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A Quick Tech Question: RA Tension Gear

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#1 RMay

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Posted 21 August 2019 - 06:13 PM

Hi all, I'd like to pose a quick RA tension question for you all:

 

While looking this morning at a new Q 3.5 owned by Forum member 'Old Don' we both noticed that the tension on his RA drive gear was much more severe than on my 1986 Standard - it is clearly not the 'buttery smooth' movement that I feel on mine, or that one might expect. On closer examination, we noticed that there are three *very* thin plates that fit into a tension gear at the bottom of the RA drive shaft. On my scope, all three plates fit within the grooved indent on the smooth gear, while on Don's scope, two of the plates rest inside the indent, and the other is below, thereby 'splitting' the plates as the RA gear moves.

 

I believe this might be an easy fix by removing the RA thumb gear at the top of the clock drive and just wiggling the shaft so the three plates all rest within the indent (but then again there may be no 'play' at all in the shaft, requiring more effort). Questar may ask him to return the scope, which would be a hassle (and perhaps should have been caught during their final QA process), but it might be a simple fix.

 

Do any of you know if this is as easy a fix as one might expect? Do any of you know if this is perhaps covered in one of the Questar repair videos that have been posted, and if so can you point us to it?

 

Thanks,

 

Ron

Attached Thumbnails

  • Q RA DY.jpg
  • RM RA.jpg

Edited by RMay, 21 August 2019 - 06:15 PM.


#2 agmoonsolns

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Posted 21 August 2019 - 06:22 PM

Questar should pay to have it returned and repaired.



#3 TerryWood

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Posted 21 August 2019 - 06:35 PM

I bought mine new in 2013 and the RA was pretty stiff. I thought it would smooth out over time with use, but it hasn't yet. If someone has a way to easily adjust it that would great. If not, I'll just wait until I send it in for a tune up. I had a 2012 standard model also (that I ended up selling later) that was very smooth. Hopefully it's an easy fix. V/R Terry

#4 Optics Patent

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Posted 21 August 2019 - 10:16 PM

All three should be in the groove. I have a video at Questarzone.com that shows how.

The key is to hook the arm I’m which the pinion pivoted and it outward to pull the pinion away from the disc edges. Then let it return and roll the knob to get the edges in the groove. I’ve used a bent paper clip for this a dozen times.

#5 Optics Patent

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Posted 21 August 2019 - 10:43 PM

It’s unclear what is meant by “stiff”. Is this force required to turn the RA knob for fine adjustments? Or slewing force?

The key adjustment for slewing is the main hub nut under the red disc.

FYI the factory service to replace worn drives (a wear item like brake pads) is very affordable. About $200 total.

#6 RMay

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Posted 22 August 2019 - 12:09 AM

Interestingly, as I look back at the picture of Don’s scope, it looks as though the plates are being ‘pulled up’ slightly and twisted or ‘pulled’ up to remain in that slot on the right ascension shaft. There may also be a second problem, which is the shaft is not spaced properly causing the stress on the plates.

Other points noted and I’m sure Don will review these...

Thanks all for your time and input.

Ron


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