SW 12” Goto Dob issue with Azimuth rate

[Startrek (Martin)]

I’ve had my SW 12” Goto freedom find Dob for 6 years now at my retirement getaway dark site and it has performed flawlessly until a few months ago.
Issue is the Azimuth drive will not accept a rate change to a slower slew speed and remains on rate 9 ( fastest ) irrespective of changing the rate on the HC, thus useless for Alignment.
Altitude drive works perfectly at all rates
Scope is stored in garage with cover and is in extremely good condition, no dust , mould , rust on metallic parts etc….It looks brand new.

Action I’ve taken to date ….,
Surfed Cloudy Nights for ideas , answers etc…
Surfed Stargazers Lounge and found a guy who had a similar issue with Az drive on his 12” Goto. He found a suspect loose conductor on the small ribbon cable going to an encoder. He pushed it home and problem resolved.
Called Graeme at SW Australia who suggested a few things to check , which I did below ……,
Updated firmware on existing HC
Replaced HC cable
Replaced motor cable from Alt box Az port to Az drive.
Opened up Az drive and checked motor connector and encoder connections.
Motor board and encoders look in mint condition. All solid clean connections
Replace existing HC with new HC
Disabled encoders on HC
Replace power supply with new

Tested scope both during a 2 star alignment and via easy tracking mode ( scope does track at Sidereal in easy tracking mode ) Same issue Az rate stuck on rate 9 or fast.
Altitude control is perfect on both modes at any rate.

One observation is that when I change rate to say 5 ( mid slew speed ) and attempt to slew scope , as I press the Az movement button I hear a click and no movement in Az , I immediately press button again and scope flies off at rate 9. This occurs in both Az directions. I did try all rate changes from 1 to 8 and same issue , Az flies off at fast rate 9 even though HC says rate selected ( eg 5 )

Az motor slews smoothly at rate 9 and sounds fine , it’s not hunting or making abnormal sounds.

SW Australia do not sell Az motor boards as spare parts ( damn )

I’m almost sure I’ve got a dud Az motor board ????

I’m pretty much got a dead scope at the moment in regards to Goto. I don’t want to throw any more money at it to resolve unless I can find a new Az motor board.

Any thoughts , ideas , suggestions most welcome

Thanks

Martin

PS : I don’t live permanently at my retirement getaway which makes testing and diagnostics problematic. The last time I used the scope and found this issue was Sept / Oct 2024 school holidays

[Rainmaker (Matt)]

I assume you have already switched the alt and az cables around to see if the problem goes to Alt with it….

[Leo.G (Leo)]

Martin wouldn't SW have a test bed they could plug the motor board into to confirm it's proper operation?
Could they possibly offer you a replacement board on loan to test it?
That's not an unreasonable request and if it fixes your issue you'd obviously be purchasing, or an exchange board?


You yourself would know this is a common type thing at companies who manufacture this stuff though, I do remember when Honda Australia couldn't fix a workmates new car (late 80s and it constantly broke down on the free-way between his home in Wollongong and work at Mascot, costing him most of his wages in tow fees) because they couldn't afford the computer test bed in Australia. Eventually the courts ordered Honda to either fully refund or replace the vehicle with another new car.


I use strong magnification and look for signs of burning on the boards or bad solder but seeing under the legs of surface mount stuff is impossible. The parts are even so small it's not so easy to pick up on a floating component but not everything is detectable like that. Otherwise it's oscilloscope and power and trace everything and I will do that for my own equipment because my time doesn't matter and I can't afford replacement parts but I've long given up repairing stuff for others (other than an original EH Holden car radio I can't get the correct original pot for or the oscillator shunt coil, the unit came theoretically working with half of the internal wires cut and incorrect, swapped components). I'm regretting taking it on for a friend, free.........


I don't know if the following link is any help, I'm guessing you've seen it but I can tell at a glance there's corrosion on the board, probable dry joints and some suspect looking soldering:


https://stargazerslounge.com/topic/3...n-motor-board/


I think the best you can do is see if you can get a loan, known working board which would confirm whether it is responsible.
I don't have one or it would be in the post within half an hour.

[Startrek (Martin)]

Originally Posted by Rainmaker

I assume you have already switched the alt and az cables around to see if the problem goes to Alt with it….

You can’t swap cables due to design of set up
The Alt motor housing acts as a marshalling centre , externally it only has the off on power switch , HC port and Az port link to Az motor
The Alt connection is internal ie : mini ribbon cables to board

Thanks for the suggestion

There’s one place I haven’t checked and that’s behind the Alt motor cover where the Az cable port is located . Next on my list to have a look

[Startrek (Martin)]

Originally Posted by Leo.G

Martin wouldn't SW have a test bed they could plug the motor board into to confirm it's proper operation?
Could they possibly offer you a replacement board on loan to test it?
That's not an unreasonable request and if it fixes your issue you'd obviously be purchasing, or an exchange board?


You yourself would know this is a common type thing at companies who manufacture this stuff though, I do remember when Honda Australia couldn't fix a workmates new car (late 80s and it constantly broke down on the free-way between his home in Wollongong and work at Mascot, costing him most of his wages in tow fees) because they couldn't afford the computer test bed in Australia. Eventually the courts ordered Honda to either fully refund or replace the vehicle with another new car.


I use strong magnification and look for signs of burning on the boards or bad solder but seeing under the legs of surface mount stuff is impossible. The parts are even so small it's not so easy to pick up on a floating component but not everything is detectable like that. Otherwise it's oscilloscope and power and trace everything and I will do that for my own equipment because my time doesn't matter and I can't afford replacement parts but I've long given up repairing stuff for others (other than an original EH Holden car radio I can't get the correct original pot for or the oscillator shunt coil, the unit came theoretically working with half of the internal wires cut and incorrect, swapped components). I'm regretting taking it on for a friend, free.........


I don't know if the following link is any help, I'm guessing you've seen it but I can tell at a glance there's corrosion on the board, probable dry joints and some suspect looking soldering:


https://stargazerslounge.com/topic/3...n-motor-board/


I think the best you can do is see if you can get a loan, known working board which would confirm whether it is responsible.
I don't have one or it would be in the post within half an hour.

Leo,
Skywatcher Australia (Tasco Sales ) is not a manufacturer or repair centre, they are a brand on seller for Synta.
Their product support is limited to warranty replacements / very minor repairs , product advice and sales advice. They don’t offer diagnostic bench testing on products either in or out of warranty.
Graeme their product support guy did offer help with some obvious things to look at.
I did have a good look at the boards / connections/ soldered points etc.. and they are in mint condition.
Years ago they did sell some motor parts and boards for “Goto Dobs” but like everything today it’s a throw a way society.
If my scope was 10 months old and still under warranty I’d personally dismantle it , throw it in the wagon and drive it to Brookvale in Sydney from the south coast.
Thanks for your suggestions

Martin

[Leo.G (Leo)]

It's sad we've become a throw away society Martin. I'm lucky in that I can and do fix a lot of stuff, I have a particular passion for old junk.
I'm also lucky my son has great eyesight and patience and he'll analyze and trace a circuit out and draw it complete in some software he has. I grew up studying electronics and a lot of years study, my son grew up watching me play with junk and with Google at hand, he designs and builds more stuff than I ever bothered doing outside of industry.


As mentioned, if I had a spare board I'd shove it straight in the post.
A suggestion I don't know of whether it would work but Aliexpress have all sorts of electronics boards but you'd have to purchase it were they to have one, no different than getting Tasco to get you one in. Though I was shocked by Tasco when I needed replacement worm gears for my GOTO mount, when David (I think) told me the price for the lot I asked him if he meant each, pleasantly surprised.

[Startrek (Martin)]

Originally Posted by Leo.G

It's sad we've become a throw away society Martin. I'm lucky in that I can and do fix a lot of stuff, I have a particular passion for old junk.
I'm also lucky my son has great eyesight and patience and he'll analyze and trace a circuit out and draw it complete in some software he has. I grew up studying electronics and a lot of years study, my son grew up watching me play with junk and with Google at hand, he designs and builds more stuff than I ever bothered doing outside of industry.


As mentioned, if I had a spare board I'd shove it straight in the post.
A suggestion I don't know of whether it would work but Aliexpress have all sorts of electronics boards but you'd have to purchase it were they to have one, no different than getting Tasco to get you one in. Though I was shocked by Tasco when I needed replacement worm gears for my GOTO mount, when David (I think) told me the price for the lot I asked him if he meant each, pleasantly surprised.

Thanks for the kind sentiment

Having a masters degree in electronics won’t solve anything unless you have the original schematic as built electronics and electrical drawings of the whole kit complete with operational notes and procedures…..
Synta being Chinese , good luck with obtaining those !!

[Leo.G (Leo)]

There's maybe a couple of zip files for some testing in this thread and a heap of signal code but I don't know if they are appropriate for your mount and I didn't download the zip file but I will sign up to get it and have a look later.
None of this may be applicable to your mount and will require you to be down south to check unless you strip the card out and I know how impractical that is without the machine but it may help..



https://www.cloudynights.com/topic/8...pcb-schematic/


I have searched online for schematics and information, as you mentioned, not easy (impossible) to get though I may know a few sites, no harm in trying even if I do turn up empty handed.


And this if it shows up:


https://inter-static.skywatcher.com/...ommand_set.pdf


http://www.skywatcher.com/download/m...n-development/

[Startrek (Martin)]

Originally Posted by Leo.G

There's maybe a couple of zip files for some testing in this thread and a heap of signal code but I don't know if they are appropriate for your mount and I didn't download the zip file but I will sign up to get it and have a look later.
None of this may be applicable to your mount and will require you to be down south to check unless you strip the card out and I know how impractical that is without the machine but it may help..



https://www.cloudynights.com/topic/8...pcb-schematic/


I have searched online for schematics and information, as you mentioned, not easy (impossible) to get though I may know a few sites, no harm in trying even if I do turn up empty handed.


And this if it shows up:


https://inter-static.skywatcher.com/...ommand_set.pdf


http://www.skywatcher.com/download/m...n-development/

At this stage it’s only an assumption that the motor board is the culprit
I’m going to carry out more testing over the next week and if I can’t resolve the issue and a replacement motor board is not available ( which is the likely outcome ) then I might just buy a new Az Alt base unit and reuse the OTA. I think Skywatcher sell just the base unit as a replacement. I’ll talk to Graeme at Tasco about it.

Cheers
Martin

[Leo.G (Leo)]

Good luck with it Martin!


Martin a quick thought, does the board have any RJ12/RJ45 port/ports for cabling?
I've come across several devices with corroded pins within those ports and also devices with collapsed pins within the sockets. It's not usually something a visual check will pick up but an internal contact only needs to not be touching for major problems.


If suspected, they are fiddly but easy to fix, I use a small bag tie (thin wire with plastic coating) with a small 90 degree hook bent at the bottom and use that to gently lift the pins, worth looking into.

[astronut (John)]

Martin, check with Adriano at TESTAR.
They have their own test bench, and Adriano used to work for Tasco and still sells their stuff.

[Startrek (Martin)]

Originally Posted by astronut

Martin, check with Adriano at TESTAR.
They have their own test bench, and Adriano used to work for Tasco and still sells their stuff.

Thanks John,
I emailed Adriano yesterday with a rundown of my issue
Hopefully he responses in the next day or two
Cheers
Martin
PS: I’ve purchased from Teleskope Express ( Europe ) before and they have a vast array of Sky-Watcher mechanical and electronics spare parts available including mother boards , motor boards , motors , cables , handcontrollers and so on ……. Mostly for EQ3 , EQ5 , EQ6-R , AZEQ6 and EQ8-R mounts , unfortunately none for the Sky-Watcher Goto Dobs !!!

[Startrek (Martin)]

Latest update …..,
Some positive news , Adriano from Testar has sourced an Az motor board for my dying Goto Dob ( don’t know the origin of the part )
Hopefully I’ll have it in a few days and hopefully it’s the correct replacement part ??
I’ll install it next week as I’m away up north until Monday.
Adriano also advised to disconnect both Az encoders ( Graeme from Skywatcher advised the same thing ) I don’t use the “Freedom Find” feature anyway.
If this part becomes a dud , he’s confident that he can source a new part from Synta ( via Skywatcher as he’s an ex Skywatcher employee)
I also have 2 other Astro resellers looking into my problem.
Worse case scenario is a new Base unit which is $2.1K

Martin

[Leo.G (Leo)]

I hope it fixes the issue Martin!

[Startrek (Martin)]

Originally Posted by Leo.G

I hope it fixes the issue Martin!

I hope so too

Thanks
M

[Startrek (Martin)]

New Az motor board didn’t fix the issue
Issue seems to be related to the encoders which cannot be left disconnected
Without the encoders in circuit the scope doesn’t perform rudimentary tasks like parking to Home Position etc…
You can disable them in the Handcontroller but I tried disabling them and re enabling them to no avail.
I’ve cleaned the optics on the encoders but still have the slew rate issue in Az axis.
Im not wasting any more time and money on this issue ( $350.00 and about 20 man hours )
Adriano from Testar is pricing me a new 12” Base unit only so I can reuse my existing collapsible OTA.
Folk on this Forum , Adriano from Testar and Graeme from Sky-Watcher have been extremely helpful
Thanks
Martin

[Startrek (Martin)]

Arrived at my South Coast NSW dark site yesterday and assembled my new SW12” Goto base unit in the garage. This new base unit didn’t have external clutches like my old unit however the Altitude tension movement was fine with a Paracorr coma corrector and heavy TV 21mm eye piece. The existing Collapsible OTA fit like a glove.
Set up the scope this afternoon as forecast was for clear skies. Completed a 2 star alignment, 2nd star Procyon ended almost bang in the centre of centering eye piece.
Selected about 6 targets ( stars and nebula ) across the sky and each target ended up close to centre of the eye piece.
Also performed a couple of Park to Home which ended up spot on.
Slewing was smooth / quiet and rate changes in Alt and Az were perfect. Shut down and packed away when that big bright moon popped its face above the horizon.
All in all a great test night for the new base unit. Glad to have my 12” scope up and running again after 5 months.
Thanks to Skywatcher, Testar and folk here on IIS

Martin

[EpickCrom (Joe)]

Originally Posted by Startrek

Arrived at my South Coast NSW dark site yesterday and assembled my new SW12” Goto base unit in the garage. This new base unit didn’t have external clutches like my old unit however the Altitude tension movement was fine with a Paracorr coma corrector and heavy TV 21mm eye piece. The existing Collapsible OTA fit like a glove.
Set up the scope this afternoon as forecast was for clear skies. Completed a 2 star alignment, 2nd star Procyon ended almost bang in the centre of centering eye piece.
Selected about 6 targets ( stars and nebula ) across the sky and each target ended up close to centre of the eye piece.
Also performed a couple of Park to Home which ended up spot on.
Slewing was smooth / quiet and rate changes in Alt and Az were perfect. Shut down and packed away when that big bright moon popped its face above the horizon.
All in all a great test night for the new base unit. Glad to have my 12” scope up and running again after 5 months.
Thanks to Skywatcher, Testar and folk here on IIS

Martin

G'day Martin. Great to hear that your issue has been sorted and you are back out observing again

[Startrek (Martin)]

Hi Joe,
Thanks
Seeing wasn’t great but still great to have the scope wizzing around the night sky with a good level of accuracy
A few more nights later would have been nice as that 90% moon rising up from the ocean’s horizon lit up the whole sky. The moons glare under darkish B3 skies always seems so much brighter than when I’m in Sydney under B8.
Cheers
Martin