Last updated: 30 June 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:	your declination
Sent:	Thursday, June 28, 2001 3:55:54
From:	sherrodc@ipa.net (Clay Sherrod)
To:	mbailey@mail.northcoast.com
Mark - your problem, based on the description and photo is that the
brass fitting has completely stripped out of the RTA unit, thereby
preventing proper engagement of the gear/clutch assembly.  This is a
frequent problem and is caused by overtightening the telescope in DEC. 
If in the future it slips on you, you should attempt to clear some of
the grease out from between the clutch and the main drive gear that you
show attached in your photo.

I think Meade would be happy to replace the RTA as Mike suggested, but
if you overclamp it, the same thing will happen again.

Best of luck to you!

Clay Sherrod
From:	rseymour@wolfenet.com (richard seymour)
Clay can answer this far better than i can (it's been over 6 months
since i was last that deep into the gearing...), but isn't
the slipping gear the very gear that is grabbed by the clutch?
So if you have disassembled it, yes, it spins freely.
When you clamp the clamp, the plastic parts grab the faces of
the gear and thereby couple it (hopefully) tightly to the barrel-
carrying arm.

One fix -many- people do is to *clean* the gear and the clamping
faces of all the excess grease that gets there... once more
turning the clamping surfaces into friction surfaces instead of
slippy faces.

You might give it a shot...
Also check out the ETX tune-ups which is a link from Mike's
Telescope Tech Info page.

Subject:	ETX-90ec dec movement(or lack thereof)
Sent:	Tuesday, June 26, 2001 10:25:51
From:	mbailey@mail.northcoast.com (m bailey)
Great site you've got!

I have had numerous problems with my etx90ec. I have owned it for a
couple of years and have used it only about 6 times. Each time I have
encountered frustrating problems. I have a pretty good grounding in
telescope operations of numerous types as well as many other technical
devices so I'm sure that my prblems are not simply mechanical

My latest problem is that the dec(alt) motor whurrs away but the scope
won't budge with either conroller (stock and autostar). The right tube
adapter broke earlier and I replaced it. All seemed well (except for the
fact that I had to replace a key component after virtually no use). But
this last time I got first intermitent, then no slewing in the alt axis.
Lots of noise, no movement. With a hand nudge I could get it to move
down but not up--motor whining the entire time--using either controller.

I partially disassembled the scope to reexamine the right tube adapter
area. The worm gear definitely moves in both directions by hand
controller. Examining the right tube adapter piece (with the gear on it
that fits into the worm gear) I found that this gear freely moves in
either direction on its plastic mounting (see attached jpg for
reference). Is this normal? It seems to be the problem. I should think
that the gear that fits into the worm gear must be securely fixed or the
worm gear vcannot possibly drive the alt of the scope. What is the fix?

Thanks a lot for your help.

Mark Bailey
Kneeland, CA
Mike here: Since the RTA has to move, the gear has to be fixed on the RTA, otherwise the RTA (and therefore the telescope) will not move in altitude (or Declination). I suspect that something is stripped on the RTA. You could ask for another one from Meade.

Subject:	ETX90 EC Stripped Screws
Sent:	Monday, June 18, 2001 20:46:44
From:	darkskies30@hotmail.com (John West)
I just got a new ETX90 EC.  As most say, optically it's excellent.  But
I've had all kinds of problems in mechanics, especially slewing.

I'm willing to do some adjustments myself, so I searched your excellent
site and followed suggestions from Jordan Blessing and Dr. Clay.  I got
rid of my AZ slop by tightening the nut on the worm gear as suggested. 
And I got my ALT clutch tightened up very nice by getting rid of the
excess grease.

But I still have slop (looseness) in ALT.  It's maybe 1/4" movement, but
it's bad because the movement easily moves objects out of the FOV.

Jordan mentioned he had a stripped screw (1 of 3) in his AZ worm gear
mounting.  I have one too (I never forced it), but at least my AZ
movement is still OK.  I also have at least one stripped screw on the
ALT worm gear mounting.  One was obviously stripped, it turned and
turned with no pressure.  The other seems to be close to being stripped,
but I don't want to keep turning it to find out.

Anyway, the ALT slop I have is due to the ALT worm gear not being held
in place tight enough.  It moves up and down a bit.

Has anyone figured out a way to fix the stripped screws on the worm gear
mounts?  Or, has any other fix been suggested?

I'd hate to send it back to Meade.  I doubt they'd fix it unless I tell
them the exact problem.  Then they would probably think I dug too deep
into the scope and caused the problem myself.

Thanks for any suggestions,

Mike here: When does the 1/4" of Alt movement occur? During slewing or tracking? If you are grabbing the tube and trying to move it by hand, this movement is not that abnormal. Yes, it would be nice if it were tighter but under normal conditions you should not be moving the tube by hand with the locks engaged.


The Alt movement occurs if I lightly bump the scope while viewing
through the eyepiece or focusing.  I know a solid bump will throw off
most any scope, but this is just a light touch, just slightly more than
the lightest touch I can do while focusing.  Items in FOV with the 26mm
eyepiece jump out of FOV.  When I had the arm open, I noticed the worm
gear mount was moving a bit as I pressed the OTA up/down.  I'd like to
tighten it, but don't think I can due to the stripped and partially
stripped screw holding the mount in place.  Slewing in ALT seems OK,
although as I slew up/down during training, I get some slight AZ
movement too (I can't exactly recenter the object with just the up or
down arrow).  I haven't been able to test GoTo yet due to lack of clear

If this is normal, I suppose I could live with it.  But the movement of
the worm gear mount concerns me.  I'm pretty sure if I eliminate it, the
free ALT movement will be greatly reduced.  When I read the tune-up
article on Jordan Blessing's site, he had a stripped screw too.  So I
thought this might be a common problem but I couldn't find any mention
of it on your site so maybe it's not so common after all.  This was a
brand new scope in a sealed box and I was surprised that 2 or 3 of the 6
mounting screws for the worm gears were stripped.

Thanks for the reply Mike!
Mike here: Well, you can use the info on the Telescope Tech Tips page on DEC or Alt axis fixes or the info from the Scopetronix site to possibly improve the hold. It does sound as though there is a problem that should be corrected by someone (you, Dr Sherrod, or Meade).

Subject:	Autostar
Sent:	Monday, June 18, 2001 13:52:06
From:	golfing18@msn.com (Michael Knapp)
I had my first real chance to use my new 90EC this past Saturday and
luckily the skies were crystal clear and dark. The Milky Way was just
jumping out. I thought I might share with everyone my first impressions
of the scope and also run a problem by you.

My father-in-law and I spent some of the daylight hours resetting the
Autostar (purchased used) and training the drives (on a cellular tower 4
miles off in the distance). Once darkness finally settled in across
Central Illinois he set up his 10X70 binocs and I set up my scope. With
home position and 2 star alignment successful I keyed in my first
target, M13. To my delight and surprise, Autostar placed it well within
the finder scopes view and with a little tweaking it was in my zoom
eyepiece view. Spectacular! My f-i-l quickly and easily found it in his
binos and it was actually visible with the naked eye. We continued
"goto"ing for a while and decided on Mars as a target. Autostar missed
it completely...not even in the finder scope. I've read posts about this
and I'm not sure I quite understand why it missed, but, it's pretty easy
to find manually. The best eyepiece I have right now is the Meade
6mm...not enough power to see detail...so Mars was less than impressive.
(doubler lens was on order but did not arrive in time...too bad!) On to
M7..cool. While deciding on my next target, Autostar did something that
leads to my question. Autostar engaged the gears and slewed the scope a
bit. I did nothing to cause it to move! My next target was M3 near
Arturus. Missed it by about a fist width...so I went to Arcturus as a
check...again missed by a fist width. I used the "sync" function to
center Arcturus and it then found M3 without a problem. Of course this
ruined the alignment for the rest of the sky. Any idea what might have
happened to cause it to move???? Maybe a glitch in the software

Overall I give the scope and Autostar an A++. The quality of the optics
and the accuracy of the Autostar are impressive. Bravo Meade. A tip for
others...a black piece of construction paper and a rubber band make a
fine dew shield. He had dew on his binocs and I had none the whole
evening (3+ hours). Also, we found it enjoyable NOT to just use the
"go-to". Instead, he would search and find something of interest with
the binocs, I would then slew over and find it with the scope. We would
then determine with a star chart what we think it might be and then use
the "info" option of the Autostar to see if we were right. I found
myself remembering constellations, stars, names and locations this way.
I probably would not remember by just "goto"ing. IMHO! Thank you for the
advise on "Turn Left at Orion". It was most helpful and right at my side
the entire evening. Looking forward to the next clear night!!
Mike here: Glad you had a great time. I suggest you upgrade to 2.2Eh (if you can). The slew problem you had will likely go away and the planets should GOTO properly.

Subject:	ETX 90 damage DEC lock
Sent:	Sunday, June 17, 2001 11:45:06
From:	ccsr@rtarling.fsnet.co.uk (rtarling)
Great site and keep up the good work!

I wonder if you can help, I purchased an ETX 90 in Canada some 2 years
ago however I recently managed to drop the case it was in and the
Declination lock now does not work.

Having taken it apart to work out the fault , it appears that the
plastic centre piece has broken, poor design it seems to me...

I have tried to re glue it etc however this has failed , could you
please advise me the best route to obtain a complete new plastic
assembly from Meade as I do not want to send the complete telescope back
to the USA from England.

I as sure other people might have had this part break or need to aware
of this weakness.

Do think I can obtain this item locally in ther UK ??


Mike here: This was a common failure in older ETX-90EC models. See my comments at the end of my initial ETX-90EC report. The part is free (at least in the United States) from Meade. If you want to try a repair yourself, see the various ETX-90EC Dec lock mods/fixes on the Telescope Tech Tips page.


Thanks your responce is excellent and is the exact fault with my scope,
I will write to Meade as yet do not have an E mail site ! and send for
some spare parts.

I will pass on your site to other ETX users in the UK.

Subject:	Flares and things
Sent:	Friday, June 8, 2001 12:26:27
From:	dad@headplant.freeserve.co.uk (Damian Davis)
Thanks for the link to Doc Greiner's site. What I was thinking of doing
was painting the inside of the baffle tube with matt black paint. I can
get at this by flipping the mirror down, and removing the rear cell
cover. Your advice of blocking the hole at the front, and the two
threaded screw holes underneath went about 50% of the way to curing the
problem. Incidentally, to block the screw holes, the sticky-on rubber
feet off the base do a fine job.

On anothe tack, does anybody know for sure whether the Meade 8-24 zoom
EP and the TeleVue 8-24 zoom EP are badge-engineered versions of the
same item? I ask because in the UK, the Meade version costs about
$375!!, but Meade will not allow US dealers to export Meade kit (anti
trust??), but no such restrictions apply to TeleVue parts.

Until the skies clear 
Damian Davis  London

Subject:	Follow UP to postallad@hotmail.com regarding ETX zoom/barlow combo
Sent:	Thursday, June 7, 2001 17:48:53
From:	tims@charter.net (Tim Sheets)
To ad a bit more to Mike's, quite accurate response, let me explain why
he suggests you might not get good views with the barlow/zoom combo.

As you increase power, by decreasing the size of the eyepiece, you also
decrease the brightness and quality of the image.  A smaller, but
brighter, and better defined image is always superior to a large, dim,
fuzzy one.

The standard suggested varies from 40 to 75 times the aperature of the
scope in inches.  I normally use 50 as the factor.   The ETX 90's
objective aperature is just over 3.5".  This would suggest that the
maximum "usable" magnification on an ETX would be about 175x.   I have
used my ETX at 250x looking at the Moon, but the image was quite poor.
Meade suggests the maximum practical magnification at 325x, but I think
that is good old marketing exageration.  And don't forget, ALL of these
values assume "good seeing" (aka, very little atmospheric turbulence to
further degrade the image).

So, assuming that 175x is as high as you would want to go, the smallest
usable eyepiece focal length would be about 7mm  (1250mm telescope focal
length/175=7mm eyepiece focal length), and you are right next to that
with the zoom.

I agree with Mike, spend the money on other accessories.  If you like
the moon and the planets, eyepiece filters are great, and will cost
about the same as the Barlow.

Subject:	ETX-90 RA
Sent:	Thursday, June 7, 2001 17:11:04
From:	stocknut@worldnet.att.net (Robert Honeycutt)
I have seen these scopes for a very good price and wonder what you think
of them for a first telescope.  I know they do not have the go to
capability of the EC series but I believe the optical tube is the same.
I am also wondering how the slow motion controls work..I cannot tell
from the Meade catalog. I assume that this will only AUTOMATICALLY work
in polar mode only but are both axis controlled by a drive? I also
assume that a wedge on a tripod would be necessary to use this feature.

I am looking for a small portable telescope that I can carry onto the
back of my remote farm in E TN where it is VERY dark. I think that this
would fit the bill and at $225 I dont see how I can go wrong. I also
would like to take some still wildlife pictures and I think this would
be great for that although I am not sure about moving the optical
tube..whether or not it has slo mo capabiities. Thanks for a GREAT
Mike here: Certainly the ETX-90RA makes a fine telescope. Afterall, that is what started this Site almost five years ago! You are correct that in Polar mode the single drive turns the Right Ascension axis to compensate for the Earth's rotation. The ETX-90RA includes tabletop legs so any stable flat surface can be used from your location. Alternatively you can mount it on a sturdy tripod that can have the head tilted to match your latitude (or use a wedge). The manual movement in either axis is manual although there are (were, at any rate) add-ons from JMI and Scopetronix that can drive the telescope in both axes. You will find these reviewed on the Accessories - Miscellaneous and Showcase Products pages.


I have one more question about the ETX 90 RA. Is deep sky photography
possible using only the polar alignment capabilities of this telescope?
Mike here: The ETX-90RA really isn't suited to deep sky astrophotography. You can do some things however (as seen on the Astrophotography Galleries on my ETX Site).

Subject:	2x barlow
Sent:	Sunday, June 3, 2001 23:02:36
From:	postallad@hotmail.com (Robert Way)
You have a great site. I have a  ETX 90 EC , and bought a Meade
4000 8mm-24mm zoom eyepiece, and love it. I would like to buy a 2x
barlow lens for it, if it will work with the zoom lens. I'm considering
either the meade #126 short barlow lens or the meade #140 apochromatic
2x lens. If either one will work with the zoom lens, which would you
buy, if price doesn't matter. Thanks in advance, and keep up the great
site going.
Mike here: Optically, I don't know if you would be able to focus with that combination. I'll leave that answer to someone who has both. But why do you want to double the zoom eyepiece? At one end, you'd have the equivalent of a 4mm eyepiece, which would likely not provide very good views with the ETX-90EC. At the other end, you'd have a 12mm, which is within the range of the zoom. So, why spend the money for this accessory?

Subject:	Baffles and Flares
Sent:	Sunday, June 3, 2001 6:55:02
From:	dad@headplant.freeserve.co.uk (Damian Davis)
I was using my ETX90EC as a terrestrial scope the other day, (looking at
the blue tit chicks in the nest box), and there was a pronounced
milkiness to the image. It was definitly due to light scatter, as moving
a piece of card around the OTA changed/prevented it. The sun was about
90 degrees off axis. I renoved the eyepiece (the supplied 26mm) and
looked down the hole. What surprised me was that the long thin baffle
tube that projects forward from the main mirror was shiny on the inside,
and I mean shiny enough to be able to make out what the scope is
pointing at in the reflection! Is this normal? If not, then please tell
me to leave it alone for fear of ruining it!
Damian Davis 
Mike here: There is a hole on the bottom of the ETX OTA where a tripod can be mounted. This hole is a source of light entering the tube, especially during the day. This could be part of what you were seeing. As to the baffle itself, you can't easily change it but if you want to try see the photos on Doc Greiner's ETX Info page (linked near the bottom of the Telescope Tech Tips page on my ETX site).

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