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Help with etx 125 ec telescope

Meade
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#1 ashikenshin

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Posted 03 December 2021 - 11:18 PM

Hello, I bought an etx 125 ec telescope a while ago. Never really gave it a proper try until recently.

The thing was a mess, the easy align procedure never works. The star it says it's searching is all the way to the other side. When I try to put it on the proper alignment the telescope decides that I'm wrong and goes back to the position where it said the star was. I was very frustrated.

 

I went back inside and started reading about this. I found weasner's site on the etx telescopes and did his guide. (downloaded the new firmware, degreased the clamp mechanisms, trained the motors ) I thought I was ready. I did a final reset and tried again. And nothing changed. The star was nowhere near where the telescope ended up. I have watched some videos about how the process is supposed to go and my telescope does this weird thing where it starts and stops several times until it reaches it's destination.

 

I really don't know what is wrong with this thing. It's supposed to be easy right? 

 

please help



#2 cookjaiii

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Posted 04 December 2021 - 12:05 AM

Do you have to manually enter date, time, and location? Universal time? 

 

I'm not familiar with the Meade system, but I'm in the middle of learning the Celestron system.  I'm glad I didn't try to start out with go-to.



#3 ashikenshin

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Posted 04 December 2021 - 12:12 AM

Yeah, each time you start the telescope you need to input date and time. location is saved though. 



#4 M57Guy

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Posted 04 December 2021 - 01:42 AM

I really don't know what is wrong with this thing. It's supposed to be easy right?

It is, but you have to work at it. smile.gif

 

Are you using used batteries, partially used batteries, fresh batteries, or direct 12V power supply?

Meade scopes behave badly with low voltage.



#5 ashikenshin

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Posted 04 December 2021 - 10:10 AM

I'm using direct 12v power supply. I still haven't taken the telescope to the field. 



#6 rutherfordt

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Posted 04 December 2021 - 11:25 AM

What home position are you starting from?  For my ETX-105, home is tube level, pointed north. 

 

You also want to be sure that you have "Calibrated Motors" and "Trained Drive."  Have you done both of those things?

 

Lastly, did you enter your longitude using the ZIP code of your town (in which case it should be right) or did you enter the longitude manually, in which case you could have it set to the wrong hemisphere.

 

Tom



#7 DAVIDG

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Posted 04 December 2021 - 11:38 AM

 The secret is that the closer the mount is aligned on true North and level and having the tube parallel to the base, the better the alignment will be.

   The first thing you should do is check the 'Home" position of the tube. It needs to be parallel to the base. So what I do is set the mount on a surface that is level. So the base is level and using a level, level the tube of the telescope. Then adjust the setting circle to read zero. Now you have that part of the Home position correct. You only need to do this once as long you don't move the Dec/Alt setting circle.

   Now you take the telescope outside, I first get the mount close to level and then point it at Polaris so Polaris is in the eyepiece of the telescope.  Now your pointing very close to true North. Now lower the tube in Altitude so the setting circle reads 0 and the tube is parallel to the base. So now the scope is pointing close to true North and also point close to the horizon so the scope is now pointing very close to 0 Altitude and 0 Azimuth. 

   Turn the telescope off and turn it on. The system now sees the position of the scope as 0, 0 and next do the alignment procedure. The scope is already in the "Home" position, pointing North and Horizontal. If you entered the time, date, Long and Lat of your location correctly then the scope should point very close to the alignment stars. Be sure the Daylight saving time is set correctly for this time of year and also that you have selected the correct telescope in the setup since the gear ratios are different for different mounts and that will cause it to be way off as well.

   What these systems are doing is converting RA/DEC to Alt/AZ and then doing an error correction from Alt/AZ based on the errors it calculates from when you first align in on the two stars. So the closer the telescope is setup to be aligned on true Alt/ Az  ie started out pointing at True North and at the Horizion , the smaller the errors and the better the pointing. 

 

             Happy Holidays !

               - Dave 


Edited by DAVIDG, 04 December 2021 - 11:42 AM.


#8 ashikenshin

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Posted 04 December 2021 - 01:38 PM

What home position are you starting from?  For my ETX-105, home is tube level, pointed north. 

 

You also want to be sure that you have "Calibrated Motors" and "Trained Drive."  Have you done both of those things?

 

Lastly, did you enter your longitude using the ZIP code of your town (in which case it should be right) or did you enter the longitude manually, in which case you could have it set to the wrong hemisphere.

 

Tom

Same for me. I use a bubble level to set up the tube and my cellphone's compass to point to true north. I did calibrate and trained drive as per weasner guide. I entered the city in which I live, the lat and longitude are close enough I think. I will try entering the lat and long values manually. 

 

I tried again now and the star that was supposed to be west, the telescope tried to find east. Maybe I put the motor's cables incorrectly. I will take it apart now and invert the cable to see if that works. The weird thing is that to find the star, the telescope doesn't move in a continuous motion but in parts, I think it rotates about 10 degrees everytime it starts. Then it stops and does it again until it beeps.



#9 NearVision

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Posted 04 December 2021 - 08:57 PM

Your last comment about moving in parts makes me think the clutch is slipping. When you tighten the clutch on the base does it go all the way to the end of the slot or stop part way? If it goes all the way it may not be tight enough. I've got one of these and it will get loose and need adjustment. check Weasner's site for instructions on how to open the base and tighten it.



#10 ashikenshin

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Posted 04 December 2021 - 09:22 PM

thx for the comments. It seems it was the polarity of the base motor that was inverted. I changed it and now it points to the correct position. It was my mistake when building it back. Too bad today was cloudy as hell and couldn't test it out in the yard. 

 

NearVision; The clutch that worries me is the one on the fork, it moves a bit when I wiggle the tube up and down. It's just a tiny bit but i dont have to tighten it as much now that I cleaned the parts of grease and added a bit of tape to the center. The one on the bottom is tight and doesn't move at all.



#11 M57Guy

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Posted 05 December 2021 - 01:56 PM

Glad to hear you got the polarity issue figured out. 

And, using a direct 12V power supply is the way to go for best performance. waytogo.gif

Also, using the nearest major city as the scope's location will be good enough, but manually entering your latitude and longitude will reduce the amount of 'correction' needed during the alignment process.

 

Let us know how it all works out after getting the scope outside under the stars.

 

Clear skies!



#12 ashikenshin

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Posted 06 December 2021 - 10:21 PM

Glad to hear you got the polarity issue figured out. 

And, using a direct 12V power supply is the way to go for best performance. waytogo.gif

Also, using the nearest major city as the scope's location will be good enough, but manually entering your latitude and longitude will reduce the amount of 'correction' needed during the alignment process.

 

Let us know how it all works out after getting the scope outside under the stars.

 

Clear skies!

It worked great! I've had this telescope for more than 10 years now and this is the first time I've gotten it to track. Following the weasner guide I think was the thing that made it all better imo.

 

Also, now that it is working I'm looking to buy some accessories. The first thing that has to be replaced/changed is the viewfinder. The thing broke since the beginning and it's a pain to keep together. But, the place where you mount the viewfinder is for this telescope only. I don't know if I can fit a third party viewfinder in there. Anyone done a cool mod to replace the stock viewfinder on these?

 

If that doesn't work maybe getting a dedicated camera, the svbony sv205 looks good I think.

 

edit: I think I found a dovetail that can be placed on top. Gonna buy it and check it out :D


Edited by ashikenshin, 06 December 2021 - 10:34 PM.


#13 cwleveck

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Posted 17 December 2021 - 04:51 AM

I use the SVBony 105 and 205 on my 125ec.
I am thinking about changing my finder scope arrangement completely.
Might be willing to work something out with you.
I'm glad to hear you got yours sorted out.
Mine was a little bit of a basket case when I got it.
Probably going to keep an eye out for focusing shift.
If your image on the camera shifts when you change direction and turn the knob the other way, don't panic. It's an easy fix.
The primary mirror can come loose. Its held on by a ring. They are notorious for backing off a little.
I didn't notice mine had a problem until I got the cameras. It's actually the reason I have two....
Long story.
The wiggle in the fork can be the motor assembly coming loose.
When I opened mine there was nothing left holding the motor in. All the screw holes were cracked. I just removed the screws and tried to find as many of the plastic pieces as I could. Rebuit them like a 3d puzzle and used super glue to put it all together. Then epoxy and stabilized the motor with hit glue when I reinstalled it all.
Works like new.


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