Problem with SW 12” Goto Dob

[Startrek (Martin)]

Due to the recent Gail force westerlies on the South Coast , I had to make a quick 2 day trip down to my holiday place where 2 x 5m trees had been uprooted, luckily no property damage. Spent all day with a chainsaw cutting it all up and a couple of loads to the tip.
As it’s a short trip I decided to wheel out my 12” Goto dob and do a bit of visual observing tonight even though seeing was poor under my bortle 3 skies ( I haven’t used the dob for nearly a year )
Commenced a 2 star alignment and chose Formalhault as first Star , slewed up to the vicinity of this Star using default 9 rate then proceeded to fine tune my centering using rate 3 speed. This where my problem started…..,
Rate 3 or slow would work on the Up and Down buttons but the Left and Right buttons remained at Rate 9 speed even though the Synscan display showed Rate 3. Tried rate 2 , 4 and 5 and experienced same problem with Left and Right buttons , Star wizzed back and forth past crosshairs and rate 9 speed. Parked the scope and shut down.
Took the Synscan HC inside and performed a Firmware update connected to my laptop ( Firmware Version 4.41.00 ) as this HC is 8 years old and has never been updated or cleaned ( it’s the first V5 series )
Also pulled the HC apart and cleaned the tactile rubber moulded contact pad and contacts etc..

Tried 2 star alignment again same issues

Also tried scope in Easy Tracking mode which tracked at Sidereal ok

Sounds like a new Synscan HC is required ??

Advice , experiences and comments most welcome
Cheers
Martin

[iborg (Philip)]

Hi Martin


My first thought is spiders or insects inside the controller.


I would open the hand controller and have a look for muck on the circuit board.


Good luck.


Philip

[Startrek (Martin)]

Originally Posted by iborg

Hi Martin


My first thought is spiders or insects inside the controller.


I would open the hand controller and have a look for muck on the circuit board.


Good luck.


Philip

Philip,
Thanks for your suggestion
As noted I did pull apart the HC and clean the silicon tactile push button pad and PC board. Looked fine no mould or dirt or bugs.
Each button has 2 copper contact points on the board so design wise it’s not the most reliable design as it relies on equal finger touch pressure on the silicon button to make clean contact on both contact points. But in saying that I’ve used these HC on EQ and AZ scopes for years without failure.
The strange thing the AZ and Alt motors are responsive and work fine it’s just the change in Rate when you drive the scope in Az, it stays at Rate 9 or fast

Hoping it’s just the HC and not the Az motor board ?

Cheers
Martin

[Leo.G (Leo)]

I believe it's the electronics within the controller which change the slew speeds, not the motors themselves (they obviously change speed but based on signal from the controller).
I'll have to ask my son when he gets up later, some years back with a small EQ goto mount we had an issue when a chip blew out, my son was trying to play with shoe string control using leads with alligator clips and they vibrated and shorted out and blew the IC but I don't remember where the chip was, I'm sure it wasn't in the hand controller but I just don't remember, I know I replaced it.

[Startrek (Martin)]

Originally Posted by Leo.G

I believe it's the electronics within the controller which change the slew speeds, not the motors themselves (they obviously change speed but based on signal from the controller).
I'll have to ask my son when he gets up later, some years back with a small EQ goto mount we had an issue when a chip blew out, my son was trying to play with shoe string control using leads with alligator clips and they vibrated and shorted out and blew the IC but I don't remember where the chip was, I'm sure it wasn't in the hand controller but I just don't remember, I know I replaced it.

Thanks Leo,
Yes I was leaning towards the HC as I assume its PCB sends commands to motor board PCB when the operator presses a tactile button on the handset. Hopefully your son can shed more light on Synscan protocol

Cheers
Martin

[iborg (Philip)]

Hi Martin


At least little critters haven't made a home inside.


Anyone nearby whose handset you borrow and/or try yours on their mount?


Good luck.


Philip

[Leo.G (Leo)]

Sorry Martin I kept forgetting to ask my son (migraines, I forget everything) but I did remember yesterday, it was the electronics in the control box itself, the one the power plug and hand controller plug into.

[Startrek (Martin)]

Originally Posted by Leo.G

Sorry Martin I kept forgetting to ask my son (migraines, I forget everything) but I did remember yesterday, it was the electronics in the control box itself, the one the power plug and hand controller plug into.

No problem , thanks Leo for replying
The only problem is that the handcontroller and power supply plug into the Altitude motor board housing not the Azimuth motor board which is mounted on the base
My issue is with Az not Alt , altitude control works fine and changes rate to any number 2 to 9.
Also I’ve done some searching around for replacement Az boards ( if I fact this will solve my issue ) and SW no longer supply replacement Az and Alt motor boards for to Goto dob range.

What I failed to check was connectivity of HC to motor board ( RJ45 to RJ12 curly cord ) However, if the cable pair send / receive in the cord that controls slewing in Az was open circuited , I would have expected Az not to work at all. Az is working but doesn’t change from default fast rate 9 to slow rate 2.
When I’m back down the coast again in late October / early November I’ll check all cables , cords and RJ connectors to ensure no continuity issues before I think about what’s next.
Cheers
Martin

[Leo.G (Leo)]

Good luck Martin!
DO you have a network tester?
I know you mentioned running an electrical engineering business (from memory), a small network tester will make checking the 2 cables a quick, easy, no fuss task. Cheap if you don't already have one at your disposal.
I'm hoping for your sake it is a cable and take a couple of spares with you if you can.

[Startrek (Martin)]

Originally Posted by Leo.G

Good luck Martin!
DO you have a network tester?
I know you mentioned running an electrical engineering business (from memory), a small network tester will make checking the 2 cables a quick, easy, no fuss task. Cheap if you don't already have one at your disposal.
I'm hoping for your sake it is a cable and take a couple of spares with you if you can.

Thanks Leo
Yeh I did run a national electrical engineering design and construct business ( now retired ) and I do have a network tester , it’s 15 years old but still works fine.
I now have a second handcontroller ( from a friend ) which I can use and test the scope as well so when I’m back down south in late Oct early Nov I can spend a few hours in the garage and try and nut this issue out.
If it is fact a faulty motor board , my scopes a dead duck in the water unless I can secure a motor board which from my early investigations is not likely
Thanks for your input
Martin

[Leo.G (Leo)]

The stupidest thing, is there a separate earth cable to either of the motors?
This won't sound stupid to you because I'm sure you've run across the problem elsewhere but if there is check it's tight and a clean connection.

[Startrek (Martin)]

Originally Posted by Leo.G

The stupidest thing, is there a separate earth cable to either of the motors?
This won't sound stupid to you because I'm sure you've run across the problem elsewhere but if there is check it's tight and a clean connection.

Leo,
This Goto Dob and most Astro EQ and Az Alt mounts run on extra low voltage ie: 12V DC either via a switch mode plug in type power supply or integral or standalone Battery. The motors are usually small stepper type or servo type extra low voltage DC. There is no requirement for an earthing conductor attached to the general mass of earth under ASNZS3000 for these motors or for that matter the mounts as well.
I had quite a few mounts and never seen provision to connect an earthing conductor. Unless of course it’s a non commercial home made mount with small AC motors ( which wouldn’t be approved and C ticked for connection to 230V mains outlets in any case )
With respect to earthing , you maybe referring to 230V single phase AC motors which are not used in commercially manufactured Astro mounts etc….

Cheers
Martin

[Leo.G (Leo)]

Probably Martin just thinking general electrical problems not thinking about mounts. Come to think of it it may have been an issue with an old 220V clock drive I used on an old mount years ago.
Now here's a funny thing, I run a separate earth lead and tent peg to the leg of my mount or I always get a tingle through the legs from the power brick and it doesn't matter what power brick I use. Nothing scary but I have wire soldered onto adhesive copper tape attached to the front leg and an RCA connector I put a RCA plug soldered to a tent peg and poke the peg in the ground.

[Leo.G (Leo)]

Besides the controller possibly a kink (broken wires) in a cable running to the motors, or bad connection. Contact cleaner and a tooth brush maybe.
Try swapping the RA and Dec cables and see if it's the same issue with the same motor.
If you're mount is running the similar DIN plugs to my Skywatcher EQ5 Pro I know the female pins can get spread with female DIN plugs though my Skywatcher is quite firm and the sockets seem to be a decent quality where wobbling cables in and out isn't so easy (less chance of spread pins), I've more seen it with old audio gear (everything had DIN plugs back in the 70s).


Still worth checking and you would have experience doing such things.