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ETX125 repair


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#1 donald

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Posted 11 October 2016 - 06:32 AM

HI; I don't see where I can get info on repairing my ETX125 so I came here.Does anyone have info to share? This scope only moves 1 1/2 inch either way nothing looks cracked and when the worm gear turns the large gear it sits on top of doesn't turn.Is this right? Thanks  Don



#2 MistrBadgr

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Posted 11 October 2016 - 11:47 AM

Not sure about the ETX, but with the DS mounts, the worm gear turns and the big bull gear is fixed to the base.  As the worm gear turns it pulls the top of the mount around the base.  In the DS mounts, there is a funny shaped leaf spring that pushes the worm gear into the bull gear.  If the spring gets too weak, it will not do that and the worm gear will not turn the mount.  I have had to bend the leaf spring to get more push out of it before.

 

If something else is stopping the movement and the worm gear is able to engage the bull gear properly, the worm will continue to turn, but since it cannot move the mount, it will rise up out of the bull gear until that part of the worm that was in the gear before comes around and it will snap back down into the bull gear, making a popping sound.

 

Hope this helps,

 

Bill Steen


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

#3 donald

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Posted 11 October 2016 - 06:20 PM

Bill; I understand and that's like what is happening only luck has it that the scope wasn't forced cause it seems that nothing is broken.It appears that the bull gear( motor) is jamed and won't turn as the worm gear turns.Does that mean the motor is bad or should I loosen the worm gear a little. I appreciate if you folks have an idea on this too. Thanks  Don



#4 MistrBadgr

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Posted 11 October 2016 - 06:31 PM

Hi Don,

 

I think I need to take some time and pull my ETX 80 apart and see how it is set up.  I am going to be fully tied up tomorrow, but maybe I can get to it the next day. 

 

Something needs to remain fixed inside, either the main gear train or the single big gear, in order to get the mount to turn.  In the DS mount, there is enough bend in the plastic of the drive system frame that it sort of winds up like a spring before it bogs down.  You should be able to hear the motor run and then get slower and stop if it is binding up near the worm gear and big gear interface.  If you do not hear anything at all and the AZ drive just does not seem to do anything, then it could be the motor or something else electrical, even the push buttons on your controller having dirty contacts.  If the motor continues to run and sounds normal, but the mount does not move, I would suspect that the worm gear and big gear are not making contact like they should when the mount is put together.

 

Bill


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#5 MistrBadgr

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Posted 13 October 2016 - 05:56 PM

Hi Don,

 

I took my ETX 80 apart enough to see how it was put together inside.  What I found was a different arrangement for the AZ setup in the ETX from the DS mounts.  The little lever on top of the base is the key, I think, if the big gear is slipping.  I am going to talk about some basic things, which you probably already know, for people coming along later.

 

First off, to be able to see inside the bottom of mine, I found three Phillip's Head screws under three of the six rubber pads on the bottom.  The three pads (every other one) that have a little dot of extra plastic next to them are the ones with the screws.  I believe there is some rubber cement that was used to glue the rubber pads in place, and I need to get some tomorrow to do a proper job of getting my scope back together.  I was able to unscrew the three screws, then with some determination, I gradually was able to work the outer plastic shell of the internal metal frame and see what is going on.

 

The little chrome coated plastic lever on the top side of the base works like a little wrench to tighten and loosen a long bolt that runs from there, down through the axis of the mount, through some washers, a bearing, and then a final threaded washer on the very bottom.  If someone takes the round plate off the very bottom, that threaded washer and the bolt screwing into it from the top can be seen.  The whole mechanism works like a clutch.  Tightening the bolt up locks in the clutch and loosening the bolt loosens the clutch, allowing the mount to be turned, when it is attached to the tripod.  Even when the bolt is tightened up with the little leaver, it will be possible to move the mount around with some force, but I would not do that if I could help it.  When the lever is pushed as far as it can go counter-clockwise to loosen the bolt to allow the mount to be rotated, there should still be some resistance, I think.

 

Don, if your bolt is loose enough that the mount is easily rotated, compared to the bottom, then that bolt may be too loose.  Taking the Allen set screw loose on the chrome leaver, then using the lever like a wrench, I was able to tighten or loosen mine and then leave the lever in a different position on the bolt head underneath.  I did adjust mine to make things a little tighter than it was, but not so tight that I could not push the lever into the stop (pushing the leaver clock-wise).

 

Whether the clutch is tight enough of too loose for the gear to have traction, you should still hear the motor and gears working inside the mount.  If not, then there is something wrong with the electrical side of things, or the motor.

 

I do not know much about the electrical side of things, but I do know a couple of the simpler things, and those have to do with electrical contacts.  The first thing to do is to plug and unplug the cord from the handset to the mount several times to try and clean up the contacts.  The second potential spot has to do with contacts under the buttons on the handset.  I am not sure which handset you have, but most of them can be taken apart carefully and the contacts under the buttons cleaned.  I have heard of various ways, including just using a clean cloth, or using a pencil eraser.  A little contact cleaner of some sort on a cloth might work better, but I am not sure what it would do to the plastic.

 

Beyond that, I do not have a clue about the electrical system.  There is, however, a site out there that can be a gold mine of information about the ETX.  Do a search for "Mike Weasner's Mighty ETX".  The website is not updated now.  Mike has had problems with his internet situation and had to give the site up in some ways.  I think there are some others that are maintaining the site as a base of knowledge on the ETX.

 

To answer your question simply about tightening the bolt related to the bull gear, I think it might help if not tightened too tight, and probably will not hurt anything to tighten it some.  It could solve the problem if that is the issue.

 

Hope this helps,

 

Bill Steen


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

#6 donald

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Posted 14 October 2016 - 12:53 PM

Thanks Bill the lever on mine is broken so I glued it and used a 1/2" wrench to loosen it and it was overtightened.Every person I read about has a problem with the arm that is the main strength of the gear bracket.I ran mine this morning and noted that though not cracked I saw it move under pressure.I think I will concentrate on that arm and do some testing on a way to make it stronger. Thanks for the info and I'LL be back.  Ps - Weasners has good pics of the gear bracket.



#7 MistrBadgr

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Posted 14 October 2016 - 03:15 PM

Thanks, Donald!  Look forward to hearing how things go.

 

Bill Steen


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#8 donald

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Posted 15 October 2016 - 04:25 AM

Bill, I believe the problem with this scope is the main motor the worm gear sits on.When trying to move the scope the motor does not turn with the worm gear so the worm turns till its end on the motor gear then it can't move anymore so it chatters.I can't seem to get an answere to this problem.I would like to know how to test the motor.I watched a you tube repair and the motor turns along with the worm gear. Thanks  Don



#9 MistrBadgr

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Posted 15 October 2016 - 07:39 AM

Donald,

 

The whole gear assembly should move with the motor, when it operates.  I do not think it should move at all unless the motor is providing the force.  The whole rig is geared down too much, I think, to spin the motor.  You have to be able to loosen the bolt with the little lever (or a wrench in the absence of the lever) enough to allow the big bull gear to slip between the other components.  If the bull gear cannot slide between the other components, then the bolt is too tight for manually turning the scope.  For a manual movement, the worm gear has to ride up and over the teeth of the bull gear and pop down on the other side of a particular gear, creating the chatter you are talking about, I think.

 

There is a "Calibrate Motor" routine in the handset.  It is located under the "Setup" section.  It may be inside the "Telescope" subsection, but that might depend on the particular handset you have.

 

 I am not sure what it is checking, but the test will run each motor a little bit in one direction.  I am guessing that it reads amps.  If it is within some tolerance band, it will note the amount and let you go on about your business.  If it is too far outside of bounds, you get a motor failure message.

 

When I first started out with a DS 2114 and a DS2090, I switched scopes on one of the mounts.  When it tried to run, I got a motor failure message and was instructed to "Calibrate Motors" and this routine was used.

 

Hope this helps,

 

Bill


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

#10 donald

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Posted 17 October 2016 - 03:22 AM

HI; Just a heads up on my progress with this etx125.I put on my 497 controller and was finally able to train it and now it moves without the skip except at the end a little.My problem now is finding the right size allen screws(3) on the back of the scope.Can anyone help me on this? The screws for the gear bracket is 4-40 which I bought at Rockys. Thank you Bill for your help!!.



#11 MistrBadgr

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Posted 17 October 2016 - 05:58 AM

Hi Donald,

 

You are certainly welcome for the help! :)

 

I do not have a clue about the Allen screws.  Anyone else have an idea, please chime in!

 

Bill Steen


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

#12 MistrBadgr

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Posted 17 October 2016 - 03:19 PM

Donald,

 

I made an inquiry about the Allen screws.  There is no documentation available and the dimensions may have changed over time.  Those ETX 125 scopes were made in two different factories.  The suggestion is that if you have one remaining screw, that you take it to the hardware store and compare it with what they have.  Thinking about this some myself, you might want to consider taking the scope itself to the store and find one that will screw into one of the empty holes to hold things in place, then remove the one remaining screw and see what the length is.

 

Hope this helps,

 

Bill


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

#13 donald

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Posted 21 October 2016 - 06:27 AM

Bill I found a guy in NY that repairs scopes and speaking with him,he seems to know about these etx scopes so I will be sending him the scope for repairs.I'll get back to you after it's repaired.Thank you for you're help.  Don



#14 MistrBadgr

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Posted 21 October 2016 - 07:05 AM

You are welcome, Don! :)

 

Glad to hear about finding someone to make a repair.  I will be interested in finding out how things work for you.  It might be nice to have the information about this person for other people as well, assuming that your experience is good.  When the dust settles on all of this, I will move this thread to the ETX section.

 

Good Luck!

 

Bill


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#15 donald

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Posted 29 January 2017 - 04:12 PM

Hello again.I sent the scope out to this guy in NY and he ended up putting a motor in and cleaning grease that I missed while cleaning  the plastic gears.He replaced the rear ota screws,the battery holder and tuned the scope up.The scope is in very good working order with no wandering when it stops and I saved quite a bit of money.He did a Great job!! Thanks Bill for helping me out with your knowledge,it's been great talking to you.  Don



#16 MistrBadgr

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Posted 29 January 2017 - 04:50 PM

You are welcome :)


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

#17 RickScofield

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Posted 29 January 2017 - 05:22 PM

Don,
May I ask who made your repairs? I'm glad things worked out for you.
RickScofield

#18 donald

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Posted 06 February 2017 - 02:08 PM

I'll ask him if it's ok.In the mean time,I ran the ETX and of course the more you do the more you find.Altho he did everything he could  to make this come alive again there were still a couple of issues that I thought to deal with.First,I found I had to really crank the dec knob to make the scope stable then as I sat behind the scope I noticed that when I moved the scope up it moved a little sideways and same with down.When I removed the lock knob and plate bihind it is a thin collor around the shaft,on the setting circle side is a much wider collor.I tried doing what I read on GO TO TUNING but it wasn't working except for putting small strips of duct tape on back of the setting circle knob so then I got the idea to clean the circle side rough up the collor lightly with 150 grit auto sandpaper then I took off the locking knob and replaced the thin collor with the the 1/2" neoprine washer roughed it up a little.When I locked the knob I seemed to use less force(something i'll work on),and when I moved it up and down it moved straight.HOORAY!!



#19 donald

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Posted 06 February 2017 - 06:29 PM

OK,I spoke to George and he said it's alright by him.His name is George Cushing  HIs phone is 518 895 8306 in NY.You'll find him in cloudy nights classifieds.



#20 donald

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Posted 07 February 2017 - 08:21 AM

I ran into an unexpected problem.When moving the scope up or down, there was a sideways shift of the tube.I searched for a cure and found one.Looking from the rear when I took off the right(DEC lock knob)there is a thin ring on the shaft and on the setting circle side is a wider ring.I tried a fix from (go to tuning)which I got off of waesners with a neoprine 1/2" washer and a stainless steel 1" washer but that didn't work.Then I got the idea to put the setting circle with two 1/4" pieces x 1 1/2 long of duct tape on the back of the knob so as to grip onto the setting circle (weasner also I roughed up the edges of the ring SLIGHTLY (150 grit auto sand paper)leveled the scope and tightened it up, then I took off the thin ring on the lock knob side and roughed up the sides of the neoprine washer SLIGHTLY,put that on and put it back together. The lock knob gripped better so I didn't have to use excessive force on it and that stopped the OTA shift.Everything is copasetic and I shouldn't have to loosen the knobs ever again.Hope this helps someone.I'm dissappointed in the fact that there are so many issues with the etx125.My first go to was an etx90 table top,I wish I had kept it cause there were no problems with it and the views were great.I hope this helps someone.Also I wonder why Meade hasn't come up with a external or internal GPS for their scopesETX or other.?Their new scopes look good but the only difference I see from the older scopes is the controller talks.I read where one guy bought one(controller) for his etx and he said it made the scope work better.Maybe,I don't know.






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