Last updated: 31 May 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:	weight?
Sent:	Thursday, May 30, 2002 11:25:20
From: (Joseph Rodricks)
It's been cloudy here for days. Thought it's sunny now, but I'm busy
moving 10 tons of stone-dust to my father's bocce court with a
wheel-barrow. Any way, because it's been cloudy I've been thinking. I
know my little ETX-90 can take a bit of piggy-back weight. I've had
webcams and SLRs on it. I also know how important it is to balance the
weight evenly, no matter how little it is. I have a few questions I was
hoping you could answer.

How much does the ETX-90 OTA weigh? How much weight can I safly put on
the OTA w/o damaging the drive unit, which I know is very fragile? If I
remove the OTA, and replace it with something else (perhaps a larger
aperature OTA) how much can the total weight w/o damaging the drive

By damaging them, I mean putting too much stress on them to have them
work, or actually damaging them.

By the way, I know this is odd, but it works for me, so I do it. I had
the common problem of clutch slippage. So I did the whole
de-lubricating, and added the washers and all of Mr.Blessing's and Mr.
Sherrod's suggestions. IT worked wonders, except my OTA's motion was a
little sloppy. I didn't want to ever-tighten the clutch so I didn't know
what to do. I went out CDDing (with a webcam) one night and accepted
that I'd have to do a bit more adjusting then normally. However, with
the added (balanced) weight of the webcam, the scope's goto was 10-fold
better and the tracking was 100-fold better. I can life with not
acurrate GOTOing but I really enjoy acurate tracking. Ever since then I
add weight to my OTA and it's perfect. Just thought I'd mention that.

Thanks for any help you can give.

Joe Rodricks
Mike here: I'm not certain how much just the OTA weighs. I have mounted a ETX-90 OTA piggyback on another ETX-90 ( Unfortunately, there was slippage in the locks. I know people have hung some pretty substantial cameras on their ETXes, with and without a counterweight. The damage won't come from the weight (unless the OTA slips and strikes something) but rather from overtightening the locks in an attempt to avoid the slippage.
Subject:	New prices on ETX's with UHTC!
Sent:	Thursday, May 30, 2002 9:48:16
From: (Theresa Parker)
I am and have been an enthusiastic astronomy novice since I received a
department store newtonian reflector for christmas as a child. Now, at
age 35, I recently decided to take up the hobby in a serious fashion.
For me this means educating my self extensivley in several areas. I am
still in process of doing this as I write. I hope for some clear days
here soon so I can take a star chart and my Nikon 10x50 binoculars out
to view and learn the sky. I have used the webs extensive resources to
educate myself on telescopes. From my experience as a child with my
cheap newtonian reflector I learned the value of good optics. I know
many people here complain about the machanical faults of the ETX'S but
there is no substitute for superior optics.Beside's there are plenty of
tips on your website that fully correct any mechainical shortcomings. So
newly armed with my knowledge of telescopes (partly aquired from your
site :>), I decided I would purchase The meade ETX-90ec. Shopping on the
internet I found the average price to be around $495.00 U.S.. Imagine my
happy suprise when I found one for sale in the Ritz Camera store in our
local mall for $499.0! The idea of actually talking to a person to help
me if I had any problems with the scope swayed me to make the purchase
from Ritz Camera. Initially, The advertised add-on UHTC could be
requested as add on from the factory for around $300 I believe. To be
honest, The effective increase of 1/3" aperture was alluring . But the
dollar per millimeter aperture ruled this out for me. So I went and made
my purchase. So far I have only gotten some good views of the moon, But
what good views they are! I haven't yet accessorized and I have been
shoping the internet today tolook for deals. Imagine my horror when I
visit and find that they have brand new ETX-90-ec's 
with the UHTC(Ultra High Transmission Coating) for only $545 plus $20
shipping bringing the total cost to only $565! I had just paid $534
total for my ETX-90-ec! So for only $30 more I could of had The UHTC!
&^%$#@%*)! After I calmed down I remembered that I had bought my scope
at an actual store. So I dug out  the receipt and read it. I was in
luck, I was still within the stores 10-day return limit. As I write I
have already returned my scope for a full refund and will be ordering
the a brand new ETX-90-ec with the UHTC from astronomics. After I
receive the new ETX (plus accessories :>)I will do some moon views with
the standard 26-mm eypiece. I will email you afterwards and let you know
if I can notice the difference the UHTC makes.

You have an AWSOME site! Thank you for all your dilligence.


P.S. Any one In the Gainesville FL area can probably find a barely used,
discounted ETX-90-ec at the ritz camera store in the Oaks mall :> .

Subject:	Just beginning
Sent:	Tuesday, May 28, 2002 8:05:53
From: (joel cortes)
I am just starting on this exciting hobby, after I have got an ETX-90RA.
This telescope count with a 26 mm eye piece and a #126 2x Barlow, nice
to watch the moon but this is not enough to get a nice seeing of Jupiter
and its moons (they appear too small). Please can you advice me
which other eye piece would give me a much better observation of the

Thanks in advance
Mike here: See the Accessory Reviews - Eyepieces page, the Buyer/New User Tips page, and the User Observations page. Also, the Observational Guides/References can help with what can be seen. Yes, there is a lot of info on these pages but it will help you learn more what you can expect to do with your ETX-90RA. Also, when considering adding eyepieces, keep in mind the magnification maximum (see the FAQ page for that if you are unsure of it).
Subject:	Re: New Meade
Sent:	Monday, May 27, 2002 22:31:51
From: (Matthew Weinreb)
Yep, I got the following message from a dealer so it looks as though I
need to wait for my new 90....  And it REALLY is a wait!!!

> Hello Matt,
> There are a couple of places that do have the old ETX-90EC in stock, but the
> new metal bushing units have not been shipped from Meade yet.  That is what
> is causing the backorder on these scopes.  I believe it is definitely worth
> the wait to get one of the new ones with the metal bushings.

Many thanks for your help

Matthew Weinreb

Subject:	ETX90EC base for ETX90RA scope
Sent:	Monday, May 27, 2002 6:57:25
From: (Joseph B. Goins)
It's been a while since I've been at your ETX site.  It's looking good.
You've got a nice site.  My question is:  Can I get an ETX EC base and
put my RA scope on it?  And are you aware of anywhere that might sell
the EC mount?  I've got an RA with absolutely beautiful optics but I
want the GOTO functions of the EC.

Joseph B. Goins
San Ramon, CA
Mike here: As discussed on the FAQ page, there is no official upgrade available that offers just the base. You can watch for sales of damaged telescopes or perhaps use a DS mount (see the Telescope Tech Tips page).
Subject:	New Meade
Sent:	Saturday, May 25, 2002 23:19:00
From: (Matthew Weinreb)
Thankyou so much for your site, it has been an inspiration to me and I
am just about to buy a new ETX90-EC on the basis of what I have read...

I live in an area of France renowned for its unpolluted skies, (both
light and atmosphere,) and there is an annual festival of astronomy in
my local town...

Just one thing, I seem to remember reading about a new cast fork
moulding on the latest scopes...

Do you know if there is an easy way for the vendor to identify if the
scope is the new model?  I am buying online and a friend will bring it
back to France for me, so I cannot check it out myself...

Also any tips you have on updating autostar with a Mac running OSX
without virtualPC would be much appreciated... As I dont think the java
updater is available as yet...

Many thanks for any help you can give

All the best and keep up the good work...

Matthew Weinreb

Please feel free to check out my work at
And my 18,000+ image online image library at
Mike here: I haven't heard that the ETX-90EC model had been redesigned; only the ETX-125EC. However, if a change has been made, the info in the article '"New" vs "Old" - How to Tell' linked at the top of the ETX-125EC Feedback page may (or may not) be applicable). As to updating the Autostar, currently you need to have Windows running.
Subject:	spare part?
Sent:	Tuesday, May 21, 2002 9:33:22
As I was putting my etx90 in "Home Position" for alignment, I noticed
that as I manually turned the assembly to a. find the stop, and b. back
to position the support arm over the control panel, there was a "bumpy"
sensation.  Upon inspection, I found a small o- ring had become lodged
in the space between the base and the moving part.  I pulled the o-ring
out and the bumpy sensation is gone.  The question is where did the
o-ring come from? and should I open up the assembly to put it back where
it goes?

Also,just to note, after updating my Autostart 497 with the 2.5ea
version, I have been experiencing a lot of problems with "rubber
banding", poor "go-to", etc... which I never had before.  I have gone
through all of the reset, initializing, calibration, training steps to
no avail so far. Any suggestions?
Mike here: As to the rubberbanding, I haven't heard of any similar reports with the newest version. Training always seemed to solve it. So, check the telescope model and try the training one more time. Also, check the batteries if you are using batteries.


From: (Clay Sherrod)
If the O-ring is black, this is a vibration suppression pad from the
motor mount in the base; it is probably okay without it, but I would
hang onto it in case you begin to experience excessive shake and
vibration from the motor when tracking.

The key to good rubberbanding control is TRAIN, and I mean really good;
you must RESET first, Calibrate the motors, then TRAIN on something a
high magnification and very patiently as precisely as possible; if you
good, start all over with the RESET and go through it again.  It WILL go
away with proper training.

Thanks so much for the rapid response.  I'll hang on to the vibration
suppressor until I get up the nerve to crack open the case to do the the
tune up steps.  My scope is just under a year old so I am still a bit
hesitant.  In the meantime, I'll re-train, hopfully using Polaris.

Subject:	ETX 90EC
Sent:	Tuesday, May 21, 2002 4:59:40
I am just about to begin looking at the beautiful night skies we have
here in Papua New Guinea with the ETX 90EC that was sent to me.  I need
some information as to how you hook up a 12 volt battery to the 12V
connector on the base of the scope. I will be making up my own
connection from a car battery. I presume the 12V connector has the
CENTER post the one that is connected to the positive post on a 12V

Many radios and the like indicate this right on the equipment. There is
no such indication and although I am certain the center post is
POSITIVE, why take a chance when there is someone who knows for sure.
Thank you for your reassurance. Am so pleased with all the items you
treat on your website. This was one of the main reasons I purchased this
Meade ETX 90. What wonderful friends I will have all over the world who
share their experiences with me.


Fr. Roger White   
Mike here: The center post is positive. See the Telescope Tech Tips page for several articles on power supplies.
Subject:	Re: 90 EC with Autostar randomly stops tracking
Sent:	Sunday, May 19, 2002 23:45:36
From: (Richard Seymour)
I couldn't tell which person wrote the following, but i had to comment:

>Possibly, or you have a bad op-amp or whatever they use to boost voltage
>in there.  See, what I think is going in inside our little blue friend,
>is that the incoming voltage is boosted (using a FET or op-amp or
>something, I didn't dig through it that closely)  Then the cap is
>setting the volts to the motors at 25v, which is why I couldn't use a
>16v or 35v capacitor.  

No, Meade doesn't "boost" the voltage inside the scope.
The motors are driven with fairly simple (probably FET) bridges 
between the power lines, so the most a motor ever sees is the 
battery voltage less a couple of FET-drops.  Call it 10v with
a 12v supply.

------+----------+-- +12v
    a |          |B
    b |          |A
------+----------+-- 0v
(how it works: to go Left, "A" and "a" conduct, giving the "m" end
of the motor positive voltage.  To go Right, "B" and "b" conduct,
giving the "r" end of the motor positive voltage.)

The large capacitors are primarily noise-filtering (in the DS-
models, Meade kept increasing their size over the course of a
year until the random slews went away...).
The 25v rating is a decent value if Meade expects to never see
more than 18v coming from the power supply... 15v would be too small.
35v would be overkill (something no-one accuses Meade of doing).
In this application, a 35v capacitor would work fine.
A 16v capacitor would be under-rated.

have fun
From: (Bryan)
Sounds good to me, but I did try a couple 35v caps and they wouldn't
work.... the motors went too fast.   And a couple 16v caps, also didn't
work.... the motors went too slow.  Thats why I am assuming the cap near
the power input somehow controls the voltage to the motors.  I thought a
FET was used to boost voltage, but more precise and can boost more than
an op-amp? My electronics classes were a long time ago, so I could
definately be wrong...


From: (Richard Seymour)
 > Sounds good to me, but I did try a couple 35v caps and they wouldn't
 > work.... the motors went too fast.
 Too fast?  The speed-9 (or "Max") is allowed to go as fast as it can.
 If you mean the sidereal tracking was "roo fast", did you do a
 "Calibration" step?
   (Setup > Telescope > Calibrate [enter] (whirr, whirr))
 That should always be done iof the power source is changed.
 >  I thought a FET was used to boost voltage, but more precise and
 > can boost more than an op-amp?
 No, a FET (Field Effect Transistor) can be thought of as simply
 a variable resistor... you can certainly -create- a complex,
 voltage-boosting system, but it requires a bunch of other parts, too.
 For simple motor control, (as in the Meade), it's just being used
 as an all-or-nothing switch.
 It's far better to use a motor of about 10v or 12v rating, and
 run it full tilt, than to use a (say) 25v motor and then go through
 the gyrations of -raising- a dc voltage to drive it.  Very wasteful
 in both parts count and battery efficiency.

Subject:	Re: 90 EC with Autostar randomly stops tracking
Sent:	Saturday, May 18, 2002 9:51:02
From: (Bryan)
Hi Bryan - thanks for the details - terrific reading!

I ran mine this afternoon on a set of Panasonic heavy duty batteries and
got about 2 hrs of life out of them.  But in that time, the scope never
once did a random slew.  It just happily tracked along like it was on
rails.  Short life, but it seemed to like that as far as tracking goes. 
Then I tried the 12 volt plug in the car and no go - it ended up taking
off on it's own again.

Well, to be honest, I've always gotte WORSE results with any electronic
device when using any type of battery labeled "heavy duty."

In case I hadn't mentioned it, except for this afternoon, I have been
running the scope with the Meade 12 volt adapter.

Another thing I observed is that sometimes after it slews, it stops
tracking and just sits there, completely quiet, other times it gives me
a Motor Fault error.  And then other times, after it slews, it starts
tracking again, but clearly not at what it says it's tracking.

I would expect those AA batteries lost voltage fairly rapidly this
afternoon and so running on a lower voltage the scope seemed to like

Thats very weird.  Reading through the articles on Mr. Weasner's site,
it seems the genereal opinion is that HIGHER voltage works better.  In
fact, from what I gather, Meade's own 12v adaptor outputs closer to 15v.
I use a 15v / 1A (1000mah) adaptor from an old flatbed scanner, mostly
because its what I had, and I don't want to give Meade any more money
for poor quality electronics.

Is this still pointing in the direction of a capacitor repair/mod??

Possibly, or you have a bad op-amp or whatever they use to boost voltage
in there.  See, what I think is going in inside our little blue friend,
is that the incoming voltage is boosted (using a FET or op-amp or
something, I didn't dig through it that closely)  Then the cap is
setting the volts to the motors at 25v, which is why I couldn't use a
16v or 35v capacitor.  When I first got my scope, I ran it on plain old
Duracell batteries (not the facy schmancy ultra super mega volt or
whatever they are called)  It worked fine through the 4 or so hours I
had it that way, the batteries never died.

I don't know if you've had a peek inside your ETX yet, but its kind of
sounding like you may have a wire that is loose (maybe caught in a worm
gear?).  One thing I didn't say in my last post is that I had the 4
wires that go through the base to control the DEC motor get caught and
ripped to shreds in the RA worm gear.  I repaced the whole set of wires
with some nicer quality copper braided wire I salvaged from an old VCR.

Another thing I am thinking is that something may be binding somewhere. 
The computer may be trying to count off so many motor turns but the
motors could be binding so the number could be way out of tolerances,
whatever those may be set at.  This would also account for your short
battery life.

Or maybe one of those universal Radio Shack adapters where you can
change the voltage and polarity.  Would running on 9 volts be possible??

I doubt 9v would be enough.  I have used Radio Shacks 12v / 1A power
supply.  It worked pretty good except the motors turned a little slower
than a 15v adaptor.  It still aligned and tracked fine though.  If you
have the Meade adaptor you might want to stick with that, unless you
suspect its failing.  I have tried a 12V / 300mah power supply and that
did NOT work.  Somebody measured the current draw with both motors
running, but I forget what the result was.... I think its on Mr.
Weasner's site.  I do know that battery voltage doesn't add up when you
measure it.  4 AA batteries measures roughly 4 volts.  Why?  I don't
know.  1.5 x 4 should be six, but its not.  I'm not sure what the number
of batteries in the ETX adds up to voltage wise.

But, given Meade's electronics quality, maybe yours actually will run
better on 9v !  You could try it and just take the adaptor back if it
doesn't work.

It seems that the ETX isn't too picky about the voltage if it gets the
job done between 12v and 15v, its own voltage regulators (the capacitor
I replaced, along with a couple other parts I didn't replace) do a good
job of supplying the correct voltage.  Either that or since the Autostar
counts the motor turns, as long as they aren't too far out of counting
tolerance, it doesn't matter how fast they are actually turning.  Which
give me ANOTHER idea!!  Maybe your IR sensors just have grease on them! 
Thats easy enough to check, and its explained very well in Mr. Sherrod's

Or can that capacitor repair/mod be done by someone who is NOT
electronically gifted?

Honestly, if you havn't soldered anything before, I wouldn't attempt it.
I basically requires you to tear out the guts of your ETX just to get
to the cap, and then the circuit board has etching on both sides, which
means you have to make sure the leads of the cap get attached underneath
the board AND on top.  I did things a little weird and wound up
soldering one of the leads to a chip after following the circuit.

Thanks, Bryan for all your input.

No prob!  I will try to help with whatever I can


OK.  I really like the greasy sensor route.  I'm going to go digging and
see whats happening there.  After that, its electronics with wires and
stuff, right up there with voodoo.

Thanks a bunch for all that!

From: (Andy Weiher)
I've just removed the worm gear and the motor assembly from the DEC/alt
arm and there is grease on the plastic gear between the sensors.

The grease isn't of sufficient quantity to bridge between the teeth of
the gear, but it does form a grease radius at the trough of the teeth.

Any ideas on an effective method of cleaning?



P.S. Looks even worse when you get close up
gear grease gear grease

Mike here: Clay has a cleaning tip on one of his Enhancement articles on the Telescope Tech Tips page.

And this:

From: (Bryan)
Yep, that grease isn't going to help anything.  You see the grease on
the white wheel, but look to the sides of it.  You will see a small
black square on one side, and a small clear square on the other side of
the white disc.  The clear one is the InfraRed emitter and the black one
is the receiver.  When the disc spins, a tab on the wheel will break the
beam from the emitter to the receiver and the Autostar counts that as 1.
 This is how the whole newfangled contraption works, so you can see how
important it is that it counts properly.

I used a soft bristled toothbrush for the wheel, and q-tips and rubbing
alcohol for the emitter/receiver.  Just go SLOW and be sure not to break
any tabs (they are pretty tough though, and even with my gorilla grip I
didn't manage to break any).  And be careful not to bend the emitter or
receiver.  I actually tugged on the cotton of the q-tip and flattned it
a bit to shove between the emitter/receiver and the white wheel without
cramming the stick part of the q-tip in there.

Ya might want to remove that big glob o' green goo from above the wheel
also (in sensor2.jpg) and anywhere else around the encoder wheel.

Good luck and BE CAREFUL!!  :-)  It seems you are on the right track,
and hopefully you'll be out observing instead of inside tinkering before
too long!


Subject:	ETX-90EC motor control circuit schematics
Sent:	Wednesday, May 15, 2002 19:41:01
From: (Arthur Kotz)
I've been pouring over your excellent site, looking for any reference to
schematic diagrams of the ETX-90EC motor control circuits.

My essentially-out-of-the-box, but older ETX-90EC (due to the fact it's
been virtually unused since I bought it back in early 1999) is
intermittent in the dec axis. It responds SOMETIMES to the slew commands
from both the supplied manual handbox, and also to the Autostar 497. At
other times, it is unresponsive (no motor current, so it isn't stalled).
When it IS responsive, both motor currents (RA and Dec) look reasonable.
Since both control boxes have the same effect, I assume the problem
isn't in the hand controllers, but in the ETX-90EC itself.

I'm an experienced "electroniker" (a physicist) so I can track it down,
but it would be a lot easier if someone out there had the schematic
diagrams of the motor control boards, etc. I have seen Dick Seymore's
excellent schematics on the Autostar, but haven't been able to find
anything on the ETX-90EC boards.

Thanks for any help.

Art Kotz

P.S. I know many, many people sing the praises of the ETX's, but
mechanically (and electrically perhaps -- I'll soon know), it's a real
pile of junk IMHO, which many of your contributors recognize as well of
course. I know Meade  is trying to make it low cost, but I always recall
the words of a friend of mine, responding to poorly designed, low cost
electromechanical equipment: "Heck! If it doesn't have to work, I can
make it even cheaper!" I think Meade's new scopes are in this class --
they don't work! -- They might as well have made them even cheaper. I'm
kind of at the "edge" of deciding to "cut my losses" and just junk the
scope. Most of the success stories I read on your site seem to be from
people who essentially rebuilt the scopes, which is commendable, but if
I were to do that, I'd rather have a better "chassis" to start from --
One would  then really HAVE something when one was done.

I sent one to my son, a mathematician, who is very interested in
astronomy, but has very little time to troubleshoot something that
doesn't work. He took it out back in 1999; it didn't work; so it's been
in his basement, unused since.

I'll give it a few more days...
Mike here: I don't recall any circuit diagrams of the ETX-90 board. As to the slewing problem, could it be due to the fact that you have not exercised the motors or even turned the gears since 1999? If I left my car parked for 3 years it would probably act a little sluggish too. You might try just exercising the gears by moving the telescope from stop to stop in both axes.


Thanks so much for the really-quick response -- as you did earlier in a
previous post.

Maybe it's just lack of "exercise," but I'm having trouble exercising
the gears because the dec motor won't run long enough to do the job --
too intermittent. With clutches unlocked, everything moves freely.
Nothing is "seized-up" in the gears, since when the motors DO run, the
currents are OK -- not stall currents. I'm trying to do some of the
upgrades suggested on

your site, but the "motors gotta run."

Thanks again, Mike.
Mike here: I forget to say to move the tube by hand, not using the controller, to loosen the grease up. But you do indicate that the tube moves freely when not using the controllers so perhaps the grease is not the culprit.
Subject:	UHTC Upgrade
Sent:	Monday, May 13, 2002 11:24:53
From: (forte88)
I saw it mentioned that only the LX200 can be sent in for an upgrade to
the UHTC on this website.  I called Meade.  They will accept my ETX 90ec
for an upgrade. The cost is only $50.00 + my shipping costs.  Sounds
like a pretty good deal.  They said that they will completely replace my
optics!  I've got my service number and sending it tonight.  I'll let
you know my results when I get my unit back.  They said about 7-10
working days to complete it.

Bob Vilums
And an oops:
Meade just called me back.  They said that they made a mistake in my
quote.  The cost is $225.00.  Not $50.00.  I opted not to send it in for
this cost.  You can, however, send it in for an upgrade if you want to
fork out that kind of $$$.
Bob Vilums

Subject:	Tubes Rings for ETX-90
Sent:	Saturday, May 11, 2002 17:10:12
I am wondering if you know of a source for tube rings for an ETX-90. I
am looking to mount my 90RA OTA on an LDX55 mount. The manual lists the
size as 104mm. I tried Parallax Instruments and Scopestuff, they have
102mm. Also Ken Dauzat will make a custom pair, but these were a bit
more than I would like to spend. I would like to use the rings so I can
rotate the tube, and I think it would be a better way to mount the
scope. Any help would be greatly appreciated. Thank You

Randy Rourke
Mike here: I believe that Losmandy has some guide scope rings for the ETX.
Subject:	re: 90 EC with Autostar randomly stops tracking
Sent:	Saturday, May 11, 2002 8:34:36
From: (Bryan)
This is the exact same thing that was happening to me until I switched
out my capacitor!  Now it works fine and I've left it tracking for a
couple hours with no problems.


Subject:	-90 EC with Autostar randomly stops tracking
Sent:	Friday, May 10, 2002 9:03:29
From: (Andy Weiher)
Love your site!  Im a new ETX-90EC owner and Ive been experiencing the
following situation:  I go through the Alignment procedure (Easy Align)
and begin tracking Venus, for example.  Usually within anywhere from 10
to 20 minutes of tracking, the scope will suddenly slew vertically 20 
40 degrees from where it was and then stops tracking.  The Autostar is
Ver 25Ea.

Any ideas?

Thanks and cheers,

Mike here: Try replacing the batteries; low batteries can sometimes cause this. You may also want to reTRAIN.


I have it plugged into Meade's 12 volt adapter, so power shouldn't be a
problem unless the household current is an issue.  Right now I'm trying
out Clay Sherrod's "Performance Enhancement - Creating the Perfect
GOTO..." in which he mentions "random slews" relating to software
downloads.  The first thing I did this week when I got this thing was to
upgrade the software.  And I didn't do it quite like Clay's description.

Further to the initial random slew episodes, I left the scope on to see
where it would point to next.  I also plugged it into Skymap Pro to see
where the ETX thought it was pointing.  It clearly showed up a few
minutes later when the cross hair indicating where the ETX was pointing
suddenly jumped about 20 deg's vertical on the screen.  The ETX promptly
slewed itself downward back to Venus so it lined up properly on the
screen. Looking at the scope, however, it appeared to simply and without
warning slew down 20 degs.  I have no idea what prompted the Autostar to
suddenly think it was 20 deg's higher than it should be.

Interesting you mentioned to check the batteries.  The lights do dim in
this house from time to time.  I'll try Clays update method and if that
isn't doing it, I'll plug it into the car or run AA's into it.

At any rate, I'll keep you posted and thanks for your thoughts.

Mike here: Ah ha! An upgrade. And I bet you didn't reTRAIN following the upgrade. Do that.


Aye-Aye sir!!!  I'm on that now - the sky is clearing so I'll sneak peak
at Saturn while I'm at it!

Subject:	ETX problems in the UK
Sent:	Tuesday, May 7, 2002 11:27:28
From: (Clay Sherrod)
To:	Laurence...
What you are seeing with the higher power eyepiece is most likely BAD is northern hemisphere-wide right now.  It is most likely
NOT due to the scope; the Meade 5" has outstanding optics....have you
looked at a star image out of focus to see if it is collimated??

Also, that backlash you are reporting is very common unfortunately in
the system.  You might try getting into the base and seeing if you can
take some of it out, per my "Performance Enhancement...." guides on under "Tech Tips...." or whatever the category is

I think for what you paid, it would be worth your while to teach
yourself how to work on this scope and do some of the modifications
necessary to make it work much better; they are all there on that
website and most work wonders!

Dr. P. Clay Sherrod
Arkansas Sky Observatory

----- Original Message -----
> Dear Clay
> I recently bought an ETX90EC second-hand on Ebay. Apart from getting
> burned by how much it cost me to import it to the UK, I was initially
> pretty happy. However, I am not so sure now. With the standard 26mm
> lens, seeing Saturn's ring and Jupiter's moons for the first time was
> very satisfying, the moon looked great and the stars in the Orion
> nebula and Plaeides looked nice and sharp . I then bought a Series
> 4000 SP 9.7mm, and that is when I started to get less happy. On what
> appeared to be a wonderfully clear, moonless night, I looked at the
> planets, which were bigger, and could just about see a hint of some
> cloud bands on Jupiter. However, when I looked at stars I was unable
> to get them to focus sharply, and they looked more like small circles
> of beads. Mars was pretty fuzzy too. I am using a decent quality
> photo tripod, which is hardly ideal, but the image did not appear to
> be shaking when it looked as I describe it (although focusing is
> tricky because of the shake when I touch the focus knob).
> Is the more powerful lens showing up the limitations  of a
> sub-standard scope? It also suffers from what I consider to be an
> unexpectedly large amount of backlash/over-run. Is there anything I
> can do? I am very tempted by your supercharging service, although I
> am a bit put off by the prospect of 2 trans-Atlantic  shipping
> charges. The scope only cost me $350 (which is a bargain compared to
> the extortionate price they charge in the UK), but it is starting to
> add up. I apologise if my descriptions are too vague for you to come
> to any conclusion.
> Wiser after the fact.
> Laurence

Subject:	ETX Baffles
Sent:	Tuesday, May 7, 2002 9:11:49
From: (Angell, James (Jim))
Are the secondary baffles still slipping out of place on the ETX 90's or was
that only a problem on older Meade's that's been fixed ?
There are some good prices on EXT-RA 90's now (I believe it's been
discontinued).   Would the EXT-RA 90's you would buy today suffer from that
problem?   Thanks. 

Jim Angell
Mike here: Unless the ETX-90RA has been sitting on the shelf for several years, I doubt that it will have the same cause. Doesn't mean the baffle won't slip if you get the telescope abnormally hot.
Subject:	Re: HELP!! ETX Dec Lock Problem.. the saga continues...
Sent:	Monday, May 6, 2002 17:25:04
From: (Doug N.)
Just to keep everyone posted, who have offered help, and those who seem
to be most interested in Meade's response... or lack thereof.

As I noted earlier, Meade's 'apparent' response was good, quick and
positive. They promised to have a new dec knob in the mail that day.
However when I had not received the new dec knob as promised, I
contacted them on April 30, 2 weeks after my initial call. The
technician I spoke to, never heard of me, nor could he find any record
of my call, or the order. He re-ordered the item, and told me it would
be in the mail within 24 hours.

It is now May 6, another week later, and I still have no dec knob. My
scope has been down since I bought it, and I have yet to see anything
but a brief moon shot, before it crashed. We get about 12-1/2 days a
year, of clear skies, here in Wisconsin. Hopefully there are a few of
those left. I doubt if I will get to see the planetary alignment, except
with the naked eye!

I wish I was back in Tucson! 300 days a year of beautiful night skies!!

I will keep you posted as to when and if, Meade ever sends me the part!

Doug N.
Mike here: For what it is worth, the telescope won't help with the planetary alignment. They are too far apart in the sky.
Subject:	re:  New ETX-90 EC Problems
Sent:	Saturday, May 4, 2002 12:29:57
From: (Richard Seymour)
I saw your note on Mike's site.

Your right/left problem might simply be that the clamp isn't

You could try simply removing the swing-arm of the clamp 
(a hex wrench is provided with the scope for doing this),
and moving it half-way of its range "looser", then
retightening the hex screw.  
That way you can now turn it a little "tighter".

I -think- this procedure is described in the manual.
It is described in a few postings on Mike's site under
"Telescope Tips"

good luck
Mike here: It is also in the FAQ page.


Thanks everyone for the support.

Here is what finally happened.  I looked at the tune-up procedure on the
Scopetronix website and followed their directions for the basics.  What
I discovered is that during shipping (I guess) the RA motor had moved
somewhat in its mounting bracket.  On the front of the motor is a rubber
o-ring that fits into a grove in the 2 piece housing and retains the
motor in a centered position relative to the gearing and optic sensor,
plus allows some flexion in the gear train.  In my case, when the motor
shifted, it allowed the o-ring to pop completely out of the grove and
the motor moved far enough away from the gearing so that it wouldn't
drive at all.  (This also explains why the telescope would train in RA
when laying on its side and not when upright.) Thank goodness it was no
more than that. After completing the basic tune up, and loosening the RA
clutch nut a bit, my ETC90 works like a champ!  Next project is to build
the #505 cable clone. Looks like all the data is available.  Thanks a
bunch folks!!

Phil B

Subject:	New ETX-90 EC Problems
Sent:	Thursday, May 2, 2002 17:42:32
From: (Bogue Family)
I am totally new to the field of astronomy and purchased a Meade
ETX90-EC over the internet.  This is a new in the box, unopened item.
Imagine my disappointment when, after installing batteries in the drive
base, the altitude would drive, but the right/left does not.  I made
sure that the RA lock was to the left.  Sometimes the unit will drive to
the right, but never to the left.  You can hear the motor spinning
though in both instances.  I lifted the unit and must have hit the drive
button when doing so, because when it was on its side, it began to drive
to the left. When I set the unit back down you could hear the motor
disengage and just run.

My problem is this.  Meade won't give me a return authorization number
since they say I am not legally the first owner, despite the fact that
the other guy never even opened the original shipping box.  I have no
receipt either. What I do have is a brand new and useless ETX.

I am a mechanical engineering tech, but I'll be darned if I can figure
out how to get the base off to look at the unit.  I figure that I can
get it working if I can keep from breaking something important while
opening the unit.  Is there a parts breakdown or a tutorial on how to
get the base off? I would appreciate your help.


Phil Bogue  (Hopeful in Cape Cod)
Mike here: Since you didn't indicate you have an Autostar I'll assume you are just using the standard controller to slew the telescope. There are two hard stops in the EC models; can you rotate the forks from hard stop to hard stop by hand (that's about 2 revolutions but not exactly)? Do you feel any grabbing when doing this rotation? Do this stop to stop rotation a few times to distribute the grease and try the handcontroller again. Be certain you are not at a hard stop. Many times this grease redistribution solves the problem. If that doesn't work and you want to delve into the ETX guts, there are various articles on the Telescope Tech Tips page, including Clay Sherrod's Performance Enhancement articles, that can help.


Thanks for the quick reply Mike.  I have my tools in hand and have read
the Scopetronix tune-up procedures. I'll let you know how it goes.

Subject:	ETX 90 Electronics question
Sent:	Wednesday, May 1, 2002 22:06:42
From: (Bryan)
Hi there, I have an ETX 90 and it worked ok for awhile, but I broke it
when I was trying to do my own "supercharge."  I put it aside for awhile
because I bought a big 6" refractor.  Well, since setting circles are
virtually impossible for me to figure out, I am fixing my ETX90.

What I broke on my ETX was a capacitor in the bottom of the mount.  I
pushed it a bit too much to the side and it pulled a lead out a little
bit.  I mashed it back together but it was broken.  The scope would
align OK after that but then the motors would "flip out" and move by
themselves.  Then the speed control would not work on the DEC drive.  It
was full speed all the time, no matter what the Autostar said.

So yesterday I ripped the entire telescope apart and cleaned/adjusted
EVERYTHING.  I also tried replacing the capacitor with a few I had in my
box o' parts.  I had a few 220uf caps but none were 25 volts (like the
one I broke).  I tried a 220uf 16v and it caused the motors to run slow.
I tried a 220uf 35v and the motors ran very inconsistant.  I knew I
needed 25v and the closest thing I had was a 1000uf 25v cap.  So I
soldeired it in and wouldn't ya know it, it seems to work perfect!!!!

So... after all my long winded blabbering my only question is, for
anyone who is more proficeint with electronics than I am, do you forsee
any problems using a 1000uf capacitor instead of the factory installed
220uf capacitor?? I am assuming the voltage rating is more important
than the farad rating. ??

Thanks for any input!

And more:
I talked to my friend (he has a degree in electronic engineering,
specializing in robotics) and he says the 1000uf cap should work just
fine, if not better than the 220uf because I won't have to worry about
the cap being "emptied" of its stored energy.  He pointed out that kids
into these loud car stereos will use big capacitors to keep the energy
constant, whereas without them the cars battery dips the power down when
the amplifiers draw too much power too quickly.  The motors that drive
the scope should have a nice constant supply of juice now, according to


Subject:	Re: Daytime usage problem?
Sent:	Wednesday, May 1, 2002 18:31:48
From: (Mark Gabrenas)
Just a followup: it's not raining tonite (yet)! I took the scope out and
tried it. I was able to focus well enough to see the bands of Jupiter
with a 9mm eyepiece. Considering that my site has a lot of light
pollution, I would say that was pretty good. Thanks for you help.

Mark Gabrenas

Subject:	Re: ETX 90EC Vertical Lock Problems.....
Sent:	Wednesday, May 1, 2002 10:15:27
From: (Ian Young)
Thank you for your helpful response, I've spoken to Meade and they're
sending a new part straight away.

Ian Young

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