Vixen Motors and controllers

[lguise]

I am trying to get the sequence of Vixen motors and controllers as used on Vixen SP, GP and GPDX Mounts straight. If you have any info and a better understanding please chip in.

So the early Vixen SPs had a stepper motor with only 5 pins? (unipolar?) I am not certain if this motor had a designation? or the designation of the controller?

My SP mount from 1989 has 8 pin plugs and so what I believe are the later MT1 stepper motors (bipolar?), it has a DMD-3 twin axis controller.

I also have a GP which has a single MT1 (8 pin stepper) but with an SD-1 controller. I have seen others identical to these but with DD-1 controllers (Twin drive)

I have owned several GPDX mounts over the years mostly these had black motor boxes with servo motors and encoders. I believe these motors were designated MT4? They operate with the Skysensor 2000

What other designations have there been and do I recall a point when the controllers were made more stable to higher Voltages?

Many thanks for any info.

Best wishes,

Linton

[Guest]

Good evening Lonton,

ok so thats what I know about Vixen step-motors:

With the Vixen SP, the MD-5 controller has been introduced, together with the MD5-SP motors. They are unipolar and need a 5-pin connector.

The motors have a built-in gear drive with ratio 1:300 afaik, so the motor actually rungs *much* faster than outer brass gear-wheel. These motors don't have a thread on top but are attached to the Vixen SP using 4 grub-screws that attach on the V-shaped upper part.

Look here (picture I found on the net, so thats not my website): http://air.ap.teacup.com/kussy/timg/middle_1313458407.jpg - of type MD5-SP are the middle and the right one.

Then there is the MT-1 motor (previously named MD6-SP), which can be controlled using the MD-6 drive and all the other newer drives. Its a bipolar motor, and has a 8-pin connector. Now, bipolar motors just need 4 connection pins! So I don't know if vixen really uses all 8 pins or if they just changed the plug to avoid confusion with the old type of motor. Actually, I saw that drives like the Boxdörfer MTS-3 have plugs with just 4 connected pins which work very well with MT1-motors.

The MT-1 motors don't just differ by the type of connection, but also the gear inside is different (1:120 afaik).

The left motor is of MT-1 type: http://air.ap.teacup.com/kussy/timg/middle_1313458407.jpg

What you see is that the MT-1 has a thread on top to attach the motor to a mount, the older motors don't.

Actually you can run a unipolar step-motor with a controller made for a bipolar step-motor -- but not vice versa. Still, this doesn't work for Vixen step-motors, as the gears are different. That's why people have to change the quartz of the controller if they want to use a MD-6 controller with an old MD5-SP motor.

I don't know anything about the DMD-3 controller; I'd guess if it works well with the MT-1 motors, it must be newer than the MD-5 drive.

Enjoy your evening!

Raphael

ps: take a look ad page 29 of the following document to see the difference between unipolar and bipolar step-motors: http://www.boxdoerfer.de/x5g4fc42/manualm3.pdf

[E621Keith]

Raphael, Thanks for the detailed information.

I have a DMD2 controller driving MT1 in RA and Dec. Although my dec motor has a V shape cut similar to the SP motor. Not sure if the previous owner machined the grove himself. It attaches to the pluck using four set screws.

As for other Polaris motors and controllers.

Vixen DD1 was succeeded by DD2. DD2 was recently replaced by DD3 which has a built in ST4 guide port. They still drives the MT1 motors, although the MT1 now comes in white.

I think Skysensor 2000's MT4 is a servo motor so it is not compatible with stepper drives. SS2K was replaced by Starbook S for no good reason, and SBS uses a newer white servo motor that is not compatible with SS2K.

[Guest]

Keith, I'm confused now -- you have a V-Shaped case (like the old unipolar motors had), but drive it with a controller for bipolar motors?

Well, the only way to find out which motor hides in the case is to open it. There are just three screws to remove, so I just took these pictures:

http://erraph.square7.ch/mt1.JPG

http://erraph.square7.ch/md5sp.JPG

Yesterday I actually recorded how the motors sound, as I was confused by the sound of my MT1-motor, but it seems to be just normal as they told me on cloudynights. If you want, you can listen to the motors here:

http://erraph.square7.ch/mt1.ogg

http://erraph.square7.ch/md5-sp.ogg

Hope this helps!

[E621Keith]

The motor I have has a gear ratio of 1/120, so it must be a modified MT1. May be Vixen converted some for the SP.

[lguise]

Just checked the various motors I have on SP and GP mount and they all have 1/120 gears. so are MT-1 (although Keith mine have a code of PF42-4813G)

My guess is Vixen continued to use old casings for a while once they switched to the newer motors?

Raphael I can't open the sound files on this computer but all the vixen stepper motors I have owned have made various chattering and knocking sounds when not under load.

Linton

Linton

[Guest]

Hi everyone,

apologies for bringing back this 9 (!) year old thread.  It's quite high up on google when searching for Vixen MT-1 motor properties , and something I wrote 9 years ago was wrong, and will be confusing to people who stumble upon this. It did actually confuse myself , when I re-read this trying to figure out what kind of motor I was holding in my hand ...

To recap and correct...

• MD5SP motors have 5-pin connectors and 1/300 gears. They are unipolar steppers. 
• MT-1  motors have 8-pin connectors and 1/120 gears. They also are unipolar steppers.
• MD-6 motors are internally identical to MT-1 motors to my knowledge, i.e. unipolar, 1/120 gears.
• There are also motors with 1/30 gear out there which were sold with older version of the SkySensor , but I have no further information on them. 

What confused me 9 years ago is that some controllers (e.g. the Boxdoerfer MTS-3  / Baader Sinus II ) drive MT-1 motors as bipolar motors. This does of course not exclude that they are unipolar motors , where the central taps are just not being used by some controllers.  Here are two websites with wiring schemes for MT-1 motors: https://sites.google.com/site/thestarjar/Home/mt1   ;    http://astrolabo.fr/?p=1586    .

Hope that'll avoid confusion for whoever stumbles across this again.

Rapha

 

Edited February 8, 2021 by erraph

[Pixies]

On 08/02/2021 at 13:53, erraph said:

Hi everyone,

apologies for bringing back this 9 (!) year old thread.  It's quite high up on google when searching for Vixen MT-1 motor properties , and something I wrote 9 years ago was wrong, and will be confusing to people who stumble upon this. It did actually confuse myself , when I re-read this trying to figure out what kind of motor I was holding in my hand ...

To recap and correct...

• MD5SP motors have 5-pin connectors and 1/300 gears. They are unipolar steppers. 
• MT-1  motors have 8-pin connectors and 1/120 gears. They also are unipolar steppers.
• MD-6 motors are internally identical to MT-1 motors to my knowledge, i.e. unipolar, 1/120 gears.
• There are also motors with 1/30 gear out there which were sold with older version of the SkySensor , but I have no further information on them. 

What confused me 9 years ago is that some controllers (e.g. the Boxdoerfer MTS-3  / Baader Sinus II ) drive MT-1 motors as bipolar motors. This does of course not exclude that they are unipolar motors , where the central taps are just not being used by some controllers.  Here are two websites with wiring schemes for MT-1 motors: https://sites.google.com/site/thestarjar/Home/mt1   ;    http://astrolabo.fr/?p=1586    .

Hope that'll avoid confusion for whoever stumbles across this again.

Rapha

 

I have stumbled across it - and it's very useful. Thank you for taking the time to update a very old post!

[Fred_76]

Hi.

I own an antic Vixen Polaris with the MD-5 Quartz controller. 

Does anyone have an idea how I could add ST4 possibility to this controller ? There are only 3 buttons :

• Stop
• x2
• x8

This idea is to link the Stop button to the RA- ST4 pin, and x2 button to the RA+ ST4 pin. Would this work if I just link the buttons like this, or do I need a more complex electronic mount (with optocouplers, resistors...).

 

Clear sky

Fred