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Bought Vixen GP with fried DD-1 controller

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#1 matti

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Posted 24 March 2011 - 05:15 PM

So, I am researching on how to make my Vixen GP work. I bought it cheap today with a broken DD-1, supposedly a common problem. The MT-1 motors work fine and the mount is almost unused.

It would be great if I could get some advice on the best route to take here. I am going to use the mount for unguided wide field astrophoto and autoguided astrophoto with a small refractor.

Should I:
1. Try to repair the DD-1 and add guideport?
2. Buy a new DD-2? ($200, does it have a guideport?)
3. Buy a compatible GOTO-system, with or without new motors?
4. Something else?

A cheap GOTO is tempting but it feels stupid not to use the motors. And what could be recommended? My budget is quite limited.

Thank you for any ideas.
/matti

#2 zerro1

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Posted 24 March 2011 - 05:57 PM

If it appears to be dead, it couldn't hurt to do a little exploratory, could just be a broken solder joint? Broken wire? does it have a fuse inside the handbox?

I tried doing some info search, it does not look as though the DD2 has a guide-port.

Is there a cheap go-to?

There are some bluetooth setups out there, I have not seen one compatible with Vixen ...Yet

#3 Patrick

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Posted 24 March 2011 - 10:51 PM

Hi Matti,

How do you know the motors are working if the controller is fried..or vice versa...how do you know the controller is fried if the motors are working?

Patrick

#4 orlyandico

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Posted 25 March 2011 - 01:10 AM

The MT-1's are standard unipolar stepper motors with an 8-pin DIN connector.

You could buy this (ebay item# 260718018071) DK-3 motor controller. It looks like a clone of the DD-1 and is probably pin-compatible.

As for auto-guiding, I added a guide port to my DD-1, using the instruction photo on the shoestring astronomy web site

http://www.store.sho.../images/DD1.jpg

note that the DD-1 uses the GPUSB-AH ("Active-High") and not the regular GPUSB.

Alternatively.. sell off your MT-1's (they tend to command a good price) and buy the complete Orion dual-axis drive which is $139. It bolts up to a GP. You can also mod the Orion drive for auto-guiding, but you will use the regular GPUSB, not the GPUSB-AH.

#5 matti

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Posted 25 March 2011 - 01:31 AM

@Robert I have opened the controller and looked for obvious problems like that, but am not that good at electronics to be able to find a problem. A guess is that one IC-circuit is fried, like described in the link below. That kind of repair is a bit too complicated for my skills though.

Cheap is a bad word, i ment less expensive, like Orion SkyView Pro and not the Vixen one that seems really expensive. This certainly will be more expensive than I planned whatever I do!

@Patrick It kind of stutters in RA like is described here: http://www.iceinspac...read.php?t=2077 I have also seen it referred to on other websites as a problem with DD-1 that it is easy to break it you use the 32x speed with a slightly too high voltage, like from a car battery. I can make both motors work as expected if I connect only the declination-cable to one of them at a time.

Someone at the Yahoo group for Vixen scopes recommended SkyView Pro as a good replacement for GP. Does anyone have a good experience with that GOTO-system? Are there any alternatives? I have also come across info that guiding might not be a good idea without servo-motors that are only used in GOTO-systems and not with my MT-1-motors.

So it seems like buying a new hand control for $200 might not be a good idea if I need to buy a GOTO-system for $500 in a year when I want to start to autoguide.

I need to get my head around this, just now it feels like I did something stupid in buying that mount, so any advice or shared experiences that can help me are really helpful!

/matti

#6 orlyandico

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Posted 25 March 2011 - 01:51 AM

matti

You don't need servos to auto-guide. I am auto-guiding with my DD-1 + two MT-1's and my GP is reporting +/- 10 arc seconds periodic error.

I would suggest go with the Sky View Pro dual axis drive. Orion doesn't sell the SVP GoTo as a stand-alone kit. If you sell the two working MT-1's you should have more than enough $$$ to buy the SVP dual-axis drive. Then mod it for auto-guiding as in my link above.

#7 matti

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Posted 25 March 2011 - 03:25 AM

@orlyandico Thank you! Didn't see your first answer before I wrote mine. The DK-3 seems to be a clone and a Google search indicates others have been lucky with it. It is not that expensive, so the best route here is to try that first. And then have the option to think about the whole GOTO-thing later. (I hope the Ebay seller can ship to Sweden, even though it says US only. Otherwise it seems like it is only sets with motors included.)

I really think I need to sort the easiest problems out first and get some simple wide field imaging going before I even think about other stuff.

What do you mean they don't sell SVP GOTO? Isn't it this one? http://www.telescope...roduct_id=07817

/m

#8 orlyandico

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Posted 25 March 2011 - 06:43 AM

matti, i thought you meant buy the SVP GoTo drive alone (with no mount).

you can get the iOptron GoToNova, or the Vixen Starbook-S ($$$) to add GoTo to your GP. but the price of the GoToNova is quite close to the price of a CG-5 ASGT or an LXD75.

If you are brave the "GotoStar" (predecessor to the iOptron GotoNova) can be had for $280 FOB China

http://njnorth.en.al..._Star_Kits.html

The same guy (Gilman of Nanjing North, gilman AT northgroup DOT cn) will sell you a DK-3 as well.. I deleted his email but I think it's $100 plus around $20 shipping.

#9 orlyandico

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Posted 25 March 2011 - 06:53 AM

Post deleted by orlyandico

#10 orlyandico

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Posted 25 March 2011 - 07:01 AM

Matti, I read the iceinspace thread and they say it's the stepper motor driver which is blown.

It is trivially easy to open up the DD-1 and replace the chip with a ULN2003. I'm traveling now so I cannot check my DD-1 but I think it's easy, you may want to check out a radio repair man (do such still exist?) in your area, even including their time to repair, it would cost less than $100.

Or if you have a friend who is a radio ham or electrical engineer or something maybe they will repair it for you for free.

#11 orlyandico

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Posted 25 March 2011 - 07:12 AM

Matti

seems the DK-3 controller will not drive MT-1's correctly.

this guy in an old A-mart ad # 268780 says

"I have no idea what this is for. I bought it hoping that it would work with my Vixen MT1 motors but it does not (Powers up just fine and seems to give the motors power but they don't turn. They turn fine with the Vixen handbox.). Has switches for N/S and 1x, 2x, and 32x."


#12 matti

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Posted 25 March 2011 - 08:22 AM

Thank you for catching that for me! Now, first I will try if my soldering skills are what they used to be. If I mess things up, I will research some of the less expensive Goto-kits. I realized I don't need to use all the functions to start with anyway. And if that works, try to sell the old motors.
/m

#13 davebl

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Posted 25 March 2011 - 09:32 PM

matti, i thought you meant buy the SVP GoTo drive alone (with no mount).


They do sell just the drive. I just bought one and installed it on my 26 year old Super Polaris mount. Works great.

Dave

#14 orlyandico

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Posted 25 March 2011 - 10:14 PM

dave, you're right. but at $500 it seems like a bad deal considering that you can get an entire used CG5-ASGT or LXD75 for less than that.

#15 davebl

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Posted 26 March 2011 - 01:37 PM

dave, you're right. but at $500 it seems like a bad deal considering that you can get an entire used CG5-ASGT or LXD75 for less than that.


That's a good point, But the SVP goto system is autoguider ready with a st-4 port, plus I really didn't want to give up my Old SP mount. Guess I'm just sentimental that way (or maybe just Mental) :grin:
Dave






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