CG-5 RA motor problems

[kd4wfw]

I have a CG-5 ASGT that is giving problems. When doing alignment, as soon as I hit enter for the type of alignment(eg. Two star, solar system ), the RA motor starts moving and will not stop until I power off the mount. I have tried different power sources. I have tried different power cords. I have taken the covers off and used electronic cleaner to clean all cable connections. I tried swapping the RA And DEC motors to see the results. The results were that the DEC motor did not run when selecting alignment type. Does this mean that it is in the RA motor? Any advice is greatly appreciated.

Kd4wfw

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[brantuk]

Hi kd4wfw and welcome to SGL

When you have the RA and Dec motors the right way round - do they both respond to the arrow keys (in both directions)?

Set the speed to 9 before you test them. At least this will check if they're hooked up and powered correctly and we can take it from there. Hth

[kd4wfw]

Thanks for the reply. I have done further testing per advice from users on the "cloudy nights" forum. The DEC motor performs flawlessly when I swapped it to the RA connector. Therefore I have determined that it is the encoder on the RA motor. I was fortunate enough to find some used CG-5 parts for a really low price which included 2 motors with encoders. So, as soon as I receive them I, hopefully, will know for sure. I will let you know the outcome.

Kd4wfw

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[brantuk]

Ok good luck with the new parts.

[billhinge]

Thanks for the reply. I have done further testing per advice from users on the "cloudy nights" forum. The DEC motor performs flawlessly when I swapped it to the RA connector. Therefore I have determined that it is the encoder on the RA motor. I was fortunate enough to find some used CG-5 parts for a really low price which included 2 motors with encoders. So, as soon as I receive them I, hopefully, will know for sure. I will let you know the outcome.

Kd4wfw

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I smashed the encoder on one of my motors when disassembling it ;-) , I was belt modding my CG5.  For future ref you can order a replacement motor from your dealer, from memory cost was about ~ £50 +/- so not too bad, could be my imagination but sounds better than original (in case you are wondering what the inside looks like)

http://stargazerslounge.com/topic/206942-celestron-cg5-motor-teardown/

[kd4wfw]

Hope I never have to see the inside of one of my motors... Those motors run $141US. I got two for about a third that price along with some other various CG-5 parts. They're used but in good shape.

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[E-Ray]

Hi kd4wfw,

I just picked up a used Celestron C6-S with the CG-5 mount. It's clean overall and hasn't been used in years - the previous owner got it as a gift and was clueless how to use it. I knew the CG-5 mount was buggy from a C8-NGT I owned years ago.

The mount immediately goes into a runaway slew after pressing Two Star Alignment without waiting for me to select the first star it chooses, Vega. A second symptom is that the Rate 9 slew will suddenly stop or drop to a very slow slew (the slew bar on the LED screen still rotates the whole time) for about 15 seconds and then resume before happening again. It happens multiple around the same location on RA from 0 to 180 degrees. 

What I have done to resolve the issue:
-          Set the DEC index to the correct side – no difference
-          Used 120V AC cable – no difference.
-          Used a DC cable from my CGEM II mount – no difference
-          Flashed hand controller to latest revs  for HC to GEM 4.21 and MC 5.20/5.20 – no difference
-          Cleaned the cable pin ports with alcohol (except the DEC input connection side – no difference
-          Changed HC and MC to original revs HC GEM 4.10 and MC 5.01/5.01 – no difference
-          Used a different hand controller and flashed to latest GEM rev – no difference
-          Tried selecting a different first star, Deneb - no difference

-          Tried factory reset - no difference 

Are there any instructions on how to open the RA motor to inspect the encoder? I saw one post by billhinge in this thread with a picture of a disassembled motor but not enough step-by-step detail for me to take one apart.

Regards, 

Ed

[bigZ]

Hi, Ed.

I also recently suffered from a runaway slew in right ascension.  This was the second time in two and a half years that this occurred.  I tore my hair out over the problem the first time, using well-meaning suggestions from the Yahoo CGEM forum members.  After much experimenting, such as you did, and needlessly spending money on parts I didn't need, I ultimately fixed the problem by replacing the entire RA motor unit.  This all happened again a couple of weeks ago.  Without hesitation, I ordered a new motor unit from Agena AstroProducts.  Unbelievably, they delivered it in two days!  By the way, I took apart the old motor unit and saw no obvious damage.  The gears and the encoder looked okay, but who knows what could've happened to the tiny circuit with sensor?

I'm not familiar with the policy of this web site about contacting someone directly via email.  If you can determine that, I'd be willing to offer more suggestions and photos.