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Synscan slow slewing problem

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#1 Kon Dealer

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Posted 25 February 2011 - 01:11 PM

Had the Synscan AZ Goto mount since Xmas and used it about 5-6 times. Last two times the Azimuth slewing has been very slow and laboured over the 90-170 degree range. Repeated without 'scope -same problem, so can't be weight of scope/not balanced. I also monitored the voltage throughout.- I use a 12V 17AH gel battery and it stayed constant at 12.7-12.8V.

Needless to say the problem is intermittent (internal connection?)

One other thing at low rates of manual slewing the Azimuth movement is "jerky", whilst the Altitudinal movement is smooth.

Any ideas

#2 Trev

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Posted 25 February 2011 - 03:36 PM

Might be catching on something in the base?

#3 DavidD

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Posted 25 February 2011 - 10:53 PM

What rate are you slewing at? That might have been changed. Push Rate then 9 to go full speed. 8 is a LOT slower than 9.

The jerky-ness could be a couple things. One could be the backlash setting. The other could be the clutching is too loose.

I have bought one of these new recently, so still trying to find my way around it. I've tightened the clutches to where manual (without the controller) is possible, but not likely. This really eliminates the possibility of manual movement, but the controller movement is better.

Does this help?

David

#4 Kon Dealer

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Posted 26 February 2011 - 08:14 AM

If I am manually slewing to an object then I use rate 9 until I get close then down to 3 or 4 for fine adjustment.
On auto slew I have no idea what it does, but if it has to slew a large distance it sounds like rate 9.

The point is that in mid slew (in azimuth, manual or auto) it can suddenly slow down, sound really laboured and then pick up again. When it does this it loses goto accuracy.
Of course it is not a regular occurence. I have just been slewing alot indoors to try and "loosen" things up/identify the sticking point and after some early hesistation, it now seems to be OK, but I'm not holding my breath!

#5 DavidD

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Posted 27 February 2011 - 10:29 PM

I think I've experienced what you are describing. I think this happens when it switches back and for between Alt and Az slewing. I think it does both axis in series, and slows down as it comes to a stop, then slowly starts going on the other axis, and then ramps up the speed. I think the inaccuracy could be in this crossover, if the clutches are slipping as it comes to a halt, or starts up. And, the more times it switches back and forth, the more possibility for slipping.

When I got my mount, the Az axis was so tight that you'd think you were going to break something if you forced it. The alt, on the other hand, would move without much force. My first impulse was to loosen the Alt to match (and it looks like it's a pain to do this). However, in doing some reading, the real answer was to tighten the alt axis, which is relatively easy to do, to match the tightness on the az, and use the hand controller for all slewing.

Now, not saying this is your issue, but I think if you tested a few slews, you should see the mount stair stepping to get to an object, and see if that is where the slowing down is, and when/where it's slipping.

David






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