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mad mean motor manipulation!


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Okay, got my EQ5 out at last. And made a rough job of polar aligning. Basically involved putting a compass right below the middle of the mount, tracing a line towards north, putting the leg with the N on it on the line, then altering altitude until the brightest star was roughly in the circle. It won't be accurate but it will do for now, just to check the motor's working.

Right. looked at a bright star, flicked the motor onto N and watched it drift across the... hang on! it's not meant to drift at all! okay, press all the buttons, at 8x, 4x and 2x, and it doesn't seem to make a blind bit of difference as to where the star is in the field of view. What's going on??? :?

I can't see for the life of me where I've gone wrong!

Help me out here!

Andrew

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good point Ant. I'll try that, but I anyway have to tighten them to get the scope to stay still, because I haven't properly balanced it yet. Anyway, correct me if I'm wrong, but Polaris is the only bright star in its area, so if I've got the N pointing north to within 5*, and I've got a bright star close to the dot in the polar alignment scope, then it can't be far wrong, can it?

Now i've pointed at a bright star, flicked the switch from off to N (I presume this refers to my being in the northern hemisphere) then that star should still be in the FOV of the EP (25mm in a 1000mm scope = 40x) after I've made this post.

Lets see...

Andrew

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okay, that star ran like hell!

I've put the motor on S this time, to see if it's maybe reversed for some reason. I can hear it clicking away, so I know it's working. Ant, do you have to tighten the locks really tight, or is it enough if it's just held in position?

Andrew

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could be I suppose, but it was making the same noise without the scope or weight. now I've only got the scope on. I think the counterweight is far too heavy.

S didn't work either :D but now my honeybunny is tired and needs company and so am I and I need hers, so though the skies are clear for once and there's astronomy that needs doing, it'll just have to wait. After all, I'm working from 7am till 6pm tomorrow. :)

C'est la vie.

Any ideas about my query anyone?

Thanks CC

Andrew

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Have you locked the gears? Where the motor connects to the shaft that turns there is a small knob thats needs to be tighened to engage the motors. Basically you should not be able to manually turn the shafts as the motors are locked on.

Hope that makes some sort of sense, I aint the best at explaining these things

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  • 2 weeks later...

I can find a knob that fits your description, but that's only on the dec motor.There's virtually nothing between the RA motor (which ticks in the appropriate manner) and the mount. There's a small cylinder around the connecting rod, that I can rotate just a tiny bit (more of a wobble really), and there's an inaccessible screw head, and an unexplained screw thread sticking out of the cylinder. It's really simple. On the other side of the shaft there's jsut the little D shaped rod for attaching a slo-mo cable.

I can't see for the life of me what's going wrong, because though I can feel and hear the motor ticking, the mount isn't moving in the slightest. I set the pointing at something, and in tracking mode, there's no movement in 30 minutes, and the same on 8x slew. Could a part be missing?

Any more ideas guys? I'll try and get a detailed photo up.

Cheers though!

Andrew

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The RA motor should have the same bits on it. Thats where the bodge comes in. I think you need to investigate how the RA motor is couple onto the shaft by taking a closer look at the cylinder that 'wobbles' a bit, it may just need tightening up a bit?

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Hope you don't mind my comment! But the cylinder you refer to on the RA looks to me like a shaft joint with two pins through it, one in the motor shaft and the other in the scope RA shaft, If any one of the pins is sheard off that could account for lack of movement, Also could account for clicking noise.can you watch the shaft either side of joint in motion to see if they are both turning?....Jeff.

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right guys. Appreciate your responses. I realise it's a very rough job, but I imagine it once worked, so it should work again one day. I'll email Nick (previous owner) and have another look to see at what stage the motor loses connection. Are you saying that the motor shouldn't be clicking at all??

Andrew

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can you watch the shaft either side of joint in motion to see if they are both turning?....Jeff.

Use this suggestion from Jeff. Put a little mark with a felt pen or something on the shafts either side of the joint and watch to see if there is movement one side or the other. If either side has independant movement from the other (or the joint) then the joint is at fault. If nothing moves it's the motor.

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Update: I can actually twist the connecting shaft all the way round, but it still wobbles freely a little, and the motor can only turn the shaft as far as the wobble. I think I'll need to put the motor where it belongs, on that lovely plate adjacent to the connector (as gordon suggested with his wonderful paint diagram), with gears. As SR expected, the two motors do indeed clash.

As for the dec axis, slo-mo cables won't move it, let alone the motor. It seems that the gears are totally locked, but I can't see any way of loosening them, or separating the gear cogs.

ANdrew

P.S. the ticking is regular and quiet. I don't think the motor's at fault at all. i'm quite sure it's the connection.

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OK remember that the motors only turn an entire revolution every 24hrs so you wont really be able to see it move. As the sound is regular and quiet it does sound like the motor is OK. I would be tempted to do as somebody said and paint a little tip-ex or similar and see if it does move. As you said it must have worked at one time so fire it up and see how it goes. As for the other gear being jammed, you should be able to unscrew the silover bit from the motor to dis-engage the gears, sometimes after I unscrew it I still need to pull the brass ring a little to dis-engage that as well, you should then be able to use the slo mo cable, it wont work with the gears still engaged.

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Thanks blinky, but I can see the motor move the shaft at 8x. It works for about 3 seconds before running out of "wobble" then just stops, although the motor's still buzzing (when I slew, then it buzzes, rather than ticks, as would be expected). I've left it tracking to see if the shaft turns, but I'm doubtful it will move at all. As such you are right that the mount makes one revolution in 24 hours, but the slow-motion makes many more revolutions, otherwise they wouldn't be slow motion. The movement in the shaft would be noticable in 5 minutes.

As for the dec axis, with a little force, I got the thing to turn with slo-mo cables, but the motor is completely dead. I think there must be a dodgy connection in the wire somewhere (you don't say!)

Andrew

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new update - getting closer all the time. Removed the motor and examined the connection. It was jsut a case of sliding the tube towards the motor. Then, even when i forced the tube between my finger and thumb in the opposite direction to which it was trying to slew, it turned through my fingers. So the connection there is fine. It's the connection to the mount that's the problem. There's a hole drilled through the tube and through the D shaped rod, and the idea is that a screw goes through it, but now that the tube is slided towards the motor, the holes don't line up, and the screw won't go through. So I've got to find out how to secure the two bitts of metal together.

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