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Orion SVP, Single Axis: Only turns one direction

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#1 Cerberus

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Posted 30 June 2013 - 10:06 AM

I have a fairly old SVP mount with single axis controller, and last night it stopped working. This morning I did a complete tear down of the RA axis, re-greased and re aligned the worm gear and motor only to find that the controller only turns the drive one direction and it is the WRONG direction for the northern hemisphere.

These are fresh batteries, the port and plug look fine, I cleaned them with light rubbing alcohol on a q-tip, I jiggled the plug and tried setting the controller to north and south but the drive will still only turn west to east no matter what buttons are pressed. I checked the visible wiring and did a quick volt-meter check, no shorts or visible issues.

I had been planning to upgrade mounts to an ATLAS or CGE, and eventually swap this over to GO-TO for a smaller scope anyways but this really has me irritated.

A search of the forum and google hasn't turned up any incidents of this happening elsewhere. I'd be happy if I could just get it to turn the correct direction, even if the controller was no longer useable for speed adjustments.

#2 rmollise

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Posted 30 June 2013 - 01:57 PM

Are you saying it won't _track_ or won't slew when you push the buttons?

If the latter, that is normal. At guiding speed, the motor usually does not engage when you press the W button, it stops...

#3 E_Look

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Posted 30 June 2013 - 04:05 PM

I think he is saying his SVP now only goes in the OPPOSITE direction.

I also have the SVP with a single axis drive. I've never taken it apart, and forgive me for asking, but it is possible that in your tear down and reassembly either the electrical polarity or the worm gear is in the wrong way?

#4 Cerberus

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Posted 30 June 2013 - 06:29 PM

The worm gears are "fool proof". They can't be put in backwards, they work in reverse and on both RA and DEC.

I think this was an issue even before it stopped working, while watching Saturn I noticed it was moving out of view faster than normal. After messing with the buttons then it decided to stop working when the gears bound up. The gears are now free and it turns great with the controller, just the wrong way, and only in that same direction.

It will ONLY turn west to east. If I let it do its thing, it turns the wrong way for the northern hemisphere. If I flip it to southern hemisphere, still turns the same direction. If I push X2 prograde, it turns the same way, if I push X2 retrograde, still turns the same way. Ditto for X8 pro and retro grade.

I looked into the soldering on the plug connections, they all look good... I guess I could try replacing the plug and the port, I'm pretty handy with a soldering iron.

#5 E_Look

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Posted 01 July 2013 - 01:31 PM

I have encountered only one issue so far with this system, and that's the system NOT stopping (resuming normal motion) after I use the 8x speed to turn west (in direction of natural stellar motion) and I have to tap the 8x east button once to make it go east. Then it'll stop, rather, resume normal tracking speed and direction. That is, I think after the use of 8x W, it stops. When I look at it inside, the motor seems to be okay, though. I'm confused on this, myself. And I wonder if this is related somehow to your problem.

I wonder how much of either of these problems is in the actual controller box, not the gear, not the motor, nor the housing.

#6 Cerberus

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Posted 01 July 2013 - 06:40 PM

The only possible answer... Is that the controllers have become self aware and are tired of being servile to the meat bags.

I fixed the issue on mine today by replacing the controller plug, the port on the mount, and giving the internals of the controller a generous spraying of electrical contact cleaner. Sometimes the "shotgun" technique is the best way to solve these undiagnosable quirks.

#7 E_Look

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Posted 02 July 2013 - 04:25 PM

LOL!

I suspect I may need to do something like that, too.

But you've at least found that the issue is the signal getting through to the motor. Where exactly the issue is physically is probably much harder to spot.

I don't really like that controller plug; basically, it's a banana plug (a BNC jack) and they get loose after a while. How hard was it to replace the plug on the box?

But I suspect it probably wasn't that plug on the box. The port on the mount may be more likely, as I can imagine that those thin little contact strips inside the port may get messed up.

Anyhow, I'm really happy your problem cleared up. I like this mount, as it's the upper limit of what I'm able to lug in and out of the house.

#8 Jon Isaacs

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Posted 02 July 2013 - 09:14 PM

Something to look at:

My Orion AstroView controller died after several years and I chalked it up to component failure. However my best friend Bob was staying with us for several months. Bob had spent more than 30 years as civilian electronics guy working on Naval electronics of all types. Bob is extremely near sighted, about 8 diopters worth so he has eyes like a microscope. He knows what to look for and he can see tiny flaws.

What Bob found was some corrosion on the circuit board. He cleaned it up and it has worked fine ever since.

These controllers are not well sealed against moisture, those nights with the dripping dew finally caught up to it.

It's worth a look.

Jon

#9 E_Look

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Posted 03 July 2013 - 01:06 AM

So it could be his liberal dose of circuit board cleaner the did the trick! I should cast a more suspicious glance at the controller box, then.






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