Some background. I've previously had trouble with my mount not guiding correctly but about a month ago after taking it apart I noticed the RA axis worm drive was tightened too much. I cleaned, re-greased and made sure everything was tightened correctly. Put it all together and removed any backlash in DEC but didn't bother much with RA as I've heard it's not as important. It worked great after that, I could get around 1"-1.3" RMS guiding pretty consistently. I would have trouble with the calibration failing from time to time as it couldn't move the RA enough but if I retried it would usually work and guiding would be great.

Last night the calibration wouldn't work at all, it would always fail on RA. So I figured the backlash has finally caught up with me and I need to tighten it, which I did. I can barely feel any backlash now, it sounds better and I figured the calibration would be no problem. But it's still causing me problems. I tried again tonight hoping it would be a fluke but it just doesn't work. I was  keeping an eye on the calibration graph tonight and it seemed to me like it would calibrate out but when it came time to calibrate in it would keep going out or perhaps jump around where it was turning around.

I'll give a log from the other night where I did several attempts. I'd love to understand how this is supposed to work, because I would expect that it's trying to move a certain distance out and then in but it'll keep doing moves even if it has seemingly gone far enough out. Keep in mind that sometimes I would touch the mount to see if I could force a movement and get further along in the process but then it could fail on DEC which I never had trouble with.

I would love some help. This feels very discouraging as I'm really looking forward to this season.
It's a Skywatcher NEQ6, rather old but I would say it appears to be in decent condition.
I'm using an Omegon 50/200 guidescope which produces some coma on the stars but I don't think this should be causing trouble.
Then I have the ZWO ASI 120MM-S.

 


 

I can add that I tried doing a calibration using the simulator and I appear to get the same error, it won't do any movement in RA.

I did an update of kstars and my indiserver/drivers not that long ago, maybe a month ago, so I'm wondering if this could be something in the latest software. My kstars stable build is from 2021-07-08.

Can you check your balance, especially on the RA axis?
For whatever reason the pulses can't turn around the RA axis.
You can try larger calibration pulses, but there's likely an underlying problem to solve.

A common issue with using the simulator to calibrate, (something I have done successfully several times),
is that you cannot calibrate nor guide while pointing at the pole.
Please make sure you haven't done that.

Hy
 

I usually have it pretty balanced, with just an indication of wanting to fall in one direction. But I could certainly try again with balance as good as I can get it and with longer pulses as well. 

I'll give the simulator another try in another direction, you're right I was pointing at the pole. This is not what I was doing with the mount though, I've done several attempts in different areas of the sky.

I made another attempt tonight, made sure it wasn't binding, I have a little bit of RA backlash but not a lot. I made sure it was well balanced and tried increasing the pulse duration but nothing really seems to help..

I'm not sure I understand what's happening. Is the RA motor trying to drive in reverse but not able to due to resistance? But wouldn't I hear the motor skipping/stalling if that's the case? I don't feel like backlash is a possible cause here. I did some testing with the hand controller before going out and when setting rate to 2 I can change direction more or less instantly. And it worked before when the backlash was a lot worse.

I was planning to see if I can run PHD2 standalone or some other software to see if I have any similar issue.

- What software version of KStars are you using? 

- can you please send a picture of your calibration options? It is in the guider options. 

- I think it would be a great idea to try calibrating with PHD2. If that does work well, then perhaps you could send a KStars log (with guide debugging turned on) of the calibration failure.

I tried uninstalling kstars and everything tonight and installing the nightly version just to see if there was any difference and there certainly was. Now I can't speak to if this was just from "reinstalling" kstars or if there was something in the nightly version that worked better for me but I got through the calibration no problem even though there was a light layer of clouds. So I'm once again confident that the mount is in good condition.

I was previously running 2.5.4 I believe with a build from the 8th of July. I'll reinstall the stable version and see if I still have any issues and post logs.

Alright, had another go with 3.5.4 stable. I was only able to reproduce it once and got a screenshot of it with my calibration settings. It was the first calibration and any attempt after that seemed to work correctly.
I'll attach a log from when I was running the 3.5.5 beta and then the 3.5.4 stable used after that.

The conditions haven't been excellent here I should say, quite cloudy and on a somewhat unstable floor on my balcony.

Alright, had another go with 3.5.4 stable. I was only able to reproduce it once and got a screenshot of it with my calibration settings. It was the first calibration and any attempt after that seemed to work correctly.
I'll attach a log from when I was running the 3.5.5 beta and then the 3.5.4 stable used after that.

The conditions haven't been excellent here I should say, quite cloudy and on a somewhat unstable floor on my balcony.

  

My HEQ5 does this often right after a meridian flip.
-- RA forward calibration goes in a wrong (opposite) direction,
-- RA reverse calibration then continues to go in the same direction.
-- after the above bad calibration is stopped and restarted - everything goes well.

HTH

Max,

In calibration the scheme first pushes the RA motor West for several iterations, then back East. It then pushed DEC South, then back North. It always does this "dance" the same way.  After a meridian flip the camera has been "rotated upside down" relative to its positioning before the meridian flip. Therefore, you'd should always find that the RA motion for calibration post-flip, as seen on the camera image, to be opposite to that before the flip. 

Of course, this doesn't explain the RA not being able to reverse direction. I am currently attributing that to some unexplained mechanical issue.
If you are suspicious that this indeed a software issue, please compare performance with PHD2
(e.g. if it never happens with PHD2 and regularly happens with Ekos, then we should investigate further).

Hy

Hy,
Yes. RA calibration forward is supposed to go in the opposite direction after the flip (since the camera is upside down).
But for me it often goes the same direction as before the flip.
Then RA reverse keeps going in the same direction.
I reported this before.
It doesn't happen always but often.

Thanks!

Just from curiosity: Is there a specific reason why you don't keep/re-use the calibration? At least during one night's session that should work.
(I'm using my guide calibration for months. My mount is fixed on a pier, though, and the OTA setup is also fixed, I just schlepp it out and put it on the mount. But as I said, as long as your mount has goto and supports pier side reporting one calibration per night should be enough...)