Asiairpro guiding issues, can someone look at my log and provide help?

Jay6879

Equipment --

Star Adventurer Pro 2i

Canon t3i Ha modified

Zenithstar 61ii

Asi 120mm mini

Asi 30F4 guide scope

Ok so for the first month or so that I had the Asiair Pro it worked phenomenally. I could set everything up and go to sleep, let it run the whole night no issues. I do that at least seven or eight times. There have been multiple updates to the AAP since then and I can't figure out if this is a software issue I'm having or it's hardware?

There have been numerous threads and numerous people who have mentioned issues with guiding, especially since the multi star update but it's hard to say for certain if the issue was update related since there are so many hardware combinations out there.

So the other night I was out for around three hours and tried all sorts of different settings and combinations to remedy the issue and I'm hoping I managed to get enough data to be useful. I'm still quite new to all this so I don't fully understand the nuances of what's contained in the guide log so any help is appreciated.

Here is the issue, I will set up calibration (single star or multi star, it doesn't seem to matter) and everything will go fine. I am easily getting 2 minute subs with round stars and could go longer. Unguided it appeared 60 seconds was max with the Zenthstar 61ii before stars went oblong so it is obvious the guiding works. I will get six to seven subs in and the RA guiding goes wild. I've seen it shoot up 50"! The star is completely lost.

My polar alignment through the AAP was showing 2" (!) and throughout the night when checked through plate solving my DEC moved less than 2', I slightly adjusted it once if I remember correctly. Everytime the guiding went wild it was only the RA I needed to adjust so my polar alignment is good I believe.

As the night went on I tried fiddling with different settings in the app, and it showed some improvement with RA numbers. When it was working it tightened up the RA, at times to sub 1". That's good! Unfortunately, like clockwork, six or seven two minute exposures later and boom it would go wild again.

I am so close to just being ready to rock here, my setup and takedown routine is chef kiss. I can use plate solve to find my object in minutes despite no goto. Everything is mint, except I have zero confidence in the guiding now because of these issues. I have to sit and babysit the thing, and it slaughters any exposure time I have. I managed to gather about an hour and a half worth of data in almost three hours because of this nonsense.

I hope I've providing enough information here to help with trying to figure this out, this forum hasn't let me down yet when it has come to my incessant questions since I started last year and I'm hoping I can get some answers on what exactly is happening here! Are there others who are having this issues? I appreciate any help, thanks in advance.

Here is the log...

phd2-guidelog-2021-07-03-232628.txt

361kB

w7ay

Jay6879 I don't fully understand the nuances of what's contained in the guide log

These are your friends:

https://openphdguiding.org/phd2-log-viewer/
https://www.openphdguiding.org/Analyzing_PHD2_Guide_Logs.pdf

Chen

StevenEvan

Hi @Jay6879,

My first thought is that there is mechanical binding happening in the RA mechanism.
It could also be a snagging cable.

Is there any way you can move the RA mechanism by hand, to check for binding?

Steve

Jay6879

StevenEvan

I just checked it by releasing the clutch and slowly turning it by hand. It felt smooth the whole way. Could a binding cable cause something so drastic?

w7ay

Jay6879

This is not your problem: but I see from your PHD2 log that you did not turn the ASIAIR DEC dither off. You might want to turn that off to avoid problems in the future. Your DEC mode appears to be correctly set.

In case there is a bug in ASIAIR that reversed the rotation matrix which associates x-y guide plate with the DEC-RA coordinates, try turning your guide camera angle by 90 degrees (either clockwise or counterclockwise) to see what the guide behavior becomes. Right now, your camera x axis corresponds to your RA axis -- change it so that the camera y axis becomes the RA axis.

You didn't happen to be guiding near the Meridian and happen to reach the Meridian Limit, did you?

Chen

StevenEvan

Jay6879 I just checked it by releasing the clutch and slowly turning it by hand. It felt smooth the whole way. Could a binding cable cause something so drastic?

There are many thing that can cause this type of problem. I'm not familiar with your type of mount, whether the RA torque would be enough to overcome a cable while tracking maybe not, I don't know.

These are just the things I would first check when my mount stalls. For me the last time I saw this type of event it was the the RA drive backlash adjustment being too tight and causing binding.

I found this:
https://youtu.be/ZDYRofBeykI
Describing how to check and adjust the backlash on Star Adventurer. As a first attempt I would check this.

Steve

Jay6879

w7ay

Hmm, I'll double check that dithering is off next time I go out. As for my cameras orientation it has always been setup like this...

You're saying to rotate the camera so the ports are side by side instead of one on top of the other?

And yes, by the end of the log it was getting near the meridian. I appreciate the help.

Jay6879

StevenEvan

Ok so that channel has basically everything I'd need to know on how to maintain the Star Adventurer, thanks for the link! I am going to go ahead and do a process of elimination, I have a new ST4 cable arriving today. I've tweaked and tested a new balancing setup (including adding a bit more weight), I'll check for backlash, I'll be aware of cable snags etc.

Hopefully I'll be able to narrow it down and figure out the issue. Thanks for the help.

w7ay

Jay6879 I have a new ST4 cable arriving today.

Make sure that what you bought is a RJ-12 cable (3 data pairs) instead of the more common RJ-11 cable (2 data pairs) that is use by household telephone connection. The RJ-11 and -12 shares the same physical connector, but RJ-11 uses only 4 of the contacts on the connector.

Strictly speaking, ST-4 is a RJ-12 (ST-4 requires two differential data pairs plus a ground wire), but you often see it colloquially called an RJ-11 connector.

Your calibration data (the first thing in that PHD2 log) showed the ST-4 cable is working. The same set of numbers show that your mount does have a rather high backlash (3.5 pixels) when the RA returned to the home coordinates.

It is still possible for the ST-4 signal that carries the RA+ and RA- signals to break contact when the mount/guide camera are at different orientation (vs gravity). Or for the ground wire itself to break contact. Shining a flashlight into the two connectors should show a row of neatly spaced pins. They are usually idiot proof, although I have seen mistreated RJ-45 connectors with bent connector pins.

Chen

w7ay

Jay6879 You're saying to rotate the camera so the ports are side by side instead of one on top of the other?

Yeah, just as a test when you have run out of options. The PHD2 log might show something we are not seeing today.

And yes, by the end of the log it was getting near the meridian.

Try guiding well away from the Meridian when testing. If the mount reaches the Meridian Limit set in the mount (usually set through the hand controller), most mounts will stop obeying the guide commands from the computer, and ST-4 guide signals too. Keep at least an hour away from the Meridian, in case the Daylight Saving Time bug bites.

Chen

Jay6879

w7ay

The helpful guy at my local telescope ahot is sending me an extra ST4 cable he had laying around, he said they don't sell them anymore so that was cool of him to help me out. I'm under the assumption he knew they were the proper cables.

I have the Star Adventurer, and if the backlash is high that's something I should address using the video @StevenEvan linked above then. I'm concerned that I'll make things worse, but I'll watch the video and see which way to turn it so I can very slightly adjust it.