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I am worried my Orion XX12G is a lemon. Need input

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#51 gnowellsct

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Posted 07 August 2014 - 03:41 AM



Still has the same "jumping" behavior, but I notice now that the altitude tracking is smooth, never a jump, it's only the AZ tracking that is jumping around. So, next will be to remove the cover on the AZ motor and inspect / relubricate. Will probably get to that tonight, but likely not be able to view again until Thursday night. Will post results and findings here. I know when slewing there is a definite spot around 140-170 degrees on the AZ circle where the motor sounds like it is slowing down and straining, so I assume the mesh needs to be loosened on this motor as well.

 

Couple of technical points--you likely have found a bad spot in AZ, even on expensive machining there is some eccentricity on a "perfect circle" -- it just gets less as the price goes up (usually).

 

One thing to watch out for is that in most positions the AZ takes the position of RA on a GEM and altitude does the work of Dec.  Put more simply, your AZ may be turning three, four, five times or more for every one rotation of the Alt motor.

 

So--your perceived smoothness of the Alt motor may, in whole or in part, be a function of its being used less than the Az motor.    Also in your tests, beware the dob hole.  As you approach the dob hole the az motor has to work very hard to get nowhere fast (same as N pole in RA on a GEM).  So the motor may protest and make weird sounds.  If you want to test in AZ you sould probably tilt 45 to 60 degrees away from straight up, then as your adjustments are refined move to within about ten degrees of the dob hole as a final test.  Of course you could swap the AZ and ALT motors and see if that makes a difference, one may not perform as well as the other.  If the swapped motor in AZ makes the same sounds it's a good bet the problem lies in the gear and/or worm adjustments.

 

Your electronics may have a programmed stop to keep you from getting too close to the dob hole.  Not sure why--a lot of dob mounts do, but have never seen it on a GEM for true N.  Maybe I haven't been paying attention.

 

GN


Edited by gnowellsct, 07 August 2014 - 03:42 AM.


#52 twoballscrewball

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Posted 07 August 2014 - 09:53 AM

Thanks for all the input. 

 

 

Just a quick note, Saturn in my area now starts the night low (guessing at about 35-40 degrees elevation) and only gets lower.   These videos were taken at a nice low angle.  Nowhere near the old dobsonian hole :)



#53 twoballscrewball

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Posted 07 August 2014 - 05:16 PM

Got a call from Orion today. 

 

They were foremost apologetic, very apologetic for the delay.   They said it was unacceptable and not typical.

 

We reviewed the issues I have had, and I advised him that I had repaired the focuser and controller, and that the only real issues I was left with were the damage in the ALT motor assembly and the sticky AZ tracking.  He said that the sticky tracking is a known issue and they have two fixes one involves the gear tension and the other something else, we never got so far as to what it exactly was. 

 

They said that considering the fact that there is damage to the ALT gearbox and a tracking issue in AZ, they are going to replace the entire base.  They are back ordered until September 2, so I will get one out of the next shipment they get.  

 

I will have to reinstall my wheels on the new base, unless I remove the new ALT motor and put it on the original side plate.   No thanks :)

 

They also said they have my order flagged and it will be opened and inspected before shipment to make sure the base is good.  They said that incoming scopes are spot checked and overall quality is usually good, and said this just sounds like a bad one.  I agreed, since I see a lot of folks here reporting good experiences, and that is also what my pre-purchase research turned up as well. 

 

Will keep this post updated.  

 

 


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#54 Donsell

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Posted 07 August 2014 - 10:34 PM

I'm glad you're finally getting someplace with them.  I hope they resolve it to your satisfaction!



#55 Glen A W

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Posted 08 August 2014 - 06:20 PM

Just hang in there.  It's a great scope, in truth.  It sounds like you just had some bad luck.

 

Although the scope is apparently not considered too expensive compared to some more custom builds, I think it's pretty deluxe by the standards of the older Dobs I've had.  I haven't noticed any problems up high with motions, like someone mentioned.  Compared to my old dobs with mirrors held in straps and funky spring-loaded teflon bearings and so on, this thing is awesome.  Overall, I am very pleased.

 

Glen



#56 twoballscrewball

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Posted 10 August 2014 - 09:19 AM

Love the optical tube.  getting great views with it, and it has held collimation now through 4 observing sessions, wheeling out and back across about 50 feet of bumpy yard and up and down a ramp with two 1" drops.  Star test looks good though I do see a difference in the outside / inside focus 'airy disc' which I think means it's under or over corrected.  However at my experience level, it's more than I need right now optically, and when I out grow it, I will just send the mirror out for a refigure and recoat, but again, it's working great as is now.  I am consistently able to barlow my Nagler 5T6 down to 2.5mm (600x!) and get respectable views of saturn.  Definitely more crisp without the barlow, but I can still clearly see the casinni division and surface banding at 600x, under relatively **** skies.  Had it out at a dark site with a good atmosphere one night so far and was extremely pleased, saw many many DSO's (just using the "tour" feature) that I have never seen before.  I convinced myself the 'blinking nebula' was actually blinking before I read up and found that it's just an illusion sue to averted/direct vision.   :) :) :) 

 

Once the base is straightened out I am sure everything will be fine.  I am very happy Orion has finally replied, and I must say that they are now all over this issue for me.  They made it sound like perhaps there was something else going on internally there that caused the support backlog, you know what they say, $%!t happens, and it usually stinks!   :) :)


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#57 twoballscrewball

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Posted 26 August 2014 - 07:54 AM

New base arrived last week, just got around yesterday to getting it assembled, have not powered it up yet but I did observe for about 30 minutes last night using it as a manually operated dobsonian.  

 

I haven't put the wheels on it yet.  I forgot how freaking heavy this base is, I was spoiled by my wheels.  This scope needs wheels :)

 

I will say that the manual operation out of the box on this replacement base is much smoother than it was on the original.  There is no slop.  The 'loose' clutch setting for ALT and AZ results in smooth effortless manual tracking, whereas the original base was sloppy and difficult to move around before I addressed it's issues.  Will hopefully power her up tonight and check the motorized operation.  

 

:)








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