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ETX Motor Unit Fault


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#1 Kruegon

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Posted 13 February 2018 - 09:37 PM

I have an ETX-60AT-BB that is giving me a motor unit fault. I have tested it with a 492 and three 494 controllers.

With the 492 controller, the Ra/Az will turn about 22 ticks on the setting circle before it stops. If I release and press again, it will move another 22 ticks and stop again. And so on.

With all three 494 controllers, during motor test, the Dec/Alt seems to pass, but on the Ra/Az test it moves about 11 ticks and fails. Using the arrow keys, I get about the same distance. I can release and press again to get about the same distance over and over.

Any ideas what is causing This? Any clues to a Did? Thanks for any help.

#2 MistrBadgr

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Posted 14 February 2018 - 08:04 AM

I sent in a note to Meade about your problem. 

 

Bill

 

Here is the response:

 

"Thank you for your email.

We would recommend trying new batteries if running on batteries, or trying external power, or batteries if you were on external power to eliminate power issues. Also they can try RESET which is the last item under the setup menu.

If these actions don’t clear the issue then unfortunately that would mean there is an electronics or motor issue. Unfortunately these were never repairable items so that would mean replacement of the telescope. We no longer make a 60 or 70mm ETX so the closest match sold by our site and dealers would be the ETX80 Observer."


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

#3 E Sully

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Posted 14 February 2018 - 02:09 PM

Have you made sure the telescope type in the controller is set for ETX60?  Have you tried to calibrate the motors or train the drive?

The only other things I can think of is either a loose wire or an encoder problem.  Have you checked the cable from the controller to the mount for continuity?  Maybe the encoder is blocked or led is not working.

My ETX90 motor fault was a broken wire.



#4 Kruegon

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Posted 14 February 2018 - 07:32 PM

No sign of a broken wire, and the motor movement doesn't suggest a motor issue. 

 

I have reset the controllers. Made sure ETX-60 was chosen. Trained the drives. Can't calibrate them as the first step of the calibration is a motor test. And thus a failure. 

 

Everything suggests an encoder issue. As I'm new to this type of scope, I'm not sure where the encoder is or what it looks like. So that puts me in an odd spot. 



#5 MistrBadgr

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Posted 14 February 2018 - 08:29 PM

It is a little bitty thing that is glued to the motor.  If it is like the drives inside a DS mount, it is looking at what looks like flat fan blades on one end of that first plastic gear piece that is attached to the motor shaft.  The end of that plastic piece with the fan blades is nearest the motor.  If one of those blades is either bent or missing, that might cause the problem.  If the blades of any form of grunge on them, that might be the problem also.  If anything has gotten on the little sensor in the encoder, that may be the issue.

 

Bill Steen


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#6 Kruegon

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Posted 15 February 2018 - 12:37 PM

I think I have located it. Looks like I could clean the encoder, but if im looking at it properly, the led and sensor may be a different story. Got a bit of figuring out to do. But not for a day or two. 

 

I have an ETX-60AT-BB And an ETX-80AT-BB. And neither was working. The 60 has the muf and the 80 had a broken Ra/Az motor bracket. So my options were, have two jacked ETXs, or canablize one to get the other working. My ETX-80 is up and running. My ETX-60 is in a dozen plus pieces until a part arrives. 



#7 MistrBadgr

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Posted 15 February 2018 - 02:15 PM

I understand the situation entirely! :)

 

Bill


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#8 Kruegon

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Posted 15 February 2018 - 05:10 PM

I have to say, after being inside these two scopes, they weren't built with the most durable or long term parts. And based on what I've read, they don't seem to last to what would be considered an acceptable end of life. 

 

I noticed similar in the NG series as well as certain aspects of the DS gen 1. Though the DS series was more resilient, if not noticebly more sloppy in its gear mating. Do you think this is built-in obsolecense? If so, it would seem to me that increasing the quality a little would be more beneficial. They should last at least until the owner feels that they've gotten fair use out of them. It would certainly encourage me to be a repeat customer. For now, every Meade I own is second hand. With the reliability issues of their beginner and intermediate scopes, why would I ever pay full price?



#9 MistrBadgr

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Posted 15 February 2018 - 07:26 PM

During those good old days, when the scopes you are talking about were made, I was told there were some issues with the makers.  I know I was continually coaching people on fixing gen 1 DS mounts.  Each fix was fairly simple, but needed to be done.  When they came out with the Gen 2 DS mounts, the complaints that I saw on this forum simply stopped.

 

Since Sunny purchased Meade and replacement scopes have become available for the ETX and DS series have become available, I have not had to field a complaint on a single product.  However, I have not used any of those new computerized scopes myself.

 

As far as optics goes, I now have an Infinity 60, 80, and 102; a Polaris 130, Eclipse View 114 in entry level scopes that I have used extensively.  All have performed so much better than anything I saw before that there is really no comparison.  For almost all of them, I saw absolutely no difference in the image of a star inside and outside focus on a star test.  Spherical aberration for all intents and purposes is zero.  I have an LX 70 mount with the eight inch f/5 and the six inch Mak OTAs.  Ditto on the optics.  With  the Mak and HD 60 eyepieces, I was able to identify the large volcanoes on Mars from my Bortle 6 back yard.  I owned an LS 8, with ACF optics........A wonderful scope that worked flawlessly for me, until it was stolen.  My Lightbridge 12 is also a wonderful scope.

 

The whole line, in my opinion, is  better than it was before, especially in the lower levels.  With the ones you have experienced, they were just not at the level inside that the newer ones are.  To some degree, the success of the modern ones is based on the lessons learned from the failures in the past.

 

Hope this all makes sense.

 

Bill


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

#10 Kruegon

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Posted 16 February 2018 - 06:44 PM

So exactly what tune ups do you recommend for the gen 1 ds mounts? I have two DS-114AT scopes. I've done several basic tune up/mods. Such as adding a leg spreader to one, replacing the chrome plastic draw tubes with black metal ones, and in the process of replacing the factory finder scopes. 

 

One has nearly perfect mirrors, the other needs the mirrors cleaned. I still need to add collimating circles to both mirrors. What do you suggest using for this? I was considering the paper reinforcement circles, but they are white and the circles are rather wide. 

 

If I could remove some of the slop from the Alt gears, it would be a great scope. I just got these recently, I've only been able to use it once. It tracked to the Andromeda galaxy almost perfectly. It was in the eyepiece, just off to one side.

 

Other than Cloudy Nights, where else can I find a telescope classifieds or swap and shop? And I get a lot of parts from Bill over at Telescope Warehouse. But he only has so much. 



#11 MistrBadgr

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Posted 16 February 2018 - 08:14 PM

Well, for a few things inside the mount:

 

1.  Just under the main bolt that holds the bottom bell on is a washer.  This thing is stamped steel.  On one side, the outside edge is rounded off nicely, but on the other, it tends to be rather ragged.  This ragged edge can chew into the top of the plastic bushing underneath.  With enough time, little splinters of plastic can come loose, jam into the rough spots on that washer and actually stop the az motion of the mount in one direction.  They work sort of like barbs on a fish hook.

 

2.  When you pull the bottom bell off and look at the az gear train, you will see a little thin strip of shiney stainless steel bent into a funny, curvy shape.  This is the spring that holds the worm gear in the train pressed up against the bull gear on the bottom bell.  Bending this spring out some can create a little more force to push the worm gear into the bull and can cut out some of the slack in the gears.  That whole framework has to twist up some before there is any actual movement.  I think having that spring a little tighter helps support the framework a bit.

 

3.  On one side of that same gear train is a little post that sticks up.  Normally, you do not want to mess with it.  It is glued down, I think, as well as having a screw holding....or should be glued down a bit.  The whole gear train thrusts against that post when the mount is turning one way, and the post is used to keep the gear train restrained for back in the other direction to keep slop levels low.  If that post is too tight against the gear frame, then the mount will not move.  You can, however, adjust the position of that post to push against the side of the gear train to minimize the slop in the az direction.  The trick is getting that thing tight enough to hold.  I have put a coat of enamel on the bottom of the post and screwed in the screw before, then waited a day or so for all the paint to dry.  I never had to take one apart after a paint job, so I do not know what problems arise and surface cleanup problems if having to work on post position again.  If you work on this post, which I call the thrust post, and it comes loose later, you will know it with all the extra slop in the az drive, which will be pretty massive.  Normally, when the post comes loose, the contact point on the post rotates away from the gear train.  In the gen 2 scopes, they made the post out of steel and had a flap that folds over an edge, preventing the post from turning.

 

I don't remember any big problems with slop in the alt direction.  Biggest issue there was the little nut on the main tightening shaft that looks like a little three legged stool,  The legs stick through three slots in the bell in the main shaft that surrounds the tension shaft or bolt.  From what I saw, the feet on the three legs can flatten out some and drag enough on the sides of the holes in the main shaft and keep the rig from tightening up correctly.  I have filed some down a bit to get a little clearance, but have wondered if getting the clearance to big would contribute to slop in that part of the drive.  The altitude drive is pretty much contained inside that arm and does not seem to have the same problems as with the az. 

 

The only issue with the alt that I could not see if fix for is that there really does not seem to be a safety relief that works if the scope goes up or down too much.  However, that has never seemed to be an issue like with the az.  With the az, catching a scope on a tripod leg will cause the worm gear in that drive, as it turns, to push against the before mentioned leaf spring, ride up the side of the bull gear teeth, and pop down in place with a full turn of the worm gear....no harm done.  When that happens, it does throw off alignment of the scope with the sky and you have to stop and realign it.

 

Hope this helps!

 

Bill


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

#12 Kruegon

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Posted 16 February 2018 - 11:50 PM

The Alt is where the slop is on both of my mounts. The Az seems to move rather well and stay stable. On both mounts, there is enough slop to move an object completely out of fov when using moderate to high power mag. 



#13 MistrBadgr

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Posted 17 February 2018 - 06:05 AM

Let me think about it a little.  I may need to pull one of mine apart to refresh my memory.

 

Does the mount seem to fight with you and want to put the object somewhere besides where you want it?


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#14 Kruegon

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Posted 17 February 2018 - 07:13 PM

Not fighting me, there is just enough loose play to move the scope a couple of inches up or down without actually moving the gears. 



#15 MistrBadgr

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Posted 17 February 2018 - 09:48 PM

That is weird.  Have you checked to see if the main altitude shaft is broken?  That is the weak mechanical link in the whole mount as far as I am concerned.  If the scope falls over from full tripod height and hits the ground with a long scope on it, there is a very great chance, maybe 95%, that the altitude shaft will break where the bell section of it and the smaller tube section farther inside connect.


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#16 Kruegon

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Posted 17 February 2018 - 11:22 PM

I'll check into that. Both mounts are the same way. I just assumed it was poor mating with the gears and sprockets. It's like the slack in a bicycle chain where there's slight play in the pedal before you get tension. Or even better, it's like the wiggle in a bedroom doorknob before the striker moves. 



#17 Kruegon

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Posted 20 February 2018 - 05:36 PM

No updates on the DS mounts yet, however I have news on the ETX front. 

 

As stated earlier, I canabalized the ETX-60 for motor parts. I need a clear night, but it appears to be operational. I just felt that if both were broken, one should work. And the 80 has more aperture. 

 

Drum roll, please! The ETX-60 is operational. Ok, mostly operational. The MUF is gone and the motor is tracking. But it' also clicking and skipping. Kinda like it has broken teeth even when it doesn't. Compared to an MUF or broken motor, that is such a small thing. 



#18 MistrBadgr

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Posted 20 February 2018 - 08:16 PM

That is great news, Dan!  I still need to pull one of my DS mounts open and see if I can figure out any other ways to get the amount of slop you are talking about.

 

Bill


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#19 Kruegon

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Posted 12 March 2018 - 09:00 PM

Had a chance to tear down the ETX-60 again tonight. Seems the culprit was the battery wires. No apparent damage, but I believe they were getting into the teeth some and causing the issue. They've been rerouted and all seems well. The ETX-60 & ETX-80 are both fully operational now.
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#20 MistrBadgr

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Posted 12 March 2018 - 11:35 PM

That is great!  Glad to hear it was something easy to fix. :)

Bill


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