Celestron CGX Motor Wiggle

[SiriusDoggy]

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. https://youtu.be/4E-oRAANk_Q ) 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.

Skip to 02:05 to get to the meat.
https://youtu.be/VsOGNNW6gqo

[newbie alert]

It will cost you nothing to remove the cap.. I had similar phd problems with my cgem and in the end had to take the mount apart.. I had a definate tick on the RA motor and 2 screws  inside the cap were poking out,1 more than the other..once they was tightened down the oscilaton stopped but the tick remained.. What I found was a flattened plastic cog, the first one in line on the spindle...what I thought would be a cheap fix replacing the cog turned into a full motor replacement..thanks celestron 

[SiriusDoggy]

Hey guys/gals,

I just wanted to post an update on my situation. I posted the same post on several astronomy forums hoping for a quick answer. One of those sites was the www.TeamCelestron.com website which is Celestron's official forum I guess.

After several comments and suggestions on Cloudy Nights and other places, I finally received a reply from an engineer at Celestron on the TeamCelestron site. He said it was definitely a problem with the motors and really wanted to take care of my issue. After checking with supervisors they have offered to replace both motors at no charge even though I'm out of warranty. Originally I was told I could drop it off and they would do the repairs while I waited. I have a friend that travels to L.A. every week for business so I was going to catch a free ride with him. I was then notified that because of the Covid-19 restrictions in California, I'd have to ship it. I was also warned that because they were closed down for 60 days (again because of C-19) that there is a long backlog of repairs. So it looks like I'm going to get the repair done for the cost of shipping but it's going to take quite a while before I get it back. My next post will not be until it's returned and I've had a chance to test it so it could be a while. But I promise more updates to come.

Edited September 22, 2020 by SiriusDoggy

[SiriusDoggy]

I received my mount back from Celestron yesterday 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...

[gilesco]

Mine generally sounds smooth, but every so often it gives a little moan, only for a second or so, and only while slewing to a position, I still get 0.7 / 0.8 RMS on a good night. Shipping to California would be expensive from the UK.

[SiriusDoggy]

9 minutes ago, gilesco said:

 I still get 0.7 / 0.8 RMS on a good night. Shipping to California would be expensive from the UK.

Yes, I think 0.7 RMS for this mount is about the best we can expect. Previously, I think my best evening was 0.58 but that was while imaging under absolutely perfect seeing conditions at 10,000' (3048m).

As for the shipping, I can only imagine how expensive that would be for you. I live in Las Vegas, NV and had to ship it to California, only 300 miles (482km) and it cost me $120 (£92).

[gilesco]

2 minutes ago, SiriusDoggy said:

Yes, I think 0.7 RMS for this mount is about the best we can expect. Previously, I think my best evening was 0.58 but that was while imaging under absolutely perfect seeing conditions at 10,000' (3048m).

As for the shipping, I can only imagine how expensive that would be for you. I live in Las Vegas, NV and had to ship it to California, only 300 miles (482km) and it cost me $120 (£92).

We have a guy in the UK who does "hyper-tuning", effectively a service on the motors, that is probably our go to place for issues like this. From what I hear he can replace worn parts etc...