Meade Autostar RA drive Reversed

[Nico13]

Hi all,

I'm new on the forum but an old star gazer from way back but it was always with someone else’s telescope.
Well my lovely wife has expressed an intrest in the stars and so I have purchased an Meade LX90 8" with a Super Polaris EQ mount that has been modified to run with Meade Autostar Goto system from good old flebay.

Sold as works well it is all in very good condition but the strange thing is that RA is driving west to east so I wonder how the original owner went.

I setup the drive for my location, went through all the other pertinent setup details, started with the mount in the park position and gave a simple task like goto the moon.

It did this without a problem but then instead of tracking RA East West it proceeded to track in reverse from West to East.
Now this may be fine if the mount is facing the other way in the northern hemisphere but not down south here.
I couldn’t find anything in the menu of the Autostar to set drive direction so can anyone help with this little problem.

Ken.

[IvanTheTerrible]

http://www.weasner.com/etx/autostar/as_align5.html

[AndrewJ]

Gday Ken

Two things can change the direction of the RA drive
Location and ratios
( What firmware are you running ??? )
( What type of motors are fitted ??? )
You must set your location correctly and confirm the latitude
is Sth Hemisphere ( sounds like you did that )
If that is OK, then the sign on the RA/Az Ratio is probably incorrect
( but the fact that the goto worked has me confused )
Just try reversing the sign of the Az Ratio first and see what that does

An excellent extra resource for your setup is
http://groups.yahoo.com/group/RoboScope/
This group deals heavily with scopes retrofitted with Meade motors.

Andrew

[Nico13]

Well here's something, I did as you suggested and altered the sign on the RA,AZ ratio from + to - restarted the drive and no change so I went back and reset it to + again and then I slew to an hour index mark and to my surprise it is now driving the correct way.
No other changes made, you tell me, one of those mysteries.

Anyway to answer one of your questions it is running Meade motors and it came with two brand new spares.

The mount is currently srewed to a piece of wood siiting on my coffee table in front of me and running some tests. When I said it found the moon in goto mode this was a rough obsevation as I could see the moon outside my lounge window and as my house is 3deg off Nth Sth I have a good reference for some rough goto tests using the computer star charts as the other refence.
I think this will give me some idea of drive ratio calibration while I'm building my pier mount as I don't have a tripod for it.

Thanks again Andrew and I'll check out the link you have there as well.

Ken.

PS
Not sure what software version other than the label on the back appears to be vers 22. A bit hard to read though as it's rubbed very faint.

[AndrewJ]

Gday Ken


Not all changes take immediately
I'm not full bottle on GEM operation in the Austostar,
but IIRC, on booting up the scope starts tracking in default mode
Only when you complete the align or ask for a goto, does it
revert to Sth Hemi tracking.


There are several types tho :thumbsup:
Readup on the Roboscope site and you will quickly see what set you have
You will need to know this when setting the correct ratios



Depending on motors and final wormwheel toothcount
the ratios are all pretty well defined now
The Roboscope site files section has several documents on it
that have all the details predefined.



When it starts, it gives the version no on the display
or go to Setup->Statistics

Andrew

[Nico13]

Thanks Ivan, this looks like a handy site.

Ken.

[Nico13]

Found the firmware version, 33f4, not sure what the latest is will have to look that up.
Did a RA timing test and found it to be 25% fast so some RA AZ ratio adjustments soon had it running on time so I matched the settings on the DEC ALT and it looks good.

The real test will have to wait until the new Pier is finished.

The only other thing I need is to chase up a dovetail plate for the mount as it came without it, the dovetail is on the Scope so I only need other half.

Thanks for the input and the links to some helpful sites, not much will happen now until the construction work is done so I'll post some picies when its all set up and running.

Ken.

[AndrewJ]

Gday Ken



43Eg is the latest "well documented" version
I suggest you also look at the StarPatch site
http://www.stargps.ca/downloads.htm
It is a much better tool to update 497Autostars
and also has the latest patches.
You may need to patch if you want to use PEC

Andrew

[Nico13]

This is all very helpfull stuff Andrew and much appreciated from you and the others who have responded to this little problem of mine.
I've still got some reading to do on some of this stuff to get a better understanding of its full capabilities.
In the past the best I had to work with was a RA drive and that wasn't even mine and that was a long time back so a bit to learn as I go with this.
I guess I'm lucky I don't have any problems with computers as that could make some of this stuff a little difficult.
Thanks again guys and this has set me in the right direction with plenty of info links to the right sites.

Ken.