Celestron AVX mount RA motor question

[particleastro]

Hello all,

only my second post on here for which I appologise, but I have been reading your site for a few weeks now and this definitely seems the place to ask questions.  If not, please feel free to move/delete.

 

I have got back into Astronomy after a few years out and bought a well looked after AVX with the 8" Newtonian.  Ideal starting point and will be great for the kids in school to use also.  Unfortunately the RA motor seems to have a problem in that it stops and starts of its own accord.  I have attached a video demonstrating the behaviour.  It is accompanied with a stop/start/grinding noise.  It makes this sound with or without load, and as you can hopefully see I even disconnected the actual gear to see if it was an artifact with the motor and not the RA ring gear/worm  gear catching on something.  I have factory reset the handset incase there was some weird PEC on it and tried it on a variety of power supplies and the behaviour is identical at all times.

 

 

 

Two questions, is it the motor, as I suspect it is, and where can I source one?  Ive been onto Tring Astro but unfortunately no reply via email yet.  Just wanted to check it was/is a motor problem before ordering one from the states.  Is the motor gearbox serviceable?

 

Thanks in advance for all your help,

John

VID_20161208_193513.mp4

[Cornelius Varley]

Hard to tell if there is a problem from the video, there is no sound either but they make a noise anyway. The easiest way to find out if there is a problem is to set the mount up and see if it tracks normally.

[particleastro]

Hi Cornelius, 

It definitely doesn't track normally, the image will drift, then the whole scope keeps around and tracks again for a little while before repeating. 

 

The guy I bought it off showed me some images he took and you could see drift in the picture then a jerk into place, just like its exhibiting. 

He had always put it down to I correct alignment but the problem definitely layer with the motor somewhere... 

 

Regards, 

John 

[particleastro]

I stripped everything down yesterday to see if I could get to the bottom of the issue.

 

I filmed another video which clearly shows the behaviour of the motor (you can see the jump at the end of the vid).  Ed from DarkSkies suggested swapping the dec and ra motors over to see if there was any change in behvaiour, and both did it in both ports.  Is there any way to check the signal coming from the board?

 

Regards,John

VID_20161215_202339.mp4

[Marci]

Try re-flashing the firmware with a copy of the latest...

 

[particleastro]

Great idea.

 

Had to wait a couple of days for a USB to Serial adapter, everything updated fine but unfortunately no improvement.  Motor just spins for a while fine, then stops goes back on itself then spins fast.  Its interesting that both the RA and Dec motors are doing the same thing.

 

Regards,

John

[Thalestris24]

Hi

Are the clutches tight and can you move in ra/dec manually without too much effort and with the clutches tightened? If you can, it's possible the clutch pads have worn. Just undo the levers to check.

Louise