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TheThing

Meade GOTO

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I've recently picked up an EQ2 (or possibly EQ3-2) with Meade motor drives on both axis and a #497 GOTO controller.

For some reason, the GOTO seems to be back to front. If I try and align, it will slew to the wrong side of the sky. For example, it seems to think Vega is in the east whereas it currently lies in the west.

I've done a reset and trained the motors. The settings are all ok - date and time correct, home town is set to Greenwich (I've tried London ad well), but it still thinks Vega is in the east.

The controller is set to EQ mode, so all seems correct there too.

Just wondered if anyone can offer any help or a manual that can assist please?

TheThing

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You are going to have to supply somewhat more information possibly a picture or two.

Meade motors and EQ mounts do not go together, especially on an EQ2 or EQ3 which is Skywatcher.

It just doesn't at this time make sense.

You can stick a Meade scope on an equitorial mount, then you would need to tell us the scope.

They may be a manual for the 497 autostar on the Meade site, they do have a lot for download.

Just what you have written does not seem right.

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post-2109-134809034812_thumb.jpg

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Hope that clarifies? The scope is an Orion ST80, but that is not significant as it does not impact the GOTO.

TheThing

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The LDX55 appears to use a tripod similar to the EQ3, but cannot see enough detail of the EQ head.

Suspect that one of the manuals will explain enough to supply an idea of the operation.

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I've got the autostar handbook and the LD one, but they don't cover why the mount goes east instead of west!

TheThing

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Only the stupid options left:

Timezone, did you set that, they have a habit of defaulting to West Coast America. You can tell these things your longitude but they still use the timezone for (I think) a time offset and that effects the apparent location.

If you are using a longitude of 0 try +0.1, the number 0 and a computer do not work well together.

Really stupid one you are aiming the mount at Polaris?

Whenever I look at an equitorial I want to evelate the scope to 52 deg then aim this at Polaris, means the mount is pointed South. Only ask as it is my first thought with a equitorial mount, just wondering if you could have done the same.

Think the clock is either 24 hour otherwise check if AM and PM is set.

It is a Meade not a Skywatcher so you enter Lat, Long. Don't laugh someone here was swearing blind for 3 weeks they had it all correct until another visited and put the location in in the correct order. Took 3 minutes then it worked.

If you have entered all the data for Epsom then most likely OK, if not and you have taken London and changed it be aware there is a London in Canada just outside Toronto. Quite big and may be in the list of Meade locations.

It will be one seemingly insignifiant bit of more or less useless data, it is just finding it that is the problem.

I have 2 Meades and the first use after a period of not using them is a cause for high blood pressure for me.

Never trust the things.

See you have a nice round 5000 posts now.

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Ok, good points, thank you.

I'll try those again. I suppose there is a Greenwich in the USA as well!

TheThing

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I tried finding the paragraph which shows you how to do it, but it'll be on this sight if anyone has the knowledge: http://www.weasner.com/etx/autostar_info.html

There is a topic relating to setting the ratios for your axes on the controller - you need to reverse the direction of the RA motor ratio by accessing the correct setup menu and changing the sign. (as the 497 is used with a number of motors and telescopes, the contoller saves the ratio of 1 turn of the worm to a complete rotation of the relevant RA/DEC axis and it's this ratio which needs to be modified).

I haven't tested this on my setup, but if it's just the RA axis, perhaps see if the hemisphere on your setup is set correctly (N/S).

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It might be cured. Just had a fiddle. I set it all up and put the time to 21:30 hours. Slew to Vega in the east.

Checked all the settings. All fine. Changed my Longitude to South and tried aligning again. It picked a star I'd never heard of and slew east again (although the scope was facing north, so it probably was heading west!)

Changed the Long. back to North. Align on Vega again and it pointed West! Looks like roughly the right place too.

Software glitch? Probably!

TheThing

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Is there an option in the menu to reverse the directions, i am sure there is.

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Now not working again! Tried the same procedure but still heading east.

I've tried reversing the directions, buy that only applies to the directional buttons for moving the scope 'by hand'.

I'm at a loss :(

TheThing

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Right, I think I'm sorted!

A chap from RoboScopes group on Yahoo came up with a simple solution.

I'll copy his e-mail here just in case anyone else needs it: -

"I have seen this problem occur at times when I converted a mount to a GOTO mount. You might try this,it worked for me. In the autostar controller find the alt. and az. setting, take note of the numbers and weather there is a plus or minus in front of the number. Do this in case you change one of the numbers. Which ever axis is slewing in the wrong direction change the plus sign to a minus or change the minus sign to a plus and try it again. If your slews are in the correct direction leave the change,if not change it back to the original,then change the opposite axis and repeat the procedure. I have done this and it worked for me numerous times with some of the mounts I have built. Remember,DO NOT change the numbers,these are your gears ratios, just the plus or minus. Hope this works for you.

Jeff "

A quick daylight test has the scope slewing in the right direction after changing the Az ration from "-" to "+" for both Vega and Altair. Just need a clear sky to test it properly.

Happy days! (So far!)

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Thats sounds interesting.

Makes you think that the + or - relate to the direction that the motors drive.

Think I will make note of this as the games my Meades get up to they will make the change themselves and I will be tearing my hair out. One did spontaneously change from Alt/Az to Equitorial once. It nearly learnt how to fly through the air.

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