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Last updated: 26 June 2010
This page is for comments and user feedback about the "ETX Classic" telescopes. ETX Classic models include the ETX-60/70/80/90/105/125 (EC, AT, BB, Premier Edition). This page also includes comments and feedback of a general nature. Comments on accessories and feedback items appropriate to the ETX-90RA, DSX, 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 for posting. Please use an appropriate Subject Line on your message per the Site Email Etiquette. Thanks. Remember, tips described on this site may invalidate the warranty on your telescope or accessories. Neither the submitter nor myself are responsible for any damage caused by using any contributed tips.

Subject:	ETX AC adapter
Sent:	Saturday, June 26, 2010 09:13:14
From:	Andy & Leah Lancour (
I have an ETX 125 that has an AC adapter for use with a cigarette plug,
which in turn plugs in to a standard wall outlet. I have read that some
people only use a portable power station to eliminate a possible power
surge risk frying their electronics. Is this a real possibility? Am I
safer/better off investing in a portable power supply? I see you have a
fine chart of power supplies in Tech Tips.

What is your opinion, Mike? I have had numerous issues with scope
failures and really am paranoid about re damaging anything. Any advice,
as always, is appreciated.
Mike here: Some AC Adapters can cause problems with any telescope. In fact, there is even a warning about the Meade #541 AC Adapter (see the Announcements: Warnings! page). But I've used mine without any problems. I also use a Celestron Power Tank (see the Accessory Reviews: Miscellaneous page). Similar models are available from many sources. And of course, there are the many models listed on that the Power Supply table.


Does the Celestron Power Tank come with a plug to go from the scope to
the unit, or do you buy that separately?
Mike here: That's a separate item. Any ETX power cable with the cigarette lighter plug on one end will work perfectly. Same for any telescope that can use external 12 VDC power; just need the cigarette lighter plug on one end.
Subject:	Polar alignment method
Sent:	Friday, June 25, 2010 10:25:02
From:	Gregory Smith (
I discovered another method related to the Kochab clock technique. Using
either a digital level/protractor or clinometer (available in various
levels of precision and cost, I got mine at Harbor Freight for under $20
and good to .1 degrees) you set the latitude of the wedge.  I did it
with the scope attached with the declination at 90 and measured off the
end of the tube.  If you have gps you can get the precise latitude from
it or as I did off an aeronautical or similar chart. I lucked out in
that I read about the Kochab method on June 14! so all I had to do was
swing the base to line polaris up with the vertical cross hair.

If one had a finder with a circular reticle of 45 minutes or whatever it
is, all you would have to do is merge the circle with polaris and you'd
have the correct azimuth.

Clinometers are available that measure in 1/4 minute tolerance for
substantially more money.

Love your site,

Greg Smith, MD

Subject:	high observatory temperatures
Sent:	Wednesday, June 23, 2010 12:26:44
From: (
Because of concern for high temperatures in the observatory I usually
remove my ETX 125 or LX 90 telecope after an observing session.  You
obviously have been seeing some quite high temperatures.  What do you do
to mitigate any problems or do you think that I am being overly
MIke here: Of course, one of the purposes of a permanent observatory is to NOT have to set up the telescope for each session. But there is the warning in the manuals about not leaving a telescope inside a hot car where the temps can really get to 120-140F. But then telescopes can be used for solar observing (with proper optical protection) and the temps of the hardware can get pretty high in direct sunlight. So, my opinion (and that of some others) is that some high temps are OK, but only up to an undetermined point. 140F would probably be bad. 120 is probably not healthy for glue and plastic parts if sustained over a long period of time. I've seen temps in my observatory here in Southern Arizona up to about 120F. I just recently added a plug-in thermostat and clip-on fan which seem to help. You can read about them (with product links) on my Cassiopeia Observatory Reports page for 17 May 2010 (,_Trifid_Nebula,_Milky_Way.html).
Subject:	classic home brewed astronomy chair
Sent:	Tuesday, June 22, 2010 14:21:04
From:	Ross Elkins (
I joined a local astronomical society and the owner of this chair
overheard me asking about one. He built it years ago, never used it and
sold it to me for $20!! My bad back was really bothering me so I'm
hoping this will be a big help.


photo photo


Subject:	ETX Metal Frame
Sent:	Thursday, June 17, 2010 19:00:40
From:	Joel Stevens (
I have an older ETX 90, now refered to as the ETX 90 RA.  I'm not too
impressed by the plastic fork assembly.  (I also have a B&L 4000 and a
Celestron 8 GPS).   I am interested in an ETX 125 PE, and I understand
this has a metal Fork and turntable assembly.  I assume it is much more
solid than my old ETX 90 with the all plastic forks.  Is this true?  
When did Meade Start using the Metal (with plastic cover) fork and
Mike here: Yes, the new models are more substantially built than the older models. I don't recall at this date when each improvement was made and to which models. Sorry. By the way, the ETX PE models have been discontinued. The ETX-90AT and ETX-125AT are still available.
Subject:	Cool Fathers Day Astronomy Gift
Sent:	Thursday, June 17, 2010 16:43:10
From:	Ross Elkins (
Got this from my daughter!



Subject:	Focusing issue with ETX 70 and a 1.25" Star Diagonal
Sent:	Thursday, June 17, 2010 05:51:25
From:	Neil Mc Lysaght (
I recently purchased a nice 1.25" Star Diagonal to use with a 4 Inch
Refractor I have. See here for details of the diagonal i'm using


The diagonal has dielectric 99% coating for bright images and works
wonderfully with the refractor and also with my ETX-90 EC and ETX-125
scopes when attached to the rear port of both scopes with an
astro-engineering visual back See here for visual back details


I have found that the diagonal produces brighter and clearer images than
those from built in flip down mirror on both scopes. I have also tried
to use the diagonal with my ETX70 AT (Same Visual back attachment
procedure) as I was really keen to see if the already excellent wide
field views of the etx70 could be improved. However I have found that it
is impossible to achieve focus with this visual back -> Diagonal ->
eyepiece arrangement. I have tried using an assortment of eyepieces but
the result is always the same. Do you know why, such a setup effects the
focus on the etx70? Is is something to do with the increased distance
between the eyepiece and the objective lens?

Thanks for the absolutely fantastic site!


Neil McLysaght (Ireland)
Mike here: As you have discovered, the ETX-70 (and other ETX refractor models) does not have a lot of focus travel. That is why a focus can not be achieved when attaching some accessories. Sometimes, adding a Barlow Lens BEFORE the accessory can help, but not always. It depends on the accessory. The only other option (and it is not really an option) is to modify the OTA to allow the objective lens housing to travel further. But that would require completely disassembling the OTA.
Subject:	Helping diagnose Problems with Friends ETX-125
Sent:	Wednesday, June 16, 2010 12:37:24
From:	Rodger C. Fry (
I am an ETX owner and also own an LX-200R-10".  I have a friend that has
an ETX-125 which  he has had for nearly 10 years but has never used the
GOTO.  This telescope obviously has a problem.

When you loosen the Azimuth clutch and rotate the azimuth from "home
position" clockwise, you can only rotate this for about 330 degrees.  I
think something must be wrong because I knew that the OTA should rotate
360 degrees +.  I verified this by doing the same with my ETX-105.  It
indeed rotates approximately 690 degrees.

What might be the problem and what recommendation might you suggest.
Your help is appreciated.
Rodger C. Fry
Mike here: There are a couple of possibilities since it should rotate nearly twice around between hard stops. The mostly likely culprit is some obstruction, typically a piece of debris or possibly a wire. You don't want to force the rotation in case it is a wire as you could cut the wire. The other possibility is a broken hard stop. You will have to open up the base to see what the problem is.
Subject:	9x50mm finder on ETX 125
Sent:	Tuesday, June 15, 2010 11:39:43
From:	Steve (
Im not over keen on the supplied optical finder scope that comes with
the ETX125, is there an easy solution, on how to mount a Orion 9 x 50mm
Don't mind doing a bit of mod work, any suggestions?
Many thanks
Mike here: There are several articles on the Helpful Information: Telescope Tech Tips page on adding finderscopes. Do a "find" on the web page for "finder".


Thanks for info, ive got the AT version, the little screw that holds the
finder on is it a bolt or screw? As i was thinking of making a bracket
but dont want to take it off and the nut fall inside (thats if its a

Mike here: From the reports, it is a screw. I don't recall any reports of anything falling inside the OTA. But check the articles.


thanks Mike

Subject:	rss feedback
Sent:	Wednesday, June 9, 2010 06:09:49
From:	Magiel Janson (
I just started using your rss feed and I saw you like to have some
feedback on that.

I like the quick updates. I do miss however a direct link to the article
in the rss message. I have no idea how to set it up, and if it's a lot
of work, so just see it as a 'nice to have' :-)

Keep up the good work!


Subject:	re: Smart finder shuts down unexpectedly
Sent:	Monday, June 7, 2010 07:54:50
From:	richard seymour (
Last month (i've been on vacation) you wrote about changing the LNT's

Yes, Meade has typos in their manuals (-sometimes- they update the
on-line versions)

The "CR2032" numbering system is based upon the physical -size- of the

20mm in diameter, and 3.2mm tall.   It's that simple.

This Wikipedia article covers them:
(starting half-way down the page)

have fun


From:	Ross Elkins (
Thanks for the info!

Subject:	Problems with ETX-90 RA control, both manual and clock drive
Sent:	Sunday, June 6, 2010 11:27:20
From:	Dr. Megabyte (M. Sunderlin) (
I've inherited an ETX-90 'Astro', I guess even before the RA model
numbering.  It seems optically very nice.  I am having some trouble with
the RA drive. From your site, it seems the RA on these oldest of the
ETX-90s is a known problem.  Wondering if you can help me narrow down
which id th emany, many fixes your site has would seem to best fit my

The biggest problem I've had is that the clock drive doesn't seem to be
tracking in the RA at all. Since I put batteries in, the motor runs, but
it doesn't seem to be engaged, regardless of where the RA lock is set.
The RA slow-motion knob is kind of stiff or maybe jerky, too.  That is,
the manual RA seems to require a bit of effort to begin moving, more
than it does to keep it moving.


Mark E. Sunderlin AKA Dr. Megabyte,  K4ED in Winchester VA
Solutions Architect, Fisherman, Tuba Player, Coin Collector, Father
"When I first got on the information superhighway,
 it was just a quiet country road" - Dr. Megabyte
Mike here: The RA problem could be the teflon pads or the clutch. You'll have to open the base to see where the problem lies. Also, check for a loose main central nut. As to the Declination shaft, that could be just a lack of lubrication. You'll have to open up the fork arm to check.
Subject:	RE: etx-90ec repair service?
Sent:	Friday, June 4, 2010 23:28:19
From:	Mark Bunch (CCD) (
Thank you for the information!

Mark B.


From:	Mike B (
I had the same problem with a Meade DS-2000 mount that I fixed by
cleaning the optical encoder on the AZ drive motor gearbox.

The controler uses feedback from the encoder to set the speed of the
drive as it slews the mount around and no feedback signal after slow
movement is commanded is interpreted as a stalled/sticky motor/geartrain
which the controller tries to overcome by applying more power to the
motor before faulting.

The encoder is a simple device that consists of a plastic slotted disk
on a shaft in the open gearbox that rotates between a small LED emiter
and a photo detecter diode, cleaning the len on both with a q-tip only
takes seconds and costs less than $0.02.

I don't own a ETX-90 or mount but I do own a ETX-60 and the mounts look
similar, removing the fork cover to get access to the drive only takes a
couple of minutes with a screwdriver.

I am not trying to reduce Dr. Sherrod's income but the fix for this
problem is so easy and quick that I hope Mr Bunch will look into
attempting it himself.

Mike B   

Subject:	etx-90ec repair service?
Sent:	Friday, June 4, 2010 10:09:19
From:	Mark Bunch (
Meade customer service directed me to you (and I have a Meade ETX-90EC (purchased
pre-1999?), and it's having some problems with the motor. When using the
electronic controller to move side to side, I can choose the speed, but
when moving up-down, it goes only one speed (no matter which speed
selected, which is way too fast).* Meade indicated they couldn't repair
it due to it "having plastic parts".

I attempted to read through many of your webpages, but some of the
repairs involve opening the scope (which makes me nervous). Have you
ever heard of this issue previously, could you recommend a repair

Thank you much in advance,
Mark Bunch
*I guess I should have had this problem fixed when it occurred 7 years
ago, instead of just putting it down and not touching it again until now
(I was very frustrated and poor back then).
Mike here: Contact Dr. Clay Sherrod for his Telescope "Supercharge" Service. The link is on the ETX Site Home Page.

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