Hello All,

I recently joined here and have been gathering and learning a lot.?
I have been fortunate to acquire a GM8 with the 492 direct drive unit and an extension installed between the tripod and the head.?

Does anyone know what size Allen key is needed to disassemble the bolts?

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Pete?

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Hmm, even new mounts get the blues. You sound like an experienced imager and have successfully used much of the same gear across different mounts and the DEC issue has remained with the Losmandy regardless of control system so most likely the issue is with the mount. I'm a long time Lomandy user and after you filter out new user error and old user error of Gemini 2 controller settings in apps that Gemini 2 is unhappy about one of the remaining common issues reported with Losmandy mounts is a slow responding DEC axis.?

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I can't say how other people have resolved this - they almost never report how things are resolved - but I know the Losmandy mount mechanics and if your DEC axis has minimal backlash the only place to look is the drivetrain between the servo motor and the end of the worm shaft. This is to say check the gearbox and the Oldham coupler grub screws.??

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P.S. Also note that if you have round solid edged stars don't worry about it until that hard edged look goes away.?

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Thanks Brendan. I will look into doing that - much better to keep everything within the same socket!

Cheers

Nick

Also note that all of the gear involved beyond the mount has been used on five other mounts by three other manufacturers without these issues. The AM5 and Phd2 gave me errors below 0.20! For hours. I realize how well something plays with Phd2 is not simple. This was just as bad with the Asiair, though I imagine they are using Phd2's code.

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I'm trying to eliminate everything I can. I am thinking of finding other software to try, though who else does guiding?

The guidescope is mounted to a rail bolted to the rings. Seems very solid. I have checked everything repeatedly. I have tried three guidescopes and three guide cameras. I have taken everything down then set it up again. The mount couldn't be more level. I used a machinist's level on the tripod where the mount attaches.

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This is about 17ish pounds of payload, a fairly short and fast f 3.8 100mm astrograph. I am pretty careful about balance.

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But yeah there can't be as much backlash as Phd2 claims. I do not feel any play in the dec plate and the worm cover moves just a wee bit as it should due to the spring. I wondered if the standoff screw is in too far. I took the cover off the motor and turned the spur gears and they seem to have a bit of drag on them and no backlash play. I will run the guide assistant a few more times and see what I get. Try various parts of the sky.

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Maybe it just needs to be broken in or something? Will be interesting to see what Losmandy says. I put a fair bit of time the last three nights working on this. Meanwhile trying to learn how to use drift alignment and Pempro. I'm used to Software Bisque's stuff. Speaking of which, I will run a few automatic TPoint models on the G11 tonight. Slewing to a 100 targets should wear in everything nicely. :)

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Might be the gearbox has the older heat welded rivets and they are broken or loose? Of these are the gearboxes with screws they can be tightened unless the are stripped. In any case you don't want the servo motors loose as this can cause tracking issues.?

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Sounds like some disassembly is required to determine what is allowing the looseness. If the OP has the old plastic rivet gear boxes and they are damaged my suggestion is to replace both gear boxes to avoid this in the near future.?

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Keep us posted.?

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Hey Ed,

For comparison, my DEC backlash (G11G with 40lb 10" newt) is generally between 1500 and 3300 as measured by PHD2 guiding assistant. I believe you mentioned that it was a fairly new mount. If you had it shipped to you the jostling may have loosened the spring loaded worm settings or you might have some play between your scope and guiding apparatus.

Can you feel any play in the DEC axis when the clutches are tightened down and you wiggle the axis back and forth?
How tight do you have the clutches?

Are you using an OAG or a guidescope??

Are all connections in your imaging train nice and stable with no play?

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Ryan

Using Phd2's guide assistant last night, it appears that my mount's dec backlash is fairly bad? I am contacting Losmandy as this mount is only a week old. Please let me know if this is simply normal for this mount.

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On Mon, Jul 29, 2024 at 03:26 PM, David Woolf wrote:

Bought a used G-11 and the RA Motor is very loose.? It still drives the gears in the gearbox, but I'm concerned.? Mounting screws seem tight.? Any fix for this?

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I just want to check. ?You said screws tight! ?When the Gearbox threads wear the screws font tighten properly so you have me Intrigued. ?

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What ver Gemini and G11 is this? Some of the older original motors had a front plastic flange that interfered with fitting. ?Sometimes !

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Maybe a video or pics of the issue might help. ??

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Brendan

Trying again tonight and having the same trouble using Nina and phd2. Have checked everything I think that matters, including the guide rate on the mount and all the particulars about the camera and the guide, scope, etc. I’ve tried calibrating over by the celestial equator and at the targets practicing with. The latest one looks a bit better, but there’s still in dec A lot of spikes have about eight minutes or more. I’m sure the amount is tracking fine without guiding. I have recorded images at 120 seconds with no guiding and they look reasonably good. I believe I have a good polar alignment tonight.

I can’t help. There’s some simple thing. I’ve got wrong here and I haven’t been able to figure it out. I did follow any other beginner guides I could find, including the one on the Losmandy website from 2017.?

David see here

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The motor screws into Plastic gearbox lands and these wear out.?? You maybe able to plastic weld it (or even some sort of glue to fix the threads) or Put in a new gearbox.?? But the above link explains it all

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Cheers

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Brendan

Hi Nick...looks good...one thing I'd do... cut the autoguider alarm cct on pin 1 of the Losmandy.?? That is Cut the PCB trace to it.?? Wire a GND jumper to pin 1.?? See cct.

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Makes it easier to get all signals and voltages from the one socket ST4.?? Sure its not standard but its for you it wont damage anything.

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FWIW....well done

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cheers

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Brendan

Hi Michael,

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To answer your question, as I understand it, I can connect my ZWO camera USB port to my computer USB and the camera autoguiding port to the Gemini (via an inverter). I can then use PHD2 to control the guiding. I think there is an 'On Camera' option in PHD2 to allow the guiding signals to be sent back to the camera which relays them out it's autoguiding port (?). I'm a total beginner on this, so please tell me if I'm wrong.

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I seem to remember somewhere that you can drive the mount's autoguiding direct from the computer, but to me this sounds more complicated since I have to convert a USB signal to my mount. Maybe that can do that later on when I have more knowledge and if there is an advantage.

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I've tried out the attached circuit on a breadboard and it seems to work for the method I have in mind. The only 'problem' is to bring out a 0V line from the Gemini to connect all the emitters on the camera port.

Bought a used G-11 and the RA Motor is very loose.? It still drives the gears in the gearbox, but I'm concerned.? Mounting screws seem tight.? Any fix for this?

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Dave

Sorry, forgot to mention a you can use to learn the hand controller. It’s an interactive HC of sorts so give it a try as well

You can set the scope in any position you deem necessary and set that as your home position. At the end of your session you just park at home position and then, on your next session, you can use warm restart.

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To set up home position star in counterweight down, scope pointing north, slew your scope to your preferred position and, from your HC select Menu->Park->Set home position

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When done for the night go to Menu->Park->Park at home position

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Keeping your scope at CWD should not be a problem as the CG is forward of the mount towards the front (north) facing leg of the tripod. The mount/tripod/scope is not going to tip over the fence on your balcony even if you accidentally trip on it :). However, using the home position is a viable option if you want to use it, it is there for a reason after all :)

Thanks for the advice.

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1. they seem fine. The first few I did with the atlas in the Asiair app were off a little, then after synchronizing those they got very close.

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2. I am pretty sure the speed is correct. The hand controller reports guiding speed during guiding and with guiding off, I can take about 60 second exposures with reasonably good results.

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I am also reading up on Pempro today and I think I will give that a try as well. I love the ProTrack feature in TheSky and from what I read, Pempro is at least that good.

Thanks Greg and Brendan

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I'm now going through the instructions and looked last night at the HC.

If I do a Warm Restart - level the scope either N or S and Set Home Position - do I lose the Park at CWD option?

Having the OTA level so high up from ground level just eases my mind a little.

I plan? on Lunar visual first, while continuing my education on this. Then some photography - Lunar and Planetary.

I admit to being confused over the East/West models - even more as I have no views of pure E or W.

Have to reread.

Will I lose much by having the OTA level for Lunar and Planetary and starting from there?

Please bear with my ignorance.

Dave