Last updated: 30 November 2008

Welcome to the AutoStar feedback page. This page is intended to provide user comments on using the Meade Autostar #494, #495, #497, cables, and the AutoStar updater software. See the AutoStar Info page for information from Meade and other users on the AutoStar, cables, and software. Send your comments and tips to Remember, tips described on this site may invalidate the warranties on your ETX and accessories. Neither the submitter nor myself are responsible for any damage caused by using any contributed tips.

Subject:	How to connect Autostar HBX to MyPAL PDA
Sent:	Sunday, November 30, 2008 15:34:25
From:	Familie Barodte (
TheSky Pocket Edition supports Autostar, buw how can I connect the ASUS
MyPal 636N PDA to my Autostar Handbox?

With the PDA was only a USB-Cable shiped.

Mike here: I did a search on the Site for "PDA and Autostar" and found a reference to a Belkin PDA USB to serial adapter, which can be used with the Meade #505 serial cable adapter kit.
Subject:	etx70at Train drivetrain failure
Sent:	Friday, November 28, 2008 03:58:52
From:	Leo Vonk (
At first my compliments about your very informative website!

The problem starts here (in drivetraing mode). When I center an object
and press enter for start training, the telescoop moves away and
backwards again, the chozen object will not come back in the center,
with the > button I can center the object, that is not a problem. But
when I train again the same problem apeared This failure stays also
after several training cycles, the object will not center. It seems that
the corrections are not being saved in the telescoop. This problem
apeared in both directions, azimut en altitude.

I did a reset, but that did not help.

What am I doing wrong?

Thanks for your advice

Kind regards,
Mike here: From your description, it sounds like you may be misunderstanding the TRAIN DRIVE procedure. But first, have you done a CALIBRATE MOTOR? If not, do that. It measures the output from the batteries and so it lets the AutoStar know how much output to expect from the drive encoders. When doing the TRAIN DRIVES, the telescope is automatically slewed a distance from the object to be centered. Then you press the indicated arrow key to bring the object back to the center of the eyepiece field-of-view. If you overshoot you have to start over. The training values ARE remembered but the procedure will always move the telescope away from the object. The values are used when slewing and GOTOing objects.


Thank you for your reply. I indeed misunderstoot the procedure. Now I
understand how it is working.

I do have a dutch software version, there is no motor calibration in it,
only motor test. If I Press enter on motor test the telesoop is lifting
a bit and after that it is going to the right a bit. Is that the
calibration procedure?

Thank you very much for your reply and have a nice weekeind Mike.

Kind regards,
Mike here: Yes, that is the same step. I guess Meade changed the name in some non-English versions.


All is clear now. Thank you again for very quick response.
Kind regards,

Subject:	autostar
Sent:	Tuesday, November 25, 2008 20:33:33
From:	Gary Russell (
I have been reviewing your sight and i enjoy it. I have settled on
buying a used ETX 125. It is an older model , a few years, but I am not
positive. It does not have a designation of PE,EC or AT. Was the
Autostar 497 controler designed for use with any ETX 125. Or is it
possible that it will not work on this scope. It does have the manual
remote with spped and focus control?
thanks for any help you can give
Mike here: The original ETX EC models shipped without the AutoStar but instead included a simple handcontroller. The AutoStar was optional. With the ETX AT and PE models the AutoStar was included. So if the AutoStar is not included with the used telescope you can purchase one. Just be certain it is a model #497 AutoStar.
Subject:	505 Astrofinder DB9 to RJ11 Pinout
Sent:	Saturday, November 22, 2008 13:27:15
From:	Larry LeBlanc (
I was referred to your site by Mark Sibole,   a Meade 4M Forum
administrator.  I received a faulty DB9 to RJ11 interface connector, 
which is part of the Astrofinder #505 kit that permits you to interface
a 497 Autostar box to a serial port on a computer.   The interface had
wires that were not even connected.  While I am waiting for a
replacement I would like to make my own. Would you happen to know what
the proper pinouts are for this interface?


Mike here: See the article "Homemade #505 Cable" on the Helpful Information: AutoStar Info page.


That was the quickest reply I ever had. I printed out the info. Just
what I was looking for.

Love your site,


Subject:	Re: Autostar 497, ETX 90C, No Dec motion in Guide mode when N/S pushed.
Sent:	Thursday, November 20, 2008 19:03:27
From:	Howard C. Anderson (
Hi Andrew,

OK, thanks.  I think I am going to have to specify centering support for
Polar mounted scopes only.  Too many variables otherwise. I have almost
NEVER used Alt/Az mounting.

Yes.  Fully aware of having to reset TTT.T to user's original value
whenever I'm not executing the centering operation.

Cannot find any definitive format for the Mg commands.  They appear to
be undocumented.  Only reference I can find is where it
Guiding commands (supported by Meade Autostar ASCOM 4.1.1 driver)
:MgDxxxx#    Move(guide)
            Where D = direction as defined by ASCOM
            xxxx is milliseconds to move
Doesn't say what is returned if anything.  Doesn't define "D" (could be
"NSEW" or "nsew" values.) Can't easily find ASCOM reference to see
whether they thought the value should be capitalized or not.

Anyway, doesn't matter.

I will use :Mn, :Ms with an adaptive timer to stop motion (already doing
that and it works well except I've been unable to use it for E/W motion
due to retrograde E/W motion. I can do N/S for any speed 0, 1, or 2. 
(Have done that successfully.  3 zips off the screen too fast...
Allowing 1 and 2 compensates for scopes that cannot reverse fast enough
in N/S direction.)

Then for E/W motion, I am going to use the user's tracking rate for
normal tracking but if I have to move the scope E or W, I will set the
tracking rate to 1 or to 120 depending on the required direction.  I
will use a software timer to specify how long to maintain that setting.
When the timer expires, I will reset the tracking rate to the user's
tracking rate. Normally the user's tracking rate will be 60.1.  But it
could be different for Lunar tracking. Anyway, I can read the value and
restore it whenever I am not calibrating E/W or centering E/W.  By using
the tracking rate, I will have a guaranteed movement speed in either
direction with no motor reversals required thus no possibility of
retrograde motion in E/W direction.

Got sidetracked today on other issues so I have not modified all of the
code yet.  Will give it a go now and see if I can make progress tonight.


From:	richard seymour (
>     *Guiding commands* (supported by Meade Autostar ASCOM 4.1.1 driver)
>     *:MgDxxxx#    *Move(guide)**
>                 Where D = direction as defined by ASCOM
>                 xxxx is milliseconds to move
> Doesn't say what is returned if anything.  Doesn't define "D" (could be 
> "NSEW" or "nsew" values.)

The direction letter is lowercase, just like the Classic :M commands.

There is no serial "response" from the Autostar upon receipt of that command.
If you send multiple, overlapping commands, the "new" command determines
the final end-time.
So :Mgw9000# (4 second pause) :Mgw9000# will stop in 4+9 sec.
You can also stop them with a :Q#

The :Mgdtttt# command is supported by all 497 Autostar firmwares newer
than 30Eb (inclusive).(and Autostar II from 1.7b onward)

The Guide speed in a 497 controlled scope is 67% of sidereal.

have fun

Subject:	Re: Autostar 497, ETX 90C, No Dec motion in Guide mode when N/S pushed.
Sent:	Wednesday, November 19, 2008 23:13:02
From:	Howard C. Anderson (
OK, I'm getting close.  I have an algorithm that will center a planet or
star except for one telescope problem.

I have motion in both Dec and RA in Guide speed so that is a major

However, when left RA button is pressed and I see motion, then let up on
the left button, the star continues to move, i.e., drifts instead of
stops.   Stops eventually but drifts about 1/4 of a 12mm view field.  I
think this is what Mike refers to as "residual drift"?   I've read
everything I can find on Mike's site and don't see anything like a guess
at what might cause this.  This residual drift does not occur in any
other direction.  This drift plays havoc with my centering algorithm
however causing "bounce" where the object oscillates back and forth as
my algorithm attempts to drive the object to the center of the video

If the worm gear is too tight against the gear it meshes with, could
that cause the problem? I had too much "slop" in RA  and did tighten a
couple of set screws to increase the pressure of the worm gear against
its target gear.

If it's not that then I don't have any idea what else it could be.  I
don't even see how that could be it but it is my best guess currently...

(This centering algorithm, if I resolve this problem, will work in
speeds 1, 2, and 3.  Probably one of the most difficult routines I've
ever written.  The acceleration that occurs in speeds 2 and 3 makes
things VERY difficult.  Wish they hadn't done that! At least I think
they did that.  Doesn't happen in classic LX-200. motion is always
linear with respect to time.)





From:	Andrew Johansen (
You may be seeing rubberbanding, or maybe the waters have stilled too much :-)
Ie you are getting to the point of sticking a micrometer onto the end of
a wooden ruler using gaffer tape ;-)
You are still limited by the drivettrain stiffness.
I did a lot of work recently on a set of late model ETXs
A lot of the backlash in RA came from "flexure" in the drive train support assy
I have a full writeup if yr interested, but basically,
to stop the RA axis "wobbling", you have to tighten the RA bearings
Doing this increases the torque required to turn the RA axis
This creates an increased axial load on the worm
To reduce endplay in the worm to account for this you have to increase the worm preload
Doing this increases the torque required to turn the worm
This results in the the plastic connector between the Gbx and worm breaking :-)
However, before it breaks, it flexes, and the amount of flexing is
relative to the speed used
Its horrible as it invoves friction and sticktion
I ended up milling a set of worm carriers so we could preset them correctly
but its a really fiddly operation
You are going to hit this problem constantly with ETXs as they have such a "relatively"
cheap drive system. Its Rafferties rules as to how each individual scope will behave :-)
However, in yr app, if you ALWAYS approach a target from "behind" yyou shld be OK
Ie if you are ahead of it, dont guide, just slow the motors
If you are behind, then apply a "speed up". This will avoid any reversing
but you still may get odd results as the sticktion breaks
Its all "relative" :-)

Mike here:
On Nov 19, 2008, at 23:37, Andrew Johansen wrote:
	> However, in yr app, if you ALWAYS approach a target from "behind" yyou shld be OK
	> Ie if you are ahead of it, dont guide, just slow the motors
	> If you are behind, then apply a "speed up". This will avoid any reversing
That's been a common recommendation for years with the AutoStar. Personally I never liked it and rarely do it.


Gday Mike

After decoding the firmware, thats how Meade do it for "gotos"
They have a means to calculate where a target "should be"
When they do a "goto", it is done in two stages
The first stage goes to a position approx 2sec "behind" where the target
really shld be
The second stage then goes to the correct posn
Thus, the last part of the goto always results in a "catchup" slew vs a
reversing slew
Cant say i like it, but within the way their system works
it seems to be the best of a bad lot, esp for ETXs which have large slop
compared to LX90s or LX200s



Hi Andrew,

Thanks!  I am assuming that by:

"Ie if you are ahead of it, dont guide, just slow the motors 
If you are behind, then apply a "speed up"."
you mean ":T+#" and ":T-#"  commands?   Had not thought of them.
It will be easy to make that change in my software.  Great idea!
I would have thought that Meade was doing that in Guide mode already...

Really appreciate your help!  If this works then I will have everything
working...  I'll let you know...

In the LX-200 classic, in Guide speed, the RA motor is simply stopped
for moving one direction and speeded up for the other direction.  We
(MAPUG list) have occasionally encountered "retrograde" Dec motion where
the scope momentarily moves in the wrong direction before moving in the
right direction. This can be corrected by making slight changes in the
positioning of the Dec motor so that the worm gear angle is made to be
slightly different.  There is no definite procedure for fixing this. 
Just fiddling until it works properly.

I used to joke around on the net that Meade probably could produce a
"perfect" telescope - for $50,000.  So you just have to try to
work-around these things.  It is a price one pays for affordable

I have imagined what a portable go-to scope would have required in the
1960's. One tractor-trailer for the computer and one tractor-trailer for
the air-conditioning system for the computer in addition to the
telescope.  Cost would have been phenominal...  Even in 1960 dollars...




Even a setting of 99 does not change the effect I am seeing...

I am highly puzzled.  I have two options both of which I might pursue:

1.   Take the scope base apart again and slightly loosen the pressure of
the worm gear against its target gear without reintroducing too much

2.  Experiment with Tracking Rate.  (Would be nice to be able to set it
to zero,0 60.0, and 120.0.  Why do I think the zero and 120.0 values
will be rejected?)

I just experimented with tracking rate against a distant palm tree.
AMAZING.  Meade did this one right!  Values 000.0 through 120.0 are
apparently all legal and the scope responds appropriately to them.

The value zero totally turns off the tracking.  Setting it to 060.1
after a zero setting has no effect.  The motor stays stopped.   It does
not recover until an E or W button is pressed.  However if I use the
values 001.0, 060.1 and 120.0 then the values are immediately effective
and I can get the smooth E/W motion that I need for object centering. I
will again revise my E/W calibration/centering algorithm and test this
tonight.  I'm pretty sure this will result in a proper semi-foolproof
solution. I will let you all know.

Thank you all VERY MUCH for your help.




Gday Howard
"Ie if you are ahead of it, dont guide, just slow the motors 
If you are behind, then apply a "speed up"."
> you mean ":T+#" and ":T-#"  commands?  
NO. They adjust the underlying tracking rate
hence setting them will upset general tracking
They should only be used for correcting "constant drift"
> Had not thought of them.
> It will be easy to make that change in my software.  Great idea!
It shouldnt have been :-)
By slow down, i meant you "never" send a command that requires the RA
motor to reverse.

> I would have thought that Meade was doing that in Guide mode already...
They do, but as you were also quoting using speeds 2 and 3, all bets are off
Also, in alt az, the drive rates change depending on orientation
Sending an RA/Az request does a "true RA" move
ie if you are at hour angle 0 or 12, only the Az motor fires
but if you are at hour angle 6 or 18 only the DEC motor fires
In between, both need to work, so it can get iffy which motor you are
> We (MAPUG list)
> have occasionally encountered "retrograde" Dec motion where the scope
I have that in DEC in my ETX125 as well, and saw it in the ETX PEs i worked on
Its pretty common.

And more:

Yes.  I think my more recent message covers the fact that I intended to
use STTT.T commands to control RA motion. Testing here indicates that
will work for Polar alignment.

Yes.  I see where Alt/Az mount would still be a significant problem if I
use STTT.T. 

So I still don't see which command you are thinking of to "just slow the
motors".  I'm still missing something?



Subject:	re: Urgent Request (dead Autostar)
Sent:	Tuesday, November 18, 2008 10:23:23
From:	richard seymour (
I agree with Mike: first try the Safe Load key combination
to see if the Autostar puts up a message.

If it -doesn't-, then you may have a blown 5v regulator inside
the Autostar, which may have been purely coincidental with
that particular power down
(i'm curious... it said "turn me off", why press [enter]?)
Pushing [enter] at that point should have had no effect
whatsoever with the Autostar, so the failure is not (or should
not) be due to that.  I've tapped many keys (experimentation)
with the Autostar in the "parked" state, and so far (knock on
plastic) it's survived.

good luck

Subject:	Rubberbanding
Sent:	Sunday, November 16, 2008 12:47:47
From:	Steve Hollar (
Mike, maybe you can clear something up for me. I have read the posts
about "Rubberbanding" and thought that was a problem I have. Now I'm not
so sure.

From the descriptions I thought it meant when an arrow key was pressed,
the object would start moving, then, when released, it would go back in
the direction it came from for a distance. The "cure" was to adjust the
Az/RA and/or Alt/Dec percent. On closer reading, this seems to be to
take up slack, or hesitation, from the time you press and arrow key to
the time it actually starts moving. The explanations make sense for
this, but, I don't see how it would solve rubberbanding. Am I
misinterpreting what rubberbanding is?

My problem is with the Left arrow. I'll press it and the object starts
moving in a short time, within a few seconds. If I stop it in the center
of the FOV, it will then move back almost to the edge before stopping. I
don't have that problem with any other arrow keys.

I've tried adjusting the percentages, but, it does not seem to do much
if anything. Can you shed some light on this? Is what I have
rubberbanding? Is there a fix for it? Thanks Mike.

Steve Hollar 
Mike here: Normally, curing rubberbanding is as simple as doing a TRAIN DRIVE. Sometimes, you may need to do a CALIBRATE MOTOR (especially if the batteries are low, you have replaced the batteries with fresh ones, or you have swapped the power source from the internal batteries to an external power source or vice versa). Then do the TRAIN DRIVES. When training, be certain to train on both axes. In rare cases, you may need to RESET, CALIBRATE MOTOR, and then TRAIN DRIVES. Changes the percentages can help (or makes worse) backlash, which the is the delay in movement.
Sent:	Saturday, November 15, 2008 18:42:02
From:	Brien Wayne (
Wayne in St.Louis,

I have a Meade ETX-125 EC with the #497 autostar controller. Recently I
used the park scope option in the utilities menu for the first time,
after the scope parked the screen display showed (turnoff scope) so I
pushed enter and the autostar hand set blacked out. I can no longer
initialize the hand set, is it a bad software glitch, or is there some
way to reset the autostar hand set not covered in the booklet that came
with it? Thank you Mike for any help you can give.
Mike here: First, please read the Email Etiquette item on the ETX Site Home Page; your email was rejected as SPAM and deleted UNREAD due to the SPAM-like subject line. Thanks for understanding. Fortunately, I accidently recovered your email. Second, when the AutoStar says to turn off the telescope, it means just that: turn off the power to the telescope. I take it that you have now done that and when you power on the telescope, nothing is displayed on the AutoStar. Is that correct?


Yes sir that is correct. I can hear the hand set click when power is
supplied, but the display will not light up or function.
Mike here: See item "Q. The power went off while I was updating my AutoStar and now it doesn't work. Did I kill it?" on the FAQ page. You will need the #505 serial cable and a RS-232 port on your computer. You will also need the AutoStar Update application from Meade's site (limited to Windows) or AutoStarX (for Mac OS X; see the Helpful Information: AutoStar Info page). If you have only USB you will need a USB-serial adapter; see the article "AutoStar and USB" on the AutoStar Info page.
Subject:	Re: Autostar 497, ETX 90C, No Dec motion in Guide mode when N/S pushed.
Sent:	Wednesday, November 5, 2008 11:34:08
From:	Howard C. Anderson (
OK.  As indicated before, I shipped the LX-90 to Meade with a cover
letter describing everything.  The person I talked with on the phone
before shipping said that my scope was pretty old and indicated that the
motor boards (1998 Rev D) were pretty old...  (He didn't say whether
they knew older boards acted weird but I got the feeling that newer ones
might have improvements...

Yesterday, I received a shipment from Meade.  They sent a whole new
LX-90! This one appears to work to spec!  I see RA and Dec motion in
Guide mode within a second or so if I set everything properly. The
trained values on this scope are RA:  879  and Dec:  1140. The trained
values on the old scope were RA:  2221 and Dec:  3961.

Was very surprised to receive a new scope instead of the one I shipped.
Presumably, that was easier than replacing the motors or the motor
control PIC chips. Anyway, looks like I can make this one work with my

Meade really did go out of their way to resolve the problem!  I am
impressed!  (They didn't take the easy way out, i.e., pretend my old
scope was working and ship it back with no changes.) Think these
messages get posted so if Meade guys ever read this, THANKS!  (Reminds
me of when the LX-200 I bought needed the data on the ROMs upgraded. 
The alignment star RAs and Decs were off by a significant amount... 
Shipped them the ROMs and they reburned them and returned them.  They
did this for several people on the MAPUG list.  Really great service
from Meade!)

Really appreciate all the help from you guys!  I could not have analyzed
the problems I was having so quickly without your generous help!



Mike here: Did you get an updated AutoStar as well? Does it have version 4.4Ea?


From:	Andrew Johansen (
Gday Howard

Just for confirmation
Your original posts were re an early model ETX 90
You have just posted re an LX-90
I assume thats just a typo ????? as they are two totally
different beasties. The LX90 has a much better support
and drive system

> The trained values on this scope are  Dec:  1140.
> The trained values on the old scope Dec:  3961.

And that is the major factor in the reversing process
However, just remember, when you release yr app
that there may be users out there with scopes like
your old one ;-)
Yours now works, so you can refine your software,
but it still may fail miserably for other users



Hi All,

Arggghhhh...  Yes I meant ETX-90 everywhere!


Mike here: Thanks. And disregard my question about the AutoStar.

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