Recently picked up a Super Polaris mount with Dec and RA motors, cabling and a Vixen DMD-2 controller. It works well, but like anything else, I would like to better understand the differences between the DMD-1, DMD-2 and DMD-3 (DMD-X?) controllers and motors, i.e. advantages, disadvantages??? I believe all SP drives are build around 144 toothed gearing, but why the changes? e.g. 8 pin cabling vs. 5 pin vs. whatever else is out there. Any information would be appreciated.
Vixen/Celestron Super Polaris drives
Posted 21 September 2020 - 07:17 PM
I think the 5-pin drives have a different gear ratio. I have a couple of 5-pinners that have been marked by a previous owner as 1/30 ratio gearing. Yes the mount gears are 144t as are just about all the clones also. My SP is using 8-pin motors with a DMD controller. I don't know when the change was made or why. I seem to remember the GP and maybe the late SP used the 5 pin motors as did the SkySensor goto.
Posted 25 September 2020 - 08:50 AM
While doing some greasing on the RA gears, I found the RA motor to have a 1/120 ratio. My controller is marked as a Vixen DMD-2 and it has 8 pin DIN cabling and connectors. Still curious about the DMD-1 and DMD-3 controllers and if these were 5 pin units. Also, did Vixen bring any additional functionality to the DMD-3 and to the DMD-2 over the DMD-1?
BTW, the grease used on the RA gear assembly was not nearly as dried out as I expected after having disassembled an early Celestron CG-5 and finding the grease had turned to glue. The Japanese Super Polaris is pretty impressive in its build quality.
Posted 25 September 2020 - 08:13 PM
I have a pdf of the manual from that period. It has the DMD-3 controller, which looks exactly like yours aside from the silk-screening on the face. You cannot tell if it's 5 or 8 pin. All the buttons and switches are the same.
I purchased a 5 pin motor years ago by accident, so I sold it. It looked the same as I recall as all of my 8 pin motors.
I have a SP and a GP, both using a single-axis drive and the SD-1 controller. I just took the SP out of storage (10 years?) and swapped out a Polaris head for my ED100 refractor. When I had them off I weighed the EQ heads (motor attached). The Polaris was 6 lb 10 oz, and the SP was 7 lb 13 oz. So only a 1 pound penalty! On the first night out with it I was astounded at how good this mount is!
One thing I love about the SP over my newer GP head, is where the RA and Dec clutch handles are located. They're always really convenient to grab, and right where you'd expect to find them. I still struggle with my GP on this issue.
Edited by SteveG, 25 September 2020 - 08:13 PM.