SkyProdigy is slowly dying

[RobertI]

Sadly my SkyProdigy mount, which I have only had a few weeks, looks like it has a terminal problem.  ? It's a second hand pre-2014 model so no warranty.  Basically as the mount slews in azimuth, it gets slower and slower until it almost stops completely, sometimes speeding up a bit and then slowing right down to only a crawl. The problem manifests when slewing counterclockwise, it's fine when slewing clockwise. 

I think I have tracked down the problem area though - I believe its the motor itself - I took the mount apart, and swapped the altitiude and azimuth leads on the motherboard and the azimuth motor showed the same characteristics as before (although via the up/down buttons on the handset). I'm pretty sure this means the power, handset, leads and circuitry before the motor are fine. 

Having done a search it appears to be a common problem on the SLT, SkyProdigy and SE mounts. Has anyone experienced this and can provide some advice?

I was thinking of posting a wanted ad for anyone who might have a non-funtional SLT or SkyProdigy so I could use the parts. I am guessing Celestron would not provide spare parts any longer? A final resort would be to dismantle the  motor. ?

Any help appreciated. ?

[kendg]

Any markings on the motor to see if you  can get a replacement on amazon or wherever?

[RobertI]

Yes, there was a label with a long number and the letters SLT, damn I should have taken a photo before I put it back together!

[Cosmic Geoff]

One of the Skywatcher mounts is very similar to the SLT, and you can buy them from Astroboot in various stages of completeness and repair.  I used the Sky-watcher bowl part to make up a wooden tripod for my Nexstar SLT mount.

I suggest you get one and see if one or other of the motor/gearbox assemblies (the Nexstar has two that look the same) will fix yours. 

[dph1nm]

Yes, my SLT (which I have had for many years) did/does this. Still works though - even though it slows it still gets the coordinates right! I believe I read somewhere that the problem is the brushes on the motor getting dirty, but I have never tried to clean mine, so I cannot verify this. It does sometimes help if you run it round and round at the highest speed for several minutes though.

NigelM

[RobertI]

Thanks for the replies everyone. Fortunately FLO have kindly investigated and Celestron can provide a replacement motor for the princely sum of £37, so I have placed the order. I'll update when I have fixed or completely broken the mount! 

3 hours ago, Cosmic Geoff said:

One of the Skywatcher mounts is very similar to the SLT, and you can buy them from Astroboot in various stages of completeness and repair.  I used the Sky-watcher bowl part to make up a wooden tripod for my Nexstar SLT mount.

I suggest you get one and see if one or other of the motor/gearbox assemblies (the Nexstar has two that look the same) will fix yours. 

Thanks, that's a good suggestion which I hadn't thought of. You are right, it appears that this is the same motor as in the SLT, Nexstar4/5 (implied by the code I was given to place the order) and probably the SW Synscan. For your info I was told the Alt and Az motors are the same.

4 minutes ago, dph1nm said:

Yes, my SLT (which I have had for many years) did/does this. Still works though - even though it slows it still gets the coordinates right! I believe I read somewhere that the problem is the brushes on the motor getting dirty, but I have never tried to clean mine, so I cannot verify this. It does sometimes help if you run it round and round at the highest speed for several minutes though.

NigelM

Thanks Nigel, I didn't know about the brushes, but that makes sense, possibly explains why it only happens in one direction (?). It was getting so slow it was virtually stopping and causing me stress during my sessions, so it will be nice to have it fixed.....fingers crossed!

[RobertI]

Quick update, a new motor was delivered to me by @FLO during the week, I managed to install it and I can report that the problem has gone and the new azimuth motor slews perfectly. I have yet to test it under a dark sky, but fingers crossed that the auto-align, goto and tracking works ok. Hopefully I can also finish my review of the mount for posterity (see separate ongoing thread).

Edited August 12, 2018 by RobertI

[Chris]

Hi Rob, Glad you're all sorted. My new CPC800 Edge did/does exactly this i.e. slewing slower and slower, stopping then creeping to the object. I've bought a better supply and beefier Astrolynx cable as I was sure it was the lack of Amps, but if not it could be the same problem you experienced. I'd better go test it out thinking about it, glad you're sorted and thanks for the reminder. 

[Chris]

On 04/08/2018 at 21:24, RobertI said:

Basically as the mount slews in azimuth, it gets slower and slower until it almost stops completely, sometimes speeding up a bit and then slowing right down to only a crawl. The problem manifests when slewing counterclockwise, it's fine when slewing clockwise. 

Yep my CPC800 is doing exactly as above despite upgrading the PSU and the cable. I had heard they had power supply issues so thought the upgrades would sort it, but it is doing exactly as you describe on the azimuth motor only anti clockwise getting slower and slower, sometimes nearly stopping and sometimes speeding right up. slew oscillates quite a bit. Think it's the motor as with yours.

[Stub Mandrel]

Sounds like worn brushes, is it a stepper or a normal brushed motor?

[RobertI]

44 minutes ago, Lockie said:

Think it's the motor as with yours.

Is yours brand new or used Chris? Would be surprising to have worn brushes problem on a new mount (if that’s in fact what the problem is!).  ? It. seems to be a problem endemic to Synta altaz mounts - they appear to use the same motors for alt and az, and I think perhaps the az motor is under specced as (a) it has it gets used more and (b) it has a lot more work to do as it has to turn against a lot more friction. Could be wrong though ....

[Chris]

19 minutes ago, RobertI said:

Is yours brand new or used Chris? Would be surprising to have worn brushes problem on a new mount (if that’s in fact what the problem is!).  ? It. seems to be a problem endemic to Synta altaz mounts - they appear to use the same motors for alt and az, and I think perhaps the az motor is under specced as (a) it has it gets used more and (b) it has a lot more work to do as it has to turn against a lot more friction. Could be wrong though ....

Hi Rob, I've started a thread and took a video of the problem. What do you think? is it doing the same thing as your Prodigy mount did?

I could of swore it was the power supply and didn't jump at checking my new PSU and cable solved the issue I was so convinced it was just that with it being a brand new scope and all. I too didn't think it would be the motor, then I saw your thread and my heart sank a bit....que me running up the stairs to check out the mount!

 

[RobertI]

Quick update - I installed the replacement azimuth motor and had a chance to test it all under clear skies last night (see observing report) - everything worked perfectly and the azimuth motor is now whisper quiet, a LOT quieter than before, so less need to worry about neighbours. It auto aligned, despite some cloud, and slewed pretty accurately so it was well in the FOV at x65. All is now ok, so I can complete my review of the mount in another thread!

PS: @Lockie Followed the issues with your mount Chris - glad Celestron are now on the case hope you get the scope back soon. 

Edited August 16, 2018 by RobertI

[Chris]

29 minutes ago, RobertI said:

Quick update - I installed the replacement azimuth motor and had a chance to test it all under clear skies last night (see observing report) - everything worked perfectly and the azimuth motor is now whisper quiet, a LOT quieter than before, so less need to worry about neighbours. It auto aligned, despite some cloud, and slewed pretty accurately so it was well in the FOV at x65. All is now ok, so I can complete my review of the mount in another thread!

PS: @Lockie Followed the issues with your mount Chris - glad Celestron are now on the case hope you get the scope back soon. 

That's great to hear, Rob You're going to have plenty of fun with that mount now, it sounds very convenient when it's running well. I'll go look at your observing report in a minute .

The CPC800 was collected today and off to David Hinds (Celestron/Vixen UK for a service) kindly mediated and arranged by FLO. FIngers crossed all goes well.