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LX200GPS makes a loud howling noise


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#1 Fivel

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Posted 15 May 2016 - 07:38 AM

Hi to the group.

I have an LX200GPS-8" that makes a loud howling noise when slewing (GOTO) between objects.

It occurs only in the DEC section, and only when slewing with the "up" arrow button. I have cleaned, re-lubed the worm and main gear, and adjusted the set screw for the proper mating of the same gears.

Otherwise, the scope operates well, and GOTOs are fairly accurate.

Does anyone have ideas on what may me causing this noise?

I appreciate any help. I also posted this on the CN forum, but there are many additional experts here as well.

 

Fivel



#2 Mark Sibole

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Posted 16 May 2016 - 01:49 PM

Louder than normal noise?Does it sound loud or does it have a grinding noise with it???


Mark Sibole
MTSO Observatory
Fife Lake, Mi.

http://astronomy.qteaser.com

#3 Fivel

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Posted 16 May 2016 - 08:19 PM

Hi Mark, thanks for chiming in.

The noise is a loud howling, somewhat like a bad automobile differential, but no grinding.

It's loud enough to mask the normal slewing gear sounds.

It only happens when slewing in the arrow "up" or GOTO in the same direction.

I have inspected the entire motor and plastic gear assembly,

as well as the helical brass worm, and it's meshing with the main gear.

Everything looks aligned and normal. Only when I apply light pressure,

to the motor housing (in any direction), dose the noise stop.

My other LX scopes (LX 90 and a previous LX 200) did not make this kind of noise.

 

I hope either you, John Piper or someone else is familiar with this issue

Thanks  again.

 

Fivel



#4 MistrBadgr

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Posted 17 May 2016 - 10:41 AM

Are there any bolts on the motor housing that could be a little bit loose?

 

Other than that, a bearing issue causes noises in larger motors sometimes...either a bearing that has gotten a little bit loose, rough surface, or loosing lubrication and getting hot.

 

Bill Steen


Bill Steen, Sky Hunters' Haven Observatory, Broken Arrow, Oklahoma

#5 Fivel

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Posted 17 May 2016 - 08:08 PM

Hi Bill, thanks for your interest and help.

I took the motor/gear assembly out of the DEC arm.

I could not see any loose bolts and the motor/plastic gear moved smoothly by hand.

My next step is to run the motor with the main worm gear removed,

to see if the motor assembly makes noise, with no load.

With the noise occurring only in one direction, it makes it more challenging to isolate.

 

Fivel



#6 Mark Sibole

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Posted 17 May 2016 - 09:30 PM

It almost sounds like a vibration from the plastic housing.If it sounds like a hollow grown there may be something slightly loose causing the vibration.

Im wondering if the plate behind the locking screw is vibration.Its kind of hard to trouble shoot a noise without being there.Try loosening up the clutch plate then slewing the button that causes the noise and see what that does.We can try to eliminate things step by step


Mark Sibole
MTSO Observatory
Fife Lake, Mi.

http://astronomy.qteaser.com

#7 Fivel

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Posted 18 May 2016 - 06:47 AM

Thanks again Mark for the suggestions. I've been extremely busy, with an inside, rainy days project with no time to troubleshoot the scope. I've been groaning about this issue since it started (sorry for the bad pun).

I hope tonight to check out your ideas, in the garage.

 

Fingers crossed.

 

Fivel


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#8 MistrBadgr

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Posted 18 May 2016 - 06:09 PM

Maybe if you did the howling, the mount would just need to groan! ;)

 

Bill Steen


Bill Steen, Sky Hunters' Haven Observatory, Broken Arrow, Oklahoma

#9 Fivel

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Posted 18 May 2016 - 07:27 PM

To Mark and Bill. Thanks again for your suggestions.

I Listened for the howling with the clutch unlocked, and with thee larger gear (behind the clutch) removed.

There were no unusual noises with the motor/gear assembly unloaded.

Whatever is causing a binding or abnormal stress on the motor and plastic gears,

in just the one direction, I cannot find it.

A long while ago, on CN and Yahoo LX200 group, I read where the helical worm could be adjusted along its axis.

When I previously removed the assembly, I unscrewed the end cap (opposite the plastic gears)

to see if I could make that adjustment. I did not see an adjustment screw behind the end cap.

Since lateral stress can create many issues with the motor assembly,

should I continue to look for adjustment screws, and attempt to move the helical worm?

If so, which direction should the worm be moved, since the noise only occurs when moving the scope up/North?

 

Fivel

 



#10 Mark Sibole

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Posted 19 May 2016 - 09:01 AM

here let me ask you a few questions.At what rate do you slew the scope?I know the faster you slew the scope the more noise it will make.If it isnt dragging and just a bit noisy(which can be from anything)Myself I would just set the slew speed down to half max speed or less.I know this does not resolve the noise issue but as I cant hear  it here to help diagnosis it.

When you re assemble things make sure you re grease everything with a very good low temp grease and line everything back up.Make sure you re train and re calibrate drives.Then as I stated set max slew speed to something a lot slower.As I am in an Observatory and many cables running to my imager and auto guider I havnt used max speed to slew in years.I can not remember what speed off hand Im using but its less than half speed.It keeps the scope 80 percent quieter and a safer speed without causing wear and tear on the gears.It only takes about 20 seconds longet to get where it needs to be and that time lost in a slew saves the gears so you gain time and usage of the gears over the years


Mark Sibole
MTSO Observatory
Fife Lake, Mi.

http://astronomy.qteaser.com

#11 Fivel

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Posted 19 May 2016 - 07:16 PM

Hi Mark, Fivel back here.

I tried setting the max. slew rate to as low as 4 (out of 9).

Some of the noise is quieter, but it only stopped the noise at the last part of scope travel.

It sounds like an amplified severe rubbing of bad (large) bearing surfaces.

Since all moving parts seem to turn smoothly, I am at a loss as to what to inspect next.

The motor/plastic gears seem fine without load and the 180 tooth main gear the same.

Put them together and the banshee lives.

 

Does anyone have other diagnostic suggestions?

 

Fivel



#12 Mark Sibole

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Posted 20 May 2016 - 02:37 AM

how is the balance on the scope?Other than that im running out of things to suggest to you..


Mark Sibole
MTSO Observatory
Fife Lake, Mi.

http://astronomy.qteaser.com

#13 Fivel

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Posted 20 May 2016 - 07:40 AM

Mark, my scopes balance is quite good. When I unlock the clutch, it doesn't move.

I am out of ideas also. I would buy the motor/gear assembly, from Meade, but if that did not fix the problem I would not be able to return it. I believe Meade only replaces a purchased defective motor unit.

Back to the drawing board.

 

Fivel 



#14 Mark Sibole

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Posted 20 May 2016 - 07:49 AM

All I can suggest now id the yahoo group with all of the members there maybe they can help pinpoint it out.Short of sending the scope in to meade thats about all I can think of now.Sorry I wasnt much help on this one.

 

Mark


Mark Sibole
MTSO Observatory
Fife Lake, Mi.

http://astronomy.qteaser.com

#15 Fivel

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Posted 20 May 2016 - 09:04 AM

Mark, you and others have been more than generous with your imd and expertise.

I did post this issue on the LX200 Yahoo group and even Dr. Clay could not get me to a solution.

I realize how difficult this can be since no one can be there with me to troubleshoot.

 

Since I will be building an observatory soon I may just forego the repair costs or Dr. Clays supercharge fee (and all shipping) and go a different route.

I have thought about deforking the OTA and putting it on a less problematic mount, such as the Ioptron Ieq45 Pro.

Meade makes great optics, so putting it on a higher quality mount, may give me better results for astrophotography.

It's a shame I could not get this issue resolved, without sending it in for repair or supercharge.

Thanks again to all for your assistance.

 

Fivel



#16 Mark Sibole

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Posted 20 May 2016 - 06:15 PM

If it other than a noise that bothers you but it tracks well and slews well why not run it ti she no go no more?Then you can send it in.I cant forsee anything major just something rubbing slightly.Last thing i can recommend is look at all lides of the fork and at the base where any of the plastic case touches and see if maybe it is dragging there.Good luck with it.If you do ever find out what it is let me know for my records

 

Mark


Mark Sibole
MTSO Observatory
Fife Lake, Mi.

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#17 Fivel

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Posted 20 May 2016 - 07:46 PM

Mark, I previously checked anything inside and outside the DEC fork for binding, rubbing or any noise, when the clutch is loosened. Nothing there. 

As for tracking, I hope to give it, and my LVI Smartguider 2 a good testing when a long spell of good weather permits.

Previously, with just a cursory Polar alignment and no guiding, I could get between 45 seconds and 1 minute (more rare).

That shows some promise for better polar alignment with guiding.

I'll see how it all works when I get it mounted in the observatory (soon I hope).

I will be trying for easier targets this weekend, Mars and Saturn.

I hope all of you who are interested, will have some great viewing and images of these Solar System objects.

 

Fivel

 

 



#18 MistrBadgr

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Posted 20 May 2016 - 09:15 PM

Thanks!  I hope you have a great time yourself!

 

Bill Steen


Bill Steen, Sky Hunters' Haven Observatory, Broken Arrow, Oklahoma

#19 Fivel

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Posted 25 May 2016 - 06:11 AM

To Mark, Bill and John, thanks again for your ideas.

I did slow the max. slew speed to4 and most of the noise is gone, so it is doable.

Next it's off to re -Train Drives and touch up collimation ( a bit off).

I hope to improve the videos of Mars, Saturn and Jupiter before attempting some DSO images.

My best to all of you for great sessions.

 

Astrophotography is like being a tightrope walker, you need great balance and sharp focus.

 

Fivel


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#20 Mark Sibole

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Posted 28 May 2016 - 10:15 AM

Thats good news.I personally cant think of the last time my scope has slewed faster than that.It may take a few seconds longer but it is easier on everything and if you have as many cables on a scope like i have on mise  slowere is definatly better.I can remember the scope going like hell and have a cable grab.Wasnt pretty and it cost me an imager....


Mark Sibole
MTSO Observatory
Fife Lake, Mi.

http://astronomy.qteaser.com




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