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Have I killed my Nexstar SE 6 mount? SOLVED

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#1 Javier Arboleda

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Posted 18 August 2013 - 09:35 AM

Hi mates!

last night I had 2 mistakes in a row... First the DC cord was trapped by rotating base, by the time I realised the problem cord was destroyed, but worse... it kept moving powered by back up (old) batteries and the diagonal hitted the base for a few seconds before I realised this second problem (as I was still shocked by previous one).

After these incidents 3 star alignment was unsuccesful (tried many times). I managed to align using Moon only, but it failed to point anything, I was even unable to get back to the Moon!

I also experienced "no response 17" failure alert several times.

I hope all the problem is just low power (batteries in th base), but it will take a few days till I return home (holidays) and I can try with new power cord from powertank.

My big concern is; may have I damaged the motors, drive gears or any position sensors??? (I am engineer but have no info on system layout). Is there any clutch or other protection system to prevent damage if base is hitted while slewing?

Thank you in advance!! And sorry for my poor English

Javier, from Spain

#2 MikeML

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Posted 18 August 2013 - 10:38 AM

There is a clutch, but tension varies. You probably didn't do any mechanical damage.

#3 Midnight Dan

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Posted 18 August 2013 - 10:56 AM

Hi Javier:

There is a clutch for the altitude axis to protect against the diagonal striking the base. There is no clutch for the azimuth axis but since you did not encounter a hard obstruction in that direction, you're probably ok.

First thing - move the scope forward on the dovetail rail so that the diagonal doesn't hit the base again. Then, I think if you replace the batteries you might be back in business. Let us know how it works out.

Also, there's a "Celestron Nexstar" forum farther down the list with lots of friendly helpful people that share your scope and can offer lots of assistance for these kinds of problems.

-Dan

#4 Javier Arboleda

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Posted 18 August 2013 - 10:56 AM

Thank you Mike,

It moves ok in both axes if I manually press the buttons... so it looks like no damage but yet unable to align or use goto.

How does it sense the position? No feeling gauge or similar that could be damaged?

Gracias!

#5 Midnight Dan

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Posted 18 August 2013 - 11:00 AM

Hi Javier:

Position sensing is only relative to where it is initially aligned, and it is done with an encoder wheel on each motor.

When you start up the mount, it assumes that wherever the mount is currently pointing is zero altitude, and zero azimuth (north). After you perform an alignment, it figures out where it's really pointing, and sets the azimuth and altitude to those coordinates. After that, whenever it moves it uses the encoder wheels to determine how far it has moved from the initial alignment location, and therefore it knows where it is currently pointing.

-Dan

#6 Javier Arboleda

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Posted 18 August 2013 - 11:03 AM

Dan, thank you.

Your reply entered as I was replying to Mike.


Hope you are right, maybe it a good idea to get new batteries... as the new cord will take long (even though I remember the scepe was useless before I bought the powertank, test will hopefully release my panic).

Yes, dovetail rail was moved forward as you said but... last night I used focal reducer, so the "safe gap" desappeared. Afetr the sacare I wont forget again.

Gracias again!

#7 Javier Arboleda

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Posted 18 August 2013 - 11:07 AM

Hi again Dan

Good to know about the posdition calculation!
Its funny how our messages cross the Atlantic as we write!

#8 MikeML

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Posted 18 August 2013 - 11:30 AM

What Dan wrote.

#9 Javier Arboleda

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Posted 18 August 2013 - 06:22 PM

Mike, Dan you were right!

I just tried it with a set of new batteries and it works fine. Either the clutch did a good job or the batteries were too weak to get the gears in trouble.

So I'll spend some money in batteries till I return to Madrid and get my new cord

Dan your recommendation for celestron nexstar forum was excellent, I had a look and learnt many good things as clutch adjustment or how to handle my mount with android tablet... just great

Gracias again!

#10 Midnight Dan

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Posted 18 August 2013 - 07:58 PM

Hi Javier:

Glad to hear you got it working and no damage was done! :waytogo:

-Dan






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