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Issue with brand new Ioptron CEM25P

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#1 Bokchoy Ninja

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Posted 03 May 2019 - 10:29 AM

I recently purchased a CEM25P mount and have an issue with the DEC drive unit.

Specifically, the gear switch locking knob on the encoder unit housing does not lock the dovetail saddle -- and the lock knob itself is very loose-feeling (I can easily wiggle it around). If I try turning the lock knob 90 degrees repeatedly while gradually tightening the tension adjuster, I can eventually get it to "catch" and the dovetail saddle will finally lock. However, at this point the lock knob still feels loose and "wiggles" around.

The RA drive unit doesn't have this problem and its lock knob feels much more secure

Anyone run into this problem?

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#2 cytan299

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Posted 03 May 2019 - 10:45 AM

I don't think the loose lock knob is a problem. The lock knob just lifts the worm away from the drive gear when the tension knobs are loose. The most important thing is that both the RA and Dec are tight and not loose after you undo the tensioners by 1/4 to 1/2 turn after tightening them.

 

But if you don't like the feel of it or think it is a problem, I wouldn't wait too long before complaining to iOptron for an exchange. 

 

cytan


Edited by cytan299, 03 May 2019 - 10:47 AM.


#3 Bokchoy Ninja

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Posted 03 May 2019 - 10:48 AM

I don't think the loose lock knob is a problem. The lock knob just lifts the worm away from the drive gear when the tension knobs are loose. The most important thing is that both the RA and Dec are tight and not loose after you undo the tensioners by 1/4 to 1/2 turn after tightening them.

 

cytan

I think I'd have to see an internal diagram to believe it doesn't affect performance. 

 

Any idea how I'd go about tightening it?



#4 cytan299

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Posted 03 May 2019 - 11:02 AM

If you open it up, you will see that the lock knob is a screw with a shoe on it. The shoe lifts up the worm assembly so that the RA or DEC can move freely. Here's a link to my ZEQ25 where you can see the worm gear assembly for the RA. It's basically the same for the DEC.

 

https://www.cloudyni...-zeq25-tune-up/

 

 

The most important part is the tension knob that holds the worm properly to the large spur gear (I called it the drive gear above, which is really not the right name for it).

 

cytan

 

P.S. I don't know if you'll void the warranty if you open it up. Like what I said above, if you're not satisfied, you should really return it and get a new one. Don't be like me, who waited too long and had to fix a whole slew of problems by myself.


Edited by cytan299, 03 May 2019 - 11:06 AM.


#5 Tristarcapt

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Posted 03 May 2019 - 11:47 AM

The gear switch does just what cytan said, lifts the worm away from the gear after the tensioning knob is fully released. It’s super obvious to see when the DEC cover is popped off. My RA gear switch is just like you’re describing. Ironically, my DEC was just the opposite. Super stiff and difficult to turn after the tensioning knob was fully released. I sent it back to iOptron and this is what they found:

Hi, Scott,

Your mount was shipped back to you yesterday, UPS tracking # 1Z88F2R20398487906.
Repair log:
1. DEC frame prevented the clutch fully release, trimmed the frame to fit.
2. Re-meshing DEC gears.
3. DEC bearings replaced (click sound).

My mount was only a couple of months old so I was a little disappointed that I had to send it back, but support was good and I had my mount back in a week (and this was during NEAF!). Now my DEC gear switch is just like my RA.

As long as with the gear switch in the locked position and the tensioning knob fully engaged there’s no play in DEC or RA I would think you’d be fine. By the way iOptron and the manual say to fully engage the tensioning knob. IF the stepper motors stall then release the tensioning knob 1/8 to 1/4 of a turn and recheck (ref step 10 of the QSG). Mine works just fine with the tensioning knobs fully engaged.
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#6 mewmartigan

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Posted 03 May 2019 - 11:48 AM

I also have a relatively new CEM25P (a month or so). When I turn the gear switches for RA and DEC I can kind of feel things going into place. At this point, with the tensioners all the way out, I can wiggle the RA and DEC back a forth a little with no resistance. Then after I tighten the knobs it locks them down pretty well.

 

So if you engage the DEC gear switch and can still rotate the saddle around, I would call iOptron.


Edited by mewmartigan, 03 May 2019 - 11:55 AM.

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#7 OldManSky

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Posted 03 May 2019 - 11:52 AM

My brand-new DEC lock knob was much like yours.  It still is (after 6 months).

I didn't see any reason to send it back, because it functions normally.  There's a bit of "wiggle" in the DEC locking knob whether it's locked or unlocked, but it's still no problem at all to tell when it's locked and when it isn't.

The PE on mine is roughly 5 arc-min P2P, and the DEC backlash is essentially non-existent.  It operates perfectly, and guides wonderfully.  I routinely get under 0.5" RMS guided performance on both axes out of it.  So no reason to send it away for a little bit of knob free-play.

 

What you do with yours, of course, is up to you.  But I wouldn't sweat it if it all works well.



#8 gotak

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Posted 03 May 2019 - 11:55 AM

Knob free play. In the UK that would have a slightly different meaning lol..
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#9 Bokchoy Ninja

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Posted 03 May 2019 - 12:02 PM

My brand-new DEC lock knob was much like yours.  It still is (after 6 months).

I didn't see any reason to send it back, because it functions normally.  There's a bit of "wiggle" in the DEC locking knob whether it's locked or unlocked, but it's still no problem at all to tell when it's locked and when it isn't.

The PE on mine is roughly 5 arc-min P2P, and the DEC backlash is essentially non-existent.  It operates perfectly, and guides wonderfully.  I routinely get under 0.5" RMS guided performance on both axes out of it.  So no reason to send it away for a little bit of knob free-play.

 

What you do with yours, of course, is up to you.  But I wouldn't sweat it if it all works well.

Interesting, any idea what the issue is or how to tighten it?



#10 B 26354

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Posted 03 May 2019 - 12:06 PM

It might be a big deal... and it might not.

 

I would definitely e-mail iOptron immediately... and if you didn't purchase it directly from them, e-mail the vendor as well, and let iOptron know that you have done so.

 

I got mine from High Point Scientific one year ago, and upon first setup, I discovered a problem with the RA-axis locking mechanism. In my case, with the RA tension-adjuster knob unscrewed, if I turned the RA Gear-Switch to its "lock" position... more often than not, the locking mechanism would not engage at all. And even when it did engage, if I tried to move the RA axis, it could be rocked a few degrees, side-to-side.

 

I e-mailed both High Point and iOptron, and over the course of the ensuing two weeks, the problem was solved by iOptron. Fortunately, all that was needed was a longer (i.e., more powerful) spring, which was simple for me to replace, once they'd sent it to me... so I happily avoided having to send the mount to iOptron.

 

I have no idea what the problem might be with your Declination gear-switch locking-knob... but in communicating with iOptron, I was warned not to use any "repair" instructions that are for the ZEQ mounts, as there are some slight-but-significant differences in internal and external construction between them and the CEM25P... including the methods by which the two plastic drive-housings are attached.

 

Also, when you e-mail iOptron, be as specific and as detailed as possible, in your description of what the problem is. In the end, they were very helpful... but it took at least three separate communications to finally clarify the situation.

 

Hope your solution ends up being as overall-effortless as was mine. grin.gif



#11 Bokchoy Ninja

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Posted 03 May 2019 - 12:12 PM

Just an update -- I have contacted the vendor and explained the issue to them. They requested that I send the item back for an exchange.

 

It may have been a trivial issue (or it might have been serious), but at the end of the day it's certainly not operating as advertised and I'd rather play it safe and get a unit that works as intended.

 

Thanks for the responses!


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#12 Chuckwagon

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Posted 03 May 2019 - 12:22 PM

It isn't a problem, ignore it.  It has ZERO impact on performance.  In fact, you want it loose, so you know it isn't partially engaging the pivoting housing that holds the gear, which might impact performance.  If you take the covers off you will see, the switch only serves to disengage the gears.  If you completely unscrew the tension adjuster, the gears can remain in mesh if the switch isn't turned.  Turning the switch pushes up the pivoting housing that holds the worm, and it then serves as a block to keep the worm from falling back into engagement.  It isn't a clutch as most would think of it.  So when it is not doing its job of keeping the gears disengaged, it is perfectly fine to sit loosely.


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#13 Bokchoy Ninja

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Posted 03 May 2019 - 12:54 PM

It isn't a problem, ignore it.  It has ZERO impact on performance.  In fact, you want it loose, so you know it isn't partially engaging the pivoting housing that holds the gear, which might impact performance.  If you take the covers off you will see, the switch only serves to disengage the gears.  If you completely unscrew the tension adjuster, the gears can remain in mesh if the switch isn't turned.  Turning the switch pushes up the pivoting housing that holds the worm, and it then serves as a block to keep the worm from falling back into engagement.  It isn't a clutch as most would think of it.  So when it is not doing its job of keeping the gears disengaged, it is perfectly fine to sit loosely.

The problem is not just that it's loose, it's that if I turn the lock knob, the dovetail plate does not lock. I have to thread in the tightener gradually while flipping the lock knob back and forth until it finally "catches". Difficult to ignore this as an issue.



#14 OldManSky

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Posted 03 May 2019 - 01:10 PM

Interesting, any idea what the issue is or how to tighten it?

No idea.  I haven't worried about it, since everything works as intended.

I'm not disputing your choice to exchange it -- do what's right for you.

 

Regarding your last post above, though, I'm betting you don't actually have to flip the lock knob back and forth -- you can put it in "lock" position (even if that doesn't lock the DEC axis), and then tighten the tension knob, and it'll "lock" without having to flip the lock switch at all.  Did you try that?  Or is it too late, and it's boxed up and headed back?



#15 Bokchoy Ninja

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Posted 03 May 2019 - 01:19 PM

No idea.  I haven't worried about it, since everything works as intended.

I'm not disputing your choice to exchange it -- do what's right for you.

 

Regarding your last post above, though, I'm betting you don't actually have to flip the lock knob back and forth -- you can put it in "lock" position (even if that doesn't lock the DEC axis), and then tighten the tension knob, and it'll "lock" without having to flip the lock switch at all.  Did you try that?  Or is it too late, and it's boxed up and headed back?

I don't even know what the lock position is on that knob since it has a huge "wiggle" (like +- 45 degrees) 



#16 mewmartigan

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Posted 03 May 2019 - 04:02 PM

Lock position for each axis is pointing at the tension adjustment screw. Sounds like ioptron is responsive to swapping it for you though. When you get the new one you'll be able to compare the feel.

#17 Chuckwagon

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Posted 04 May 2019 - 12:34 AM

The problem is not just that it's loose, it's that if I turn the lock knob, the dovetail plate does not lock. I have to thread in the tightener gradually while flipping the lock knob back and forth until it finally "catches". Difficult to ignore this as an issue.

You don't "lock" the switch.  You simply place it in the "disengaged" position (which moves the gear out of engagement) or into the "engaged" position.  Moving the switch to the disengaged position, if the tension knob is still in place (you can completely remove it) there will be a little force needed, but that's normal.  When you put it back into the "engaged" position the normal procedure is to tighten the tension knob all the way, not a hard tight but just until it's all the way in, and then back it off 1/4-1/2 turn if needed.  While tightening the knob it is normal to slightly move the axis back and forth a tiny amount  to insure the gears don't engage on top of the teeth but rather settle into each other.  But you don't need to wiggle the engagement switch to do that, it doesn't position the gears, it just engages or disengages them.  And, if you have your zero position marked, you can tighten the tension knob while insuring you are still at zero as the gears mesh.  Some mounts don't "need" the tension switch backed off at all from full in.  But I think most folks feel better if it's backed out a little.  You can test it by turning it all the way in and then slewing at full speed to both sides of the mount.  If you get motor stalls (the ugly grinding noise) then you need to loosen it some.  (The stalls don't hurt the mount, they just screw up the zero position which you can easily reset if you've marked it, so don't be afraid to test.) 

 

The tension knob has a spring in it, so the effort of turning the engagement switch can vary based on the position of the knob and how much tension is present.  And, there is a point at which the knob is screwed in far enough that the knob itself will prevent the hinged plate from disengaging the worm, so at that point it would be very difficult to move the switch.  (As in you'd need to break something.)  But what you have described is the normal functioning of the various parts.  And while you may get a different sample where the engagement switch fits more snugly into it's housing and doesn't seem loose, its operation will be the same.  I fear you will end up even more frustrated with the delay and shipping when the mount you get back behaves the same way your current one does, though it may not have a "wiggly" engagement switch.

 

Another item to note, on some mounts, the spring inside the tension knob may need to be stronger or the hinge plate adjustment altered if the hinge plate is a tad too tightly adjusted, as the motion to return the gears to engagement might not fully complete.  In such cases, the hinge plate can be adjusted (the best choice) or the spring made stronger (easier route.)  You can tell if this is happening by very gently wiggling the axis right after tightening the tension knob.  If there is a very tiny bit of play, you may need to adjust it.  Typically, the play will go away after a little time passes as the spring will eventually finish pushing the hinge plate back down.  But how long that takes would be hard to gauge, so it's probably best to get it so there is no play and you're ready to go as soon as the tension is set.  On my mount I did both, adjust the hinge plate and make the spring a bit stronger.  (I had a spring kit from an older ZEQ25 that had 2 springs that sit one inside the other which Paul Chasse used to sell, and I used that.)  It did not affect my tension knob positioning (I run mine almost all the way in, maybe 1/10 of a turn out) and the mount doesn't have any stalling issues.

 

Hope that helps.


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#18 Bill001

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Posted 01 May 2020 - 07:04 PM

I recently purchased a CEM25P mount and have an issue with the DEC drive unit.

Specifically, the gear switch locking knob on the encoder unit housing does not lock the dovetail saddle -- and the lock knob itself is very loose-feeling (I can easily wiggle it around). If I try turning the lock knob 90 degrees repeatedly while gradually tightening the tension adjuster, I can eventually get it to "catch" and the dovetail saddle will finally lock. However, at this point the lock knob still feels loose and "wiggles" around.

The RA drive unit doesn't have this problem and its lock knob feels much more secure

Anyone run into this problem?

Why am I not surprised to find this post.  Bokchoy, did you have iOptron service your unit under warranty or did you find another solution as those discussed above?

thnx

Bill 



#19 RogeZ

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Posted 03 May 2020 - 09:01 AM

Considering his issue is just a design characteristic of the mount, half of this thread is just here to mislead people technically even though the experienced users point out the facts.

Edited by RogeZ, 03 May 2020 - 09:04 AM.

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