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Author Topic: Slewing Goto problems  (Read 12091 times)

cuivenion

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Slewing Goto problems
« on: April 29, 2016, 11:51:40 »

I have an EQ5 controlled via AstroEQ. I've noticed that when slewing east when I stop the slew it just keeps going, unless I tap west a few times and then the mount stops. Also occasionally when slewing north I'll have to hold down the button for quite a few seconds before the mount starts to move. I can hear the stepper motor but the mount doesn't seem to move.

These problems have been steadily getting worse over a few sessions and is effecting the accuracy of my gotos. Is this likely a simple case of backlash and/or belt tension that can be adjusted or something more serious. Any advice you have would be great.

I'm thinking it's more to do with the mount than the motors or AstroEQ, although my wiring is never brilliant at the best of times.
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TCWORLD

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Re: Slewing Goto problems
« Reply #1 on: April 29, 2016, 16:40:17 »

Odd indeed.

Next time you are running it, keep an eye on the USB and status lights. Does the behaviour change while its running in some noticeable way? It sounds almost like the power supply may be fluctuating enough to reset or confuse something.

Also, check the output voltage of the supply if you can. When the motors are running you may see the voltage drop if the supply is struggling to give enough power.

For the north axis, check that the pulleys are not slipping - have the grub screws worked loose? Also have a look at the backlash in the mount - can you spin the pulley back and forth a long way without the mount moving?
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Tom Carpenter (AstroEQ)

cuivenion

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Re: Slewing Goto problems
« Reply #2 on: April 30, 2016, 12:28:24 »

Thanks for the reply, I'll check it out.
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cuivenion

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Re: Slewing Goto problems
« Reply #3 on: April 30, 2016, 12:30:50 »

I've just noticed that the RA worm moves up and down slightly as it rotates, would this be a problem?
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cuivenion

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Re: Slewing Goto problems
« Reply #4 on: May 02, 2016, 17:26:52 »

OK, I've checked it all out and pulley on the RA and DEC axis had a very loose grub screw which I've sorted so thanks for that. The problem with the north/south axis is backlash.
I've tried to adjust but I just can't get it near the RA which is spot on. The problem with the East overunning is one I couldn't recreate, It's behaving fine now and all the indicators on the AstroEQ box seem to be behaving normally. I presume that the status light is meant to flicker very fast when connected to Eqmod?

The RJ11 connectors for the motors have theirs metal pins exposed somewhat. Is it possible that dew is effecting them as they are quite close together?

I'll try insulating them properly before my next session.
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TCWORLD

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Re: Slewing Goto problems
« Reply #5 on: May 02, 2016, 23:20:36 »

Glad you sorted one of the problems. I find a bit of semi-permanent thread lock (adhesive) is a good idea on the grub screws as it will stop them vibrating loose.

The status light should flicker fairly rapidly. It toggles every time EQMOD sends a command - which happens quite frequently as every few hundred milliseconds EQMOD polls the mount to see where it is. If it ever stops blinking it means that EQMOD is no longer talking to it.

It's possible that dew is affecting it, but not sure how it would cause the problem you are seeing. It's also possible that one of the commands gets corrupted and confuses my synta command decoder for a bit, though it is usually pretty good at coming back from things like that (not that it happens very often).

See how it goes and if you keep seeing issues I'll look into it further.

Tom.
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Tom Carpenter (AstroEQ)

cuivenion

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Re: Slewing Goto problems
« Reply #6 on: August 10, 2016, 17:54:35 »

Hi, I've changed the connectors and I still have an issue with the east continuing to slew. This also happens on gotos, and is like a slow drift that doesn't stop until the west button is pressed once or twice. The drift does stop on it's own after about 5-10 seconds. This happens everytime I use the mount, is there a chance there's a fault with the motor?
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TCWORLD

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Re: Slewing Goto problems
« Reply #7 on: August 11, 2016, 23:24:13 »

It's possibly a communications or firmware issue.

Could you let me know what settings you are using and which firmware.

Tom.
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Tom Carpenter (AstroEQ)

cuivenion

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Re: Slewing Goto problems
« Reply #8 on: August 12, 2016, 14:04:52 »

Thanks for the reply, here is a pic of my settings:



For some reason I have to reverse the RA to get proper performance as well. Both the motors are wired exactly the same way so that ones a bit of a mystery to me too.

I'm using the standard gearing for the EQ5 as outlined in your guide and I'm very happy apart from these couple of niggles. Thanks for the help.
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cuivenion

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Re: Slewing Goto problems
« Reply #9 on: August 12, 2016, 18:50:22 »

Just to add I'm using the gear ratios for the eq5 as per the configure file for the custom eq5 configuration.
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cuivenion

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Re: Slewing Goto problems
« Reply #10 on: August 17, 2016, 15:29:03 »

I've tried a different power supply, still the same.
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TCWORLD

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Re: Slewing Goto problems
« Reply #11 on: August 17, 2016, 15:53:41 »

There's a beta version of the firmware and config utility in the beta firmware releases part of the forum.

Would you be able to give that a try and see if the problem persists?

Also, if you could make a short video showing the issue, that would be helpful.

Tom.
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Tom Carpenter (AstroEQ)

cuivenion

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Re: Slewing Goto problems
« Reply #12 on: August 17, 2016, 18:10:08 »

Thanks, I'll give it a try.
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cuivenion

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Re: Slewing Goto problems
« Reply #13 on: August 20, 2016, 14:27:12 »

Hi here's the vid, east is when the star is travelling left. Unfortunately it cuts off when it's still drifting and it's harder to see at the short focal length I shot it at. If It's no help I'll redo it at a longer focal length.

https://www.youtube.com/watch?v=H-QwV2nLE8Y&feature=youtu.be
« Last Edit: August 20, 2016, 14:30:11 by cuivenion »
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cuivenion

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Re: Slewing Goto problems
« Reply #14 on: October 13, 2016, 17:34:50 »

Hi, I'm still having the issue with the east axis over running I've tried the new config and firmware. I've tried replacing the connectors as well. I'm at a bit of a loss to be honest.
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