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Vixen DMD-2 and DD-1: interchangeable?

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#1 twhite

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Posted 08 October 2013 - 01:32 AM

Before I go plugging something in to something else and accidentally releasing the magic smoke supply, I wanted to confirm whether or not the DMD-2 and DD-1 controllers and associated motors are, in fact, interchangeable? I believe that they are, but wanted to get confirmation. I am buying another older Vixen mount that is coming with dual motors and a DMD-2 controller, and would prefer to use a DD-1 controller with it. I have an extra DD-1, as well as a DD-1 that's modded for autoguiding, hence the question... thanks in advance for replies.

Tony

#2 sky_dave

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Posted 08 October 2013 - 02:09 AM

I have a DMD-3 controller and it is compatible. The circuit board is actually labeled DMD-2. So not totally sure about the DMD-2. Vixen changed the gear ratio and voltage on the motors to improve slew times on GOTO systems. When they did they changed the motor cable connector from 5 pins to 8 pins. If the motors on this mount have 8 pins they will work with the DD-1. If only 5 pins then no good.

#3 orlyandico

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Posted 08 October 2013 - 02:14 AM

they are both stepper controllers, but one has a 5-pin and the other an 8-pin plug. if the plugs are the same they are probably electrically identical -

https://sites.google...tarjar/Home/mt1

the DD-1 (I used to have one) uses the 8-pin DIN plug. Some ads/posts on the internets leaves me to believe that the DMD-2 can drive the MT-1.

but if you're in doubt, use a multimeter to check the wiring on your new motors. these are ordinary unipolar steppers so easy to figure out (use the pinouts from the link above).

#4 twhite

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Posted 08 October 2013 - 04:06 PM

Thanks. One mount with 8-pin connectors uses the DD-1, the other the DMD-2. I didn't recall their being any difference between the two. However, I wasn't sure if the steppers had a different degrees/step rating or not. Only way to check, I assume, will be to disassemble the entire system and check them.

I know there's a difference in the go-to motors as they're closed-loop with built-in encoders (I used to have one) and I think they're servos rather than steppers anyway.

#5 orlyandico

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Posted 08 October 2013 - 07:14 PM

There's no difference, they're both 48 ppr Nippon Pulse tin cans. Not sure if the gearing is different though (the DD-1 uses 120:1 gearboxes). But gearing differences wouldn't release the magic smoke.

Definitely the GoTo (except the original SkySensor) uses different motors. The 48 ppr, 120:1 motors are too slow for GoTo, running full-bore they can only do 40X sidereal or so.

#6 twhite

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Posted 09 October 2013 - 10:19 AM

Many thanks.






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