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Old 20-07-2018, 01:47 PM
alval (Alan)
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Meade ETX 125 Observer. What’s new, disassembly and photos.

Hi all,

I figured a few of you who frequent this forum may have had dealings with this scope in the past, and going by other forums discussing the older models it may have been a love hate relationship. There doesnt seem to be much info on the new one, whats changed and what hasn’t. So the new etx observer model which came after a hiatus of a few years probably has most of you thinking its more of the same and no different to the old models.

I’ve had mine for over a year now and had cause to open it up recently. So I took some pictures along the way. ( Why? Well thats a another long story that I wont go into here other than to say the QC issues havent changed much ).

So firstly whats the same.

The tripod is basically the same set up, other than the attachment screws are now aligned across east west so to speak, so you dont have to tilt to tighten the screws.

The ota is also much the same, the optics are still good with a dovetail to hold the red dot finder. It has a metal threaded rear port inserted into the plastic housing with a metal flange screwed onto it from inside the housing clamping it in place preventing it pulling out.

The fork mount does look similar to the older ones except now it has the control panel on the fork arm and the battery access is now from the top, thats where the similarity ends.

The inside is completly different, the main base, pan and fork arm assembly is made of aluminium castings with plastic coverings. All the important threads have brass inserts moulded into the plastic.

In the dec drive fork arm the declination drive gear and worm are substantionally larger, the clutch also looks larger with a redesigned gearbox and circuit board in the arm. These are all easily accessed with anything swapped out in minutes if needed by removing 5 socket head screws holding the fork cover. (hopeflluy not needed in the future but easily done)

The fork with the dec setting circle has the hard stop for over zenith and a
tension spring which loads up as the ota approaches horizontal, reducing the weight on the worm gear.

To get to the RA drive the base cover comes off with a screw under each of the six rubber pads, and I kid you not in saying that removing them was the hardest bit of the whole exercise and took the longest. I resorted to a razor sharp 1/4 wood chisel to carefully carve and scrape them off removing all glue. Bunnings have replacements.

The metal base is sturdy with a central post, to this what I call the pan (looks like one) is attached by a bearing and the RA gear and clutch. The forks are attached to the pan with three socket head screws each side. The worm
gearbox is accessed from underneath and easily removed. To access the RA worm gear and clutch, remove the forks, then the plastic top cover. The RA gear also appears larger. When the clutch is tightened the gear stays in place and the worm moves, hence no hard stops in the RA drive.

In short it is sturdy, the parts are well cast and finished, with plug in electrical connectors and flat cables. Everything is easily accessed and removed (other than the rubber feet). A couple of modified allen keys and screw driver is all you need

Now reassembled correctly it works great, aligns and tracks well in alt/az. Suits my needs fine for the moment.

Hope this is of interest to someone.
Alan
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  #2  
Old 21-07-2018, 06:14 PM
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netwolf
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thx nice to see the innards of the new one. Wonder if Meade may now also sell the motor focuser upgrade for this hard to find the old 1247 for the 125 pleanty of 1244 for the 105/90. But no 1247 these days to find
Hopefully the focus mechanics and motor are the same.
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Old 21-07-2018, 08:44 PM
alval (Alan)
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Location: Northern Adelaide
Posts: 73
Hi Netwolf

I wouldnt hold my breath for a purpose built electric focuser for the etx. The rear of the new one doesnt have any provision for mounting one without modifcation. The new focuser is still a bit sloppy(6.5mm hole with a 6mm shaft). I made a bush to take out the slop and new focuser knob with small and large diameter this seems to keep fine focus shakes to a minimum.

Alan
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