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C9.25 mount problem

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#1 ihateclouds

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Posted 30 December 2012 - 10:19 AM

Hi there, I need a little advice here.... I have bought a c9.25 with equatorial mount. The mount has had problems since the beginning, in cold conditions (-10 celsius) it would start slewing and wouldn't stop until I killed the power. I sent it in for repairing (the hand control and mount) and it came back now after 4 months. When I tried it yesterday (this time using a celestron cable and not using my usual powertank) I had exactly the same problem. I contacted the vendor and he is saying that they couldn't replicate the problem at the workshop...... What do I do now? I mean the problem is there!... I have checked connections, battery levels etc... As it stands, down to -5 celsius the mount works fine... colder than that I have massive problems..... this is a fact.... what can I do now? Send it to repair again ??? :bawling:

#2 Midnight Dan

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Posted 30 December 2012 - 11:22 AM

I would speak to the vendor again and focus on the temperature issue. Make sure they duplicate exactly what you're doing. If they're just checking it out in their workshop, then of course it won't fail. Let them know what the temperature has to be, how long you had it outside before it started failing, what you were doing when it failed, etc.

However, before that I would look at your power situation. At that temperature, batteries do get weak and the voltage can drop. When the voltage is insufficient you can get all kinds of crazy behavior like slews that won't stop.

Do you have an AC power adapter you can try instead of the battery? Another option would be to put the battery inside an insulated box (a picnic cooler would work) and put a heating pad inside to keep it warm.

If you try these things and the mount still fails at cold temperatures then it's definitely the mount and you'll need to talk to the vendor again.

-Dan

#3 Bob Griffiths

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Posted 30 December 2012 - 11:29 AM

Set the darn thing up in your living room just to see if it works at room temperature...or if the problem still exists..yu can rule out temperature and start looking at 3 tons of other possible causes...

EXACTLY what mount are you using...

Bob G.

#4 Geo.

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Posted 30 December 2012 - 02:30 PM

Sounds like your HC needs a warmer....

#5 ihateclouds

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Posted 30 December 2012 - 03:48 PM

Hei there! The mount I have is a computerised Advanced GT model CG-5 Equatorial.... Yep, the vendor knows everything. I really made sure to explain the problem, when and how it happens.... it seems weird to me that they weren't able to replicate the problem. They told me it could be a powertank/low voltage problem. I bought an ac adapter (i called it celestron cable before, my bad) and exactly the same happens. ALSO, following advice over here I built a pouch for my HC and I use warming pads but the result is the same.... Everything goes great down to -5 celsius.... problems start at temperatures lower than that... it goes completely slew nuts at -10 and below.... I have this problem and the vendor claims they cannot replicate it.... pretty frustrating

#6 hopskipson

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Posted 30 December 2012 - 06:25 PM

Sounds like a power problem from the behavior of the mount. Is it possible that as the temperature drops the connection shrinks thereby making the connection loose? My friend, you are a real trooper to be out at -10 :bow:

James

#7 Tel

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Posted 30 December 2012 - 06:44 PM

If the vendor can't replicate this problem, can you not suggest, or even insist, he/they replace this particular mount ? After all, presumably he/they must regard this mount to be in a faultless condition from his/their own testing and thus should have no real reason not to exchange it; at least so that you can carry out a comparative test ? :idea:

If the power source is confirmed sound and the hand controller kept well above the -10C ambient temperature while the mount is operational, then I see no other way to resolve this but to try another mount under the same conditions: witnessed if possible by the vendor.

Where incidentally, do you stand with regard to the warranty on this 'scope/mount assembly ?

Best regards,
Tel

#8 Arctic_Eddie

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Posted 30 December 2012 - 07:06 PM

Send the vendor a video of the mount in running and failing mode. Include a view of a thermometer. He can't argue with the evidence.

#9 ihateclouds

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Posted 30 December 2012 - 11:35 PM

Send the vendor a video of the mount in running and failing mode. Include a view of a thermometer. He can't argue with the evidence.


Thanks to all the advice!!! I love this one in particular though... a 30 seconds, uncut video! Maybe they do not trust me but what can they say after they see it with their own eyes?? I'm starting to storyboard now! :foreheadslap:

#10 Arctic_Eddie

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Posted 31 December 2012 - 10:26 AM

Put the video on YouTube so the vendor and Celestron can view it as many times as needed. Thereafter, they cannot claim they lost the email or attached video file.

#11 John O'Grady

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Posted 11 January 2013 - 11:58 PM

You might be able to isolate/characterize the problem a bit further.

Do these uncontrolled slews affect one or both axis?

If its just one axis and it's always the same axis then it might suggest a connection problem somewhere on or between the motor control board to the motors.

Otherwise, if the slewing can occur on either axis then I agree with the earlier posts that its likely a power problem. You'll want to check both the source (i.e. battery) and power at the motor board. I'd actually be tempted to strap a dew heater strip to the panel that covers the motor control boards. Just in case a its a problem on the motor control board, this might help heat the air slightly under the panel and transfer enough heat to the motor control board. If the slewing does not occur with the heater strip in place have a look at the motor control board and if the board was poorly soldered (i.e. cold solder joints or shows other signs of concerns) then I'd ask the vendor to replace the control board. There are other options to using a dew strip but you want to be careful to avoid heating things too much and too quickly.

I don't own a CG-5 but if I did, these are some of the items I'd look at.

Another thought is that if the heater strip does solve the problem, you may be able to avoid the problem just by sheltering the control panel from the wind or by insulating it better. Maybe this is something that you've already tried.

I hope you work it out.

Best Regards,
John

#12 RTLR 12

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Posted 12 January 2013 - 05:15 AM

I have seen this once before and the problem was the MC board. It would only happen at temps below 30ºF. The replacement of the MC board fixed the problem.

Stan






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