Calibration issue

[Eric Mong]

Hello, 

I have some difficulties to calibrate my EQ8R-Pro, It is quite impossible to calibrate it properly, it barely works when I calibrate west side but not at all in east side. 

last night it also failed to measure backlash cause the mount doesn't go south ! 2 days ago I succeded to mesure backlash, it was about 11 000 ms !

I have this problem since a couple a week.

The last night log  : https://openphdguiding.org/logs/dl/PHD2_logs_Ty2M.zip 

Thanks for your help

Eric Mong

[Bruce Waddington]

Hi Eric.  I think you've got a pretty severe cable-routing problem when the scope is on the east side of the pier pointing slightly west of the central meridian.  Here's why I think that:

One bad calibration was done at an hour angle of 0.05 (0.05 hours west of the central meridian):

In all of these RA is red, Dec is green.  You can see the Dec moves got started reasonably well but then the Dec movement was clearly disrupted.  The next example was done at an hour angle of 0.11:

The problem is equally severe although it looks like it eventually cleared and the Dec axis got moving again.  The final example was done at an hour angle of 0.26:

This looks like a fairly normal result for your mount.  So the first thing to do is to slew the scope back to the failing positions and look for something that is binding or pulling.

Good luck,

Bruce

[Eric Mong]

Thanks for the analysis, 

I really do not undestand wich cable is involved, on EQ8R I suppose that only 2 cables can be a problem power and control and both are fine !

If I calibrate west of the meridian it's really weird 

But west is OK

The complete log is here : https://openphdguiding.org/logs/dl/PHD2_logs_nu5S.zip

If you have any clue 

Regards 

Eric

[Brian Valente]

Eric 

It's not specific to any one cable. The point is the original results show something is getting in the way of your mount moving properly at certain locations

Can you also post a few pictures of your setup from different angles. I'm not sure which calibration this unguided result below came from, but you can see the dec (red) is being influenced by your RA's periodic error. That can mean your guiding setup has moved and compromised your calibration.

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Brian 

Brian Valente

astronomy portfolio https://www.astrobin.com/users/bvalente/ 

[Eric Mong]

Thanks Brian, 

Some picture of my setup from different angles :