Strange problem where DEC starts shooting North

[Derek Fage]

Hi there,

I was doing some testing the other night with my new Askar FRA400 on a Star Adventurer GTI.  All was going reasonably well with guiding then I started having a few problems the weirdest one being the DEC suddenly started shooting North.

Had some other problems that I think may have been due to losing stars, but the DEC shooting up a few times had me confused so I thought I'd see if anybody could help by checking logs.  I've also looked at the debug logs and used GSS analyser to analyse the logs and it flagged up 184 move status 1 count - and I can see move fails I the debug log.

I checked for cable snags etc but couldn't see any.

I've uploaded my log file to https://openphdguiding.org/logs/dl/PHD2_logs_CjsU.zip

Thanks

Derek...

[Bruce Waddington]

I think you definitely have quite a number of problems to sort out here,  I didn't see any guiding sessions that I thought went "reasonably well."  Did you polar align the setup?  But to answer your specific question about run-away Dec, you needed to pay attention to the alert message PHD2 provided:

Alert: PHD2 is not able to make sufficient corrections in Dec.  If the side-of-pier has changed from where you last calibrated, check to see if the 'Reverse Dec output option' on the Advanced Dialog guiding tab is wrong. If so, fix it and recalibrate.  Otherwise, check for cable snags, try re-doing your calibration, and check for problems with the mount mechanics.

You calibrated on the east side of the pier and the runaway Dec started when you went to the west side of the pier.  You need to set the option to 'Reverse Dec output after meridian flip' - that's on the Guiding tab of Advanced Settings.  

Bruce

[Derek Fage]

Thanks Bruce,

It was polar aligned to about 5’ as I know I’ve got bad DEC backlash and one of your videos said that 5-10 could be helpful in these situations.

I’ve since set the reverse dec output after meridian flip as I did see that as when it started getting worse (even chatGPT told me to do that - should have tried that earlier).

This was definitely the worst session I’ve had (I’m a newbie) and it was the first where I had a meridian flip whilst imaging (I’d done some to just test it would flip and not catch anything in my setup) and thought the calibration went OK.

When I said reasonably well I was watching guiding graph that seemed to have error around 1.7 which seemed reasonably consistent until things started going a bit haywire but revisiting this using PHD2 log viewer graphs doesn’t look great.  Wierdly, the good subs I ended up with (and there were not a lot) seems to show round stars.

Happy with any other suggestions as I wait for clear skies again.  Next session I’ll focus on guiding and going through a meridian flip now I’ve made that change to see how it goes...

Thanks for your help (and videos!)

Derek…

Sent from my iPad

On 25 Apr 2026, at 17:13, Bruce Waddington <bw_m...@earthlink.net> wrote:



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