Last updated: 30 April 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:	ETX 90EC Vertical Lock Problems.....
Sent:	Tuesday, April 30, 2002 16:37:34
From: (Ian Young)
My ETX 90EC has just developed a problem - the vertical (or declination)
knob won't tighten and the scope slips and points to the floor. I've
undone the knob and inside there's a brass round type of nut set into
the plastic. The knob screws into this. Unfortunately this nut has lost
it's grip with the surrounding plastic and simply turns when it gets to
almost tight.

I've tried using strong glue to stick the brass bit back but it won't
stick strongly enough to get a firm lock on the scope.

I was wondering if anyone else had this problem with their Meade scope
and how you managed to fix it.


Ian Young.
Mike here: The repair is easy, once you have the part (Right Tube Adapter) from Meade. In the states they will send it out free. Don't know about the UK. To see the repair, look at the bottom of this page:
Subject:	ETX-90EC Dec Worm End Play
Sent:	Sunday, April 28, 2002 20:47:16
Wonderful site!
I have a question regarding an ETX-90EC with Autostar. I hope I'm
following the correct procedure (?)

I bought one on the "first" ETX-90EC telescopes in Jan of 1999, and have
not used it much at all -- (My primary telescope is an 8 inch LX200).

I'm trying to tune it up a bit and get it in good operation for my son
to use (in a different city). The Dec worm gear has end play as
described in some of your archives and in Jordan Blessing's ETX/EC Tune
Up article. However, I am unable to tighten it any further than it
already is. There is still considerable end play -- I'd guess 20 mils or
more. What is one "pushing against" when attempting to tighten the end
nut? It appears the only thing holding the other end is the white
plastic gear beyond the bearing. Is that tight enough and rugged enough
for the nut to "push against?" In my case, I'm guessing the nut is
already at the end of its threads (about 1/8 inch of "open thread" above
the nut), and perhaps whatever the nut works against has slipped a bit
or was never "far enough on."(??)

Can a thin washer be put under the nut to "take up the slack?" As is
(and as it was shipped), the end play results in about 1/4 inch or more
up/down motion at the front end of the OTA -- too much I'm sure.

Fortunately, the RA worm seems tight. By the way, the RA worm gets all
the grease "cleanly rubbed off" in the center -- it's very shiny,
indicating the gear is rubbing very hard in the worm. Regreasing it
doesn't help -- it gets cleaned off and shiny in a few turms. Is this
normal for worm gears, or are they engaging too tightly?

Thanks for any advice?

Art Kotz
Mike here: First off, upgrade the Autostar to the current version from Meade's site (assuming you have the proper cable and OS). The version from 1999 is way old. You may have to put the Autostar into SAFE LOAD as described in the README if it the original version. As to the DEC play, are you seeing this when pushing against the tube by hand rather than when slewing using either handcontroller? Some play is normal; the Autostar attempts to compensate when you TRAIN the drives. And don't overtighten either axis lock; that can cause damage and may be the cause of the wearing you see.


Thanks so much for the quick reply. I'm trying to get it in shape for my
son before I leave it with him at his home in the Wash DC area (I live
in Minnesota and will be leaving in 2 days, so you can see why I really
appreciate the quick replies).

The OTA play is from moving by hand, but it is loose enough that it
gives an "uncomfortable feeling" and the home dec position is pretty
poorly defined. I realize the training should take care of the
"backlash," but it's quite a bit of delay in dec movement.

It's virtually a new scope since it's only been used 3 or 4 times in all
this time -- so little or no wear -- yet. It's been somewhat of a
disapointment due to the lack of rigidity, vibration, etc. (Got spoiled
on the LX200 I guess, even though lots of people "knock" that as well.)
Hope I can get it in reasonable shape since my son enjoys that sort of
thing, but with a new infant child he has little time to fool around
with "mickey mouse" equipment. The 5-planet alignment got us out the
other night, so I decided to leave it with him rather than take it home,
adjust it, and ship it back.

Thank you again for the quick and knowlegeable replies and a GREAT site
-- wish I'd discovered it sooner!

Art Kotz
Mike here: You mentioned that the HOME DEC position is pretty poorly defined. Not certain what you mean by that. In Alt/Az, the tube is horizontal. In Polar mode, it is parallel to the forks. Unless you have checked the DEC setting circle for accuracy don't use it. I just eyeball the HOME position. (If the DEC scale is off, see the FAQ for info on adjusting it.)

And an update:

The nut was indeed at the end of its thread, so I put a THIN brass
washer (1/4 in. hole) below the nut -- and below the original thick
steel washer and original "spring" washer, since the nut is a shoulder
nut as you probably know, requiring a larger hole in the stock washers
to go over the shoulder.

It now works GREAT! I can adjust it for any amount of end play
desireable now,

Thanks again for the site and fun reading.
Art Kotz
And this:
Thanks for the reply.

By "Home dec position poorly defined" I  meant due to the loose dec
worm, the OTA tube could "flop" up and down 1/4 in. to 3/8 in. pretty
much on its own (in Alt- Az OR Polar). That's all moot now since I added
the washer and tightened the worm end clearance -- no more up/down flop.

Thanks again for your kind attention and wonderful site. It is greatly

Art Kotz

Subject:	Daytime usage problem?
Sent:	Sunday, April 28, 2002 12:25:33
From: (Mark Gabrenas)
I have just purchased a used ETX 90EC. The unit showed up well packed in
the original Meade boxes, plus other boxes and packing around these. It
is in cosmetically great shape, I can't see any scratches or damage on
the scope or the lens/mirror. When I try to focus on objects more than
about 1/2 mile away, I can't seem to get a good, sharp image. Anything
closer than this reveals a great image. I took it out during the day to
check (most celestial objects I can think of are more than 1/2 mile
away!) and it seems to be consistent. I am using the standard 26mm
eyepiece, which also seems to be in great shape. Any ideas what might be
wrong? It is a great unit and otherwise performs much better than the
ETX60 I upgraded from.

And although you hear it all the time, great site. Without the advice of
you and all your readers, I don't think I would have ever got the
alignment of the Autostar down.

Mark Gabrenas
Apple Service Manager
Apple Certified Technical Coordinator
Elkco Corporation
Mike here: Since it has been raining (according to your AstroMac posting) I assume you have not actually used it on the Moon, stars, or planets. I suspect you may be seeing the results of turbulence near the ground due to various heat sources and other junk in the air. Let me know when you have a chance to view the night sky through the ETX.


Actually, I did have one good night where I was able to look at the
moon, Jupiter and Saturn (I had a long day, but got the scope that night
and had to try it). I was able to see both Jupiter and Saturn easily,
but found it very difficult to focus on them. The moon focused fairly
well. I plan on trying again the next good night I get and I will let
you know.

End of 30 April update

Subject:	Re: ETX 90EC/Autostar problems
Sent:	Thursday, April 25, 2002 13:35:07
Hey, Mike, thanks so much for such a rapid reply. Here's us with all
sorts of planets on show and no alt movement on my scope!

Yup, I checked the batteries straight away, no change. I am a
long-in-the-tooth radio maintenance engineer, used to fault finding on
all sorts of modular equipment, from old valve radars to present day
digital phone switches, which is why I got that sinking feeling when
this problem came up. Since the Autostar gets it's power from the scope
on switch-on, I figure that when I plugged it in, something in the
Autostar blew on power-up, and that then blew something in the scope

If I plug in the Autostar now, it is totally blank, with no response to
any keys. If I plug in the regular controller, I get az movement but no
response to the two alt keys. (though when I first power it on, I get
the flashing LEDs, and if I press an alt key, although the scope doesn't
move in the alt plane, it does complete the initialisation, and leave
the  #1 LED lit) This further confirms to me that the scope electronics
are blown in some way.

I've since discovered that the scope is still in warranty, having found
a receipt for 1st July last year, so I'm about to e-mail Meade in the
U.S. to see what can be done. My friendly UK Meade importers won't
support Meades bought overseas, (without payment), which I thought was a
bit mean, but that's international businesses for you!

Thanks again for your comments, hope you have clear skies for the
planets, we saw Mercury, Venus, Mars Saturn and Jupiter all lined up on
Tuesday nite as we came out of the pub. Course, it could have been the

Cheers, Geoff Honeyands, somewhere slightly south of Oxford.
Mike here: Yep, you may be right that something is fried. (By the way, Meade has no customer support email address.)


Talked to Meade US (we have cheapcheap phone access to US!), and I'm
sending them the Autostar, which dont weigh too much, and I've asked
them if they'd supply the two PCBs in the ETX for me to replace. Should
be interesting, but then the Customer Support page on their website does
say they will go the extra mile to keep the customer happy! I'll keep
you posted, thanks for your interest,
Geoff H.

Subject:	re: ETX90EC Image Vibration Problem
Sent:	Wednesday, April 24, 2002 21:41:08
From: (Richard Seymour)
> I think the problem is due to the motor drive as
> looking through the eyepiece, the image constantly alternates between
> sharply defined images and a vibration-induced blurr over a cyclic
> period of a few seconds.  This period conicides with the alternating
>  pulse/quiet/pulse sound from the altitude drive.

The only time i have met that symptom (how many is a "few seconds"?)
was with a 4504 telescope... every 13 seconds it would "click" during
sidereal tracking... it turned out to be a -slightly- loose motor,
being pushed out of gear engagement for only one tooth of a middle stage.

> I have however no problem with the tracking or GOTO performance of the scope

The "hopping tooth" -did- affect accuracy, but not by much... when the 
scope was moving quickly it didn't jump as much.  It was mainly detected
by hearing it, and -feeling- the motor box "snap" slightly as the motor
moved -back- into position.

Shimming the motor retainer would have fixed it.  But the owner had a
replacement motor box from Meade, and that -truly- fixed it.

So -closely- investigate how well the motor (or other parts) are being
held in place... you may also have a slight amount of dirt (or hair,
or a burr) hiding somewhere.

If you can -watch- the motors and gears move under power, you might see
one gear which spins once in the same time span as the sound.

YOu could also choose Terrestrial mode, and try moving the Dec/Alt motor
at the slowest speed with the Autostar.  Listen for the sound, and try
to stop -when- it happens.  Turn off power, and disassemble to see what
position the mechanisms are in.  This could be very tedious to track....

good luck
From: (acc)
Hi guys
Thanks for your wonderful support.  I have partially disassembled the
fork and observed the drive train while it is powered by Autostar.  The
vibration originates entirely from the motor!  It is more of a pulsing
from the motor as it is being driven by the Autostar in astro mode. 
Turning the motor (carefully!) by hand reveals no problem from the
gears.  Also, the pulsing is especially observable at the slower speeds
but none at all at speed 9.

I know pulsing is a standard way to get slow speed control from a motor
but the problem is that this pulsing is sufficient to cause image
blurring on my scope.  (My mount is sturdy and shld not be the cause of
the problem.)  Wonder if Dick knows of any previous Autostar versions
which pulses the motor more gently... :p  I'm using ver 2.1ek.  Maybe I
will switch to a Ver 1.3 and see if the problem persists.  Or could it
be that my fork is 'too flexible'?  :)

And i found that I cannot mount the scope in Polar mode to get round the
problem as this would mean missing out a good portion of the southern
sky as I'm near the equator.  Sigh.  :)


Mike here: I would suggest upgrading to the current version on Meade's site.


From: (Richard Seymour)
CC: (Mike Weasner)
>  Wonder if Dick knows of any previous Autostar versions which pulses the
>  motor more gently... :p  I'm using ver 2.1ek.  Maybe I will switch to a
> Ver 1.3 and see if the problem persists.  Or could it be that my fork is
> 'too flexible'?  :)

My fork is flexible, too... i'm trying to remember -back- to 21eK,
and i don't remember extra vibrations.
There have been quite a few updates since then. At least nine.

The motor itself could be the problem... a dirty/worn commutator
could make one portion of its rotation under-powered compared to
the rest.  Unplug the motor (or are they soldered? i forget)
and check the resistance while you slowly manually turn it...
you should see the interruptions as the brushes pass across the
gap between segments, followed by the more-or-less equal values
as the brushes rest firmly on the segments.  If one portion is
significantly higher or lower resistance than the others, that
could be the problem.  Be aware that a DC motor acts as a generator
when manually turned, and don't blow out your ohmmeter by spinning 
too quickly.  A few trips around with a voltmeter before using
the ohmmeter would also show changes in load/output. 

Metal shavings or dirt caught inside the motor so that
they interfere with rotation at one spot (but you would probably 
have felt that during manual turning).  Even a slightly worn motor
shaft bearing, allowing the rotor to shift a -tiny- bit at one 
point (and, other than a general "looseness", i don't think you 
could feel that.

If feasible, i'd recommend moving -forward-, not back (although 1.3 was
a fairly nice version)... the current version is 24Ea.  
You will also require the new Updater program to install it.
(and the new Updater is -much,much- nicer than the old Updater)

available at:
Perhpas a call/fax to Meade to get a new motor? (i don't know if
they will supply a motor in isolation... perhaps contacting
(via Mike's site?) anyone who has a dead circuit card in a
DS- motor kit... you could extract the motor. (i do NOT know if
they're the same)

good luck

End of 27 April update

Subject:	ETX90EC Image Vibration Problem
Sent:	Tuesday, April 23, 2002 4:55:01
From: (ACC)
I have been using the 90EC and autostar for more than a year now and
have been happy with it until recently when it started to give me

I notice that my altitude drive produce a very slight vibration that
causes noticeable image blurring even at a low magnification of 50x.  I
know that the altitude drive is the culprit as stopping the motor
temporarily will get the image back into sharp focus.  I have opened up
the fork but the gears seem to be OK.  The vibrations seem to be caused
by the pulses from the motor as it is driven by the autostar.  The noise
from the motor is easily audible even during tracking.  I'm residing in
Singapore so sending the scope back to MEADE doesn't seem like a good
option.  Does anyone know a solution to this frustrating problem?  Now,
to get a sharp image, I  have to 'trick' the scope by doing a
synchronisation so that the motor is stopped.  Not a very nice way of
observing that's for sure :-)


p/s: thanks Weasner for your site which is a wonderful resource for all ETX owners.
Mike here: You can try moving the scope up and down manually (not using the controller). Do this with the axis lock UNLOCKED. If you don't feel any "grabbing" then there is probably nothing catching the telescope as it moves. Next step, do a RESET, RECALIBRATE, and reTRAIN on the Autostar. That may improve things. If you still have the problem, let me know. You could also try mounting in Polar mode (which removes the altitude drive from the tracking process).


I have verified that nothing is catching the scope as it moves. Doing a
complete reset-calibarate-retrain has not helped either.

The 'vibration' can be felt as a very slight pulsing of the OTA if I put
my hand against it.  I think the problem is due to the motor drive as
looking through the eyepiece, the image constantly alternates between
sharply defined images and a vibration-induced blurr over a cyclic
period of a few seconds.  This period conicides with the alternating
pulse/quiet/pulse sound from the altitude drive.  (I have however no
problem with the tracking or GOTO performance of the scope).

Yup, mounting in polar mode is a good get-around.  Thanks for the
suggestion.  But I would have to beef-up my scope mount as being juz 1
degree north of the equator makes for a very unstable 90EC in polar mode

Mike here: OK, lets try a couple more things. Move the telescope around both the horizontal and vertical axis several times, back and forth (hard stop to hard stop). That may help distribute the grease and provide reduced vibration. Also, you didn't mention the type of mounting you are using. Could you have over or undertightened the bolts holding it to the tripod? Did you change the mounting recently?
End of 24 April update

Subject:	ETX 90EC/Autostar problems
Sent:	Sunday, April 21, 2002 10:04:01
Hey, guys, a question from sunny England, tho' I have a nasty feeling I
already know the answer.

I bought a 90EC and Autostar last year in March, when I was over staying
with friends in Pensacola. The combination has worked fine since then,
but for about the last 2 months I have been just using the supplied
electronic controller, not the Autostar. So, last night, I figured it
was time to hook up the Autostar and use the scope in anger. I switch
the ETX on, with Autostar connected, and get no display, and no reaction
to any button presses. The backlight to the display is on, but that's
it. Bigggest problem is that when I remove Autostar and refit the
Electronic Controller, I have no responses to up/down commands. I've
tried unplugs and replugs, all with power off, but still Autostar
remains blank, and still I have no up/down reaction on the EC. The EC
reacts normally when you switch on, but the won't up/down. In addition,
pressing either of the Az buttons gives about a 4 second slew (but only
the once!). So my ETX is poorly. I'm pretty sure some of the electronics
have blown, but just in case you guys have seen something like this
before, I figured I'd ask.

Any advice appreciated! 
Cheers, Geoff Honeyands
Mike here: Well, the obvious question: have you installed fresh batteries or tried a proper AC adapter?
End of 21 April update

Subject:	ETX/RA problem
Sent:	Wednesday, April 17, 2002 6:23:02
From: (The Design Fort DTP)
I love your website! Thank you for a great page like this.
I have a problem with my 90 ETX/RA. The drive doesn't work anymore. I
took it apart and found out, that the motor itself is still running, but
the "Gearbox" with the little plastic gears has looked up. All my
attempts to free them failed. It seems that I can't open up the gearbox
since it is riveted together. I think I have to replace the part. Do you
know where I could get this part, or is it part of a bigger replacement?
Maybe you have one?

Any help would be appreciated.

Thanks for your time.

Annapolis Royal, Nova Scotia, Canada
And this:
From: (Clay Sherrod)
Unfortunately the motor and gearbox assembly is one in the same and you
much replace the entire unit.  Although there are many ETX RA scopes out
there, I very rarely see any for spare parts and this item is NOT
something that typically gives any problem at all....the best solution
is to contact Meade and see if they can arrange to send you the entire
assembly since you are in Canada and shipping the scope may not be
practical....otherwise they likely will ask you to send it on in!

Of all the spare parts I keep on hand from salvaged scopes, this is one
I have not seen lately!  Sorry!

Clay Sherrod

Subject:	etx-90 question
Sent:	Tuesday, April 16, 2002 14:03:52
From: (Grellas)
I just purchased an etx-90ec.  I took it out the first night and saw a
few planets. Unfortunately - they were really small and hard to see in
the 26mm.  Do I need to purchase other eyepieces to be able to see
things well with this scope or are there objects I can view comfortably
with the 26mm?

Maybe I should just buy your book. :-)  Thanks.

Mike here: There are many objects that will appear nice in the 26mm. But increasing the magnification will enlarge objects like planets and the Moon and allow you to (perhaps) see more details. Adding the #126 2X Barlow Lens is a good starting point or some other short focal eyepiece. Keep in mind the maximum magnification formula (see the FAQ page if you are unsure). See the Buyer/New User Tips page and the Accessory Reviews - Eyepieces page for more on eyepieces.
End of 17 April update

Subject:	Conversion of ETX
Sent:	Thursday, April 11, 2002 12:39:30
From: (Hostetter, Stan)
Mr. Weasner, I just received a copy of your book Using the Meade ETX and
would like to know something. It never fails with me, and I'm sure
others have had this happen too, but it couldn't have been much over 6
months when Meade came out with the new ETX-90EC. Of course I had just
purchased the ETX-90RA.  What I would like to know is can the 90RA be
converted to the 90EX by the Meade Corporation?  I look forward to your
reading your book and if you could help out with my question it would be

Thank You,
Mr. Stan Hostetter
Fishers, In.     or
Mike here: See the FAQ page for info on the non-existent upgrade from the -90RA model.

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