AM5 guiding issue, random RA instabilities: Page 3

AM5 guiding issue, random RA instabilities

kaelig

Many thanks for the assistance to Optique Unterlinden center for my issues.

Send the mounts in China is not the best solution for everyone.
A local assistance in Europe will be a better solution for you and for us.
Of course in case of big issues, ZWO assistance in China could become necessary.

祝您旅途愉快
Zhù nín lǚtú yúkuài

Support@Seestar

kaelig Thank you for your feedback. We understand that local assistance in Europe would be more convenient for users, and we will take this into consideration.

retman

Support@Seestar This is an excellent response. Thank you!

KHj89YaN

Support@Seestar

Thank you for the detailed response and information. It's much appreciated since I'm trying to keep track of this issue. Is ZWO concerned that this potential problem with motor and harmonics is more widely distributed amongst all AM5N units?

Support@Seestar

KHj89YaN Yes, this is not an isolated case, and we are actively working on a solution.

kaelig

Support@Seestar
Thank you for your reply. Optique Unterlinden seems OK to make the repair if you give the technical informations and the parts to make the job. Perhaps you could collaborate together in order to have a repairing center in Europe.

I was the first in my astronomy club to buy a ZWO mount. Thanks to my result with this mount, several friends has bought one too. I feel responsible towards them. When I write here for a lasting solution in Europe, I do not think about me but I think to them.

it will be a great improvement for the customer service.
It will make the difference with the other companies which sell uname mounts.

KHj89YaN thank you for your participation
@retman thank you for your participation

KHj89YaN

Support@Seestar

Understood.

To refine my question, is ZWO's position that this is a widespread defect/problem that will affect all AM5N mounts that have been sold to the public? Is there a potential for a recall of the product?

Support@Seestar

KHj89YaN
It is unlikely that all AM5N mounts are affected. If the issue is related to software, there is no need for a recall. If it is a hardware problem, it would likely only affect some production batches. We are actively working on a solution for the issue.

KHj89YaN

Support@Seestar

Thank you for this information. Is ZWO under the impression that there is a software issue in tandem with a hardware problem regarding this fault? Is there any timeline currently from ZWO regarding when they will be able to make an announcement regarding AM5Ns and affected models? How widespread is this fault?

Thank you very much for answering all the questions as best as you can. I appreciate it and those who are tracking this problem do as well.

F5146666

o82KUdLn

Good to read that this workaround seems to have worked also for you! (even if just temporary) Please keep us posted how this develops over time on your side.

I also did not have any RA-issues for now since I swapped back my RA harmonic drive (<0.9" total RMS). But I had the advantage that I could spin my drive with a power drill when I had it removed from the mount before installing it back again. As I only collected about 10 hours of guiding since then, I will continue testing and keep sending the PHD2-Logs directly to ZWO for review. Let's see, if the RA-spikes are coming back.

Andreas

kaelig

F5146666

Thank you Andreas for your answer. I do not understand what you have done with the power drill.
I will interested to understand it. If you have a post, I will be interested by the link.
You go further than me in the solutions 😃

F5146666

kaelig

I used a power drill to turn the inner shaft of the RA harmonic drive while holding the outer harmonic drive housing. This way I could run in the harmonic drive more quickly than using it in the mount and turning it over the RA-motor. I didn't make a video or take any photos of this process, sorry!

Hopefully this explained it more clearly.

Andreas

kaelig

F5146666
thank you for your answer. I am not able to do that. Could you explain me why you do that and how it solves the issues.
It is for a better understanding.

F5146666

kaelig

Sure. When I recognized that my RA-motor is snapping back during tracking (I had to let my mount run open, without the cover & side plate to see that), I decided to start my own investigation. I am an aerospace engineer with electronics background and have experience in fault investigations down to the lowest level. When I had everything disassembled I could feel a different breakaway torque and smoothness between the DEC and RA harmonic drive, as soon as the drive belts were removed. This was when I suspected the RA harmonic drive to be the root cause of this issue (and I still do). At this time I was not aware that there might be a wave spring washer inside the drive potentially causing breakaway torque (thanks to the member of CN that gave us this valuable insight). Very small and slow movements are horrible from lubrication perspective. So I thought giving the RA harmonic drive some turns could distribute the lubrication more evenly and probably also move/break up potential debris. But the wave spring washer (if installed at all) would perfectly fit to this failure pattern.
But let's wait and see what ZWO's investigation ultimately concludes. I offered them my help for this investigation and still are.

Andreas

KHj89YaN

F5146666

Indeed, I am also thinking that the wave spring washer is probably the root cause. Depending on where it was procured from, perhaps a different vendor than the original AM5s, that could account for it potentially being machined at a different quality.

Support@Seestar

KHj89YaN
We’re not completely certain, but it’s most likely a hardware issue, since not all mounts are affected.
We are actively testing solutions, so please be patient—there may be results soon.
So far, this issue appears to be limited in scope. Please don’t worry, if any problems are confirmed, we will address them promptly.

KHj89YaN

Support@Seestar

Thank you for the additional details and I will continue to monitor this thread for additional details with requests for updates as 30 day markers pass.

F5146666

YPaWt83D

Good to read that. Thank you for sharing this information!

Support@Seestar

Any update on your investigation?

Andreas

A51O69EE

I'm deeply saddened to report that the same curse has afflicted my AM5n as well. The mount was purchased in February 2025. As of last month, my guiding was phenomenal, allowing 10-minute exposures with no problem. This night (Sep 19), somewhat regular spikes began to appear in the RA axis. The guiding is otherwise perfect, except for periodic huge deviations. The issue temporarily subsided when the mount meriflipped from the east to the west. Nevertheless, as the photographed object progressed to the lower portions of the sky, the spikes re-emerged. I updated the firmware, but the issue persists. Will try to swing the RA axis a few times in each direction at full speed and see what happens.. I'm really disappointed at the moment.

From Slovakia
Drahomír

A51O69EE

Update: I have rotated the RA axis 360 degrees several times in both directions at full speed. So far, the spikes in the RA axis have not emerged (guiding proceeds at 0.6 - 0.7 total RMS; PA was done down to 7" total error). However, I'm not counting on this as the final, reliable solution for the future.

KHj89YaN

A51O69EE

I would recommend sending in a RMA ticket for your mount to simply get it into the queue. Given that the rotation in RA as a temporary solution is just that, temporary, I would proceed with sending in a ticket so that the problem can be documented and counts can be updated.

kaelig

A51O69EE

Hello, I am sorry that you have this issue. The high speed rotation of the RA axis is perhaps the beginning of the solution.
Could you make several nights with guiding and say here if the spikes have completely disappear?
All the experimental results are important.

Thank you for your help

A51O69EE

KHj89YaN Sure, I have prepared an RMA ticket. However, I did not take any screenshots or photos, nor save the guide logs (due to sheer frustration at that time), so right now, I have no attachments to send with the RMA. On the other night (after I had rotated the RA axis several times), I was ready to document the issue, but the guiding was good/ok all night, as well as the next one (i.e., the RA deviations did not occur).

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