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Last updated: 4 November 2012

Sent:	Sunday, October 28, 2012 23:50:53
From:	Raymond Rester (
It's about time I took a few minutes and write you. First off, thanks
for an amazing website full of info people like me need and really can't
find anywhere else without parsing through pages of useless info.

This email is a two part message, one I wanted to give you some info you
could possibly forward on to others who may find it useful as I've not
seen a lot of Mac based feedback related to Autostar, StarPatch and the
dubious ASU.

I started out with a small DS2000 70mm refractor I bought off Craigslist
for pennies, it had two DS motors and the #492 controller. Shortly after
buying that scope I found a nice used Meade 10" StarFinder EQ scope with
the JMI mobile stand, all for $200.00. I was super excited about the big
scope and setup in the backyard on the pool decking and since then my
life has been hell.... *L* I live smack in the middle of the DFW area of
Texas and we have light pollution out the wazoo here so it's difficult
at best to find more than a handful of stars with the naked eye. As you
might imagine, it's not easy finding the Veil Nebula or the Sombrero
Galaxy when you can't hardly see many guide stars not to mention I
really don't know the sky as well as I should. I'm 54 years old and my
brother has always been a scopehead and some has rubbed off but not as
much as I thought...

Anyway, the big ole Starfinder has the RA drive and that's fine but it
don't really help me find jack.. The guy I bought the scope from told me
the only thing he knew that worked to drive the Meade was the Magellan 1
and 2 units. He didn't think it could be made to GOTO.. well the more
I've used this scope the more I feel I need GOTO capability. I did
several searches in the past and for whatever reasons I never found any
info about modding the scope to work with Autostar. I figured it was
locked into the models  it shipped with from the factory. Well enter
"" and my heart skips a beat. Between you and data-plumber I
convinced myself it was time to start shopping for a #497 handbox as I
already had the Meade junction box for power, motors and controller off
my little toy DS scope plus the two DS motors. 

I bought a used Autostar #495 handbox off ebay and went to Fry's
Electronics down the street from me and bought a USB/Serial Adapter for
less than $20.00, it's the Micro Connectors, Inc. brand. It says it
works with Windows 7 all the way back to Windows 98. It says on the box
it's Mac OS compatible but listed no OS versions so I took a shot as it
was only $17.99 I think.

I made a #505 cable with some parts from Fry's as well, cost me $4.00 to
make it myself and that included the RJ11 cable and the female DB9
serial connector kit that came with an RJ-11 jack on the backside..

I use a 2.2GHZ Core2Duo 15" Macbook Pro (circa 2007), OS 10.7.4 Snow
Leopard and VMWare's Fusion 3.5 I think it is and then I have Windows XP
SP2 running inside Fusion. The only thing with this setup that could
trip someone up if when they connect the USB/Serial Adapter make CERTAIN
you are already in Windows, every time when I plug it in within Windows
I get a prompt asking me which OS should use this device, just click
Windows, you have the choice to check a box in that window to "always
connect to XXX OS selected". I don't do that as I may want to use it on
the Mac side and don't want to chase down and resolve any possible
connectivity issues so I do it old school and it works every time. I've
tried Meade's ASU 4.92 Updater as well as the latest StarPatch app which
I love BTW. I like being able to edit what options I want in my patch
updates to my Autostar.

I started having problems with my Autostar handbox after getting into
the updating and scrolling through the contents of the handbox, the
display started acting up. It sometimes goes all red, sometimes it fades
to black or almost black, most of the time it just throws up garbled
data to the display. Very frustrating as this started about the time I
was ready to try it out. I went back online and did a bit more fishing
for info, found that cooling the handbox down in the fridge sometimes
help, then do a reset and then re-update. Well, I found that cooling it
down makes the display work for a while but eventually it stops again or
gets garbled after 10-15 minutes, sometimes much less. I had trouble
sourcing a replacement lcd display as does everyone else looking for
these things, then I read something about AutoStar Suite can control the
handbox from the computer.  I searched and found a web edition of
Autostar Suite, I think it was on Meade's website, about 220mb or so. It
was free to my delight, I wasn't sure if it would work or help me but it
has been a Godsend as I can use it to drive the handbox just like I was
using the real thing. I downloaded and installed it on my XP Windows
side of my Mac and it fired right up and connected with zero problems. I
work with computers for a living and was pleasantly surprised it worked
without a bunch of headaches that I expected I would encounter.

I would like to ask you if you agree with me that the only thing wrong
on my handbox is the display or the cable to the display because I get
no garbled text on my laptop when using the handbox controller of
Autostar Suite, it simply works every time. I just plug it in, the scope
is on and Autostar is running, I don't do a special chant or anything
when firing it up and hoping everything talks to each other. I even
clicked the "Speech" checkbox at the bottom of the Autostar Suite's
handbox controller and the damn thing started talking to me! Sweet! 

That is what I wanted to share with you, maybe others can get their
Mac's running Autostar, StarPatch, etc. running at least OS 10.7.4 and
VMWare Fusion 3.4 or 3.5 version, I forget which it is.

Now the second part, I have my scope built and modded with the DS motors
and worm gear reduction on both axis. I used the stock RA worm gear and
worm shaft. I removed the control box, the motor and encoders that are
stock on the 10" StarFinder EQ. I mated a DS motor to a new worm shaft
that has the Meade DS plastic output gear on one end and the shaft goes
into the stock worm shaft support block, the worm slips over the shaft
and is pinned to the shaft. I had no idea if I could have used the stock
RA motor and encoder, didn't really want to try it as I worried I could
damage either the handbox or the stock RA motor/encoder unit or both.

Next I made a bracket for the DEC motor, also a DS motor, I used the
small Meade 60 tooth spur gears found on the DS2000 scope when I gutted
it for parts, I used the stock shaft the 60 tooth gear came on and found
a bearing the right size to fit on the large flat shoulder part plus a
smaller bearing for the very end so it has two ball bearings supporting
the output shaft. The output shaft has a 15 tooth timing belt pulley and
I used a Gates 130XL belt and a 30 tooth nylon timing pulley I drilled
out and bolted it to my DEC circle ring. Works as intended with minimal
backlash but I think I can compensate for the backlash.

The real problem I have is and I don't know if you can help or not is my
calculated gear ratios seem off. If I setup a 2 star alignment I home
the scope to point to the north star then pick Vega, it slews towards
Vega  but doesn't get very close. I have to manually move it a good bit,
sometimes the width of my fist at arms length is as close as it's came
to aligning to Vega from German North. Then I may pick Deneb or Altair
for my second star and again it seems to overshoot on the RA and the DEC
is close but not right either. Sometimes it will error on alignment,
sometimes it is successful. No matter which it is if I pick an object it
may slew close to it but most of the time it's way off.  So, I have to
ask you, what the hell am I doing wrong??? *L*

I found the gear ratio mulitplier table for the Meade 60 tooth base.
0.0228xxxxxxxx * my gear ratio should give me a Az. Ratio of X.XXXXXX On
my DEC axis, I use the 60 tooth meade spur gear, then I have a 15 tooth
output gear going to the final 30 tooth gear on the DEC shaft. I
"assume" that my correct DEC ratio is 60/1 off the stock worm gear then
double that for my two pulleys on the output, 15t to a 30t pulley, I'm
figuring the 60/1 ratio gets multiplied by two for a final ratio of
120/1. Right? 

On my RA axis, I use the stock worm gear and worm shaft that came on the
starfinder, just swapped motors out so both motors are the same Meade DS
motors. I counted the teeth and came up with 144 tooth spur so I have to
believe/assume that is a 144/1 ratio.

So I have came up with a Az/RA Ratio of  +3.285264
and my Alt/DEC ratio is: +2.737719

I'm using the published 0.022814333333333 * # of teeth/ratio to get
these values.

I have always calibrated my motors and then I train my drives using tree
tops off in the distance as my reference points. I normally use a Meade
25mm Super Plossl as my alignment eyepiece.

I've tried going back and re-training the drives but get no better

I enjoy the scope more now that I have two axis motor control that works
very well manually from Speed 9 fast slews to Speed 3 for dialing in a

My sidereal seems to track OK for now but I've obviously not spent much
time tracking something but it seems no worse than my RA tracking on the
original scope which wasn't bad! I even set my setting circle to zero
hour on my RA and turned the scope on at the top of the hour and would
check back at 15 min, 30, min and an hour to see if the motor tracking
was about right, and it seems to be quite close, I let it run about 3
hours and it was always within the thickness of a setting circle hash
mark from where it should be after running for a certain time. With the
GOTO slew off as much as it is, it seems like my sidereal speed would be
off as well and maybe it is but simply visually observing the setting
circle movement versus time lapsed it seems quite close.

I'm not giving up, but I'm thinking my ratios are not 100% accurate,
otherwise the darn thing should track and point better than it does.
After doing a firmware update I noticed a few new items in the list, one
in particular is the RA and DEC Train Drive Edits. I forget the values
but one axis had a value of eg: 5418, the other axis may show a value of
26287. I have no idea what these numbers mean nor how to manipulate
these numbers to improve the drive system. Also, I have the PEC option
enabled, for the N tooth option plus I checked the LXD 144 tooth also. I
haven't tried using the LXD as my scope type. I've only used the 114/EQ
option you have to manually enable. Should I try using and LXD scope
instead and try that? 

One last thing and this will probably sound very stupid to you, the
Autostar has left, right, up and down arrows.
Can you tell me which way these should slew the scope? I can't find
where that info is... as this is a scratch build, I don't have a

So, if I'm looking to the north, behind my polar aligned scope, if I
press the LEFT arrow, I assume the scope should move on the RA axis from
Home Position aligned over the polar axis and start tilting left or to
the west.
RIGHT should move/tilt the scope to the right when looking north behind
the scope.

Then, the DEC axis,  I have UP and DOWN, can you tell me which direction
is UP? Is it CW or CCW when looking down from above the scope?

I had a hard time at first, my RA was tracking the wrong way. I tried
Reverse L&R in Autostar but that only flipped the manual direction of
movement, the sidereal was still going the wrong way. I was about to
swap wires on the motor when I found out by using a Negative RA Ratio
value instead of a Positive one it reversed the sidereal direction. I
haven't seen that info posted and seems as it could be helpful to

I know this is a very long message and I apologize for it's length but I
had to spill my guts to you and hope you could glean something from my
attempts to get this pig tracking correctly.

best regards and keep up the great work, I don't know if YOU know how
handy your site is for us backyard engineers.

Ray Rester
Mike here: Thanks for the Mac use info. As to the screen problem, yes, it could be display, the connection to the display, or the electronics controlling the display. It could also be low power level. Have you replace the telescope batteries? For non-standard gear usage, you might check the Roboscopes Yahoo Group ( As to the slew arrows direction, the direction depends on user preference. You can change the direction in the Setup: Telescope menu.


Sent:	Thursday, November 1, 2012 13:32:57
From:	richard seymour (
Hoo, boy... where to start?

Let's start here:
> I'm not giving up, but I'm thinking my ratios are not 100% accurate,
> otherwise the darn thing should track and point better than it does.

But your "watch the RA scale for drift over time" supports the idea that
you have the *correct* Ratio value (at least for RA).

> After doing a firmware update I noticed a few new items in the list, one
> in particular is the RA and DEC Train Drive Edits. I forget the values
> but one axis had a value of eg: 5418, the other axis may show a value of
> 26287. I have no idea what these numbers mean nor how to manipulate
> these numbers to improve the drive system.

OK... those numbers are the amount of measured backlash in your
motor/encoder-to-telescope drive assembly, measured in arcseconds of
telescope motion.
In other words, if you reverse the "5418" axis, the motor has to turn
the amount that *should* have moved the telescope 5418 arcsec (i.e. 1.5
degrees) before it actually DID start moving.  The "26287" axis is far
far worse... that speaks of 7.3 *degrees* of slop, which is, indeed,
about a fist's width against the sky.
That alone could account for your under/over shoots (although usually
it'll produce "under").  Such excessive backlash usually speaks of a
set-screw holding a gear to a shaft being far too loose.  OR the worm
driving the final gear having too much "end play".
(or the final driven gear not being securely mounted to the DEC or RA

The values are initially "set" by you doing the axes' Train Drive procedure.
You center a target, then the scope slews out and back, asks you to
re-center, then it goes out and back again, and asks you to recenter
It's possible that the 7.3 degrees of slop is exceeding the Autostar's
ability to properly measure it, let alone accurately account for it in
later slewing.

Once the backlash is taken up (by slewing westward and releasing the
key) it does not affect the sidereal drive... thus you're seeing the RA
scale progress properly.

My creaky old ETX90 has 1100 in the RA axis, and 3300 in the DEC axis,
to give you a comparison number.  I don't recall ever hearing an LXD55
or 75 (Meade's GEMs) being above 1000, except in cases where the
transfer gears (the one before the worm) being loose on the shafts (if
the set-screw is a little loose, the gear will rock until the screw hits
the sides of the D-shaped shaft's flat area, then the scope will move.)

So my first suggestion is to really *scrutinize* your gear and mount
system, looking for anything that's loose.  If you have a spring-loaded
worm-into-final gear meshing system, verify that it's just a teeny tiny
schooch loose (don't force the worm into the final gear, that will
damage the gearing).  Check that the worm cannot shift *along* its
length (that's the "end play")

As for the display, my first stab there would be to release the latch,
pull out the flat cable, maybe dry-wipe it once, slide it back in
squarely and relatch the zero-insertion-force connector's securing

As Mike said, join the Roboscope group and trawl through the "Files"
page (and back traffic).  Putting Autostars on GEMs was their first
mission/goal... long before Meade offered the LXD family.

good luck

And more:

Ahh... another thing you can try to verify (or re-calculate) your

You can measure a traveled angle, and compare it with what the Autostar
thinks it did.

To do:
Align (or make believe) the RA axis to point North (the usual Polar
Arrange the scope so that the OTA (optical tube assembly) is pointing at
the horizon, due south. (assuming you're in the northern hemisphere)
Lay a torpedo level or carpenter's level on the OTA to assure flatness.

Tell the Autostar: Setup/Targets/Terrestrial (enter) to stop the
sidereal drive.
(not 100% necessary, but avoids feeling rushed)

Bring up the Autostar's "Status" display by pressing MODE for 3 seconds,
then releasing.
The DEC should read the negative of your latitude (approximately)
Now slew the OTA "up" (yes, the "up" key show move towards the pole from
this location).
Stop when the OTA is pointing straight up (as shown by the level).

If your DEC ratio is correct, it should have shown 90 degrees of travel.
(example: if you're in Florida (Lat=30), the initial DEC reading would
have been -30
After the 90 degree slew, it should read +60)

If the DEC reading thinks that you traveled MORE than 90 degrees, the
ratio is too large.
(if it's 5% over, then the Ratio is 5% too large)(see "tooth note", below)
If the DEC reading thinks that you traveled LESS than 90 degrees, the
ratio is too small.
The "ratio" is the number of encoder "ticks" per arcsecond of OTA travel.
(Tooth note: many of the smaller Meade scopes (and the DS motors) have a
 36-tooth encoder vanes on the motor shaft.
If one encoder vane-gap is dirty (filled with grease, usually), then one
gap is missed during every rotation.  That 36-to-35 drop takes 10
degrees out of a 360 degree swing.
If you see precisely +/- 2.8% error in tests, suspect that as a cause.

Testing the RA axis is a little harder, but similar.
Point the OTA due East or West ...use the level to level the OTA.
Rotate (using Right/Left) until the OTA is pointing straight up.
Verify that the RA readout changed by precisely 6 RA hours. (which is 90
RA values are in "time", to convert to degrees you multiply by 15 or
divide by 4.
1 hour is 15 degrees.   1 RA minute is 0.25 degrees.   1 RA second is
0.0041666 degrees.
Convert the displayed RA motion to degrees, and compare to "90" as you
did with the DEC.

backgrounder (written for Alt/Az scopes... the GEM mount will show weird
Alt/Az vaules):

good luck


Whoops.. i forgot:
In order to remove the (probable) backlash from the previous test sequence,
always "sneak up" on the starting "level" position from *below*
(i.e. point at the ground by at least 10 degrees, then bring it up to level)

That will take the backlash out of the picture for that 90 degree swing.

good luck

And this:

You can use the level to measure the backlash...
bring the scope up (as above) to level.
Now push the opposite direction slew key.
How far does the Autostar's display thinks it moved *until* it actually
DOES start to move?
(you could use the "Edit Training" menu to zero the Train results, which
would make the Autostar assume there's NO backlash, thereby giving the
above test an accurate readout)

There may be a little motion at the start of the reversal (offloading
gear pressure), but you're looking for "it really hunkered down and
started moving")

good luck

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