CGX Backlash and guiding problems

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AstroBee
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CGX Backlash and guiding problems

#1

Post by AstroBee »

I've had my CGX since almost the very beginning. I was on a waitlist after it was announced so it's safe to say mine is an early model. Anyway, Over the several years now I've had minor issues but nothing that's not to be expected from a mass-produced Chinese mount. It came out of the box making the whaling banshee noise during movement. (If you aren't familiar with the noise, here's a short video. ) I sent it back and it was quickly replaced, only to have the same noise come back again later on. Rather than wait on a return again, I posted the above video and learned of the necessary adjustments to solve this issue. Over the past couple of years when I noticed guiding starting to slip, a quick adjustment to the infamous two screws has always solved my problems. Then about 2 weeks ago my guiding in PHD went from a Total RMS of .70 up to around 1.5. At 1.5 my stars are no longer round. I struggled with adjustments and it would be good for a day or so then get even worse. Last night my Total RMS was reading 4.x+ and my stars were just nice long trails. A friend told me to take the motors off and do the wiggle test to see if the bushings in the gear reduction are shot. Well, apparently they are as he said there should not be this much wiggle on the gear. I don't know what "normal" is because I've never removed the motors prior to today. So is this normal? Take a look at this short video to see the problem up close.

Meade 12" GPS SCT, Classic Orange-Tube C-8, Explore Scientific 127mm ED, StellarVue SV70T, Explore Scientific 152mm, Edmund Astroscan, CGX Mount, iOptron ZEQ25 Mount, Lunt 80mm Ha single-stack solar scope.
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Re: CGX Backlash and guiding problems

#2

Post by yobbo89 »

I think you have hit the nail on the head on what part has failed . if you ever get a replacment, make sure there is only enough tension between the motor and the worm via the pully belt.you should be able to pinch the belt in the middle with a 3-5 mm flex. btw have tried pulling apart the gear reduction and possibly replace any indidual items in it ?
scopes :gso/bintel f4 12"truss tube, bresser messier ar127s /skywatcher 10'' dob,meade 12'' f10 lx200 sct
cameras : asi 1600mm-c/asi1600mm-c,asi120mc,prostar lp guidecam, nikkon d60, sony a7,asi 290 mm
mounts : eq6 pro/eq8/mesu 200 v2
filters : 2'' astronomik lp/badder lrgb h-a,sII,oIII,h-b,Baader Solar Continuum, chroma 3nm ha,sii,oiii,nii,rgb,lowglow,uv/ir,Thousand Oaks Solar Filter,1.25'' #47 violet,pro planet 742 ir,pro planet 807 ir,pro planet 642 bp ir.
extras : skywatcher f4 aplanatic cc, Baader MPCC MKIII Coma Corrector,Orion Field Flattener,zwo 1.25''adc.starlight maxi 2" 9x filter wheel,tele vue 2x barlow .

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Re: CGX Backlash and guiding problems

#3

Post by Graeme1858 »

My CGX was really loud in slewing in one direction in RA as you describe. But the guiding was ok. It's gone back to the supplier now because the control board has packed up. The delivery company lost it initially causing a delay of a week then they dropped it and have damaged it! Prior to that the black paint flaked off the inside of the OTA and Celestron blamed me for it! So the delivery company incompetence will probably be my fault too. Very poor manufacturing quality. This equipment should be designed to operate in harsh conditions for a decade. Very poor Celestron customer service. I don't think these people realise how devastating their attitude is, the CGX is not a two bob toy, I can't go out and buy another one!

I hope you get sorted. Think I'll go fishing.

Regards

Graeme
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Celestron 9.25 f10 SCT, CGX mount.
ZWO ASI294MC Pro, Canon 600D, Altair GPCAM2 290C.
Celestron 80mm Guidescope, QHY5-II Mono.
Miranda 10x50 Binoculars.
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yobbo89
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Re: CGX Backlash and guiding problems

#4

Post by yobbo89 »

somone at cn linked bushing/bearings to replace in the gearbox on the main shaft to the belt.

https://www.ebay.com/c/25021016882

https://www.bocabearings.com/products/s ... -nb2-22106

https://www.cloudynights.com/topic/6839 ... se-in-cgx/

https://www.cloudynights.com/topic/6882 ... vo-motors/

i think there are two sizes you need
scopes :gso/bintel f4 12"truss tube, bresser messier ar127s /skywatcher 10'' dob,meade 12'' f10 lx200 sct
cameras : asi 1600mm-c/asi1600mm-c,asi120mc,prostar lp guidecam, nikkon d60, sony a7,asi 290 mm
mounts : eq6 pro/eq8/mesu 200 v2
filters : 2'' astronomik lp/badder lrgb h-a,sII,oIII,h-b,Baader Solar Continuum, chroma 3nm ha,sii,oiii,nii,rgb,lowglow,uv/ir,Thousand Oaks Solar Filter,1.25'' #47 violet,pro planet 742 ir,pro planet 807 ir,pro planet 642 bp ir.
extras : skywatcher f4 aplanatic cc, Baader MPCC MKIII Coma Corrector,Orion Field Flattener,zwo 1.25''adc.starlight maxi 2" 9x filter wheel,tele vue 2x barlow .

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yobbo89
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Re: CGX Backlash and guiding problems

#5

Post by yobbo89 »

i'm pretty sure the cgx and cgx-l use the same motor/gearbox.


copied from user moonrider at cn


Posted 11 May 2020 - 03:51 PM

striderdixon, on 11 May 2020 - 1:55 PM, said:

Mariner 2. I have a CGX-L with the same noise you are experiencing in the same spot.


Can you go into more details on the bushings that you replaced in the gear box. Where did you get said parts and what numbers. Not sure if the CGX-F00-3 is he same part on the CGX-L or whether it requires a different motor.
anyway, I have never felt that my cgx-L performed up to expectations. Appreciate any help you can give me.

Here is the Supplier for the inner bearing. It is an ABEC 5 but does work well.

https://www.bocabear...yzz-5-nb2-22106



Keep in mind that you will need 2 of the outer bearings and one inner. These are very small bearings especially the inner. Any other questions feel free to ask. Link for outer bearings.



https://www.ebay.com...xAAAOSw0e9Ux0ap


Edited by moonrider, 12 May 2020 - 02:46 PM.
scopes :gso/bintel f4 12"truss tube, bresser messier ar127s /skywatcher 10'' dob,meade 12'' f10 lx200 sct
cameras : asi 1600mm-c/asi1600mm-c,asi120mc,prostar lp guidecam, nikkon d60, sony a7,asi 290 mm
mounts : eq6 pro/eq8/mesu 200 v2
filters : 2'' astronomik lp/badder lrgb h-a,sII,oIII,h-b,Baader Solar Continuum, chroma 3nm ha,sii,oiii,nii,rgb,lowglow,uv/ir,Thousand Oaks Solar Filter,1.25'' #47 violet,pro planet 742 ir,pro planet 807 ir,pro planet 642 bp ir.
extras : skywatcher f4 aplanatic cc, Baader MPCC MKIII Coma Corrector,Orion Field Flattener,zwo 1.25''adc.starlight maxi 2" 9x filter wheel,tele vue 2x barlow .

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Re: CGX Backlash and guiding problems

#6

Post by AstroBee »

Thanks for all the assist folks. I've posted in every forum I can think of including CN and TeamCelestron. I've got several replies in CN as well.
yobbo89 wrote: Sat Sep 05, 2020 6:16 am ...make sure there is only enough tension between the motor and the worm via the pully belt.you should be able to pinch the belt in the middle with a 3-5 mm flex. btw have tried pulling apart the gear reduction and possibly replace any indidual items in it ?
I never adjusted belt tension as I assumed it was set properly from the factory. And we all no what ASSUMING means....There was a fair amount of flex on the belts.
I haven't torn into either motor yet, I guess that's the next step as I'm dead in the water at this point.
I'll keep everyone updated in this post if I hear from anyone from Celestron. fingers crossed.
Meade 12" GPS SCT, Classic Orange-Tube C-8, Explore Scientific 127mm ED, StellarVue SV70T, Explore Scientific 152mm, Edmund Astroscan, CGX Mount, iOptron ZEQ25 Mount, Lunt 80mm Ha single-stack solar scope.
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Re: CGX Backlash and guiding problems

#7

Post by AstroBee »

Just an update. The consensus on other forums was that the bushings are shot on both my RA and DEC motors and they have been sent to Deep Space Products for a re-build. I never adjusted belt tension and was the original owner of the mount so that probably means the belts were most likely too tight from the factory.
I'll keep everyone up to date when there's progress. It's gonna kill me to miss the September dark sky period but it had to be done.
Meade 12" GPS SCT, Classic Orange-Tube C-8, Explore Scientific 127mm ED, StellarVue SV70T, Explore Scientific 152mm, Edmund Astroscan, CGX Mount, iOptron ZEQ25 Mount, Lunt 80mm Ha single-stack solar scope.
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Re: CGX Backlash and guiding problems

#8

Post by AstroBee »

UPDATE: 09/13/2020

I've finally made contact with Celestron and they are looking into my problem and they may cover it as a warranty issue even though I'm past my warranty. We shall see. More updates to follow.
Meade 12" GPS SCT, Classic Orange-Tube C-8, Explore Scientific 127mm ED, StellarVue SV70T, Explore Scientific 152mm, Edmund Astroscan, CGX Mount, iOptron ZEQ25 Mount, Lunt 80mm Ha single-stack solar scope.
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Re: CGX Backlash and guiding problems

#9

Post by AstroBee »

UPDATE: 10/24/2020

Celestron received my mount on 10/01/2020 for repair. Today, 10/24, I'm waiting on the UPS driver to drop it off. Not bad as far as round-trip repair time goes.
Of course, it is returning just in time for this cold front/clouds that are rolling into our valley. I'll give a PHD2 guiding report the first clear night I have.
Meade 12" GPS SCT, Classic Orange-Tube C-8, Explore Scientific 127mm ED, StellarVue SV70T, Explore Scientific 152mm, Edmund Astroscan, CGX Mount, iOptron ZEQ25 Mount, Lunt 80mm Ha single-stack solar scope.
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Re: CGX Backlash and guiding problems

#10

Post by AstroBee »

I received my mount back from Celestron yesterday around 6pm and we had a "clear" night last night so I set it up to do some quick tests. Horrible seeing conditions with everything swimming all over the place and the wind didn't help either but I still managed a Total RMS of around 1' which was pretty good considering the conditions. As the mount was failing the RMS was around 3.5-7' so I'd say this is a definite improvement. I can't wait for a clear, calm night with good seeing...
Meade 12" GPS SCT, Classic Orange-Tube C-8, Explore Scientific 127mm ED, StellarVue SV70T, Explore Scientific 152mm, Edmund Astroscan, CGX Mount, iOptron ZEQ25 Mount, Lunt 80mm Ha single-stack solar scope.
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Re: CGX Backlash and guiding problems

#11

Post by AstroBee »

Seeing was horrible again tonight but I couldn't resist giving the mount a run-through. I tested it on its return Saturday but that was just for our club's virtual star party. No real imaging. Seeing was horrible again tonight but there was no wind so I wanted to see how well it would guide. Total RMS was around 1.0" again like the other night.



Here are the best 90 minutes from 120 minutes worth of 60-second exposures on M27 in Ha. Stacked with Astro Pixel Processor.

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Meade 12" GPS SCT, Classic Orange-Tube C-8, Explore Scientific 127mm ED, StellarVue SV70T, Explore Scientific 152mm, Edmund Astroscan, CGX Mount, iOptron ZEQ25 Mount, Lunt 80mm Ha single-stack solar scope.
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Re: CGX Backlash and guiding problems

#12

Post by Graeme1858 »

Looks like you're back in the game then!

Regards

Graeme
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Click Here for the AP Processing Challenge!
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Celestron 9.25 f10 SCT, CGX mount.
ZWO ASI294MC Pro, Canon 600D, Altair GPCAM2 290C.
Celestron 80mm Guidescope, QHY5-II Mono.
Miranda 10x50 Binoculars.
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