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CGEM Won't Guide

Celestron equipment
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#1 David Moulton

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Posted 22 August 2019 - 05:50 PM

PHD2 is telling me that my CGEM I mount is not responding to declination pulses. I am definitely not getting good guiding. The star cross test does not produce a cross, just a straight line. I have tried some manual guiding as PHD2 suggests. It seems like it is inconsistent. Sometimes it responds, sometimes not. The attached photo is part of a star test image.

 

I also notice that when I watch the eyepiece, moving in either RA direction is pretty smooth. In the down declination direction, the star moves for a bit and then stalls briefly, and then starts moving again. Up declination seems smooth. I'm not sure what that means. I don't feel like I have a big backlash problem.

 

The mount is carrying a C9.25 and 70mm guidescope. I'm not using a ST-4 cable.

 

I'm not sure where to go at this point. I've been thinking of doing a Hypertune on this mount. Would that help?

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Edited by David Moulton, 22 August 2019 - 05:59 PM.


#2 dcollier

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Posted 30 August 2019 - 09:29 AM

Was this mount work before you tried guiding?  Or is this your first attempt at guiding with this mount? 

 

 -Dave 



#3 Geo.

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Posted 04 September 2019 - 03:27 PM

The dec pause is caused by backlash. That can be tuned by the HBX utilities. Should be covered by the manual.



#4 KLWalsh

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Posted 04 September 2019 - 08:28 PM

PHD2 is telling me that my CGEM I mount is not responding to declination pulses. I am definitely not getting good guiding. The star cross test does not produce a cross, just a straight line. I have tried some manual guiding as PHD2 suggests. It seems like it is inconsistent. Sometimes it responds, sometimes not. The attached photo is part of a star test image.

 

I also notice that when I watch the eyepiece, moving in either RA direction is pretty smooth. In the down declination direction, the star moves for a bit and then stalls briefly, and then starts moving again. Up declination seems smooth. I'm not sure what that means. I don't feel like I have a big backlash problem.

 

The mount is carrying a C9.25 and 70mm guidescope. I'm not using a ST-4 cable.

 

I'm not sure where to go at this point. I've been thinking of doing a Hypertune on this mount. Would that help?

If you’re not using an ST-4 cable, are you running PHD2 with ASCOM? I’m wondering how PHD2 is talking to the mount.

Also, is the scope well balanced in both RA and Dec? If it’s not balanced well, the motors may not be able to provide sufficient torque to overcome the imbalance. And of course, make sure the clutch locks are tight.


Edited by KLWalsh, 04 September 2019 - 08:30 PM.


#5 David Moulton

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Posted 04 September 2019 - 10:48 PM

I have been guiding with this mount for about 2 years and it’s worked fine. PHD can send guide pulses to the mount directly, it doesn’t need an st-4.

A couple of nights ago I switched my handset out for the one I’ve only used on my AVX mount. PHD seemed to be fine after I did that. That handset is a USB, not a serial, so I think maybe my usb to serial converter is the problem. Thinking of buying a usb handset for the cgem.


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