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Gem28 stops tracking with ASIAIR

iOptron GEM28 William Optics Redcat 51 M42 IC434 Troubleshooting
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Borja Serra avatar
Borja Serra avatar
Hello,

I recently acquired a GEM28 and have been using it some nights. I use it with a WO Redcat 51 and ASI533MC-PRO with the ASI120mm and miniguide scope.
I Polar align it, frame, focus, guide and start an autorun session. My problem is that after a few frames (it is pretty random) it stops tracking. I only managed one with no issues. I have been reading a lot around on people having the same issue but have not found anybody providing a solution. These are the things I have done:

- Updated both GEM28 and ASIAIR to the latest firmware
- Make sure I have home and park positions properly set for every session
- I use independent power for both ASIAIR and GEM28. The GEM28 uses the one from Ioptron.
- I tried connecting to the mount over Wifi and USB. Lately only USB (the one provided by Ioptron).
- I checked that cables didn't get stuck around the mount and could cause any issues.

I checked the logs and normally there is no evidence of any issues but one mentioned the mount disconnected. The issue normally occurs after dithering (set to Distance 10px and interval of 3 frames). I did a test of 5h without guiding and it worked without issues. I also must say that my targets have been pretty low on the sky M42 and IC434 (at around max 20deg). I also start tracking right after meridian so no meridian flip needed.

Has anybody experienced similar issues and has found a solution? If I press tracking again it will work but I am not there constantly checking ofc.

Thank you for your help smile
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Number_5 avatar
Number_5 avatar
I have essentially the same setup for my travel package. I did experience this one time and discovered that, while my USB cable looked ok from afar, it had some damage upon closer inspection. In many cases the simple things may be the hardest to detect. I would make sure that you have good quality cables connecting your equipment as a first step.
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Borja Serra avatar
Borja Serra avatar
Thanks for the reply.
I will have a look at all connections. I guess you mean the USB from ASIAIR to Handcontroller?
Number_5 avatar
Number_5 avatar
Borja Serra:
Thanks for the reply.
I will have a look at all connections. I guess you mean the USB from ASIAIR to Handcontroller?

Correct....I mean all connections are worth checking, but the USB from the ASIAIR to the hand controller is what caused my issue.
Dave Ek avatar
Dave Ek avatar
Borja Serra:
Thanks for the reply.
I will have a look at all connections. I guess you mean the USB from ASIAIR to Handcontroller?

Correct....I mean all connections are worth checking, but the USB from the ASIAIR to the hand controller is what caused my issue.

Had the very same problem myself with my GEM28 and a PC. The USB cable between the two was the culprit.
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Mickaelle (kaelig) avatar
Mickaelle (kaelig) avatar
Check the cable and change the USB connection (not the same cable). I have also meet an issue with an intermediate USB hub … I have removed it and replace by a Pegasus one, the issue was solved.
Borja Serra avatar
Borja Serra avatar
BTW do you power the ASIAIR from the USB C or the 12V input?
Number_5 avatar
Number_5 avatar
Borja Serra:
BTW do you power the ASIAIR from the USB C or the 12V input?

12v input, never tried to power via USB C
Mark Germani avatar
Mark Germani avatar
Borja Serra:
I also must say that my targets have been pretty low on the sky M42 and IC434 (at around max 20deg)


I have recently experienced a similar issue with the CEM26, the centre-weighted sibling to your mount, and the ASIAIR Mini. Also, specifically, with low-on-the-horizon targets (IC434). Same gear I always use, the only change has been the target. I haven't touched the firmware (I don't own a PC) but I've got good power supply (both on their own AC adapters) and the cables have always worked well for me. It often happens after I ask the mount to slew to a target, after a random number of good (tracked) subs. It happens over and over and over again. My fix has been to send the telescope to home position, cycle the power on the mount, and slew back to my target. The rest of the session seems to be problem-free after that.

You mentioned that it tends to happen after dithering. Since the mount is slewing (albeit a short distance) when asked to dither, perhaps that's the linking factor. I also dither (every 5 subs - my DEC takes forever to settle!) but I haven't made a connection between dithering and the tracking glitch but it's entirely possible. Maybe slewing at low altitudes is problematic for these mounts, for some reason?

I'll keep watching this topic (I posted one too a while back but had no response). I hope there's an explanation, but until then maybe just cycle the power and see if it holds?

CS,
Mark
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Borja Serra avatar
Borja Serra avatar
Sounds interesting Mark. As of now, I have been powering the ASIAIR through the USB C so I will also upgrade to 12V input power and see if it also makes a difference. I changed to a higher target and increased the exposure of the guide camera to 2s, no issues with that for the whole session. I will keep updating in case that helps later on to other people or others can relate.

Thank you all for your help smile
Mark Germani avatar
Mark Germani avatar
Borja Serra:
I changed to a higher target and increased the exposure of the guide camera to 2s, no issues with that for the whole session.


I really think it's the height of the target... interesting! We should still be able to image lower-altitude targets though, so I hope we find a solution other than cycling the power. My guide camera is a 2s as well.

Powering the ASIAIR with 12v is a good move, regardless - I power my ASI533MC (at -15C) from the ASIAIR (cheeky!) as well as my EAF, and have never had issues, but then I've always powered the ASIAIR with the 12v AC adapter.
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Roy Hagen avatar
Roy Hagen avatar
I`ve had these problems with my GEM28 from a few month after purchase( Dec. 2021) and mostly at objects hanging low. 
I found a sluggishness in the dec. axis caused by tightening the bearings to hard, and this sluggishness made it impossible to balance the telescope good enough, so when dithering in the dec axis the scope either stopped tracking or ran away.
Better balancing made the trick for me
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Dave Ek avatar
Dave Ek avatar
Roy Hagen:
I`ve had these problems with my GEM28 from a few month after purchase( Dec. 2021) and mostly at objects hanging low. 
I found a sluggishness in the dec. axis caused by tightening the bearings to hard, and this sluggishness made it impossible to balance the telescope good enough, so when dithering in the dec axis the scope either stopped tracking or ran away.
Better balancing made the trick for me

@Roy Hagen ​​​​​, what do you mean when you say "tightening the bearings too hard"? Are you referring to the gear meshing adjustments? This problem (the mount stopping tracking for seemingly no reason, and generally poor guiding) continues to plague me.
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Roy Hagen avatar
Roy Hagen avatar
Dave Ek:
Roy Hagen:
I`ve had these problems with my GEM28 from a few month after purchase( Dec. 2021) and mostly at objects hanging low. 
I found a sluggishness in the dec. axis caused by tightening the bearings to hard, and this sluggishness made it impossible to balance the telescope good enough, so when dithering in the dec axis the scope either stopped tracking or ran away.
Better balancing made the trick for me

@Roy Hagen ​​​​​, what do you mean when you say "tightening the bearings too hard"? Are you referring to the gear meshing adjustments? This problem (the mount stopping tracking for seemingly no reason, and generally poor guiding) continues to plague me.

No, the shaft is held inside the dec. housing  by two tiny ball bearings bearings, set in a distance of about 40mm.
At the end of the shaft there is a nut to to tighten the bearings together and  without a spacer between the bearings, it is possible to tighten the bearings to hard axially. I made a quick sketch and took a picture of the nut with my iPhone
Everything is held in the correct position by the nut an the nut is easy to adjust if you can get a pair of straight snap ring pliers.
A bit sloppy and fast drawing, but I hope it is possible to understand,
Dave Ek avatar
Dave Ek avatar
Roy Hagen:
, the shaft is held inside the dec. housing  by two tiny ball bearings bearings, set in a distance of about 40mm.
At the end of the shaft there is a nut to to tighten the bearings together and  without a spacer between the bearings, it is possible to tighten the bearings to hard axially. I made a quick sketch and took a picture of the nut with my iPhone
Everything is held in the correct position by the nut an the nut is easy to adjust if you can get a pair of straight snap ring pliers.
A bit sloppy and fast drawing, but I hope it is possible to understand,


Thanks @Roy Hagen that's helpful.
Rob avatar
Rob avatar
Borja Serra:
Hello,

I recently acquired a GEM28 and have been using it some nights. I use it with a WO Redcat 51 and ASI533MC-PRO with the ASI120mm and miniguide scope.
I Polar align it, frame, focus, guide and start an autorun session. My problem is that after a few frames (it is pretty random) it stops tracking. I only managed one with no issues. I have been reading a lot around on people having the same issue but have not found anybody providing a solution. These are the things I have done:

- Updated both GEM28 and ASIAIR to the latest firmware
- Make sure I have home and park positions properly set for every session
- I use independent power for both ASIAIR and GEM28. The GEM28 uses the one from Ioptron.
- I tried connecting to the mount over Wifi and USB. Lately only USB (the one provided by Ioptron).
- I checked that cables didn't get stuck around the mount and could cause any issues.

I checked the logs and normally there is no evidence of any issues but one mentioned the mount disconnected. The issue normally occurs after dithering (set to Distance 10px and interval of 3 frames). I did a test of 5h without guiding and it worked without issues. I also must say that my targets have been pretty low on the sky M42 and IC434 (at around max 20deg). I also start tracking right after meridian so no meridian flip needed.

Has anybody experienced similar issues and has found a solution? If I press tracking again it will work but I am not there constantly checking ofc.

Thank you for your help

When it stops tracking, are you able to move the mount with the hand controller?
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Borja Serra avatar
Borja Serra avatar
I have not really tried but good point Rob. I just pressed 0 sometimes and it turned the tracker back on.
Adrian avatar
Adrian avatar
Your thread has prompted me to get my CEM25-EC out and try to fault find again. Very similar problems to the above - everything starts of okay and then as the imaging progresses RA tracking faults start to arise. I've stripped the mount and cleaned it thoroughly with no improvement. I also have a problem where the mount and ASIair do not communicate the RA/DEC settings for a given imaging session. Like you I have replaced the battery but GPS performance can still be a bit iffy at times. I am convinced the problem lies in the handset or interconnecting wiring but so far I've had no luck tracking it down.

Support for the CEM25 is pretty much non-existent in the UK. The appointed repair agent doesn't even respond to enquiries. The 8408 is "Unavailable" and when you can find one the price is extortionate - buying one could just represent good money after bad.

Good luck and I will monitor your progress and report anything I find which may be of value/interest.

These two images show the problem:

Tracking starts okay and then stops:


Tracking doesn't start at all:



All a tad frustrating!
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Borja Serra avatar
Borja Serra avatar
Some updates since last time.

I made some changes and have been shooting 6-7 times without any issues, both medium-low and low targets (around 10C). I also tried both the Autorun and Plan modes.

The changes I made were:

- Balance the mount properly, meaning I checked the balance on both RA and DEC so there is no unnecessary strain on those axes. It might be that previously it was slightly unbalanced.
- Now I power the ASIAIR mini with a 12V 7A supply, and the ASIAIR powers the ASI533. The mount always had an independent supply (the one coming with the GEM28).
- Added an autofocuser for the Redcat. Not that it should have any effects on that issue (other than balance) but it is still a difference smile 

I hope it helps other people too smile
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