开云体育

Thanks, Tom.

Thanks, Brendan. I'll try your suggestions and will search through the forum for more info.

Check the setscrew on the belt pulleys. Check both. They can come loose..?

More inserting circles. Best to do a search of the forum posts like this explain them better

?

滨’ve never used them, yes shame on me. ?

Also forum search for 492 drive issues. ?Info is available from year 2000’ish onwards. ? Most Topics have been covered dozens of times. ?Not fobbing you off it’s just sometimes easier to search. ?

But if you need more info post away

?

cheers

?

--

Brendan

Swap Ra motor drive plug to DEC and visa versa?

?

Since they are the same you need to probably give some DEC commands to see if it moves. ? But since DEC is now Ra it should.?

The motors have gears inside ….sounds like a stripped gear. ?You can take them off and then run them on the bench to make it easier. ?Remember to mark which is Ra and DEC so you can follow your actions?

?

From memory setting circles have a friction grub screw somewhere. ?Which allow you to move it to local Sidereal Ra setting for that date. It’s probably stuck to mount, not to axes. ? 滨’m not really sure. ?I was waiting for someone more knowledgable than me on these matters to post.?

--

Brendan

New owner of a blue GM-100, S/N 0082.

Here's my problem: The RA motor works, and I can see the worm gear turn either direction, but the setting circle never moves.

The Dec motor worked last week, and I could see the belt move. Now it makes a clicky sound but the belt does not move.?

The 492 unit appears to be in solid working order. I have a couple other 492s, so I could swap one out and see if that makes a difference.?

The clutches work smooth and easy with no slop.?

What should I check out next?

You mighty be able to borrow (deposit required) a set like that puller from Advance Auto or Auto Zone.

Hi Bill,

?

Here is the bearing puller kit:

?

?

Just a few taps with the hammer slide will knock out the needle bearings. I wouldn't recommend any other tool as you more likely will start damaging the bearing seats or the end lips with screwdrivers, hammers or other basic shop tools. One tool will fit the needle bearings, and one of the smallest ones will fit the worm bearings (see pics). The new needle bearing should be tapped in gently with a rubber hammer or piece of soft pine so the races don't get dented. Losmandy lubricates these with the Jet-Lube Artic grease, which you can get online or in their bearing relube kit.

?

Good luck,

?

John

--

_____________________________________________________________________________________________________________________________________________________________________________

Losmandy G11G2 on pier; refurbed Losmandy G11 with OnStep controller; SkyShed design roll-off observatory; ZWO ASI2600MM-P; ZWO ASI071MC; Sky-Watcher Esprit 100 ED with field flattener; Celestron C925 Edge HD with 0.7XFR, William Optics Zenithstar 61 APO; PHD2, NINA, Sequence Generator Pro and PixInsight user

Check your DIN cables/Sockets are not failing from slight movement or vibration. ?

?

When I test these I twist and move the cables inside the sockets (gently but firmly), side to side and slightly in/out. ?To ensure I don’t get runaway from either a bad PCB pin joint or bad DIN socket pin to cable (Aka it’s not making good contact). ?Even seen cracked PCB traces from constant removal/insertions. ?

?

Also subject your PCB to a vibration test ….tap the PCB with a small stick all over. ?I use the wood handle of a fitch brush. ?I have seen CPU socket/Pin corrosion that only showed up doing this test. ??

Moisture tends to react with these CPU socket contact fingers and differing metal of the CPU pins itself (galvanic). ?And they are corroding with age and moisture. ? I have seen a few like this.

?

The only fix is vac-desolder the CPU socket, solder a new one in and use a new CPU. ?

Strangely the Pic44C’s sockets and ICs do not suffer from this fate! ?Go figure! ?

滨’m saying some issues like runaway are not just motor related.?

cheers. FWIW

--

Brendan

Thanks for the response.?

Have already checked the encoder seems spotless, cable ok as working with the my original pre SVM servo.?

Have been in contact with Tanya at Losmandy today... hopefully will get this issue sorted.

?

Peter

On Sun, May 18, 2025 at 06:56 AM, Peter wrote:

Has anyone had SVM-HT servo motors that stalls?

During an imaging session a couple of nights ago SGPro failed to platesolve, went out to check & found Gemini1 hand controller indicating a stall... weirdly the motor was running at excessively fast spinning the scope like a windmill while wrapping the power & USB cables around the mount! reset everything but this just kept happening.?

?

I tested the mount next day & all seemed fine, only difference was a higher daytime temperature... next clear night worked fine until a drop in temperature!?

Swapped out the SVM-HT for an original motor I still have & all went well for the rest of the night, think that confirms the SVM-HT has a fault!?

?

Any help with this would be appreciated.

Thanks,?

?

Peter?

?

?

?

?

Could be the cable or the encoder has failed or is dirty.? Do you have a spare longer DEC cable as I tell people to keep on hand for just such occasions?? If not buy one from Losmandy to confirm it is not the cable.? In the meantime you can try to see if the servo motor has any debris in the encoder reader under the metal cover.? You can do a visual inspection and often you will see dust or fuzzy stuff from mites or spiders.? This blocks the optical encoder and you get runaways.? Clear this out carefully and see if it resolves the issue.? If using a known good cable and cleaning the encoder slit fails to fix it AND the servo fails on the other axis using the known good cable the issues is likely the servo board or encoder read head.? Probably should see if Losmandy can help you at that point.??

?

HTH!?

?

--

?

?

?

Closing the loop on this for others.

?

End result fixed most problems. Tasks completed to do that:-

Cleaning and regreasing done and found the Dec/RA motor cogs (under the external covers) were heavy with baked on grease so cleaning them up and regreasing them is a good idea.

Readjusted the Dec worm gear per video a couple of times until I got the backlash under control.

Redid PEC with good results.

Redid PHD2 Guiding Assistant and Calibration assistant - got to an acceptable result but will let it learn for a while also. Once I get a view of the backlash trends I will then tinker with TVC.

?

Thanks all,

Ken

"The needle bearings themselves are like little roller pins, with tiny handles that fit in the races. Some of these were broken off in my G11 after the first 3 years of use. If you get the bearing puller I recommended, you can pop these out quickly.?"

?

John,

?

I'm unable to find your recommendation for the bearing puller. ?Could you please repost it?

?

Thanks,

Bill

Chip, John,

Please take your personal squabbles off-line.?

?

It's been posted here before and I guess it's time to repeat it again: personal attacks are not allowed. If you disagree with someone, post a cogent technical rebuttal, provide supporting technical evidence, or describe your own experience to the contrary. Attacking another member or their credibility is a quick way to lose member privileges.?

?

And to be clear: nobody here speaks for Losmandy except for Scott, his employees and associates. And they are members here, just like you and everyone else.

?

Regards,

?

? -Paul

On Sat, May 17, 2025 at 02:59 PM, Chip Louie wrote:

The rule with bearings here is if the wear is just normal polishing and the shafts are not damaged like galling or wide deep scratches and there is not lip being formed on the shafts there is no reason to replace them.? Clean with solvent, blow dry with shop air and relubricate them.? Scott Losmandy will tell you the same thing for all bearings, this is his advice regarding his mounts.? I would take his advice unless you want to spend money for not good reason or increase the likelihood of bunging up your mount. Regarding the clutch adjustment knob side thrust bearings, again if there is no wear or damage to the rollers or races just clean, dry, relubricate and reinstall them.?

?

Worm bearings are a no brainer as they are cheap to replace and as stated almost impossible to get clean enough once contaminated.? You might want to spend some of the money you just saved by not replacing the needle and thrust bearings on slightly higher precision bearings for the worms bearings.? The standard R4 bearings may contribute to some worm noise.? Pass on expensive ceramics, just buy higher precision stainless steel bearings but don't get too carried away with the tolerance level, they will need to run smoothly in extreme temperature shifts.?

?

Just leave the drive system conversation here.? I think you'll have an audience.? I always find it entertaining to see what people think even if it is often based on conspiracy theories. LOL.

?

Hi Jesse,

?

There are no rules for when or how to replace your bearings. It's all based on what you find when you do your disassembly. Some people here who claim they speak for Mr. Losmandy in fact do not, have not been authorized to do so, nor are they company representatives. You can call their office to verify this. Personally I give no credence to guys who have never posted even one astrophotography shot, or have never shown even a single guide chart that shows the mechanical performance of their mount. It's all armchair astronomy otherwise.

?

If your mount is approaching 30 years old, more than likely you need a full overhaul. The true test of the bearings is not how shiny they look, but what the measured thicknesses are compared to the original parts. If the washer, bearing, washer assembly under the ring gear is not the right height, the worm will not be centered on the ring gear and they will not mesh together correctly. The needle bearings inside the mount are one of the most neglected parts since they are hard to reach, hard to clean, and are not easy to relubricate. The needle bearings themselves are like little roller pins, with tiny handles that fit in the races. Some of these were broken off in my G11 after the first 3 years of use. If you get the bearing puller I recommended, you can pop these out quickly. There is no need for three even though there may be space for the third. The whole set of bearings and washers for the mount is probably a few hundred bucks (not counting tariffs or other increases over the last few years), a minimal cost in the effort of AP. Once you have the mount apart, that is the time to replace these maintenance pieces so you don't have to go fishing for sources of guide errors later.

?

Please send me a PM if you need more help with the OnStep conversion, which outside the general purpose of this forum. You can turn your older mount into a high performance low error machine with a little TLC.

?

CS,

?

John

_____________________________________________________________________________________________________________________________________________________________________________

Losmandy G11G2 on pier; refurbed Losmandy G11 with OnStep controller; SkyShed design roll-off observatory; ZWO ASI2600MM-P; ZWO ASI071MC; Sky-Watcher Esprit 100 ED with field flattener; Celestron C925 Edge HD with 0.7XFR, William Optics Zenithstar 61 APO; PHD2, NINA, Sequence Generator Pro and PixInsight user

On Sun, May 18, 2025 at 10:23 AM, George Cushing wrote:

Pretty sure that the worm wheels are anodized after machining. Lapping will remove that hardened surface that results from that process. So not only is lapping unnecessary, it's to be strongly discouraged.

?

Scott says that too!? ?

?

--

?

?

?

Has anyone had SVM-HT servo motors that stalls?

During an imaging session a couple of nights ago SGPro failed to platesolve, went out to check & found Gemini1 hand controller indicating a stall... weirdly the motor was running at excessively fast spinning the scope like a windmill while wrapping the power & USB cables around the mount! reset everything but this just kept happening.?

?

I tested the mount next day & all seemed fine, only difference was a higher daytime temperature... next clear night worked fine until a drop in temperature!?

Swapped out the SVM-HT for an original motor I still have & all went well for the rest of the night, think that confirms the SVM-HT has a fault!?

?

Any help with this would be appreciated.

Thanks,?

?

Peter?

?

?

?

Forgot to say….that stainless stud looks bent. ? Your standoff looks not square in images

?

You can replace this stud. ?3/16 x16 tpi I think. ?Not sure length. ? Remove one and measure.?

FWIW

?

--

Brendan