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12” LX90 R.A. Issue


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#1 RickScofield

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Posted 08 February 2018 - 12:43 PM

Hello All,
I am having a slight problem with my 12” LX90 horizontal, R.A. slewing via the hand paddle, when I am trying to center an object the telescope actually moves in the opposite direction that I have selected for a short time and then begins movement in the correct direction. This is a very obvious issue at slower slewing speeds like 4 or under. I have an 8” LX90 and it seems to slew just fine regardless of speed. Has anyone else had this issue? Any idea what the problem might be?

THANK YOU,
RickScofield
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#2 MistrBadgr

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Posted 08 February 2018 - 12:55 PM

Hi Rick,

 

Have you tried to re-train the drives?  With the DS series, what you describe was an indication that the scope did not know what the backlash was in the gearing.  Possibly, with use, the gears have worn in a bit.

 

Bill


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Bill Steen, Sky Hunters' Haven Observatory, Broken Arrow, Oklahoma

#3 E Sully

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Posted 09 February 2018 - 05:41 AM

I would look to see what your setting is for Alt percent and Az percent are set at.  This setting is used to compensate for backlash in the drive system.  You can adjust its value from 0 to 100 till you get the response you want.  Just make sure you don't change the Alt or Az Ratio.  After setting the percent I would train the drive.


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#4 RickScofield

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Posted 09 February 2018 - 01:38 PM

Thank you all for your replies, my issue was not with training %’s it turned out to be an issue with the worm gear and the big stainless steel drive gear. I took the bottom off the scope and the spring loaded bracket for the brass worm gear was very loose. I tightend the upper screw for the bracket taking the sloop out of it making sure the bracket and gear still flexed. I also reseated the pin that holds the gear on the shaft. At this point I cleaned all the Meade grease off both gears and replaced it with Pete Paterson’s grease that I had left over from a clutch replacement. I put it all back together and now it’s working just fine.

Thank you all again,
And thank you Pete for the super grease.

Rick Scofield

#5 MistrBadgr

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Posted 09 February 2018 - 05:30 PM

Thanks, Rick!

That is good  information to have on here.  :)

 

Bill


Bill Steen, Sky Hunters' Haven Observatory, Broken Arrow, Oklahoma

#6 RickScofield

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Posted 09 February 2018 - 09:44 PM

Bill,
Necessity was the Mother of INTERvention in this case. I didn’t really want to tear into it but then I didn’t have much choice. There is very ltttle information available about the RA internals but then some of this is just common sense.

Thank you as always for your help.
Rick




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