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CGE Pro run away RA motor - super high speed!

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#1 shootingsta98

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Posted 16 April 2018 - 10:18 AM

My CGE Pro has been working fine for the last year or so since I got it. Yesterday, when I powered up the mount, and started it from hibernate mode, the RA immediately took off at a speed I did not even realize the mount was capable of. I shut it off immediately to avoid the OTA from slamming into the mount.

 

I have submitted a tech problem form on Celestron's web site. Has anyone else had this problem? What was the outcome?

 

Bob



#2 rmollise

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Posted 16 April 2018 - 10:54 AM

My CGE Pro has been working fine for the last year or so since I got it. Yesterday, when I powered up the mount, and started it from hibernate mode, the RA immediately took off at a speed I did not even realize the mount was capable of. I shut it off immediately to avoid the OTA from slamming into the mount.

 

I have submitted a tech problem form on Celestron's web site. Has anyone else had this problem? What was the outcome?

 

Bob

 

There is basically one reason for this to occur:  communications failure concerning the motor encoder. Causes? The encoder can be bad (it is integral to the motor). Or you could have a bad cable/connection. Check and clean all connections in the electronics pier for sure. You can try doing an HC reset, but that rarely helps. Nor does reloading firmware help. This is almost always a hardware problem.


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#3 Astro-Master

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Posted 16 April 2018 - 11:00 AM

 I bought a new CGEM II mount Nov 2017 it had the same problem after the first hour of use.  After many calls to

tech support, and trying everything they said to fix the problem, I sent it back for a replacement.  The new mount 

works fine so far.  I think it was a wire shorting out inside the mount somewhere.  I was lucky it failed so soon, they

replaced it right away.  I love the new mount, it works great for my 10" LX 200, and my 180mm Mack.



#4 niteman1946

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Posted 16 April 2018 - 11:46 AM

My CGE Pro has been working fine for the last year or so since I got it. Yesterday, when I powered up the mount, and started it from hibernate mode, the RA immediately took off at a speed I did not even realize the mount was capable of. I shut it off immediately to avoid the OTA from slamming into the mount.

 

I have submitted a tech problem form on Celestron's web site. Has anyone else had this problem? What was the outcome?

 

Bob

Good luck Bob!

 

I had mine for a bit under a year with three returns to Celestron.  Two were for runaways.  The first was for RA and the last was for DEC.  I agree with you that when it occurs, it's really scary.

 

Mine was likely going back to them for the forth time in early January.  However, Celestron either took pity on me, or just got tired of my complaints.  So it is now in their hands and will not be coming back to me.

 

Mark



#5 f430

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Posted 16 April 2018 - 11:51 AM

When I had a DEC runaway, it turned out to be a faulty motor/encoder unit. They replaced the DEC motor/encoder unit under warranty, and its been working great ever since! 

To start the repair process, I called them, and skipped the email part.

 

I had excellent customer service with them, and have no complaints what so ever! 

 

John


Edited by f430, 16 April 2018 - 05:00 PM.


#6 shootingsta98

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Posted 16 April 2018 - 12:03 PM

Hopefully I'll hear back from Celestron soon. I had numerous issues with another CGE Pro mount that was returned to Celestron five times before they finally replaced it with a new mount, the one I am having problems with now. The deal was that because they swapped the old mount with a brand new one, there would be no warranty on the new mount. This feels like a very bad deal now.

 

My hope is that they will be familiar with the problems and can send me a new motor/encoder assembly that I can replace myself, and I'll be back enjoying my C14. 



#7 rmollise

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Posted 16 April 2018 - 01:50 PM

Hopefully I'll hear back from Celestron soon. I had numerous issues with another CGE Pro mount that was returned to Celestron five times before they finally replaced it with a new mount, the one I am having problems with now. The deal was that because they swapped the old mount with a brand new one, there would be no warranty on the new mount. This feels like a very bad deal now.

 

My hope is that they will be familiar with the problems and can send me a new motor/encoder assembly that I can replace myself, and I'll be back enjoying my C14. 

 

Frankly, 'twere me, I'd let them fix this one and sell it _immediately_ (making sure to inform the buyer it has been back and what for). Sometimes you just gotta cut your losses. ;)

 

Another consideration is there is currently no telling how much longer the mount will be produced and supported thereafter. My guess is the CGX Pro may spell the end of CGE Pro production.



#8 shootingsta98

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Posted 16 April 2018 - 02:07 PM

That’s what I am thinking, too. 🙁 I just might sell my C14 OTA as well and go with a smaller telescope on a higher quality mount.

#9 George N

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Posted 17 April 2018 - 09:54 PM

Frankly, 'twere me, I'd let them fix this one and sell it _immediately_ (making sure to inform the buyer it has been back and what for). Sometimes you just gotta cut your losses. wink.gif

 

Another consideration is there is currently no telling how much longer the mount will be produced and supported thereafter. My guess is the CGX Pro may spell the end of CGE Pro production.

Just checked - CGE Pro is no longer listed on the Celestron website, either as a 'mount' or as a part of a telescope. I think it has been gone for a while, replaced by the CGX-L. Not sure about support and parts.

 

This is all kinda scary, since I know of two of these mounts holding C-14 EdgeHD scopes at NY 'public observatories'. Such institutions are usually pretty poor - so I doubt that they have a lot of funds to be replacing the mounts. One is a year old, and the other is two - and both work just fine - for now.

 

I have a friend with a CGX-L in his observatory for a year and he is quite happy with it.



#10 rmollise

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Posted 18 April 2018 - 08:55 AM

Just checked - CGE Pro is no longer listed on the Celestron website, either as a 'mount' or as a part of a telescope. I think it has been gone for a while, replaced by the CGX-L. Not sure about support and parts.

 

 

 

The mount is definitely gone from their website, and I suspect you are correct, that it is now gone for good (though I assume their are still mounts in existing dealer stock).


Edited by rmollise, 18 April 2018 - 08:55 AM.

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#11 shootingsta98

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Posted 18 April 2018 - 04:29 PM

My mount fixed itself!  Of course there must be an intermittent problem that has not been identified yet.

 

Celestron asked me to swap cables, power up the mount, and it worked perfectly. Bad cable?? Not so fast, switching the cables back again, the mount still behaved normally.

 

So what could have happened the other day when the RA took off like a bat out hell?

 

Celestron wants me to swap cables back and forth several more times to see what happens. I'm guessing that nothing will happen.

 

Intermittent problems are my least favorite type of problem. I prefer that when something breaks, it stays that way.

 

Bob



#12 DuncanM

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Posted 18 April 2018 - 06:54 PM

My new to me CGE Pro was sent to Celestron by the previous owner, and after testing Celestron replaced the cables and the mount has been good ever since. However the old cables test fine.         



#13 choward94002

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Posted 18 April 2018 - 06:57 PM

The CGE Pro (like the CGE) has connectors that oxidize, especially if they are exposed to the elements ... I hit mine periodically with "DeoxIT" D series [https://www.amazon.c...deoxit d-series] ...


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#14 shootingsta98

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Posted 19 April 2018 - 10:29 AM

Perhaps the issue may have been oxidized connection pins? Seems to work okay now. But is this the more likely cause of a high speed run away motor on the RA? I mean, that think was screaming fast when it happened.

 

I can't help but wonder if there is some other issue that caused this intermittent problem.

 

Did anyone else experience a run away motor that happened once and then went away after detaching and reattaching cables?


Edited by shootingsta98, 19 April 2018 - 10:32 AM.


#15 Maurolico

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Posted 19 April 2018 - 11:27 AM

Did anyone else experience a run away motor that happened once and then went away after detaching and reattaching cables?

Yes, even when detached and reattached. Meade LX600 fork mount. Once we were setting the dome/scope rotation after a critical software update and since the PC restart - while the dome was rotating correctly - the scope didn't move from its vertical home position. So the dome was stopped by software and a bandmate removed the USB cable from PC for then re-insert it. At that point the scope istantaneusly did start in DEC from ALT 90° with incredible velocity that was quitted by hitting the scope's power button. In about 3 seconds, the scope ended at the corrispective ALT of 15°! After the power resume and a new scope alignment (that issue made the scope crossing the meridian in north direction like we were in the southern emisphere, let say, the aperture was looking toward the ground) the problem never happened again, though, and is still unclear what was the cause, whether bad data packet, serial data multiplication or just a static discharge.


Edited by Maurolico, 19 April 2018 - 01:24 PM.


#16 shootingsta98

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Posted 19 April 2018 - 06:26 PM

Celestron asked me to run the mount without a telescope on it several times, each time removing and reinstalling the cables, and trying again. The mount slowed properly every time.

 

Then I put the C14 and the counterweights back on the mount so that the mount could be tested with a heavy load. Again, the mount is working without any issues. 

 

I've reported these results to Celestron to get their take on it. Perhaps it was a faulty connection or oxidation as some have suggested.

 

Thanks to all of you for your suggestions. 

 

Bob



#17 freestar8n

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Posted 20 April 2018 - 03:33 AM

One thing that may help is to use custom rate 9 to reduce the max slew speed, so it never intentionally slews quickly.  If you can tolerate slowing down goto's - it is something to try.

 

Frank



#18 rmollise

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Posted 20 April 2018 - 10:07 AM

My mount fixed itself!  Of course there must be an intermittent problem that has not been identified yet.

 

Celestron asked me to swap cables, power up the mount, and it worked perfectly. Bad cable?? Not so fast, switching the cables back again, the mount still behaved normally.

 

So what could have happened the other day when the RA took off like a bat out hell?

 

Celestron wants me to swap cables back and forth several more times to see what happens. I'm guessing that nothing will happen.

 

Intermittent problems are my least favorite type of problem. I prefer that when something breaks, it stays that way.

 

Bob

 

To me, it's pretty obvious it was a bad connection. As in the connector not making good contact for some reason or the other. Dirt...corrosion...not properly seated. Who knows? Do as Celestron says and monitor the situation thereafter. 

 

When you have these sorts of runaways, cables and connections, as I said, are always suspect. Certainly before you go replacing motors. Contact cleaner is your friend.


Edited by rmollise, 20 April 2018 - 10:08 AM.

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#19 rmollise

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Posted 20 April 2018 - 10:09 AM

One thing that may help is to use custom rate 9 to reduce the max slew speed, so it never intentionally slews quickly.  If you can tolerate slowing down goto's - it is something to try.

 

Frank

 

That will have absolutely no impact on his problem--which is communications with the declination encoder.



#20 Lola Bruce

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Posted 20 April 2018 - 11:30 AM

As Rod stated trying to set a speed limit does not work for this kind of failure. When encoder communication fails the servo control has no idea if it is moving much less how fast.

Bruce



#21 MJB87

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Posted 20 April 2018 - 04:05 PM

Derek at Celestron calls this “ludicrous mode” and it typically indicates a failure in the motor/encoder.  I had it happen after two years. Replaced the motor/encoder and all was fine afterwards.  It is possible to replace the motor yourself. Not too complicated. Just don’t lose any screws.


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#22 freestar8n

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Posted 20 April 2018 - 04:29 PM

That will have absolutely no impact on his problem--which is communications with the declination encoder.

As you can see by MJB87's quote from Derek at Celestron, the cause may be a failure in the motor/encoder itself - and not "communication" with it.

 

I am familiar with the OP's problem and have also had to replace a motor on my cge-pro.

 

When the problem happened, it started to happen regularly - and I found that reducing the max slew speed was beneficial.

 

So my advice to the OP is based on direct experience and a good understanding of the issue described.

 

Frank


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#23 shootingsta98

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Posted Yesterday, 12:11 AM

How much does Celestron charge for a replacement motor/encoder assembly? 



#24 freestar8n

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Posted Yesterday, 12:27 AM

How much does Celestron charge for a replacement motor/encoder assembly? 

I'm afraid it is fairly expensive nowadays.  You would need to ask them.

 

If you saw the very fast motion - it was probably either when first turning the system on, or when doing a goto slew.  I never saw it happen when it was simply tracking at slow speed - which is evidence the encoder is working fine - and that higher speeds trigger the problem.

 

The failure modes for the encoder itself are mainly accumulated dust and debris - and possibly a weakening of the LED.  I don't recommend it - but you can pry open the encoder and look at it - as I did.  It looked pristine - and I was even able to clean the LED and sensor a bit - but all with no benefit.  And the encoder itself is not intended to be replaced.  There is a very tiny, tiny hex grub screw attaching it, and there may also be loctite involved.  I don't think it can be removed and replaced without extraordinary measures - but again I don't think the encoder is the problem.

 

Separate from the encoder, the motor itself has at least one semiconductor element that I believe is the culprit in this situation.  My impression is that the motor lifetime could be extended and the likelihood of a runaway could be decreased - by reducing the max slew rate via custom rate 9.

 

If you do get a new motor, it is fairly easy to exchange it - as mentioned above.

 

If things are working for you now, they may be fine for some time.  And reducing the max slew rate may extend it even further.

 

Frank


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#25 shootingsta98

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Posted Yesterday, 04:27 AM

Frank, thank you for your insight on this matter. I'm going to NEAF today and will stop by the Celestron booth to ask questions about the motor. As I said, my mount is performing normally now, but it is good to know what the problem might be, and how to deal with going forward.

 

Bob




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