Skywatcher Az GoTo - Intermittent "slow down"

[AdeyG]

Hi Mike,

I am a maintenance engineer for a Tape manufacturing company and one of our suppliers for bearings and transmission parts got them for me,

I think they were between £5-10 each ( i can't remember sorry!)

They need to be quite a low stack height, if i remember correctly it's about 5mm.

Clear skies

Edited October 19, 2010 by AdeyG

[MikeWilson]

I'm hoping my issues are now resolved as FedEx came to collect it today. Hope the Synta distributor can reproduce the fault and fix it.

[AdeyG]

Hope you get it sorted soon!

Clear skies

[Trevor-Austin]

Are FLO good with sorting out issues with these? Seriously thinking of getting 1, anyone changed the tripod or is it even possible?

[MikeWilson]

Hi Trevor,

FLO are very good with sorting out these issues. The first Mak they sent me had dust inside the collector plate. They sent a new one out to me pretty quickly (within a few days). The mount they organised for collection next day. Fresh brand new OTA arrived after my holiday (I took the old one with me). I'm not sure what's going to happen now re: my mount, I guess it will be fixed and returned to me by the upstream distributor.

@AdeyG - thanks! Me too!

[Trevor-Austin]

Great thanks, heard a lot of good things about them. If I go new think that's my source.

[MikeWilson]

Since starting this hobby last July I've gone with FLO for most things. Some things I have even found marginally cheaper elsewhere but while the service from FLO is maintained this good, I'll stick with them where I can.

[Trevor-Austin]

yep, think I/m convinced, now what to get

[Leems]

I've just fixed mine I took the motor out split the motor off the gearbox split the gearbox and washed the grease off with silicone lube then re greased with new and it now works perfectly fine

[Baffa]

My Celestron SLT mount have it's Az motor die twice on me, both started with the slowdowns and then they just ceased to function after some use. I haven't bothered fixing it the second time, I bought a NEQ6 instead

[Leems]

I've just fixed mine I took the motor out split the motor off the gearbox split the gearbox and washed the grease off with silicone lube then re greased with new and it now works perfectly fine

Turns out only worked for an hour now the same has to be the motor only had it a week bought second hand so I'm stuffed does anyone know we're I could get a new motor

[kilix]

Hey guys,

Sorry for necroing this old thread, but I figured, that it may become useful for someone like me, who faces the same problems with quirky movement of alt motor of a SkyWatcher AZ GoTo mount. So, I've read pretty much everything on the internet regarding this issue, nothing helped, what I did is this:
Disassembled everything, took out the motor+gearbox assembly. Tried to run it, motor running slowly still. So, next logical step is to remove the gearbox and search for culprit there. I did that, you don't need to worry about not being able to assemble the gearbox again. It contains about 6 gears, there is literally no possibility to assemble it wrong, those gears wont fit any other way. They will only fit the way they are supposed to be. Be careful though, there is one infinitesmall washer on the last bronze gear, don't lose it like I did and then I searched for it for 2 hours.
So with the gearbox out of the way, only the motor + pinion remained. Tried to run it, still no improvement.
Last thing to try is to disassemble the motor.
Careful here, it's almost like clockwork. Brush holders are thin like matches, carbon brushes are about 1x1x3mm big, which is not big at all. The retaining springs are made of some nice material, looks like gold coated maybe, but they are really small and can jump out during disassembly.
Here is the the motor, you can see the really tiny brushes in right-center:

 

and as you can see on this photo:

 

the commutator is covered with schmoo. So I cleaned the commutator, brush holders and brushes with tetrachloroethylene, then I applied contact spray. The commutator+brushes are shiny like new. Assembled the motor, BAM, it runs crazy fast and steady.

Apparently, the grease from gearbox entered the motor and fouled the commutator+brushes. So, next logical step is to remove all the grease from the gearbox, replace it with sane amount of nice vaseline and assemble everything back together. I also recommend removing the cheap grease from the huge aluminium gear and teflon pads and replacing it with some more useful lubricant.

Edited January 15, 2017 by kilix
typing errors

[happy-kat]

Good read. You've probably got a spare motor now have you cleaned your original as well?

[Knighty2112]

2 hours ago, kilix said:

Hey guys,

Sorry for necroing this old thread, but I figured, that it may become useful for someone like me, who faces the same problems with quirky movement of alt motor of a SkyWatcher AZ GoTo mount. So, I've read pretty much everything on the internet regarding this issue, nothing helped, what I did is this:
Disassembled everything, took out the motor+gearbox assembly. Tried to run it, motor running slowly still. So, next logical step is to remove the gearbox and search for culprit there. I did that, you don't need to worry about not being able to assemble the gearbox again. It contains about 6 gears, there is literally no possibility to assemble it wrong, those gears wont fit any other way. They will only fit the way they are supposed to be. Be careful though, there is one infinitesmall washer on the last bronze gear, don't lose it like I did and then I searched for it for 2 hours.
So with the gearbox out of the way, only the motor + pinion remained. Tried to run it, still no improvement.
Last thing to try is to disassemble the motor.
Careful here, it's almost like clockwork. Brush holders are thin like matches, carbon brushes are about 1x1x3mm big, which is not big at all. The retaining springs are made of some nice material, looks like gold coated maybe, but they are really small and can jump out during disassembly.
Here is the the motor, you can see the really tiny brushes in right-center:

 

and as you can see on this photo:

 

the commutator is covered with schmoo. So I cleaned the commutator, brush holders and brushes with tetrachloroethylene, then I applied contact spray. The commutator+brushes are shiny like new. Assembled the motor, BAM, it runs crazy fast and steady.

Apparently, the grease from gearbox entered the motor and fouled the commutator+brushes. So, next logical step is to remove all the grease from the gearbox, replace it with sane amount of nice vaseline and assemble everything back together. I also recommend removing the cheap grease from the huge aluminium gear and teflon pads and replacing it with some more useful lubricant.

Nice diagnostics. Well done!  

[kilix]

1 hour ago, happy-kat said:

Good read. You've probably got a spare motor now have you cleaned your original as well?

nope, I was on a verge of buying a new motor, but then I thought "it's already screwed up, no further harm will be done, when I look inside" and I did that. What encouraged me the most is the fact, that there is no decent SkyWatcher parts supplier in our country, so buying a new motor from UK and paying for postage would be like 50-60€. The only other option was to buy the entire tripod+head for 90€, which I can buy in Slovakia.

I will probably do this procedure to AZ motor too, as a precaution. AZ motor works well now, but I suspect, that it will be filled with that lard-grade schmoo too and it's only a matter of time before it starts failing.

[happy-kat]

Is the commulator the black centre bit please?

[kilix]

7 hours ago, happy-kat said:

Is the commulator the black centre bit please?

yes. The cylinder structure out of which the axis protrudes. If it were not covered with dirty grease in this photo, you could've seen copper commutator bars.

When you disassemble the motor, you can gently pull out the white plastic brushholders and then you can also pull out the entire rotor+commutator assembly. Makes cleaning easier.
Again, there are tiny tiny washers on the axis, so be careful.
Just be gentle when pulling the axis out of the bronze bushing, pull only along the rotation axis, do not wibble-wobble the axis, or you will bend it.

Edited January 15, 2017 by kilix

[Pinkbirdactual]

I have a celestron nexstar 130 slt computerized mount... I've had it a week, took it outside twice and it is completely dead... I'm well within amazons return policy and I'm sending it back up and getting the 130 eq instead.. I had fun with this scope but now I have to wait two more weeks b4 I can go out..

 

I advise against buying any newer model atm.. seems like this is a reoccurring issue.. EQ seem to be the way to go unless you are a tinkerer 

[dph1nm]

Just to note that 8 years on from my original post in this thread my Nexstar 102 SLT is still working, albeit with some rather random speeds when you try to move it quickly!

NigelM

[AdrianVarga]

On 18/08/2009 at 11:09, Macavity said:

Sadly, I suspect any plaudits may have been premature...

I left the mount - with my MAK127 attached, overnight, and, this morning, it was "back to it's old tricks". From a cold start the motor again struggled. But, having traversed a region of track, it then moved fairly freely!

I sense I might be barking (meowing) up the right tree but, as yet, have not "cracked it". Perhaps the lottery of (distributor) substitution will get you a "better" example of this mount? For braver souls, removal of the Silver plastic cover reveals:

The above show the NUT you have to remove. Observe and maintain the correct ordering of metal, plastic and compression/split washers! The gear housing has to be "jiggled" to remove (and replace) it. This (presumably) to mesh-unmesh the large gear with the final drive pinion... You then have TWO parts to the assembly:

The Main Mount arm, with the gear housing removed. Here we see the THREE circular "plastic" Pads which form the bearing surface, against the LARGE gear (below)...

The large Gear Housing. This shows the internal face of the Gear, after a few passes over full Altitude range. You can see how the "Plastic" Pads have swept a track clear of excess(?) grease - Or maybe sufficient lubrication?

At THIS point, I'm not really sure how to proceed. I sense(!) I may be "right" re. the nature of the problems in this example of the mount. Clearly, by running the mount for a while "things improve", but this hardly inspires confidence! I must admit I'm a bit disappointed with the whole thing - despite initial promise and GOOD tracking etc.

Maybe a "better" grease would remain(!) between the Pads and the metal surface? Any Experts in lubrication (Tribologists?) out there? Thoughts / Speculation / Inspiration welcome!

Is there a spare part for someone?

[m.tweedy]

15 hours ago, AdrianVarga said:

Is there a spare part for someone?

Try Astroboot

https://www.astroboot.eu/AstroBoot

Edited January 6, 2020 by m.tweedy
additional info