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AVX DEC Oscillation

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#1 bdyer22

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Posted 03 April 2020 - 11:19 PM

My AVX has a new problem.  The DEC motor when turning counter clockwise now exhibits one of two new behaviors.  

  1. It will start oscillating back and forth
  2. It will just take off in the counter clockwise direction - this has only happened once

In either case the DEC motor audibly makes a higher pitched sound and seems to increase speed.  This seems to only happen on go-to's or Starsense alignments.  It was recently retuned to me from Celestron for another issue - which I think is fixed

I was hoping it was just a bad cable, but I don't think it is.  I tested with a small ethernet patch cable, making sure none of the wires crossed in the cable, but the dec exhibited the same oscillation with both cables.

 

The encoder is not loose on the shaft.  I did check that earlier in the week.  I'm a little handy when it comes to basic electrical and mechanical - electronics are beyond me.
 

Anyone got any ideas what could be the issue?  Thanks



#2 SkipW

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Posted 04 April 2020 - 12:35 PM

Sometimes I experienced dec oscillation, other times, not. When starting an alignment, RA would slew to the expected position but dec wouldn't - it would just swing back and forth. When investigating, I discovered that one of the spring wires that serve as the connectors inside the RJ 45 jack on the dec motor housing was skewed to the side. Using a small dental pick, it popped right back into place, and has been trouble-free ever since (knock wood!)

 

Get a bright flashlight and peek into the jacks at both ends of the dec motor cable and see if something is awry.


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#3 bdyer22

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Posted 04 April 2020 - 01:51 PM

Thanks for the tip!  I checked the pins and didn't see anything out of position.  Using a pair of needle tweezers to pull them up a little bit, but still have the issue.  Luckily it's a pretty persistent problem.  It never freaks out when the DEC is turning clockwise - only counterclockwise.

I'm currently trying to isolate the issue and will post what I've tried.  Appreciate the info, I doubt I would have thought of that.


Edited by bdyer22, 04 April 2020 - 01:53 PM.


#4 bdyer22

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Posted 04 April 2020 - 03:04 PM

Ok, I think it's gotta be something in the mount.

 

I'm not getting any errors in the HC.

Have removed every accessory and swapped out the Starsense HC with the original.

Have tried AC adapter and battery power sources.

Have tried w/ scope and no scope.

Have tried out different DEC cables.
Has only occurred when the DEC is slewing counterclockwise.

Will occur on goto's, Starsense alignment slews and manual slews.

 

I have emailed Celestron, but with current events I'm no sure if they're working - which is understandable.

 

Is there anyway to test the motor control board or motor? Remember, I have limited electrical skills. :)




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