ETX PREMIER EDITION FEEDBACK
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Last updated: 31 December 2008

This page is for user comments and information specific to the ETX PE (Premier Edition). Feedback on the specific PE technologies (Automatic Alignment + SmartFinder, Level North Technology) will be covered here. Feedback on the Autostar Suite AE (Astronomer Edition) will be posted on the regular Autostar Suite feedback page. Items that are applicable to all ETX models (EC, AT, PE) will continue to be posted on the other appropriate feedback 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-90PE Automatic Alignment with Autostar Problems
Sent:	Tuesday, December 30, 2008 21:36:52
From:	Mark Wade (theengineer@latech.edu)
I just got a new ETX-90PE for Christmas, and I have a few questions.
First, in the instruction manual for the scope, it says that the LNT has
a factory set clock. However, when I turn on the computer controls, I
occasionally have to enter the time. When it doesn't prompt me to enter
the time, it gets it automatically, but it's not even close to the local
time corresponding to my zipcode.

My second problem comes with the automatic alignment. I follow the
instructions on setting the scope in the home position, but when it
slews to the first alignment star, there are no bright stars in the
vicinity (using spiral search). I'm guessing that these two problems are
interconnected seeing as it won't find the star if it has an incorrect
time. Meade tech support hasn't given me a clear answer on whether or
not my LNT is getting the correct time. Any info would be great. Thanks!

Mark
Mike here: If the AutoStar can't get the time from the LNT it will default to 8PM (2000) on the last date that it was used. If the connection is intermittent it could be a loose wire or loose or bad LNT battery. There are some PE troubleshooting tips on the Helpful Information: Telescope Tech Tips page you might want to read. One other point, I recommend using City Name instead of the Zipcode when entering your site location. It seems more reliable. As to alignment stars not being near where the telescope is pointed, check the Daylight Saving setting. The problem could be the clock error you have experienced or a location error as well. One other point: spiral search is intended for finding faint objects near where the telescope is pointed. It moves around in a very small area of the sky. Normally it will be better to see the alignment star in the sky, then the red-dot finderscope (LNT module), and then in the eyepiece. If you are unfamiliar with the night sky, there are alignment star charts on the Helpful Information: AutoStar Info page.
Subject:	Finder scope for ETX-90 PE
Sent:	Sunday, December 21, 2008 10:37:53
From:	popp0012@umn.edu (popp0012@umn.edu)
I am a new ETX-90 owner and have run into a number of issues that I am
looking for some assistance with. My scope comes with a red-dot finder
integrated into the LNT unit. While I find this a useful device, I do
not find it to be an adequate substitute for a finder scope. I live in a
metropolitan area and can only see first and second magnitude stars
through the SmartFinder. I was wondering if there was a (simple)
solution for mounting a finder scope on the right side of the OTA,
opposite the SmartFinder's screen. Ideally, I would like to mount an
8x25 right angle finder there.

Thanks for your input! I have another question about my LNT which I am
sending in a separate e-mail.

regards,

Jon
Mike here: Perhaps the article "Multiple Finderscopes on ETX" on the Helpful Information: Telescope Tech Tips page will give you some ideas.

And:

Subject:	LNT problems on new ETX-90 PE
Sent:	Sunday, December 21, 2008 10:51:37
From:	popp0012@umn.edu (popp0012@umn.edu)
I am hoping that you can help me with a problem I am having seemingly
with the LNT unit on my scope. I received my ETX-90 PE about two months
ago and was having difficulty getting it to align properly. Upon
start-up the Autostar was always asking me for the date and time. Doing
a bit of reading, I learned that this was likely due to a dead battery
in the LNT. I checked the battery in the LNT and discovered that it was
in fact completely dead (it did not register at all on my volt meter).

I replaced the battery and calibrated the sensors. The telescope seemed
to be tracking properly, but I was not out long because the weather has
been cloudy, cold (-10* F at night). This week, the LNT unit appears to
be acting up again. It is not keeping track of the date and time, and I
suspect that the battery is dead again. Any guesses about what is going
on?

Thanks so much!

Jon
Mike here: I haven't heard of the LNT battery dying that quickly. So, unless there is some shorted circuit in the LNT, it might be just a bad battery.

And:

Thanks so much for your input! Have a great holiday season.

Jon

Subject:	etx 125 pe
Sent:	Friday, December 19, 2008 19:27:56
From:	Bill & Kathy Squires (wtsquires@comcast.net)
These scopes are worthless. I bought one from woodland hills telescope a
few months ago and had to return it three times for the same error
message " motor fault".... they eventually referred me to Meades quality
control manager in California and he admitted they have been having
problems since they outsourced production to china... no apology, no
offer of compensation, didn't even ask me if I would consider a
replacement scope that they would be sure was functional.... he just
said they were aware of the problem and were working on it... I wonder
how many thousands of scopes are sitting on shelves  in the US right now
with the same problems.  Meade could care less.
Mike here: Just like tainted candy and toys, items from China have had a bad run in 2008.
Subject:	Re: ETX125PE - Goto problems - Defective or Training Errors?
Sent:	Sunday, November 30, 2008 22:06:58
From:	dan colesworthy (dancolesworthy@mac.com)
I just tried it (EASY ALIGN), in the middle of the dining room.  Mount
and scope were leveled, home position (azimuth) was estimated for North.
 1st Star was Capella.  Scope traversed ~60  degrees from North Home
position. Altitude was 57 degrees.  2nd Star was Rigel, scope traversed
to about 127 degrees, altitude was 31 degrees.  I then did a goto
Polaris.  Scope traversed back very close to 0 on the RA/Azimuth axis,
altitude was 43 degrees so 3 degrees high.

According to Starry Night SW, at 9:45 pm MST, Capella was at AZ 57
degrees, ALT 60 degrees.  Rigel was at AZ 131 degrees, ALT 28 degrees.

I set the RA/Azimuth scale to 0 with the scope in the home position. 
Assuming my arithmetic is correct, the scope was pointing a bit east of
true north in the home position.

Since i trained the drives on Polaris,  it appears that for targets
higher than 40 degrees the scope points low and for targets lower than
40 degrees, the scope points high.  Training?
Mike here: Use the AutoStar MODE menu display for position readouts. The setting circle tape can slip.

And:

From:	richard seymour (rseymour@wolfenet.com)
From the -symptoms-, i suspect you've dirt or grease occluding one of the encoder disks.

(but first, i'm going to disagree with Mike and say that Polaris is an
excellent Alt/Az mounted drive training target.  We'll leave it as an
exercise for the student to work out how many arcseconds it would move
during a five minute training session, since it's only 3/4 degree from
the pole. For an LX200gps it might matter.. for an ETX, it won't).

Now: how to diagnose a dirty encoder:
(a) power up scope, [mode] for Menu.  Don't bother to align.
(b) press [mode] for 3 seconds, release.
(c) you should now be seeing a Focus menu, or RA/DEC values.
(d) tap [scroll down] once or twice to reach the Alt/Az readout.
(e) assuming you didn't align, they're probably close to zero/zero.
(f) pick up the scope, plop it back down aimed at a landmark.
(Polaris would do, too, but this can be done in the daytime)
(g) note the AZ readout.
(h) now slew the scope a full 360 degrees until the landmark is recentered.
(i) TEST: did the Az readout -also- show 360 degrees? i.e. did it return to
(for example) zero?
(j) now slew -back- that same 360 degrees to recenter the landmark,
and check the reading.
(k) Analysis: if the reading only showed 350 degrees, precisely one
encoder vane-gap is occluded.  If 340 degrees, two are.

(l) for DEC, it's a little harder (you can't go 360).
(m) what i do is put a torpedo bubble level on the corrector cover plate,
and perform a 90 degree slew up, using the level to check for the distance.
Once again, the Alt readout should also show 90 degrees.  Since it's only
a quarter circle, the error for one occluded vane would be 2.5 degrees.
If you run the scope from its lower limit to its upper limit, and use
the DEC/Angle scale on the left fork as a guide, you can expand the error
a bit.

There are 36 vane-gaps on an ETX's encoder disk, so lowering that to 35
by blocking one reduces the measured angle by 1/36th.

If either of these tests reveals the error, then it's a case of opening
the scope and cleaning the encoder.  If it's an Az error, the screws
are probably hidden under the rubber feet. (be careful of the short
battery compartment wires when you open it)
If it's an Alt error, the access to the encoder is more difficult:
you have to remove the OTA (optical tube assembly) in order to remove
the fork covers (i think.. i have an older model ETX90).  There are a
number of "how to take it apart" guides on Mike's Telescope Tips page.
http://www.weasner.com/etx/techtips.html

good luck
--dick

And:

From:	dan colesworthy (dancolesworthy@mac.com)
Thanks very much for the advice.

I tried a modified version of the Azimuth test.  Taping the RA scale to
the mount above the scale.   Both 360 degree clockwise and counter
clockwise movements returned to just about the same 0 spot on the RA
scale.  Will try the test again when I can use a suitable target during
daylight - next weekend perhaps.  The only anomaly was a change in the
Alt readout from 0 to 3 31 17 during a clockwise rotation about the Az
axis.  The change in Alt readout for a counter clockwise rotation was 11
seconds.

Altitude tests from level to +90 degrees as indicated by the Alt readout
had the bubble of the level across the scope end showing level at +90 as
sell as level along the scope tube when horizontal.

I don't think either test showed enough deviation to be an occluded
encoder disk.  So perhaps some portion of my goto problems are due to
poor motor training.  I am not sure that training will explain
"automatic" alignment/goto errors though.  So I am still suspecting the
LNT module.

Truthfully, I wonder if I am expecting too much?

When weather and work permit, I'll take the scope outside and try again.

Thanks for your advice and encouragement!

Dan Colesworthy

And:

> The only anomaly was a change in the
> Alt readout from 0 to 3 31 17 during a clockwise rotation about the Az 
> axis.  The change in Alt readout for a counter clockwise rotation was 11 
> seconds.

There should have been NO change in Alt if you were only slewing in Az.
(i'll let the 11 arcsec go by as "reading jitter")

If the Alt encoder feedback system is gratuitously throwing a 3.5 degree
error at you, your GoTo's are, indeed, going to be toast.

Did the 3 degrees creep in (gradually increasing as the Az slew progressed),
or was it a "step" increase (one moment near zero, the next instant 3d 31m)?

May I assume the Alt did not -move- during that Az slew?

Something is definitely sick in there.  Unplugging the LNT to see if
it gets better is certainy reasonable, but i fear it's the DEC card
at fault (or the Autostar's communication thereto... try swapping the
handbox cable end-for-end to see if the symptoms change.  That shuffles
which wires carry what signal and can reveal a flakey connector-crimp).

good luck
--dick
Mike here: Perhaps changing batteries or switching to a different power source might help as well.

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Copyright © 2008 Michael L. Weasner / etx@me.com
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URL = http://www.weasner.com/etx/archive/dec08/etx-pe.html