233 replies to this topic

[clamchip]

You can try strap wrenches.

Buy a pair like these:

https://www.harborfr...iece-69373.html

 

Robert

[LukaszLu]

The problem is the relatively delicate tube, which is easy to deform. What will remain of collimation after such a deformation - even a minimal one...? It's scary to grip harder with your bare hand...

 

For now, I soak the crack in WD-40 and heat it up. If there are oxides there, no treatments or devices will probably help. More advanced methods would probably be needed - ultrasound, etc.

[clamchip]

I was worried about deforming the tube with the strap wrenches. I was trying to remove a cross threaded

4 inch lens on a Celestron AZ 102. I tried everything else so this was do or die for the stubborn lens.

It work great. The rubber straps I thought for sure would break but they didn't. The straps are a bit slick

and slipping but I cleaned then for better traction and it worked fine.

Another idea is find a helper with strong hands to grip the tube with both hands, and you use both hands

on the cell.

 

Robert

[LukaszLu]

For now, I have a hole in my gum from a pulled tooth, so I can't stretch my wonderful muscles too much :-)

[Dave Trott]

I have had great luck with the strap wrenches shown above. 

[rolo]

Sometimes removing the tube with uniform pressure is more effective than sheer strength alone. Get a helper and make sure the objective cell is threaded on to keep the tube from deforming and for even pressure.. Some rubber gloves will help get a good grip as well.

[deSitter]

Sometimes removing the tube with uniform pressure is more effective than sheer strength alone. Get a helper and make sure the objective cell is threaded on to keep the tube from deforming and for even pressure.. Some rubber gloves will help get a good grip as well.

If you grip the tube it can transfer the grip to the threads. Aluminum threads can be rough and if you push them together at all, they are stuck to each other.

 

Lukas try grasping the WALL of the tube instead of the entire tube. Try this at various azimuths and then pull tangentially to the tube.

 

-drl

[LukaszLu]

Thanks gentlemen, I have to wait until the hole in my gum heals because I don't want to damage the clot. After removing the broken root, I was bleeding heavily for several hours and I wouldn't want it to happen again. I have already prepared the rubber gloves, and in the meantime I may be able to find the strap wrenches mentioned above.

Edited by LukaszLu, 05 February 2024 - 06:52 PM.

[LU1AR]

Thanks gentlemen, I have to wait until the hole in my gum heals because I don't want to damage the clot. After removing the broken root, I was bleeding heavily for several hours and I wouldn't want it to happen again. I have already prepared the rubber gloves, and in the meantime I may be able to find the strap wrenches mentioned above.

The first time I took my ETX90 apart, I used a leather belt inside a tube -as a strap wrench- and another in the vise, holding the tube. So that when I applied force they would adjust.
It was easy to disassemble, both the front lens and the rear sector.
For a long time, I used my ETX without the front mirror baffle. But I added an external rubber tube that extends about 15 cm. forward the tube. It works perfectly.
May you be successful in your work.
Edgardo

[LukaszLu]

Thanks, I had a break for a while, I'll have to go back to testing with belts. The biggest problem is getting hold of the rear cell. Using primed holes or clinging to the screws in them seems quite risky...

[clamchip]

I needed a helper to unscrew a 90mm lens retaining ring and my wife wore her dishwashing gloves as

mentioned in this thread and gripped with both hands around the lens cell while I unscrewed the ring with my spanner wrench. Those gloves stick good and doubled her power. It's no wonder she never breaks anything

like I do.

I was also thinking a hot wet towel wrapped around your tube just might expand the aluminum tube

enough to release it's hold on the cell.

 

Robert

Edited by clamchip, 18 March 2024 - 11:35 PM.

[RichA]

Hello again. Let me stimulate the discussion a bit.

 

After a long time, I finally managed to remove the plastic casing using WD-40 and a hair dryer. I have reached the stage visible in the photo - and here again there is a blockage: unscrewing the cell from the tube seems to be an impossible task. A hair dryer doesn't help, and I'm afraid to drizzle WD-40 along the edges because if it soaks the matte interior of the tube, it may no longer be cleaned effectively.

 

Normally, the plastic back will just slide off.  The one you have is "off."

[Far-Out]

ETX90 EC

Hello fellow astronomers I need some info  about my thrift store find.The optics seem ok a little dusty but good, needs a good cleaning.

Comes to focus, powers up.

 

A ETX90 EC.

It says on front optics’s made in USA. What about the rest of scope, where made?

Assembled in Mexico the from USA parts,( is this considered the USA model ?).

It was missing finder has bracket ring to hold finder. Are these difficult to get?

Missing Auto-star Handset, I think the model number is 497? Are the 497 handsets available?

Missing knob to focus. Are the focus knobs available?

I have an add out here on CN for parts. 
Any help will be appreciated.

Best Larry

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[deSitter]

ETX90 EC

Hello fellow astronomers I need some info  about my thrift store find.The optics seem ok a little dusty but good, needs a good cleaning.

Comes to focus, powers up.

 

A ETX90 EC.

It says on front optics’s made in USA. What about the rest of scope, where made?

Assembled in Mexico the from USA parts,( is this considered the USA model ?).

It was missing finder has bracket ring to hold finder. Are these difficult to get?

Missing Auto-star Handset, I think the model number is 497? Are the 497 handsets available?

Missing knob to focus. Are the focus knobs available?

I have an add out here on CN for parts. 
Any help will be appreciated.

Best Larry

Used Autostar 497s are getting harder to come by, and you have to vet a used one because they tend to develop display issues owing to the sort of traces used on the display cable. A functioning one is $100-$150. A new Audiostar can be had for about $200. The Autostar II does NOT work and in fact you may damage your scope. The rare Autostar 495 also works, as does the 494 - the latter is a simplified version sufficient to operate the telescope and get it set up for tracking.

 

Alas you cannot effectively use the ETX-90EC if the handbox is absent or the motors are not working.

 

Note, you are missing the focus knob. In this condition, it is possible for the mirror to completely detach from its support. Do not hunt endlessly for focus or you risk detaching the threads in the focuser mechanism which moves the mirror to and fro. I would think your first task is to find a suitable knob. The stock knob is rather minuscule. I don't remember the shaft diameter offhand but it is about 4mm. Check with a caliper, or see below.

 

There is a vast lore on this scope to be found on Mike Weasner's ETX site here:

 

http://www.weasner.com/etx/menu.html

 

-drl

[oldmanastro]

ETX90 EC

Hello fellow astronomers I need some info  about my thrift store find.The optics seem ok a little dusty but good, needs a good cleaning.

Comes to focus, powers up.

 

A ETX90 EC.

It says on front optics’s made in USA. What about the rest of scope, where made?

Assembled in Mexico the from USA parts,( is this considered the USA model ?).

It was missing finder has bracket ring to hold finder. Are these difficult to get?

Missing Auto-star Handset, I think the model number is 497? Are the 497 handsets available?

Missing knob to focus. Are the focus knobs available?

I have an add out here on CN for parts. 
Any help will be appreciated.

Best Larry

Optically this telescope should be excellent as most of the US made ETXs are. I have owned an ETX90EC for 21 years now. The only problem has always been the 497 Autostar hand controller and the loss of the display as mentioned in a previous post. There is also the manual hand controller that permits the use of the telescope in polar mode. The finder is no big deal. It is very difficult to use anyway. Adapting a red dot finder should work much better. There are vendors in eBay that sell Meade telescope parts. You may find the focusing knob there. Autostar hand controllers, used ones, are expensive. The lowest I have seen is $80 for one of them. Good luck on your project. The optics will not disappoint you.

[jrussell]

I have both an RA (original tracking only model) and an EC model (as you have). The RA model was all US built and honestly, there's not a lot of difference between them. I actually had both out the other night to look at the moon as I had been wanting to compare them. I think the older RA model is just slightly better than the EC model, but not enough to be worried about. The ETX's are generally very good optically as I'm sure you'll find out.

 

Regarding the missing parts, as mentioned the finder scope being missing is no great loss. Unless you're a contortionist using one is a more effort than it's worth. As far as the focus knob, there are focus extenders available that will actually make it easier to focus the scope than using the original knob. They can be found on ebay, or are really simple enough to make yourself with a few materials.

 

The 497 controller will definitely be the most problematic to find as they are getting more scarce, but not impossible to find. In addition to the displays going bad, some also have a problem with the buttons. There are fixes and replacements for both, so the potential problems aren't insurmountable, but they exist. If you get a 495 controller there is an update available that will make it operate as a 497.

 

A somewhat bigger possible problem area is the gears and motors. The ETX line is kind of notorious for problems with these. Both my ETX's have been deforked because the mounts went kaput on me. With the EC I worked on it for months before finally giving up. That said, if the mount is, or does go bad it's not the end of the world. It means you have no tracking and no goto, but you still  have a very fine OTA that can be put on a different mount which is what I did. In fact, there are some people that still wanted tracking and goto abilities and mounted their ETX on a mount that gives them that. I don't mean to sound like a negative Nellie, I just want you to be aware. The ETX's are hated by some, and loved by many. The hate is generally focused on the mount but the love is all about the OTA. It's fantastic on the moon and the planets, as well as some of the brighter DSO's.

 

Lastly, in addition to Mike Weasner's site mentioned above, there's also the Meade Computerized Telescopes forum here which will be of tremendous help to you.

[MarkMittlesteadt]

I've owned  multiple examples of every size ETX there is. Optically they are hard to beat. It's the mechanicals of both the mount and the back housing. One can remove it from the mount and replace the back with an aluminum Wegat plate. 

 

My all-time favorite was an optically perfect ETX105 that a friend I sold it to brought with him recently for me to clean up. I regret ever selling it. 25+ years later and it's still perfect despite the flaws in it's mount, which still works.

 

You can see the replacement focus knob extension in this pic. It allows you to focus even when pointed at zenith...

 

 

You can also replace the useless stock straight through finder for a 6X30 RACI.

 

 

Edited by MarkMittlesteadt, 20 August 2024 - 09:42 AM.

[MarkMittlesteadt]

I'm all finished up cleaning and testing my old ETX for a friend I sold it to. 

 

Here's a couple of better pics of it in the sun, if that helps you with modding your 90...

 

 

[justfred]

The stock finder is definitely the source of 25% of the complaints about the ETX. Mine has the 90 deg  right angle adapter kit and it makes all the difference. If you twist the right angle finder about 30 degrees away from the telescope it helps even more.

 

I see you're using the 492 controller - the 497 controller is the source of another 25% of the complaints about the ETX. Use the 497 as long as it lasts but learn to use the 492 and always have one handy. 

 

Quality optics in an economical, compact, usable package. I can put up with its quirks. 

 

The ETX has encouraged a lot more people into the hobby than it has discouraged.

 

Fred

[CHASLX200]

The stock finder is definitely the source of 25% of the complaints about the ETX. Mine has the 90 deg  right angle adapter kit and it makes all the difference. If you twist the right angle finder about 30 degrees away from the telescope it helps even more.

 

I see you're using the 492 controller - the 497 controller is the source of another 25% of the complaints about the ETX. Use the 497 as long as it lasts but learn to use the 492 and always have one handy. 

 

Quality optics in an economical, compact, usable package. I can put up with its quirks. 

 

The ETX has encouraged a lot more people into the hobby than it has discouraged.

 

Fred

I slapped a real finder on my 125.

[geekay]

I slapped a real finder on my 125.

I'm looking to do the same. What brand and size did you use, and how did you do it? I'm wondering whether there might be a way to fit an 6x30 RACI into the ETX's stock viewfinder holder.

[Terra Nova]

Used Autostar 497s are getting harder to come by, and you have to vet a used one because they tend to develop display issues owing to the sort of traces used on the display cable. A functioning one is $100-$150. A new Audiostar can be had for about $200. The Autostar II does NOT work and in fact you may damage your scope. The rare Autostar 495 also works, as does the 494 - the latter is a simplified version sufficient to operate the telescope and get it set up for tracking.

 

Alas you cannot effectively use the ETX-90EC if the handbox is absent or the motors are not working.

 

Note, you are missing the focus knob. In this condition, it is possible for the mirror to completely detach from its support. Do not hunt endlessly for focus or you risk detaching the threads in the focuser mechanism which moves the mirror to and fro. I would think your first task is to find a suitable knob. The stock knob is rather minuscule. I don't remember the shaft diameter offhand but it is about 4mm. Check with a caliper, or see below.

 

There is a vast lore on this scope to be found on Mike Weasner's ETX site here:

 

http://www.weasner.com/etx/menu.html

 

-drl

It’s good to note that Weasner’s site is still up. The site itself and it’s old html structure looks a bit obsolete, but still lots of good information.

[Terra Nova]

I've owned  multiple examples of every size ETX there is. Optically they are hard to beat. It's the mechanicals of both the mount and the back housing. One can remove it from the mount and replace the back with an aluminum Wegat plate. 

 

My all-time favorite was an optically perfect ETX105 that a friend I sold it to brought with him recently for me to clean up. I regret ever selling it. 25+ years later and it's still perfect despite the flaws in it's mount, which still works.

 

You can see the replacement focus knob extension in this pic. It allows you to focus even when pointed at zenith...

 

 

You can also replace the useless stock straight through finder for a 6X30 RACI.

 

 

It’s nice to note that the Wegat plates are still available. If I were to buy another scope, (which I'm not), it would be a deforked ETX 125 with a Wegat back. It would be like having a poor (wo)man’s 5” Questar field model, (that is sadly never going to happen now that Questar seems to have scrapped plans for the Q5).

Edited by Terra Nova, 01 October 2024 - 02:44 PM.

[ericb760]

De-forking my 125 and adding a Wegat Back breathed new life in to this aging OTA. I was able to fit a pair of rings on it using two strips of thick felt I bought from Scope Stuff. It may not be pretty, but it works perfectly. Now I can throw it on my AVX for goto capabilities, or throw it on a manual Alt/Az mount for a quick grab-n-go scope.
 

[gelkin]

I've been looking at an ETX90 locally that has an unfamiliar finder on it. Carefully scanned through all the photos but I don't find optics made in usa like i've seen on others. Were some made else where ? Any good ? 

Thanks