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Celestron VX mount

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#876 dragonslayer1

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Posted 14 September 2013 - 10:36 PM

Just giving you a hard time LOL :lol:,,, check out Mars too. enjoy your scope,
Kasey

#877 cn register 5

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Posted 15 September 2013 - 05:06 AM

I agree with what Chris is saying - Rod does hold some serious weight on CN. But for the sake of this conversation, I agree with Rod. How about you just post your results?


OK, let's try it.

AVX mount, 12V SLA battery.
Power on, waiting to be ready, no tracking 0.24A
Aligned and tracking 0.3A
Slewing RA full speed, no load 0.5A
Slewing Dec, full speed, no load 0.45A
Slewing to object, both motors 0.63A

If I apply a load to the motors to simulate being out of balance the current increases but I couldn't get a single motor above 0.7A, that's total current draw.

I was using a StarSense so that includes the StarSense module. I doubt that the normal HC will be much less.

So allowing an average of 0.5A would seem reasonable for estimating battery life.

Why the high power specification for the PSU?
This is because when DC motors start they take a much higher current while they are starting. This is only for a short time but the power supply must be able to deliver it. This is for such a short time that it doesn't make much difference to the average current that affects how long a battery will last.

This is the result of actual measurement. It is not speculation, guesswork or made up.

Chris

#878 DaveJ

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Posted 15 September 2013 - 10:20 AM

This is the result of actual measurement. It is not speculation, guesswork or made up.


Thanks, Chris. Very good data. I've experienced nearly the exact same readings with a CGEM DX with two well-balanced side-by-side refractors mounted with a combined weight of over 50lbs. Balance makes the difference when it comes to stressing the motors and increasing current draw.

#879 nodalpoint

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Posted 15 September 2013 - 04:10 PM

Terrific shots, nodalpoint! What're you using to autoguide?


Thanks! Using the Orion 50mm guide scope and an ASI120MM camera with PHD. Pretty basic.

#880 Eric38

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Posted 11 October 2013 - 08:42 PM

Been doing some visual observing with the AVX and a de-forked C8. I think the C8 is going to stay with the AVX until I get a newer one, as the one I have is over 25 years old. Not that that is a bad thing though. The goto accuracy is the best I have ever experienced. I have had a Meade, still have an Ioptron smartcube and Orion's intelliscope push to. It gives the user great confidence in knowing once slewed to an object it will be there. If I can not resolve the object I know it is not the mount but other factors like seeing, light pollution or the optical train. Last Wed the 9th was a fantastic evening with a limiting visual mag of about 6. Mag 9.5 to 10 were about the limit with a 26mm wide field eyepiece. Neptune and Uranus were really awesome to find and observe. Even got the Sculptor galaxy (NGC253). The mount is sturdy and very capable. I may need to get another counter weight because I have maxed it out with my visual set up and I suspect that camera equipment would be as heavy or heavier. Counter weights from my CG-4 will fit though but I do not like to scavenge from one set up to the next.

Not sure what you mean regarding USB-serial. A Keyspan works just fine with my VX and Windows 7 64-bit machine. ;)


What is a "Keyspan"?

#881 Carl N

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Posted 12 October 2013 - 10:33 AM

Read the manual. You can switch the routine to have the alignment stars be on either side. That way the calibration stars can be done on the side you are planning most of your visual use.

#882 DaveJ

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Posted 12 October 2013 - 10:47 AM

So lets say I am going to stay exclusively on the east side of the meridian. Where should I pick my 2 alignment stars? I am guessing on the east. Should I still do 4 calibration stars on the west even though I am never going to observe over there? Is there any way to pick them on the east and will that make it perform better?


The major reason for adding the calibration stars is so the firmware can calculate the cone error. However, if you stay exclusively on one side of the meridian, cone error is not so much a problem. Keep in mind, though, that if you do want to find something on the "wrong" side of the meridian, the cone error will probably render accurate gotos impossible. Additionally, the ASPA won't function correctly since cone error definitely is taken into account by the ASPA routine.

#883 DaveJ

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Posted 12 October 2013 - 11:12 AM

What is a "Keyspan"?


Here you go...the best, most compatible "USB to Serial" converter out there, in my opinion. I've used it with various PCs, various OSs, various external hardware requiring all manner of communications without any hitches whatsoever. Keyspan USA-19HS Hi-Speed USB Serial Adapter for PC or MAC

#884 dr.who

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Posted 12 October 2013 - 06:29 PM

And time for a question of my own...

I have two AVX's. One I use for outreach since it's a bit banged on (from using it for outreach) and the other I was planning to use for AP.

As I was using the AP mount I noticed odd behaviors.

Problem #1: When I would be doing alignments and using the UP direction button on the controller it would pause and then there would be a big "jump" in the motion almost like it was releasing stored tension on the worm drive and catching up to the point where it should be. It would do this if I was centering an object in the EP as well after alignment.

Problem #2: It would slew to the point where the OTA was pointing straight up and the weight bar was 90* to the ground with the head facing West and bar East. The motors would continue to run at full speed #9 but the mount would not move.

Problem #3: When I would target something near zenith it would be several degrees off target. Yet anything below 70* elevation would be fine.

This was not unique to one scope. It occurred with the 11" (where I first noticed it), the 8", and the Tak.

Defective mount/worm gear? Or am I missing something. Balance is good on all three and locks are tight but not hard tight. Battery is fully charged and it occurs when I run it on line power from the garage as well. Those were the first three things I thought of and checked.

#885 Eric38

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Posted 12 October 2013 - 06:30 PM

Thanks Dave, for the link.

And to Shaka, I have had no problem what so ever with the goto finding and nearly centering every object regardless of it's location in the sky or the initial orientation of the alignment procedure. Just set up the scope and use it.

Dr Who, problem #1 sounds like the backlash is set too high for the RA positive adjustment.

#886 Carl N

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Posted 12 October 2013 - 06:35 PM

It's what I do.

#887 dr.who

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Posted 12 October 2013 - 06:37 PM

Hey Eric,

Thank you. I will check that. What is default? I ask because I don't think I played with that setting...

#888 EFT

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Posted 12 October 2013 - 06:54 PM

And time for a question of my own...

I have two AVX's. One I use for outreach since it's a bit banged on (from using it for outreach) and the other I was planning to use for AP.

As I was using the AP mount I noticed odd behaviors.

Problem #1: When I would be doing alignments and using the UP direction button on the controller it would pause and then there would be a big "jump" in the motion almost like it was releasing stored tension on the worm drive and catching up to the point where it should be. It would do this if I was centering an object in the EP as well after alignment.

Problem #2: It would slew to the point where the OTA was pointing straight up and the weight bar was 90* to the ground with the head facing West and bar East. The motors would continue to run at full speed #9 but the mount would not move.

Problem #3: When I would target something near zenith it would be several degrees off target. Yet anything below 70* elevation would be fine.

This was not unique to one scope. It occurred with the 11" (where I first noticed it), the 8", and the Tak.

Defective mount/worm gear? Or am I missing something. Balance is good on all three and locks are tight but not hard tight. Battery is fully charged and it occurs when I run it on line power from the garage as well. Those were the first three things I thought of and checked.


Number 1 is generally a sign of worm binding due to the spacing between the worm and ring gear being too tight. The worm binds and the motor board applies more power to the motor until it breaks free. Then it rushes ahead momentarily before coming back down to the normal speed. It's doubtful that the alignment would remain accurate after this.

Number 2 is an odd one that would suggest that either the clutch(es) is slipping or the gears are disengaging for some reason. I think that it is most likely that the clutch is slipping and you might not be as balanced as you thought. If it is the gears that are the problem, then it is more likely that the spur gears are disengaging rather than the worm and ring gear. It's possible that the setscrews on one of the spur gears is loose, but I would expect it to be a constant problem, not an intermittent one.

Number 3 is almost definitely related to number 2. That is, something is slipping.

So you appear to have one problem where something is too tight, and another problem where something else is too loose.

#889 dr.who

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Posted 14 October 2013 - 03:52 AM

Thank you Ed!! I will be calling Celestron first thing tomorrow to talk to them about a RMA.

#890 Dr.Don

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Posted 17 October 2013 - 01:27 AM

I had a similar problem with a brand new AVX. Instead of the Up button, I saw the same thing with the Right button. It didn't always fail but when it did the exact thing you described happened. I returned it within the 30 day period and got a new replacement. It was no hassle at all except::: Celestron wanted everything back and shipped me a whole new C9.25 system. Fortunately I still had the boxes and most of the packing material. But I had to pack up my C9.25 and everything. Fortunately I bought it from Orion and their store is a 10 minute drive from my office. My new one works great.

#891 SkipW

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Posted 17 October 2013 - 08:43 PM

Can someone explain the "Get Axis Postn" command. I thought this would show me the Alt Az coordinates. But when I tried it on the moon last night it was showing me an Altitude of 357 degrees which is obviously impossible. Even when I'm pointing at the North Pole it says 90 alt and 90 azm.

The mount has been aligned and it does show the proper RA Dec for any object. The gotos and tracking are otherwise perfect. I'm just wondering what is going on with these alt/az coordinates. Is there a bug here?

The Axis Positions are the physical position of the RA (Az for an Alt-Az mount) and Dec (Alt) Axes. I was hoping the same thing you were, but nope. I don't think it's a bug, but the names are certainly misleading with an Eq, to say the least!

They both read 0 - 360, and indicate 90 and 90 at the index positions. Your "Alt" of 357 represents a Dec of -3 degrees; does that sound about right? I think when they read 0 and 0 you're pointing to the celestial equator and meridian (assuming mount perfectly aligned and leveled, no cone error, etc., etc.), but haven't actually checked this. Same (equator and meridian) for 180 and 180 from the other side of the mount (need to check).

#892 mamamia

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Posted 18 October 2013 - 01:47 AM

Holy AVX thread Batman, I was thinking about getting IEQ30 for my new scope Edge 8HD and Es 102 used for Visual and future AP. Now, I am heading to buy an AVX.

#893 MartinTreadgold

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Posted 24 October 2013 - 05:58 AM

no, you won't have done any damage to the mount motors if thats what you mean, but check the cable connection plug/socket isn't damaged though

#894 schluterdude

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Posted 24 October 2013 - 08:02 AM

I run a large newt on mine, and occasionally the bottom of the tube gets hung up on a leg. That's why there are slipper clutches! They aren't meant to take a healthy diet of slippage, but every once in a while.... That's why they are there!

I also do not tighten the snot out of them. Just enough to hold everything snug, but loose enough if someone leans on it, it'll move. I'd rather line it back up than risk a ding in the worm assembly....

#895 schluterdude

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Posted 25 October 2013 - 08:02 AM

I would.... If you tighten them too much, kinda defeats the purpose...

#896 MartinTreadgold

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Posted 28 October 2013 - 04:01 AM

should be firm, but don't force it.

#897 Live_Steam_Mad

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Posted 07 November 2013 - 12:51 AM

Hi, can someone confirm please that the Celestron Advanced VX (AVX) mount has NO "back drift" / "rubber banding" at say 250x ?

My local friend Jon H. has an LX90 that we are having rubber banding problems with ;-

http://tech.dir.grou...ns/topics/84960

i.e. I make the star go to the left edge of the FOV in the 8mm eyepiece and then come back to the centre and it stays there, same with the star being made to go to the right hand edge of the FOV and then coming back to centre it stays there also, BUT with the vertical direction, it does NOT cooperate properly. When I ask it to make the star go to the top of the FOV and then bring it back to the centre, it then drifts downwards about 1/4 of the FOV towards the bottom edge, and MUCH worse when make the star go down to the bottom edge of the FOV and then back up to the centre, it drifts back down by 5/8 or nearly 2/3 of the FOV until it's near the bottom edge of the FOV. I trained drives carefully at 250x and did callibrate motors and GOTO's are pretty accurate and tracking at 250x is good but it does this rubber banding thing and it annoys me.

Do the AVX / CG5 / EQ-5 / HEQ5 / EQ6 / GM11 / GM8 / LXD75 mounts do this?

I want to buy a GEM that does NOT have this rubber banding issue at all, I was going to maybe buy an LX90 but the problems are putting me off and I might well get a GEM instead.

Regards,

Alistair G.

#898 Skunky

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Posted 07 November 2013 - 01:26 AM

It's called backlash.. and all those mounts listed will have backlash..

You can spend $15,000 on a AP1100 with encoders if you don't want backlash... or any belt driven mount.. 10 micron too.. Your not going to get a backlash free mount under 8k, At least not an Equatorial Mount.


#899 orlyandico

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Posted 07 November 2013 - 01:48 AM

Yup, backlash in RA is normal, and expected. My Mach1 has backlash in RA (not much, but there). In theory I can tune it out with the backlash setting, but why bother.. it would screw up the autoguiding.

#900 rmollise

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Posted 07 November 2013 - 08:15 AM

BUT with the vertical direction, it does NOT cooperate properly. When I ask it to make the star go to the top of the FOV and then bring it back to the centre, it then drifts downwards about 1/4 of the FOV towards the


"Vertical" is meaningless in this context, so I can't tell you which axis is affected, but I would guess declination. A little backlash (what is "rubberbanding"?), especially in dec, is to be expected in this and similar mounts at this price level. ;)






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