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CGE exorcised & exercised

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#1 MadBulgarian

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Posted 21 March 2009 - 03:29 PM

A while back on the CAT forum I flamed Celestron a bit (well, a lot) about a CGE-1100 that kept spinning its DEC axis like that little girl in The Exorcist.

I'll spare you the gory details and the pea-soup graemlin because the whole thing is now fixed, thanks to the generous help I received on this board.

The problem was in the connection between the Dec cable and the RJ45 plug on the Dec motor housing. This connection experiences twisting forces as the RA axis turns. The Cat 5 Dec cable, being cylindrical and stiff, resists the torsion enough that the wire contacts inside the RJ45 plug become intermittent.

A whole boatload of seemingly random problems ensue. The thing starts behaving like a demon. (I swear I had a girlfriend in college like that - sweet & innocent one moment, and hurling lightning bolts the next...)

I suspected bad cables from the beginning, but after going through a pile of cables from different sources I couldn't be sure - the problems persisted. What solved it was David Pavlich's link to a site that sells flat cables. The flat cables flex with the movement of the RA axis, and keep their contact better. Thanks, guys!

And check out this Saturn from two nights ago!

Tony

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#2 Dan G

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Posted 21 March 2009 - 05:09 PM

Tony -

Glad you resolved the issues. I enjoyed my CGE a great deal. The shot of Saturn is awesome!!

Dan in NY

#3 David Pavlich

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Posted 21 March 2009 - 05:35 PM

Hey Tony! That's terrific. I knew that we'd get through it eventually. Like I said, 90+% of the problems with a CGE involve the Dec cable/socket combination. Good form, all 'round.

David

#4 Buzzer

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Posted 21 March 2009 - 09:41 PM

Dave, Way to go finding these cables. It happen to me Friday night. I was trying to do a flip on M-82 and just as the scope started to slow down, it went 90 MPH in the wrong direction. I just ordered some 2' cables and hope that is the end of that. Good looking out, Andy

#5 David Pavlich

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Posted 21 March 2009 - 09:46 PM

Dave, Way to go finding these cables. It happen to me Friday night. I was trying to do a flip on M-82 and just as the scope started to slow down, it went 90 MPH in the wrong direction. I just ordered some 2' cables and hope that is the end of that. Good looking out, Andy


Hey Andy....I'd like to take credit for the cables, but CN's own Marty T is the one that found them (now known as Marty cables :grin:). I was just the messenger. But I had such good luck with them, I'm always really happy when I can pass along my good fortune.

David

#6 Alph

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Posted 22 March 2009 - 12:59 AM

What solved it was David Pavlich's link to a site that sells flat cables.



I am afraid your problem is not solved. It will come back sooner or later. Many folks reported problems with the miracle cables. If you really want to solve the problem, think about the RJ45 connectors not cables.

#7 David Pavlich

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Posted 22 March 2009 - 11:18 AM

What solved it was David Pavlich's link to a site that sells flat cables.



I am afraid your problem is not solved. It will come back sooner or later. Many folks reported problems with the miracle cables. If you really want to solve the problem, think about the RJ45 connectors not cables.


Alph could be correct. As I've shown in my little turorial, I replaced the Dec socket board. Time will tell if the socket has been compromised by the inherent stresses place on it by the stiffer cables.

David

#8 MadBulgarian

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Posted 25 March 2009 - 02:32 AM

Of course, you are right. The CGE is now worse than ever...

After exhaustive testing with the new cables (indoors, during the day) it now refuses to keep still. It jerks and loses alignment, refuses to move the RA axis, and generally behaves like before - just more randomly.

Question: Who do I write to at Celestron? The regular channels are worthless - it takes them a week to reply (when their site is not down) and clearly they are incapable of fixing the problem.

Who has had experience getting Celestron to pay attention?

Your help is much appreciated.

#9 Arbacia

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Posted 25 March 2009 - 03:30 AM

I use a very flexible round serial cable (9 wires + shield) and used shielded RJ45 conectors, the 9th wire was solded to the rj45 shield.

To secure a proper contact, I use the point of a knife to open a little bit the lateral sides of the RJ45 shield

Finally I used some autoadhesive cable clamps (double side 3M tape) to fix the cables securely to differnent parts of the mount. For each cable one clamp on the cylinder base and other the motor chassis. For the DEC cable I use an aditional clamp fixed on the lateral of the AR Axis box (lateral to where the polar finder is attached).

Adjustable Self-Adhesive Cable Clamps:
http://www.maplin.co...?ModuleNo=26845

Other:
http://www.icorally.com/wire-cable.htm

#10 MadBulgarian

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Posted 25 March 2009 - 04:07 AM

Aha! That's what I was looking for.

Now the question is whether to just open up the stinkin' thing and fix it - this shouldn't be brain surgery here - or trust Celestron to fix it again.

Hmmmm. Let me think a moment about this...

:roflmao:
MMMM...BBBWWAAAAAHAHAHAHAHAHAHAHAHAHAHAHAHAHA!!
(Did I just use the words "Celestron" and "trust" in the same sentence??)

Arbacia - thanks for the pointers. I was just back outside securing the cables so they don't move as much... just like you said. The big problems occur when the hand control spiral phone cord touches one of the Cat 5 cables.

I'll try the RJ45obotomy next.

#11 Strgazr27

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Posted 25 March 2009 - 06:49 AM

Although I'm sorry to hear the problem has returned, flaming Celestron again will likely only get your post moderated. There are more than a few members who have had nothing but praise for Celestron and it's CS, myself included. I know that Dave P. recently recieved a replacement DEC board from Celestron. Perhaps you should drop him a PM to see who he contacted. If I remember correctly, it was an easy transaction between him and Celestron.

FWIW, I've had 3 CGE's and never had an issue with cables. Buzzer (My best astrobud) is waiting for his set of cables to show up.

#12 David Pavlich

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Posted 25 March 2009 - 08:40 AM

Aha! That's what I was looking for.

Now the question is whether to just open up the stinkin' thing and fix it - this shouldn't be brain surgery here - or trust Celestron to fix it again.

Hmmmm. Let me think a moment about this...

:roflmao:
MMMM...BBBWWAAAAAHAHAHAHAHAHAHAHAHAHAHAHAHAHA!!
(Did I just use the words "Celestron" and "trust" in the same sentence??)

Arbacia - thanks for the pointers. I was just back outside securing the cables so they don't move as much... just like you said. The big problems occur when the hand control spiral phone cord touches one of the Cat 5 cables.

I'll try the RJ45obotomy next.


My educated guess tells me that your Dec axis socket is compromised because of the stresses of the stock cable. Here's what I did to cure it.

Take a screen shot of board, email Celestron and include the picture and tell them you need one of these. There's 2 wires to solder. It's a pretty simple fix.

David

#13 Chris Rowland

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Posted 25 March 2009 - 12:44 PM

I'm a little surprised that some enterprising person isn't selling a replacement circuit board that has a better 9 pin plug on it.

Chris

#14 Bowmoreman

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Posted 25 March 2009 - 02:08 PM

Dave, Way to go finding these cables. It happen to me Friday night. I was trying to do a flip on M-82 and just as the scope started to slow down, it went 90 MPH in the wrong direction. I just ordered some 2' cables and hope that is the end of that. Good looking out, Andy


Hey Andy....I'd like to take credit for the cables, but CN's own Marty T is the one that found them (now known as Marty cables :grin:). I was just the messenger. But I had such good luck with them, I'm always really happy when I can pass along my good fortune.

David


As have I, "Marty's cables" (from VPI) have saved my bacon... in my obs, when it got colder than about 5C the stock cables would get so stiff that they'd cause intermittent contact and I'd lose tracking... drove me NUTS..

got 2 each of the 2' and 3' flat cables from VPI (I like having backups and options) for a total of (as I recall) $15 shipped...

Never had a problem since...

Anyone with a CGE should just do this... its cheap and works and they are seriously flexible compared to stock.

clear enough skies

#15 Arbacia

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Posted 25 March 2009 - 06:21 PM

MadBulgarian,
For the hand control cable... use an extension phone cable of six wires (6p6c). Those of 4 wires do not work properly. I am using permanetly a 6m phone extension cable.

Bowmoreman,
I agree that the Marty's cables should be a cheap solution, but in the States. I must pay a lot for shipping to Europe. On the other hand, I got the solution with material that I had at home.

Cheers,
Patricio

#16 Alph

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Posted 25 March 2009 - 06:40 PM

I agree that the Marty's cables should be a cheap solution,


Hmmm... Have you guys been smoking something? MadBulgarian just reported that the Marty's cables did not work for him.

#17 Arbacia

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Posted 26 March 2009 - 01:50 AM

I agree that the Marty's cables should be a cheap solution,


Hmmm... Have you guys been smoking something? MadBulgarian just reported that the Marty's cables did not work for him.



Alph, read my previous message. The anterior to the quoted. :grin:

Something about clamps and 9 wire round cable



Madbulgarian,

Have you try that?:

To secure a proper contact, I use the point of a knife to open a little bit the lateral sides of the RJ45 shield

Use also the phone extension cable and the hand control spiral chord never will touch the DEC/AR cables.

Moreover, I use the clamps near the conectors

#18 Bowmoreman

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Posted 26 March 2009 - 10:51 AM

I agree that the Marty's cables should be a cheap solution,


Hmmm... Have you guys been smoking something? MadBulgarian just reported that the Marty's cables did not work for him.


there are TWO different problems here, the "Marty's cables" only address one of them.

They address the "you really need a flexible cable that will not bind up, including especially in the cold". That non-flexibility, over time, puts strain on the socket, ultimately leading to non and/or intermittent contact.

Once THAT occurs, adding flexible cables can't solve the problem. only ensuring tight connection can solve that aspect.

But again, if you don't ALSO get flexible cables, fixing the socket will only, ultimately, have the same problem recur, because the "root cause" hasn't been addressed...

Apparently I (and many others it seems) have caught it "in time" with the addition of flexible cables and apparently not (yet) suffered the loosening of the sockets/contacts.

Note: this is my THEORY, but as an ex Electrical Engineer it first the data points that I've seen first hand, and heard second hand...

The REAL root cause is a bad design, but fixing that requires far more drastic steps on our parts! So, we're left with next best.

I'd recommend everyone who has a CGE to replace with these (or equivalent) flexible cables BEFORE they have the problem. It is cheap preventative medicine, does NOT damage, and in many cases solves the problem if already experiencing it.

clear enough skies






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