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Gemini Motor Mounting Damage?

James Richards All Messages By This Member #33906 Hi, ? A bit of background first:? ?I have a very old, but faithful, Losmandy G11.? I upgraded to Gemini 2 about a year ago.? Last night I had been successfully autoguiding with PHD2 for a few hours. ? After midnight I executed a go-to to an object in Cassiopeia.? It was nearly overhead.? The mount head collided with the RA motor!? I have NEVER had this happen in many many years of using my G11.?? ? I decided to re-align and did several go-to's to rebuild the model.? All seemed fine.? Slewing seemed fine.? I started autoguiding with PHD2 and RA guiding immediatley went off the chart.? I checked cabling - OK.? I unplugged and replugged the RA cable - OK.? I slewed the RA several times and it seemed fine.? I started PH2 again and RA guiding went off the chart.? Ugh.? ? This morning I visually checked the RA motor and housing - it looks ok.? The mounting seems fine and tight.? I have not taken the RA motor off the mount yet.? I have the feeling that since it slews ok, I won't be able to see anything wrong.? I greatly would appreciate any suggestions before pulling the motor off.? ? Thanks!
Paul Kanevsky All Messages By This Member #33907 Hi James, did you try to run PHD2 guide calibration? That should tell you if the mount is responding to guide commands, and how well. ? Regards, ? ? -Paul ? On Mon, Oct 7, 2024 at 01:10 PM, James Richards wrote: toggle quoted message Show quoted text Hi, ? A bit of background first:? ?I have a very old, but faithful, Losmandy G11.? I upgraded to Gemini 2 about a year ago.? Last night I had been successfully autoguiding with PHD2 for a few hours. ? After midnight I executed a go-to to an object in Cassiopeia.? It was nearly overhead.? The mount head collided with the RA motor!? I have NEVER had this happen in many many years of using my G11.?? ? I decided to re-align and did several go-to's to rebuild the model.? All seemed fine.? Slewing seemed fine.? I started autoguiding with PHD2 and RA guiding immediatley went off the chart.? I checked cabling - OK.? I unplugged and replugged the RA cable - OK.? I slewed the RA several times and it seemed fine.? I started PH2 again and RA guiding went off the chart.? Ugh.? ? This morning I visually checked the RA motor and housing - it looks ok.? The mounting seems fine and tight.? I have not taken the RA motor off the mount yet.? I have the feeling that since it slews ok, I won't be able to see anything wrong.? I greatly would appreciate any suggestions before pulling the motor off.? ? Thanks!
Chip Louie All Messages By This Member #33909 ? James, ? Limits!? Also look for hidden damage.? The servo motor fasteners often damage the gearbox threads and the backing plates of the original G11/GM8 mounts were heat riveted and tended to break or get loose with age and impacts like this which allows the internal gears to behave badly even though you can't see anything.? One of the many used G11 mounts I have owned had this hidden issue and a new gearbox fixed it.?? ? Also if you retained the servo motors and just added a new Gemini 2 controller and HC as I did another potential issue is that some high hour mounts are showing their age with worn commutators and the motors can need replacing.? But this is less likely given that you had a mount strike.?? ? ? -- Chip Louie Chief Daydreamer Imagination Hardware? ? ?Astrospheric - South Pasadena?
James Richards All Messages By This Member #33910 Thanks Paul, ? The PHD2 autoguiding was working near perfectly until this happened.? I had just finished over of hour of imaging a planetary.? When I wrote that RA guiding was a problem, to be clear, there was no RA guiding all.? The RA line was off the chart in two seconds.? So I am unsure if calibration would help in this case.
Paul Kanevsky All Messages By This Member #33911 On Mon, Oct 7, 2024 at 03:55 PM, James Richards wrote: The PHD2 autoguiding was working near perfectly until this happened.? I had just finished over of hour of imaging a planetary.? When I wrote that RA guiding was a problem, to be clear, there was no RA guiding all.? The RA line was off the chart in two seconds.? So I am unsure if calibration would help in this case. The first thing to check is that your Gemini settings are still correct. For example, HC mode should be Photo or All-Speeds, otherwise no guiding will happen. Then, check that you have the correct mount type selected, and after that, that the tracking speed is set to Sidereal. These are all things that will cause guiding (and/or tracking) not to work, while slews and gotos will continue to work fine. If no luck, take off the RA motor off the mount and turn on Gemini, Cold start it. See if the motor starts to slowly rotate. ? Regards, ? ? -Paul
James Richards All Messages By This Member #33912 Thanks Chip, ? My G11 is the CG11, when Losmandy and Celestron combined their product offering way back when.? When I ordered my Gemini 2 also got new servo motors and new gearboxes.? ? I pulled it apart and can't see or feel anything amiss.? The gearbox turns freely.? The gearbox threads seem ok.? I'll reassemble it and perhaps that may fix the problem.? If it doesn't, what do you recommend the next step should be?? A new gearbox?? I wonder, is it possible that it affected the worm? ? James
Chip Louie All Messages By This Member #33914 On Mon, Oct 7, 2024 at 01:43 PM, James Richards wrote: Thanks Chip, ? My G11 is the CG11, when Losmandy and Celestron combined their product offering way back when.? When I ordered my Gemini 2 also got new servo motors and new gearboxes.? ? I pulled it apart and can't see or feel anything amiss.? The gearbox turns freely.? The gearbox threads seem ok.? I'll reassemble it and perhaps that may fix the problem.? If it doesn't, what do you recommend the next step should be?? A new gearbox?? I wonder, is it possible that it affected the worm? ? James Hi James, ? My guess is that it is a coincidence and there is nothing wrong with the actual hardware based on the fact that it slews and GOTOs fine.?? ? Maybe you should look at the system that's NQR.? Have you checked your auto guiding hardware?? If you are piggyback auto guiding maybe the guide scope focus, adjustable rings, focuser or camera was knocked loose?? Check closely, it doesn't take much to knock adjustable rings out of wack or just a little bit loose.? If OAG guiding check focus and confirm the camera is firmly clamped in the focuser or holder.? ? That's all I have without seeing it. Keep us posted and please tell us what actually.fixes the problem.? ? -- Chip Louie Chief Daydreamer Imagination Hardware? ? ?Astrospheric - South Pasadena?

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