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CEM25P problem with DEC movement

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45 replies to this topic

#26 cytan299

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Posted 11 February 2019 - 03:22 PM

Yes, basically they are asking to me dismantle and see if there are any obvious issues with the hardware.

Unfortunately, you *have* to open it up. I had a completely loose drive gear:

 

https://www.cloudyni...loose-dec-gear/

 

Also after tightening it up, the DEC controls got better, but I think the belt is too tight and choking the worm. I still get bad DEC movement when trying to move it under low speed. I haven't had a chance to open it up again to tune though.

 

I know a lot of people swear that iOptron products work great, I, OTOH, can only swear at iOptron products.

 

cytan



#27 tkottary

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Posted 11 February 2019 - 07:48 PM

Thanks for the tip, when I opened the Dec gear last week I did not see any lose parts, I was able to move the drive gear slightly with hand but did not notice my DEC saddle move.

I will try that thing again. I plan to fully open it this week when I get time. 

 

Agreed I am not impressed with iOptron  product now, only bough this because of it being lightweight.



#28 gotak

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Posted 11 February 2019 - 08:18 PM

It's shipped a long way and if you ordered online it shipped the last few miles and maybe thrown in the truck and then your porch.

So it's not too surprising if something come loose.

There are exactly zero mounts shipped long distance that doesn't have such risks.

In the end their design is very simple so shouldn't be too hard to fix if it's a simple lose component.
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#29 StarMike8SE

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Posted 12 February 2019 - 09:58 AM

Wow, I guess I have to open mine up as well.  This is not what I wanted when I bought this.  I noticed the saddle has a little play in it, which concerns me.  While guiding I will get around 0.8" RMS error for several minutes, then get a big jump to 2.5".  It eventually settles but takes awhile then I will get another big jump.  sounds like some backlash or something loose



#30 santafe retiree

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Posted 12 February 2019 - 10:41 AM

Here are the "official" links for adjusting the belt tension and removing play in the Dec and RA axes:

 

http://www.ioptron.u...elt_tension.pdf

http://www.ioptron.c...Play_Fixing.pdf

 

I opened mine up for a "look see" and it is a very simple operation 

 

BTW mine regularly guides at 0.5 RMS and never above 0.8 -- total load is 18lbs (ES 102 FCD100 aluminum tube, Astromania 60mm guidescope, ASI224 as guider, Canon T6i as imager)

 

Cheers,

 

Tom


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#31 StarMike8SE

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Posted 12 February 2019 - 10:54 AM

Here are the "official" links for adjusting the belt tension and removing play in the Dec and RA axes:

 

http://www.ioptron.u...elt_tension.pdf

http://www.ioptron.c...Play_Fixing.pdf

 

I opened mine up for a "look see" and it is a very simple operation 

 

BTW mine regularly guides at 0.5 RMS and never above 0.8 -- total load is 18lbs (ES 102 FCD100 aluminum tube, Astromania 60mm guidescope, ASI224 as guider, Canon T6i as imager)

 

Cheers,

 

Tom

Thanks for sharing



#32 tkottary

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Posted 12 February 2019 - 01:49 PM

Update: Opened up the dec casing last night . Noticed that when the tension knob was fully tight, I could still move the worm house casing .  I had to slightly nudge it in.

 

This was the reason for play in dec saddle. Adjusted couple of  bolts  that was mentioned in the pdfs and play went away.

 

Moving the drive gear moved the dec saddle smoothly without any noticeable backlash. 


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#33 cytan299

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Posted 13 February 2019 - 06:54 AM

Wow, I guess I have to open mine up as well.  This is not what I wanted when I bought this.  I noticed the saddle has a little play in it, which concerns me.  While guiding I will get around 0.8" RMS error for several minutes, then get a big jump to 2.5".  It eventually settles but takes awhile then I will get another big jump.  sounds like some backlash or something loose

Or too tight. See this:

 

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

 

cytan


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#34 StarMike8SE

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Posted 15 February 2019 - 10:46 AM

Or too tight. See this:

 

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

 

cytan

Thanks



#35 StarMike8SE

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Posted 20 February 2019 - 07:08 PM

Here are the "official" links for adjusting the belt tension and removing play in the Dec and RA axes:

 

http://www.ioptron.u...elt_tension.pdf

http://www.ioptron.c...Play_Fixing.pdf

 

I opened mine up for a "look see" and it is a very simple operation 

 

BTW mine regularly guides at 0.5 RMS and never above 0.8 -- total load is 18lbs (ES 102 FCD100 aluminum tube, Astromania 60mm guidescope, ASI224 as guider, Canon T6i as imager)

 

Cheers,

 

Tom

Looking at these PDFs, this looks a little daunting.  I am not the best handyman. You guys say it is easy, I just don’t want to damage my mount



#36 gotak

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Posted 21 February 2019 - 06:56 AM

Looking at these PDFs, this looks a little daunting. I am not the best handyman. You guys say it is easy, I just don’t want to damage my mount


Well it is going to carry some risk. However, if you take your time and do everything slowly and carefully it should work out ok.

The real risk is if you cam the worm over the wheel. If you avoid that the rest is a lot less risky.

#37 Stephen S.

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Posted 21 February 2019 - 10:25 AM

Looking at these PDFs, this looks a little daunting.  I am not the best handyman. You guys say it is easy, I just don’t want to damage my mount

Maybe get your local scope dealer to do it?

 

cheers,

 

Stephen



#38 StarMike8SE

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Posted 21 February 2019 - 10:30 AM

Maybe get your local scope dealer to do it?

 

cheers,

 

Stephen

no local scope dealer.  I will take ti slowly



#39 eshy76

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Posted 22 February 2019 - 04:50 AM

I also had some minor play in my CEM25P DEC saddle - it wasn't affecting my images, but not ideal right? I ended up following those instructions listed above and also the youtube videos from Paul Chasse to open the mount cover to see if I could identify the problem.

Sure enough - I could see straight away that the plastic stopper connected to the DEC gear switch (to be honest, this was about 6 months ago - it was either the tension screw or the DEC gear switch, but either way you could see quite quickly that what was causing the play in DEC), when fully engaged was not quite reaching the DEC motor to keep it fully in place...so I ended up using a shim...i.e. a small piece of cardboard between the DEC motor and the plastic "stopper" to make sure the tension screw/gear switch stopper reached the DEC motor when engaged.

Dismantling was not an issue - just be systematic with the screws as you remove them - keep them in groups so you remember what goes where. A magnetic screwdriver or extreme care not to drop them would help too (I used the latter!).

Put it all back together and no more play...but in every day use, instead of tightening the DEC tension screw all the way now, I have to back off slightly or else the mount struggles with slewing. 

A relatively simple fix, but not what you would expect from a new piece of equipment. Otherwise, it's been a great mount though! 



#40 drewh111

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Posted 23 February 2019 - 02:00 PM

This may not be relevant but I had this problem - I left the polar scope led plugged in and the mount was hanging up on the plug when it slewed. Made a funky noise but didn't hurt anything. Make sure all your wires and cable are clear before using.



#41 Arringar

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Posted 24 February 2019 - 08:49 PM

TL;DR

I had an issue with play in the dec axis of my CEM60EC. I removed the saddle and the top cover to see what was going on inside to cause it. When I did this it didn’t happen anymore. I put it back together and it still didn’t happen. I put the cover over the dec motor and the issue came back.

What I observed was that if the screws on the dec motor housing were particularly tight it created tension that pulled the worm away from the wheel just a tiny bit. The screws that hold the housing attach directly to the bracket that holds the motor assembly. Slightly loosening these screws fixed the issue and now my dec axis is perfectly solid.

Edited by Arringar, 24 February 2019 - 08:51 PM.

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#42 StarMike8SE

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Posted 25 February 2019 - 01:40 PM

TL;DR

I had an issue with play in the dec axis of my CEM60EC. I removed the saddle and the top cover to see what was going on inside to cause it. When I did this it didn’t happen anymore. I put it back together and it still didn’t happen. I put the cover over the dec motor and the issue came back.

What I observed was that if the screws on the dec motor housing were particularly tight it created tension that pulled the worm away from the wheel just a tiny bit. The screws that hold the housing attach directly to the bracket that holds the motor assembly. Slightly loosening these screws fixed the issue and now my dec axis is perfectly solid.

Interesting you said this.  I did the belt adjustment and had no play in dec saddle, then when i put the dec cover back on, it came back.  I will try loosening them


Edited by StarMike8SE, 25 February 2019 - 03:06 PM.


#43 Arringar

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Posted 25 March 2019 - 01:53 AM

Interesting you said this.  I did the belt adjustment and had no play in dec saddle, then when i put the dec cover back on, it came back.  I will try loosening them

 

Did loosening those screws solve your issue as well?  Just curious how it went.


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#44 StarMike8SE

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Posted 25 March 2019 - 02:44 PM

Did loosening those screws solve your issue as well?  Just curious how it went.

No, I need to open it up again



#45 mewmartigan

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Posted 01 July 2019 - 01:43 PM

Okay so when calibrating in PHD2 I get a warning about poor DEC movement probably caused by backlash on my CEM25P.  The procedure in the pdf file for checking/tightening the belt didn't seem to bad so I figured I would give it a shot.   Silly me...nothing is ever easy.

 

The screws holding in my DEC motor seem to be a bit to short. They were not tight when I went to loosen them and applying just a bit of pressure to the motor as in the pdf just caused the motor to pop off the screws entirely.  Putting it back together, the screws are just not long enough to properly grab the motor and again just spin endlessly when trying to tighten.

 

I have an email in to iOptron support....I hope the simple solution is they just send me slightly longer screws or I take my current screws down to Lowes. 

 

Anyone that has done this procedure find that you can actually tighten those motor screws down and hold the motor securely?

 

In the end I am sorry I ever tried to fix it, haha. Should have just used backlash compensation in PHD2.



#46 mewmartigan

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Posted 01 July 2019 - 03:57 PM

Well to update my own post, ioptron's solution was just to remove the washers.
Motor sits tight now. No idea if the belt is tighter now but it is all back together and ready for a test. Hopefully tonight.


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