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ETX-90 PE has no RA motor, gear or circuit board - Need Pics!

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#1 JoeVanGeaux

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Posted 28 February 2020 - 06:39 PM

Hi All! 

I am the owner of a new-to-me ETX-90, apparently, the Premier Edition. The previous, and original, owner said its about 5 or 6 years old and in great shape but it won't track anymore, so I snagged it in what appeared to be a great deal.  The previous owner said he used it about 10 times, put it away for a long time and then it quit tracking. (Evidence of leaking batteries looked like the culprit on quick inspection.) He said he removed the cover from the base and then had a change of heart and put it back together. 

I knew similar units had experienced an almost predictable set of issues and none of those seemed too tough to remedy... until I opened up the base to assess the damage, that is.  Upon opening the base, there it wasn't!!  I mean that literally, there was no motor, no drive gears, no control board... only one gear mounted on the central pivot and the roughed-up backside of the circuit board that receives the power and controller cables (the wires and plug for the DEC motor was still there, thankfully).  How this miracle of selective tele-deportation took place is likely limited to assertions directed at his lack of mechanical skills... and his honesty, I suspect.

I have fixed my share of ridiculously tortuous gizmos in my day but, more often than not, I had something to look at to start with.  I was hoping just to fix a stuck gear, broken plastic piece or soiled circuit board - something, anything!!  There was nothing there to fix!  And nothing to reference for obtaining replacement parts. I called around since the actual ID of the model was still in question, but now it looks like its an ETX-90PE (with the star field print on the tube and most parts for an LNT sensor).

My request of visitors to this post is for pictures of the innards behind the bottom plate on this particular model - and what might be under that, if available, since the empty base plate would go a long way to confirm the correct parts to look for.  Also if someone has some part numbers, that would be fantastic!  I have seen a few photos in this forum of what I only think is the as my model but I can't be sure, especially since I got two totally different answers from the Meade tech support today.  One says each sub-model of the ETX-90 has a different motor and drive assembly and, then, on a second call (that was supposed to be just a follow-up), the tech guy said they are all the same.

Any help would be much appreciated!

 

Joe



#2 JoeVanGeaux

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Posted 29 February 2020 - 08:40 PM

I finally got my picture sending issues fixed and I know peeps on this site love pictures!!  These may help to illustrate my issue/question.  It may be a while before anyone actually removes the base cover plate on their unit but I'm patient.  Mine is the Meade ETX-90PE (PE= Premier Edition. also seen as "Premium Edition").   Basically, I think its just an ETX-90EC or even ETX-90 (??) with a few features (bling) that don't impact how the RA drive was made.

So, when you do open up yours, snap a picture of the insides and post, here.  Many thanks and good karma will be sent your way!

Pic 1:  The outside OTA mounted on twin-tined fork mount (for overall ID of this model)

Pic 2:  The cover plate over the battery box and RA drive components (I've seen the same scope have ET-90EC printed here, too.)

Pic 3:  The insides of under the base cover plate and battery compartment (Where the RA drive components were expected to be, but weren't.)

 

Thanks!

Joe

Attached Thumbnails

  • Nameplate on Mount (2).jpg
  • Nameplate on Mount (1).jpg
  • Under the base cover.jpg


#3 OzAndrewJ

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Posted 29 February 2020 - 09:26 PM

Gday Joe

 

Based on your piccies, i have attached the best fit piccy i have of what goes in there.

It looks like the same as in most versions of the ETX, but most are black plastic not blue.

I dont know if there are specific part nos for the bits, but you will need to find them second hand

as Meade no longer support them.

Telescope warehouse would be a good place to start.

 

Andrew Johansen Melbourne Australia

ETX base.jpg


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#4 JoeVanGeaux

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Posted 29 February 2020 - 11:46 PM

Thanks, Andrew!!

Can you tell if that printed circuit board is attached to the drive unit or if its mounted separately?  I found a used unit (not purchased, yet) but don't know how to identify the board.  I assume its the motor driver board that converts digital to analog to the DC servo.

In any case, karma to you!

 

Joe



#5 OzAndrewJ

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Posted 01 March 2020 - 01:10 AM

Gday Joe

The PCB screws to the gearbox assy and can be unscrewed if required.

Ref attached piccy of the PCB + Gearbox from my test bench based on an ETX-125.

( I am not 100% sure if the ETX-90 used exactly the same parts )

The three arrows show where the securing lugs are to mount the unit in the base.

The 2 circled screws are what locks the gearbox to the PCB.

The main reason it comes as an assy is there is an encoder disk on the motor axle

and this fits between a LED and receiver unit that are fixed to the PCB

so the 2 need to be fixed together before installing.

 

Andrew Johansen Melbourne Australia

ETX RA Assy.jpg


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#6 JoeVanGeaux

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Posted 01 March 2020 - 11:37 AM

Thanks, Andrew!  From what I've read the ETX Premier Edition in the 90mm and 125mm both had the same drives, but not 100% sure.

Has your RA drive failed?  If you locate parts, please let me know your source.

Regards (and thanks, again!)

Joe



#7 OzAndrewJ

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Posted 01 March 2020 - 03:51 PM

Gday Joe

My drive hasnt failed, but getting parts down here is less likely than in the US.

My "testbench" is made using bits that were removed from damaged units.

 

Andrew Johansen Melbourne Australia



#8 Myk Rian

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Posted 04 March 2020 - 01:16 PM

Here's my ETX-90ec after I repaired a trace.

 

20200216_163054.jpg


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#9 JoeVanGeaux

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Posted 05 March 2020 - 09:44 AM

Myk,  thanks for the photo.  I'm beginning to think this is what mine had before it was eviscerated.  I continue to hold out hope that I'll find these parts for mine.

I have two quick questions for you, though.  I noticed you twisted a few wires and snugged them around one of the mounting posts.  Is this original or is this what you've done to manage the wires for preventing chaff and pinching?

Also, when reading about repairs and such on these bases, there was always caution given to the battery pack wires.  I don't see any in your photo.  Do you have a separate plug or connector for them or have they just not been re-attached when the photo was taken?

My apologies if one or both questions are foolish or trivial, but remember, my scope base was empty and I had nothing to go by except for the pics of other's scopes, plus the confusing info I got from the Meade peeps.

 

Regards,

Joe



#10 Myk Rian

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Posted 07 March 2020 - 07:40 PM

The twist is factory. You don't want to break any of the wires. It keeps them steady.

I cut the battery pack wires off and use a 5.5x2.5mm barrel plug and fused cord connected to a small 12v lead acid battery. Plug it into the panel and you're all set. Don't bother with 8 aa batteries if you want it to perform well.
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#11 JoeVanGeaux

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Posted 11 March 2020 - 10:46 AM

The twist is factory. You don't want to break any of the wires. It keeps them steady.

I cut the battery pack wires off and use a 5.5x2.5mm barrel plug and fused cord connected to a small 12v lead acid battery. Plug it into the panel and you're all set. Don't bother with 8 aa batteries if you want it to perform well.

Thanks!  I was thinking its a factory layout but had no innards in the base prior to getting the scope, so I had no reference and wasn't sure how things stretch and shift inside the base when its moving.

When I get mine back together (I have a helpful lead on some parts), I also intend to rig it for use with a separate battery pack as you've also done.  Especially since It appears the initial damage was done by several burst batteries.

 

Joe

All the best!

Joe



#12 Myk Rian

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Posted 11 March 2020 - 01:10 PM

I use a farm, electric fence, 12v lead acid battery. About $15. The Meade power panel has a 5.5x2.5mm barrel plug connection.
Make sure you get the polarity right. The barrel is -, and the pin is +. If you have any old wall wart power supplies, check the plugs on those and cut the whole wire off one that fits.
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#13 Myk Rian

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Posted 11 March 2020 - 01:11 PM

I use a farm, electric fence, 12v lead acid battery. About $15. The Meade power panel has a 5.5x2.5mm barrel plug connection.
Make sure you get the polarity right. The barrel is -, and the pin is +. If you have any old wall wart power supplies, check the plugs on those and cut the whole wire off one that fits.
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#14 JoeVanGeaux

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Posted 17 March 2020 - 06:41 PM

I use a farm, electric fence, 12v lead acid battery. About $15. The Meade power panel has a 5.5x2.5mm barrel plug connection.
Make sure you get the polarity right. The barrel is -, and the pin is +. If you have any old wall wart power supplies, check the plugs on those and cut the whole wire off one that fits.

Thanks, Myk.  I am still without any parts of the missing innards at this point, but will be sure to consider your helpful suggestions.

 

Regards,

Joe




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