.

Is there anybody that can give a suggestion how to rebond the sleeve? 
At moment I cleaned up the lens form the glue ... let's say that the ETX
works all the same .... BUT!!!

Regards to all
Mario Agus - Italy
p.s. great site
Mike here: Glad you like the Site. Sorry to hear about the baffle problem. The best choice is to return it to Meade but if you want to try to fix it yourself see the three articles on baffle repair on the Telescope Tech Tips page.


I didnt take enough time to look the site entirly amd the answer was
My best regards

Mario - OLbia, Italy

Subject:	gears
Sent:	Wednesday, June 12, 2002 11:18:55
From: (Clay Smith)
like your site, just starting out. have a etx90ec. i used the gear drive
to point it directly overhead to see jupiter, ( a few months ago) and
heard a grinding noise as it pointed straight up. i would think they
would have stops in them to keep them from doing something like this. it
wouldn't move much after that, so i took it apart and there is two small
plastic gears that look alike just different positions and one of them
is missing some teeth. is there anywhere i can get replacements without
sending in to meade. they want a ridiculous amount and they won't sell
the gears to me directly. (it's out of warranty, bought it second hand)
somebody should come up with some hardier gear material or replacements
i just pointed it up. any ideas? have pics of the gears if the parts are
available. thanks in advance.
And from our hardware expert:
From: (Clay Sherrod)
It does sound as if the scope moved past the hard stop and torqued out
until the small gear stripped; it should not have gone over that limit,
but sometimes when moving manually, the scope will keep on going as far
as you try to force it.  I assume that this was NOT a "Go To", but you
had manually slewed to that position.(?)

Meade's policy is just as you state and you nor I , nor any dealer can
buy these parts; the only options you have at this point will be to try
to find a "salvage mount" to retrieve the gears from or send to Meade.

At last report, Meade's charge to fix this - and everything else that
you report when you send it in at one only $75; that would be
a pretty good investment if other work or replacements needed to be
made, and you can request an optical collimation at the same time for no
additional charge.

Best of luck!

Clay Sherrod
And a response:
yes, i manually slewed it. i appreciate your reply. thanks. i guess i
will have to bite the bullet. sounds like a good side business for
someone, make generic replacement parts for meade scopes, high quality
of courese!
thanks again.

Subject:	ETX 90
Sent:	Tuesday, June 11, 2002 23:12:57
I have a ETX 90 Telescope and while I can use it to it's modest uses, I
have trouble getting images like the examples I see on your website.  Do
you use different lenses and eye pieces?  I have a 26mm, 18mm, and 9mm
lenses as well as the Barlow 2x lense.  I have a blue and red filter for
the scope as well.  Any information you can provide would be much
appreciated.  Thank you and have a good night.

Gene Kenney, PN2/USN
Mike here: You have an excellent set of eyepieces. Keep in mind that many of the images you see on the ETX site and elsewhere have been digitally enhanced and may not accurately reflect what the eye sees. Can you be more specific about your problems?


When I look at Jupiter or Saturn I only see a small image, even when I
use the 2x lense.  Also, I can only get a outline of the Crab Nebula (by
Orion).  I have a blue and yellow lense but can't seem to make those
work correctly.
Mike here: You should be able to see cloud bands on Jupiter (even without a filter) and the Rings of Saturn. However, Saturn is essentially gone from viewing now and Jupiter is low in the west at sunset, meaning the views will be distorted by the atmosphere. Many deep sky objects are faint fluzzy blobs in small telescopes. Photos can store up light over long periods of time; that accounts for the difference you see in photos vs your eye.
Subject:	Delay in Dec response
Sent:	Sunday, June 9, 2002 13:37:42
From: (Joseph Rodricks)
I recently  completly disassembled my ETX 90. I cleaned it throughly and
de-greased alot of surfaces that shouldn't be greased. I took apart the
gear box and motor drived units. I have two qaustions. One is simple:
what is the right kidna of grease to use and where do I get it? However
the second question is a little more involved.

I've noticed a considerable delay in the dec drive's response time. This
is not the typical gear lag noticed when changing drive directions. It
seems there is any where from 1/2 to 1 1/2 seconds of delay from when I
push the AustoStar's button and when the motor actually powers up. This
happens reqaurdless of slew speed and only on the Dec drive. I have
taken the fork arm cover off with and without the weight of the OTA. If
I have described the problem correctly then you won't suggest the
Alt/Az. % adjust. (Because, as I know you are aware, that solves a
different, bu simular problem.) By the way, I have tried it, just for
kicks, and it doean't work. I'm not sure if it's a motor problem,
software, or what. My gear box is nice and tight and there is virtually
no compensation needed for the gears to catch up to themselves.

Please send any thoughts or suggestions. Also, I am still looking for
the right grease. Thank you

Joe Rodricks
From: (Clay Sherrod)
If there was "no compensation needed" for backlash then there would not
be any delay; you need to remove the fork arm cover and press a speed,
say "5" and watch each and every gear.  One of the small transfer gears
must be slipping until it reaches a high point on the small axle; at
that point it likely is engaging....once moving it will stay moving
until stopped.

If you press a slew key (which direction, by the way...up or down or
both?") watch each gear.....if all move instantly, then there can be
very little delay.  So, something must be hesitating from bottom to top.

ALSO, on of the most common problems for folks who work on their own
scopes is overtightening EVERYTHING....the gear system MUST have some
slack or you will burn up the motor and strip the gears.

I have seen 2-3 second or longer delays from:

1) worm gear tightened down way too tight and not turning freely as it
should....should spin like a top with the flip of your finger without
the other gears attached at each end;

2) clutch assembly too tight;

3) worm pressed entirely too tightly against the drive gear; this
binding will wear your motor out.

Based on the fact that it worked fine before you did your exploratory,
and the amount of delay,  would say that you clearly have overtightened
one part of this gear train.

Check that first.

Clay Sherrod
Previous to my exploration, the OTA was slipping. Then I remove the fork
arm covering and watch the gear train work (without any weight of OTA-
so clutches are not the problem)  I am able to very specifically
localize the problem. The gear train is properly aligned and greased,
once it starts spinning there is no delay and everything is tight. It's
tight in a good manner, as gears should be, but not overtight. The
problem, I believe, may be the actual motor itself.

On the end of drive shaft (for lack of a better term) that actually
comes out of the motor is a gear that (I assume) is permenantly attached
to motor. It is this that is slow to start. This is true even when there
is no gear train! In the picture below I have painted to the gear which
is slow to react. Remember that once this starts to spin (regaurdless of
the autostart speed setting) the rest of the drive train reacts
instantly. I am so close to perfection I can taste it!

Maybe my Autostar? I've never used another Autostar, though from day 1
it always seemed that I had to bear down on the buttons a little too
much to get things to respond. I wonder if it is, perhaps, that Autostar
itself that it giving the command late. Clay, you once had my autostar,
I doubt you remember but I would think that you would have mentioned to
me if it felt there was something wrong with mine. So I guess I can rule
that out. Thank you.

And this:
From: (Clay Sherrod)
Joe - I think I know what the problem are hearing motor
activity far ahead of actual kinetic response.  What I believe has
happened is that the windings in the small motor are likely going bad
and NOT producing enough magnetic torque when first activated to "get
the ball rolling."  It is requiring the motor to spin and build up
enough kinetic energy to convert to the necessary flux to spin the shaft

In some situations, you could merely add more spunk ("volts") to push
the motor past its present limits but that is not desirable here,
PROVIDED that you are not attempting to run with the AA
are using a reliable power source, right?

Unfortunately you have done yeoman's duty in perfecting this drive
system, but you are to a point that - unless you can find a substitute
motor (and Meade will NOT sell you one!), you may have to accept those
momentary delays.

Best of luck....

Dr. Clay
Thanks. What if..

I get a simular motor and put the same gear on the end of it that is on
it now? With the optical sensors still work right and the Autostar still
know where it is pointing?

From: (Clay Sherrod)
If the motor is the same input voltage and SAME RPM coming out it will
do might have a bit of a problem placing the motor into the
space allowed with the scope however.  Just make sure of the can check by putting a large cardboard disk on the end of
the shaft and timing the revolution of a white dot you paint on its edge
from one point all the way around to the same point again....I actually
have forgotten what the r.p.m. of the tiny Meade motor is...however, you
CAN use the RA motor as a test to determine since they are the identical
motors in both RA and DEC.
What is the proper grease to use when lubricating the gears and all? By
the way... My Meade AC adapter is not putting out what it should... I'm
off to Radioshack to buy another, maybe this is the motors problem...

Joe Rodricks
Joe -by "not what it should...." how much are we talking about?  Indeed,
if the voltage is low, this could very well slow down response time, but
keep the voltage between 12V and 15V for consistent (and safe)

Clay Sherrod
As high as 15? I was thinking 12-13.5. The more the merrier. Mine is
putting out 9.6. I never would have checked if you didn't mention that.
What kind of grease should I use to lube the gears?

White lithium or Mobile 28 Red Avionics grease.
Yes, 15V is optimum for good dependable operation.

And then:
15V, I can do that. Any idea on howmany Amps she pulls ?

After I lube her up and give her the new juice, I'll let you know how
she preforms.

From: (Clay Sherrod)
All you will need will be about 1 amp maximum...that is actually too
much, but it will be fine.  I highly recommend that you put an in-line
fast burn fuse in the line however if you are going to put something

Best of luck!
And from the Autostar expert:
From: (Richard Seymour)
> I've noticed a considerable delay in the dec drive's response time.
> This is not the typical gear lag noticed when changing drive
> directions. It seems there is any where from 1/2 to 1 1/2 seconds of
> delay from when I push the AustoStar's button and when the motor
> actually powers up.

Question: does it happen when you use the small Hand Controller
instead of the Autostar? (assuming you have one)
If it does -not- happen, then it's an Autostar thing, not scope-base.

If it's an Autostar thing, some do exhibit "Slow buttons", caused
by any number of factors (one of mine is dreadfully slow, the other
is snappy).  One of which is dirt between/on the rubber key-backs
and the Autostar's circuit card which senses the presses.
Clean with a dry cloth or Kleenex.

And we're talking ETX90 here, right?  Then you could try swapping
the Dec and RA motor connectors where they plug into the power panel,
and see if the symptom moves to the other axis.
IF it -doesn't- move, it's the DEC unit.
IF it -does- move, again the finger of blame points at the Autostar.
(or the cable.. flakey connectors could delay the motors' understanding
of the pulse sequences)
When you've got the plugs swapped, only the main slew keys will be
useful... any Alignment or GoTos will try to smash the telescope
into the base... test with RA nd Dec clamp loosened.

good luck
And this:
From: (Richard Seymour)
Joseph Rodricks wrote:
> 15V, I can do that. Any idea on howmany Amps she pulls ?

An ETX90 (or at least: mine) only pulls 500 ma or so.
(my 500ma RadShack lump feeds it nicely, measured voltage
remains above 12v)

I would worry that you're seeing the Meade supply only put out 9v.
That -may- mean that something is drawing FAR too much current
and consequently pulling down the Meade power lump's output
(one -benefit- of an unregulated supply is that it won't
move heaven and earth (or burn bridges and circuit traces) 
to keep its output up at the rated level).

It's also possible that the Meade lump (are they passive or switching?)
has lost a rectifier in a bridge, so that you're measuring a half-wave
output, where the meter might be averaging the waveform and giving
an incorrect number (i.e. it -could- be peaking over 12v, but the
 average "DC" value is around 9v)

or: why i like oscilliscopes...

have fun

Subject:	Meade 90-EC Making some weird noises when using the controllers
Sent:	Sunday, June 9, 2002 13:11:37
Great site (Never heard that one before, I'm sure) I looked in the
archives for the solution to this problem but I could find it.

I bought my Meade ETX-90EC just yesterday on the 9th and I'm having a
great time with it but I noticed that while using the controller that
comes with the scope, or with the Autostar 497 controller the telescope
will make some noises while I'm not pressing any buttons on the
controller to move the scope.

It kinds of sounds like the gears are trying to move. It makes this
noises continuously until I turn off the "off" button on the base of the
scope. Other than the noise everything in the scope is working.

Any help on this problem would be greatly apreciated.


Mike Monahan
Mike here: See "One of the drive motors runs continuously but I don't see any movement of the telescope tube. Is something wrong?" on the FAQ page.
Subject:	re: weight?
Sent:	Friday, May 31, 2002 23:26:36
From: (Richard Seymour)
Hi, Joe... long time no read...

> added weight, better tracking and GoTo's...

Ya know?  I wonder if you're seeing three effects:
worn main Dec bearings (so they're sloppy),
a slightly displaced worm drive,
and inertia.

The added weight forces the Dec axles to -stay- down in their
bearing sleeves, and that, in turn, keeps the "big" gear fully
engaged with the worm.  Hence better control of the motion.

Toss in the mechanical damping effect of the added mass
smoothing out the jiggles and jerks of the drive, and you've
probably got it.

(now, of course, i could turn the screw and say: the bearings 
might be so -worn- due to excessive loads... but that'd be mean.)

In my ETX90ec i improved the worm's drive by slipping a small shim
of file folder cardboard behind the worm's cast metal holder, 
which pressed it -ever- so slightly more into the gear teeth.
Slop dropped from 3 degrees to 1.

have fun

Feedback Archives

Check the Feedback Archives for previous editions of the ETX-90RA and ETX-90EC User Feedback pages.

Return to the top of this page.

Go to the ETX Home Page.

Copyright © 2002 Michael L. Weasner /
Submittals Copyright © 2002 by the Submitter