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Schematic for DD2 (DMD-2?) Hand Controller?

Accessories Beginner Cassegrain Celestron DIY Equipment
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#1 fjparks

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Posted 22 February 2021 - 07:31 PM

I have my Dad's old Celestron Super C8 Plus or more likely it is a Powerstar 8. (Has both manuals but it is DC powered).

The drive is not working (no LED illumination on the hand unit and the drive does not move). 

The hand controller is a DD2 (DMD-2?)

It is center pin negative and has been reverse polarity connected to 12V.

I fixed this, but still have no illumination of the power LED and no drive motor movement.  
The is a diode in series on the 12V input (presumably for reverse polarity protection) and it tests good, as does the 8V LDO regulator.
Any chance someone has a schematic for the PCB?
Thanks,

Fred

Attached Thumbnails

  • Hand Unit M.JPG
  • Base M.JPG


#2 photoracer18

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Posted 22 February 2021 - 07:43 PM

If there is no light on a Vixen type controller from the early days its most likely looking for the opposite polarity. Of course you could still be having some electronic issues leftover. And I am not sure that Celestron might have converted all those controllers they made for the C8s to +12v. And that controller is not a DMD or a DD as it has different parts and controls from the Vixen controller. I am betting if you plug +12v into it the light will go on., assuming its not dead. Did you replace the diode using the same orientation as the dead one? You know that toggle switch on the top there is the on/off switch, correct?


Edited by photoracer18, 22 February 2021 - 07:44 PM.


#3 telesonic

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Posted 23 February 2021 - 05:51 PM

Fred,

 

Before you get digging too far into your controller, here are a few things that come to my mind: (now that you have the correct center-negative power adapter)

 

1) I do see some rust on the screws on yours - check to make sure that all electrical contacts are clean. On the 12v jack and also the 8 pin DIN jack/plug. Perhaps there is corrosion.

2) These can be powered 2 ways, if I remember.  A) you can plug the power supply into the handset or B) you can plug the power supply into the 12v jack on the drive base. IIRC it should work either way. Keep in mind though, the 12v jack on the base may have been rewired to center positive at some point - verify that it hasn't been changed first.

 

3) I'm not certain on this - but the map/lamp switch may need to be turned on to power it up, it's been a few years since I used mine so I don't remember exactly. Try that, and see if your LED illuminates. In the following link I provided - that does seem to be the case on some of these. (It's a few pages in) Photoracer also mentioned this above.... so give this a shot first, if you do. If your lamp does not illuminate, it may be possible that it was fried from reverse polarity, but still test the drive for movement. If so, easy fix.

 

Also, the drive on this is reaaly slow, and pretty quiet. Mark your housing and RA circle with a pencil - then let it run pluggged in for an hour or so, it will have moved a bit.

 

I don't know if you have came across this thread yet or not, but it may be of help:

https://www.cloudyni...-c8-plus-mount/

 

 

Hope you get yours working, they are very cool old drive setups. I still have mine, and could probably answer any questions regarding the 12v socket wiring on the base if needed.

 

Temp



#4 fjparks

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Posted Yesterday, 08:01 PM

Photoracer,

It was center pin negative and so it had be reversed poetized since the cigeret lighter adaptor in the case was "normal".

I have fixed that and the series diode on the positive input tests good and I have 12V in and 8V out of the 8V regulator.

However, I did not try the toggle switch after fixing the polarity, so I will give that a shot. (I'm not too proud for an easy fix :-)

Thanks for the feedback



#5 fjparks

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Posted Yesterday, 08:13 PM

Telesonic,

After fixing the polarity, I have 12V in and 8V out of the 8V regulator in the hand controller.

After verifying that the motor wasn't moving by watching the worm gear, I have been working with just the hand controller unplugged since I figure that there is not point till I fix whatever is keeping the LED from illuminating.

Thanks for pointing out that I also need to re-wire the 12V jack on the base.

I think I will go back and mark the drive and let it run for a while just to double check that it isn't moving as you suggested.

Thanks for the feedback

Fred


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#6 telesonic

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Posted Yesterday, 10:51 PM

No prob Fred!

 

Okay, now that you have a confirmed 12VDC in and tested the regulator in the hand controller for output, that is a big step in the right direction. I think you may have it most of the way fixed..... here are my thoughts: in order of importance

 

I have been working with just the hand controller unplugged since I figure that there is not point till I fix whatever is keeping the LED from illuminating.

 

#1

The stepper motor in this drive will not run unless the hand controller (8pin din) is plugged into the base - keep this in mind when testing. The entire clock circuitry is housed inside the hand contoller.  That said, until you are sure of the polarities being right, I wouldn't plug anything in just to stay safe.

 

#2

You may not need to re-wire the 12v jack on the base, in fact - I'd advise that you don't mess with it now. I probably still have some pictures on my PC that shows the correct (center negative) wiring that is on my Powerstar base. If I don't have them in my folder, I will get you some new ones tonight.

Don't change anything wiring-wise yet on the base!

 

 

Gimme a little bit, and I will upload some pictures of the base wiring for these scopes. Mine is stock, so it should be easy to compare to yours. I remember this comong up once before, so I may still have my pics here - if not, I'll get some new ones for ya.

 

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#7 telesonic

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Posted Today, 01:07 AM

Okay....  here it is.

 

Well, I didn't have the old pictures in my files, so I had to take some new ones  - So, here is my Powerstar fork base - picture of the front panel:

And yes, it's a little dusty, and I found a spider web or two..... eek! grin.gif

 

Powerstar Base
 
Left is the 12VDC jack assembly (center negative on these)
Middle is the 8 pin DIN socket for the hand controller, and the green photoshop mark is the alignment stub / tab.... whatever you call it, for the HC box.
Right side is the 1/8" phono jack for for the motofocus unit.
 
Now, I disassembled this by removing the 4 screws on the front panel - easy.
 
So, here is the panel removed from the base -
I flipped the base / cover plate to the left, so the orientation of the 12V socket will be on the right hand side..... I did a quick text overlay to illustrate how it should look.
The 12VDC socket is the one with the Black / Red wires. This is the correct polarity on the drive base, on mine.
 
 
Powerstar Wiring (front panel)01

 

When flipped, it's easy to see....

Yellow wires on the left are the motofocus jack
Red / Black on the right are the 12VDC
 

Hope this helps,

T

 

 

 




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