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DD-1 Dual axis controller dead

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#1 mawkernow


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Posted 27 November 2012 - 03:48 PM

I've recently come to find my DD-1 dual axis motor controller is dead, i.e. nothing happens when connected to a power supply.

Has anyone had one of these die, and know where to start with it?

I'm using this with a GP mount with RA and Dec motors, on which an Orion (UK) Optics Newtonian is mounted. As far as I'm aware, the motors themselves are OK.

#2 BillBwithley


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Posted 27 November 2012 - 06:15 PM

Bad news about your Vixen Controller. What power supply were you using ? I have one of these and I use the supplied battery case that uses 8 D cell batteries with no problems.
Apparently this controller will fry if you use more than 12V unregulated. I believe this is a known problem.

#3 Geo.



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Posted 27 November 2012 - 10:29 PM

Have had one around for a while, but it seems that it should use a LM7805 for IC power. The LM7804 should handle the transients. The stepper driver uses IC power and supply power, so it'd be a suspect.

#4 rjsc2000


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Posted 28 November 2012 - 08:05 AM

Was the controller working ok? Did you changed the power plug for some reason? Many times the polarity is wrong and you blow up the 7805 that should exist right after the power plug in the unit.

#5 mawkernow


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Posted 30 November 2012 - 02:11 PM

I did change the power plug, but it was still 12V dc. I've tried a simple 12V mains adaptor, as well as a 12V from a power tank neither works.

I don't remember any specific time it stopped working, just that it didn't on the first time I used it in a good while.




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Posted 30 November 2012 - 05:20 PM

I've fixed a number of these. The problem is the cheap version of 7805 voltage regulator that is used in them and the fact that the polarity of the plug uses the center pin at ground vs the more common way of having the center pin hot. It can't take it if the polarity is reversed and it gets fried. This is what most likely happened. You can get much a better quality LM7805 from Radio Shack for under $2.00 and it takes about 15 minutes to replace. It is located at the bottom of the controller and attached to a metal bracket that is used as a heat sink.

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