ETX125 Motor Drive Repair

[@yellowleafproduction7221]

Have bought a second hand ETX 125, and watching this has given me the information I need to relube the drives and gears - which it probably why it does not track great. Thanks!

[@darrenmarceau2155]

Appreciate the time and effort you put into this video. It gave me some guidance on how to fix my telescope. I must disagree with you on the grease being the issue that caused the mounts to break. While it was most definitely a contributing factor, the root cause was poor engineering and design. I thank you again for all you did as it is helping me to repair mine.

[@ccarlley]

I agree it should have been a much beefier drive system! Thanks for watching and sharing.

[@NuvinGoonmeter]

Thanks, your video allowed me to dismantle to declination motors and gears of a ETX-90EC which is very similar. The motor and gears we all ok but they got stuck over time. I manually rolled the gears and then activate the motor and all working fine now.

[@ccarlley]

Excellent! Thanks for letting me know about it 👍🏼

[@jadesystem]

Excellent technical video on the Meade ETX-125. Thank you for your expertise. Easy to listen to, well made, clear instructions, and overall an excellent repair video. Thank you so much !!

[@edgardomaffia471]

Thanks for sharin your experience. The worm's grease hardens and lock, at the point that cannot be turned by hand. Torque breaks the gearbox. After doing THE SAME REPAIRS, I notice that the green grease covering the gears ATTACKS THE BLACK PLASTIC of the housing. Shortly after repair, my ETX failed again. They were pieces of plastic detached from the casing, which had gotten between the gears. When disassembling the casing, it fell apart into fragments. Especially where the gears anchor and bolts pass. Now I am converting my 20 years old ETX to eliminate the computer (It never went well); and motorize it with a controller on Right Ascension ax and a DC motor in of Elevation. The OTA is excellent.

[@ccarlley]

EDGARDO MAFFIA, good lord, your experience sounds way worse than mine. Kudos for sticking with it

[@edanderson4263]

I was having problems with my ETX 125. AZ drive train needed repair. Your video was exactly what I needed to help me make the repair. Thanks so much for making this available.

[@timwhitlock3500]

Excellent review! The same plastic brace broke in my etx125 azimuth drive. My piece broke further up where it joins the gear housing so I was able to epoxy it back together and then strengthen the repair with a steel washer. I'm afraid that it may break again at the same point yours did and I will be in there again. They really skimped on engineering these drives robustly.

[@ccarlley]

Thanks Tim. Hope one repair is all yours needs.

[@elvicentefernandez]

Sir, you are a very good mechanic, marking everything before disassembling is key, I have worked with mechanics that disassemble everything and they can't put it together because they didn't make a single mark. Thanks for the video.

[@ccarlley]

Carlitos Navas, thanks very much for that sentiment. I am forever grateful for all of the KZbinrs who have taken time to put out 'how to' videos. It's because of them that I have the nerve to tear stuff apart ;-)

[@kendps1587]

Got the same problem, meade should step up their game and go for aluminum with all this moving parts. I guess its part of their marketing strategy 😏😏😏... cool video though it helped me big time and saved money for repairs! Thanks!

[@mattmacd2009]

JB weld........simply awesome stuff. I recently rebuilt a plastic 'ball & turret' joint with JB.

[@martinhodnett2586]

Very useful. The azimuth motor casing on my ETX105 is falling apart. I reinforced the cracked drive shaft arm with a paperclip around the outside edge encased in epoxy. That has lasted for over 15 years, still successful. I like your putty solution for the motor mounts. My next step (if I cannot afford a new telescope) is to measure up and draw a new casing - reinforcing and thickening weak points - and 3D print it in ABS plastic. Things to do in retirement!

[@ccarlley]

Martin, a bold and high tech adventure to 3d print as a solution! Please let me know how it turns out.

[@martinhodnett2586]

@@ccarlley - three years has passed, I retired, lost access to a 3D printer and not going to spend £1k on one either. Scope still works with my bodge repair but is hardly used, too much light pollution. Hope you got yours sorted out.

[@ccarlley]

@@martinhodnett2586 Thanks for the update. Same here. This TS is gone and I got a 10" dob in its place. Light pollution is a problem here in Mississippi too but, at Bortle 3, I shouldn't complain 😉

[@martinhodnett2586]

@@ccarlley fairly recently had LED street lights put in, that put a white glow on everything. Then neighbours put automatic security lights all over the place. Add starlink satellites and air traffic from Heathrow - gave up! I'm in Uxbridge, west London, UK.

[@jerrykorten664]

Great video! Just what I needed. Looks like people should be putting in fuses on those motors to limit their torque. The fuse would blow indicating a lube job is required. Can use panel mount fuse casings. Just a thought.

[@ccarlley]

And that's a great idea! Sure would eliminate the damage and rebuild!

[@edgardomaffia471]

ATTENTION ETX OWNERS: Most of the failures are due to the hardening of the grease (Black) of the bronze worm of both axes. The green grease from the gear case also weakens the black plastic and makes it brittle. NEVER USE AN EXTERNAL SOURCE WITHOUT A VOLTAGE REGULATOR. Unregulated sources, when disconnected, increase their voltage to 18 volts and when connected, they burn something inside: Also AVOID PLUGGING IN OR UNPLUGGING THE AUTOSTAR CONTROLLER, because the connector can cause the power to come on before the ground. Thus, the return of current is done through the drivers, which burns them. I hope this serves someone.

[@robertcouchman9787]

what a wonderful video! very clear, concise. no useless wasted material. loved every moment

[@ccarlley]

Thanks for that Robert!

[@davidrfloyd]

Thanks so much for posting this. Helped me figure out how to figure out how to fix the right tube adapter on the scope I was given. Hoping to get out with the ETX90 as soon as possible!

[@theinvisibleartists4444]

Yes sir I know all about that OCD! Thanks for the video very helpful.

[@bongofury3176]

Mine still works fine but I am preparing myself for your impressive fixes... No need to separate optical tube - far safer not to. Your video has given me the confidence to delve into my ETX. Wishing you clear skies and a calm jetstream...

[@ccarlley]

Bongo Fury - Kind words Bongo. Hope you never need to.

[@ccarlley]

An update to this fix: The drive trains are working superbly. One thing I should have paid closer attention to is how much torque the worm gear nut was originally installed with. I probably set mine too loose as I notice more play when the scope changes direction. Not bad, but noticeable. My recommendation is to count the number of exposed threads on the end of the worm gear shaft (beyond the nut) before disassembly. Besides that, she's works great.

[@4801328]

Chuck Carlley may I send my unit over

[@ohwell2790]

Where can I get one of these female telescopes?

[@HugoToledo]

First, thank you for this video. It is helping me with my ETX-90 repairs. One suggestion: I am pretty sure you should never tear apart the optical tube assembly (OTA). Separating the OTA sections can damage the focusing and will certainly introduce dust into the house. I see on the great Weasner site (of all things ETX) where someone else has taken apart a 125 as you did, but unless you need to muck about with the inside of the OTA, you're always going to be much better off removing the entire OTA just by unscrewing the four hex nuts, two on each side of the OTA, closest to the eyepiece. Thanks, again!

[@ccarlley]

Good point on the optical portion. In retrospect, there's a lot of things I would have done differently on this job. The Weasner site is a gold mine!

[@saukpcrepair4497]

Was simple really. Removed all the broken plastic, replace all screws with nuts and bolts, the bolt heads are lower then the 3 nubs where the clutch sits, so the clutch functions as it should. The screws on the motor were also replaced, only place a screw head appears is on the little Meade name badge for the bottom motor bolt...I am good with that. In tests it functions as it should, clutch works as it should, only "drawback" is there is no adjustment for tension in the worm gear, but with the ignorant design by Meade engineers there was no adjustment in their design. total cost of the repair, including a new nylon washer for the clutch assembly was less then $6, and I got way more hardware then I needed at least enough to do 2 more. I figure if I ever need to add the ability to adjust the gears, it would be simple to just "slot" the holes the screw head is on and there's your adjustment. So far this has preformed flawlessly and now this telescope does as well as it ever did, the date on the OTA was 2004, and with this repair I figure I will see many more years of use along side my LX90 12

[@TelcoKen]

Great information. I have a weird clicking noise when raising the altitude (Declination drive), Where it seems to be slipping. Now that I've seen your disassembly, I feel comfortable in investigating the issue. Subscribing!

[@BrianSheppard]

Great video. Exactly what I've been looking for.

[@ccarlley]

Thanks Brian.

[@ccarlley]

Thanks very much guys for your responses on this. I'll be very interested to hear your results and how you correct your problem. I'm irritated with the gear lash slop that I created by not calibrating the worm gear torque. But not yet irritated enough to fix it :-)

[@diginewark7843]

Thanks - we had a problem with the gears slipping in the base. Our solution was a little different - the screws holding the gear assembly in place had become very loose over time, so the entire gear assembly would wobble about and slip when turning. Tightened up the screws, and it works like new! (Luckily no need for epoxy, or 3d printing new plastic components!)

[@uzenzo2]

Thanks so much. Going to try your epoxy idea.

[@freddyacosta2358]

Awesome, thank you very much. Subscribed.

[@TheTotalhunk]

Hey Chuck, great video. As a RC hobbyist for many years, I personally wouldn't trust super glue on plastic parts. Great for wood, but plastic surfaces that must withstand stress, NO. I would have probably roughed up the surfaces and used a high quality epoxy...or perhaps Gorilla Glue. Never tried using it but I hear it's tuff stuff. The good news is, if you gottta go back in, you can torque the worm gear nut correctly.

[@ccarlley]

I've never had good results with Super Glue (cyanoacrylate) on ANY materials in the past. It is superior for gluing skin though :-) I'm jealous that it's worked for you. But Super Glue was right there handy so it was my choice. Surprisingly, my scope's slewing like a dream so I ain't goin' in until she breaks (like you suggested). I guess I'll put up with the worm gear slop until then. Thanks for the comment Roger.

[@akc5150]

Hi. Great and helpful vid!! I have the problem where my scope slews fine counter clockwise but makes the horrible clicking/skipping teeth noise going clockwise and doesn't move. Is this likely to be the same issue do you think?

[@ccarlley]

Sure sounds like it. Interesting that it's only in one direction and I'm assuming your base is level. It may not be the exact same problem as mine but it will be something similar causing the gears to separate. You going to take it apart?

[@en2oh]

great video. thanks for sharing this. I suspect that the mechanism for the ETX60 would be similar. That being said, did you really need to remove the optical tube to do this? Since you did remove it, do you have to collimate the optics? Thanks Doug

[@ccarlley]

Thanks Nitrous. I did have to remove the tube so that I could understand how to disassemble the fork assembly. Maybe there's another way but I wasn't aware of it. Removing the optical tube does not affect the optics provided you don't jar it. And there really is no collimation needed on a Mak or SC like you would do on a reflector.

[@scook1113]

Hi Chuck man. The 60 base is different but while looking at it I found the thumb screws that hold the scope to tripod. Were somehow stopping the mechanism. Took them out stood it on a table and it worked ok but verrrry verrrrry slow and that's with a new battery. So grease is the word!!! So a strip down is still needed!!!! Will let you know what happens good Sir!!!!

[@ccarlley]

As you may have read, I kick myself for not torquing the worm gear back to original specs before reassembly. Hope you have better luck.

[@bbabien]

thats a very bad move as there is no need to actually open the tube and expose the mirrors and interior to dust and air and possibly fingerprints, all you need to do is remove the 4 allen screws and the whole telescope can be removed from the fork, then remove the screws from the fork to expose the gears and motor.

[@hobbylyfe4716]

how do you get to the tabs if you don't take the scope off?

[@johns250]

@@hobbylyfe4716 It doesn't seem like you need to manipulate the tabs at all.

[@larrylevine130]

Thanks for your video, Chuck. I feel like I have a copy of Gray's Anatomy for the ETX-125. I am seeing the same problems in the AZ axis as you described. I machined a new bracket (metal) to replace the broken motor mount tab a the end of the AZ motor holder - epoxied it in place. However, I also spotted the broken spur drive gear retainer which you replaced with a plastic part. What I don't know how to do yet is how to remove the AZ gearbox. I removed the 3 screws but it won't budge. I assume I have to remove the black metal disk (clutch pressure plate?) that sits atop the large gear stack. I also assume that once the gearbox is removed the worm gear axle assembly can be taken apart and the new retainer can be slipped over the spur gear. Do I have that right? Thanks for the tip about the lithium grease as a replacement. I am an engineer by trade. I can't believe that the parts inside this telescope are not designed to take the loads that they will see when predictable failures (e.g. hard grease or hitting a motion stop) are encountered. Many thanks.

[@ccarlley]

Thanks very much Larry. I'll bet you've overcome the AZ gearbox issue by now. Honestly, it's been so long that I'm fuzzy about the details of disassembly! Your comment has given me a much needed boost to get back into my TS and take the slack out of the worm gear so thanks for that.

[@darrenaddy3287]

TreMENDous video! (See what I did there?) I have accumulated an ETX-125EC, a Made in the USA ETX-90 & an ETX-70 and I believe I’m going to do this to ALL of them, just to check everything out & replace the grease. Any tips for REMOVING the OLD grease? Or is it basically just a wipe off process? Thanks again for such a thorough walk-through!

[@ccarlley]

A fine dose of mirth, sir. Yes, I just wiped off the old grease in lieu of spraying a degreaser. Chicken, I guess. Congrats on tackling such a large job!

[@SheWolf_73]

I have same problem. Moves perfectly right or left but won't move up or down yet i can hear the motor trying

[@ccarlley]

I'm not surprised. There are many good tips in these comments should you decide to take this problem on!

[@DylaniaCat]

Yup, I have the same problem too. Great vid Chuck.

[@Hey_BK]

Thank you sooooo much for this video!!!!!

[@ccarlley]

Your comment makes it all worth it 👍🏼

[@Hey_BK]

@@ccarlley ☺️☺️☺️

[@stevenpatch7240]

Hey Chuck, thanks for the video. Do you know how to remove the PC board that the battery wires are connected to? I recently acquired a ETX 125 and there were batteries left inside and they corroded like crazy. I cleaned out the compartment and bought a USB AUX cable to control the scope from my computer since there is no handbox and the scope started smoking! I took off the bottom plate carefully and the black and red wires were no longer connected and there is corrosion all on the inside. I'm hoping to clean it up and re-solder the wires to test it again. I doubt it will work but I'm willing to try.

[@ccarlley]

Sounds like you've acquired a project! Honestly, since I didn't have a prob with the PC board, I didn't bother looking. But as I remember, the layout seems pretty straightforward. My only advice is that if it doesn't come off like you expect there's prolly some pesky wires behind the PC board you might have to wrangle. Holler back when you fix it and share the drama.

[@stevenpatch7240]

@@ccarlley Thanks for the quick reply! The board just looks soldered to the plastic front plate where the cables connect to so I don't know about getting it off without breaking something. I'll update if I'm able to fix.

[@scook1113]

I'm off to take my base off. Super glue and lube at the ready. I bought a etx 60 form a twat who must have known it was broke but not to worry now!!! I will do the Alt as well just to be sure!!! Thanks man!!!

[@ccarlley]

May the force and the glue be with you

[@jeffreyflandro9609]

Thank you for the video. My ETX 125 has a problem with the Azimuth. I can move it clockwise but nothing counter clockwise. I don't hear anything. Any suggestions?

[@edgardomaffia471]

Just before breaking the plastic gear support. Disasemby and clean the wormgear grease.

[@georgerothbart6214]

Great video. I believe my azimuthal clutch is slipping and needs cleaning. How do I get the clutch? Please advise.

[@ccarlley]

Thanks George. You can't get replacement parts that I'm aware of. But if you meant how do i get TO the clutch, it's those bottom 3 screws. Am I on the right track?

[@Tamesi1]

Wow, almost same thing happened to my ETX-70 and to a recent pre owned ETX90EC,,, they have similar problems , also found that both have main on /off switch problem, had to bypass it .. good optics, but plastic parts not very good, I think they may be having problems with the plastic molding process, they should be using better engineering plastic , or probably they are not drying plastic correctly ,, I think mechanical properties in parts is the problem and most probable is to low time while drying pellets.. while molding process is taking place....

[@mikeries8549]

You're complaining about plastic that's twenty years old when it failed..

[@Eugene2ndW]

Is there a need to "zero" out the alignment or indexing the gears?

[@ekummel]

I know that this is an old video, but for anyone else looking at this, rather than use the epoxy to glue those plastic posts, look into using superglue and baking soda. I'm not joking. Go and google it. There are some really good videos here on KZbin about it. It's makes strong repairs and allows you to even build broken plastic parts back up.

[@ccarlley]

So Ed, I too have heard rumors about this and it being hard as diamond 😳. In your experience does it adhere well?

[@ekummel]

@@ccarlley not only does it adhere well, ive used it as filler to build up deteriorated plastic through multiple applications of superglue and baking soda over and aver until youngest the desired shape and size. Kinda like 3d printing with baking soda!

[@nelsonrivera6575]

Great video ,Chuck , im hoping it works for my etx 90 ,which i purchased new but it has 10+ years and neither the Alt nor the Azimuth work ,i can hear the motor running when i press the buttons but no movement neither way , so im hoping this will help me ,Subscribed by the way ,great info here

[@fazergazer]

How do you take the right side fork arm off? It doesn’t seem to want to budge

[@ccarlley]

GW, did you figure it out? It's been so long I can't remember!

[@gerthie]

Hi Chuck just got my etx 70 out After it slews a bit it stops it reads motor unit failure any idea 😩

[@ccarlley]

Just a guess - do you hear it slow down before it stops? Does it seem like it's encountering resistance?

[@gerthie]

@@ccarlley yes it slows

[@ccarlley]

I am no expert on these but if the slowing seems resistance related (rather than the fine tuning of the slew) I can only imagine that, once again, old grease may be the culprit. However, if your scope has been used regularly maybe it really is in the motor. I know that's no help but probably better than what Meade will provide. If you go into it let us know what you find.

[@gerthie]

@@ccarlley thinking it’s grease 😎

[@johnbatchler8551]

Can u three print those mounts and put it together plus I order a new battery Holder for it to see how much damage the acid battery did

[@mguerramd]

Another option is to remove optical tube assembly and back cell, and affix it to a better go to mount that doesn’t have such cheap gearing. Rather than fixing an admittedly poorly engineered drive system. There is a mounting plate on the back cell with two 1/4-20 threaded holes to enable this. It might be overkill but you could mount it to a Meade LX65 mount, a Sky Watcher AZ- GTI, Orion Star Blast, and any of a number of others. You fasten an L bracket to the scope and a dovetail to the other leg of the L bracket. Check this out: m.kzbin.info/www/bejne/gZWxkpaKjZqLZqM

[@ccarlley]

Thanks for this alternative! Going by the exponential suck factor of the original base, this is a welcome thing to try.

[@westwater73]

Cigarette Ash and superglue is a good fix also.

[@doubled83]

What did you use to re-lubricate the worm gears?

[@ccarlley]

I used just regular ol' white lithium grease from Auto Zone. Seems to be doing OK. Thanks for the view!

[@saukpcrepair4497]

the gear assembly shown at 7:51 is a horrible engineering design. 2 set screws to adjust tension on the gear, anchored by 2 mounting screws 1/4" inch away. This design must fail and break the mounts. Since replacement mounts are impossible to find, it shows that all these must fail at one point or another. I am dealing with the same issues in mine. The solutions will be smarter then the original design.

[@ccarlley]

Let us know what sorcery you come up with.

[@piotrjanicki6154]

good video. thanks

[@pascalgaulin3405]

Hi Chuck, First of all, thanks a lot for posting this video. It's great and it helped me to understand why my ETX-125 scope is no longer rotating properly!! Now, I have a question: at 13', how did you manage to put this small piece of white plastic around the gear axis? I'm struggling to remove the gear from its axis... Thanks!

[@ccarlley]

Thanks for the comment Pascal,It's been so long since I've worked on it, I've forgotten how I got the white plastic on there - sorry. I'm guessing that the gear had a screw of some sort through it and I removed the gear. I do remember taking the entire worm gear assembly apart so maybe I put the white plastic support on at that time. Wow, that was not much help was it! Good luck.

[@martinhodnett2586]

Hi Pascal. You've probably fixed yours by now but Chuck was right. Take the nut off the end of the shaft and draw it all the way out, then put the replacement on and reinsert the shaft into its holder. My scope broke in the same place and I fixed mine by super-glueing a paper clip around the part - I also used a soldering iron to melt the plastic back together. It worked for me.

[@stevenbrown5693]

@@martinhodnett2586 Im working on this right now and I am stumped on how to get the white gear off the end of the shaft. I took the allan screw out but I can't figure a way to pull that gear off the brass shaft. Its really on there!

[@martinhodnett2586]

@@stevenbrown5693 evening Steve. It is so long ago now I've forgotten what I did! I think I took the gearbox housing and shaft assembly out as one then removed a slotted screw from the far end of he drive shaft. With that free I could draw the shaft forward out of its mount and then out of the gearbox holder. I don't recall taking the white gear off the end of the shaft. Bear in mind, I can't remember what I had for breakfast this morning, let alone X years ago! :-)

[@walterbishop3668]

How portable is it? can I load it in a big backpack?

[@ccarlley]

Regarding the ETX125, it'd have to be a pretty big BP. You could probably cram the tripod in there too. Sounds like a PITA to haul it for very far but I guess a very dark sky would be worth the trouble.

[@walterbishop3668]

Thanks for the fast response. I was going to buy the etx90 but it seems the difference between etx90 and 125 is pretty much.

[@dedskinprodcerdj4273]

I tell you what , My Logitech Racing Wheel for consoles and PC is made better . Premium quality indeed .

[@guitaristdotcom]

I was thinking of buying one of these, but after seeing this -- no way. Cheap plastic junk, looks like. So many companies that used to have good reputations have gone downhill these days. I'll keep looking for a quality scope. Good work on your part, though.

[@ccarlley]

Thanks very much. I still haven't gotten around to taking the slack out of the worm gear but that's way down on my list. The optics on this scope are great but yes, the motor drive is cheap. Thanks for the view!

[@adamt5986]

I would think that Meade would make better telescopes...

[@ccarlley]

Well, at least their optics are great 👍🏼 Adam T. I think that they are great for the money. I think the problem with my t/s was that it sat unused (unexcercised) until the grease stiffened. That alone added the stress that broke the scope. If i used it all the time from day one I'll bet she'd still be working fine.

[@adamt5986]

Chuck Carlley yeah I’ve got an lx200 that I have sent in twice for repairs. Not cheap. The azimuth motor struggles with the weight. I’m going to take a look myself when I get a chance. Great video!

[@Україна-ц7э]

They call me the telescope chiropractor

[@boogermeister1]

Or just defork the etx and mount the ota on a good goto mount and have at it. Get rid of the crappy Meade drive assembley

[@ccarlley]

A fine idea!

[@TheGabrielStudios]

It’s terrible that the video was recorded vertical. Next time rotate your phone 90° please. Its really hard to whatch this way.

[@christianfontaine712]

Cheap can motor...plastic gears , hig price. Very disapointed.