EEVblog #390 - Mantis Elite Microscope Review

[nixxon]

I just received the first out of five Original Mantis magnifiers. I had to open it to fix several issues. I understand that pictures of Mantis guts are sparse, so here are some pictures taken while the unit was repaired and cleaned.

Issues:
1) Align optical path (left down) - not fixed - adjustment screw malfunction
2) Remove dust from lenses, mirrors and beam splitter - OK
3) Fix right lamp tilt mechanism - OK (pushrod had fallen off, secured with original 3mm set screw)
4) Fix intermittent fan - OK (Spade connector was too wide and made bad connection)
5) Insert 2 missing 3mm screws to "mirror assembly chassis" - OK

The viewing head splits in 2 halves after removing 4 screws (2 behind the viewing head and 1 in each lamp socket.)

The lower half of the viewing head (black) contains the objectives, 4 plane mirrors, all electric parts and lamp tilting lever and pushrods. All 4 mirrors in the lower half are fixed to a separate plastic framework/internal chassis by double sided tape. Very strong adhesion. The mirrors feel well secured in place and not delicate at all. It was no problem to genly wipe them clean with cotton cloths (pieces of old T-shirt) and bathroom glass cleaner.

The top half of the viewing head contains a beam splitter, 2 concave mirrors (one for each eye) and the viewing screen (lens). The mirror in the back of the viewing head (left image) is supposed to be slightly movable by turning the larger Philips screw behind the viewing head. The screw is malfunctioning in my unit, so I have not yet been able to perform a proper optical path adjustment. (The left image is a bit higher than the right image). Does anyone know how this adjustment screw is supposed to work? (is it a multi turn, threaded adjustment screw or a one-turn excentric screw where oposite sides represent the extreme adjustments in either direction?). The Operating instructions and Service Manual implies that the adjustment screw is used for horizontal alignment, but I suspect they meant vertical adjustment. As I hold a screw driver to the adjustment screw and apply pressure, the left image is temporarily lowered in the better direction.

[nixxon]

more photos

[H.O]

Thank you for posting that!
I have one in serious need of cleaning but have been "afraid" to take it apart risking misalignemt of the optics and no info on how to realign it. Now I know it's not really that complicated. Thanks!

[Ingineer]

That's the older model too.  I can say that the newer models are a lot simpler inside.  It's really easy to clean the optics, and splitting the case will not misalign anything.  You can even get a good amount cleaned just by removing the glass screen from the viewport, that way you don't even have to split the case.

I still want to know how they integrate the camera though!

[deanclaxton]

Thanks nixxon for those photos! You gave me the guts to open up my M001 today and give it a clean.

Here is a photo of the adjuster on the rear - the screw justs goes through a metal plate on the mirror and therefore adjusts the mirror in/out with the screw rotation.

[Romain]

(old thread, but posting this for future reference)

On deanclaxton photo it looks like there is a small spiral spring behind the plate to push it forward when the screw is unscrewed.
Mine was off just like yours. Screwing it down raises the left eye, while unscrewing it lowers it.

[toybuilder]

Thanks to everyone that contributed to this thread.  Based on the info here and having seen a Mantis a few times before, I gambled on eBay for an in-rough-shape Mantis.  I figured it would at least be an interesting learning experience. 

Whoever tried to fix it before didn't have enough information/knowledge to get it to work. 

The main issue was having to fix the mounting of the lower concave mirror.  One of the plastic tabs was broken off, and the previous repair attempt screwed the mirror down rigidly so that it couldn't move for adjustment.  After patching the mounting point and mounting the mirror with a lit bit of play, I was able to adjust the vertical alignment.  (There were a few other issues: https://twitter.com/toybuilder/status/1745185277981974770).

For anyone else looking to fixing one up, I would say that if you have basic optics knowledge and can work methodically, the Mantis is actually pretty simple and straightforward.   Yes, you need to have the optics aligned, but the lower mirror assembly is pretty much solid and don't need adjusting.  It's mostly making the small adjustments to get the beam splitter and the concave mirrors positioned where they need to be.  If the housing is intact, it should just be a matter of adjusting a few screws and turning a knob.

[thm_w]

Looks similar to the unit I have, JBWeld PlasticWeld or equivalent is your friend when bonding to and building up this cheap plastic.

As for your camera, you can get a microscope camera from aliexpress for <$150 that will be more than good enough if you need to document extensively.

[toybuilder]

So my unit was "cross-eyed" at the optimal viewing distance because I had the bottom (back) mirror mounted too far down on the right hand side.  I added a plastic washer behind the mounting plate on the right side to shim it and turn the mirror angle slightly more to the left.  That fixed the offset (and also improved the vertical alignment range).  Now, I get eyes-correct image at the optimal viewing distance and an excellent FOV.

Aligning this without factory fixtures means having to open, adjust, and close the unit a bunch of times to get it right.  But now that I've got it working right and mounted on an inexpensive monitor arm, I've got a frankenMantis that should make it much easier to do SMD rework.

BTW, my Mantis is missing the lens turret -- so I've just (for now) taped a simple double-convex 200mm FL lens at the entry aperture.  That seems to give an approximate 2X magnification.  Basic double-convex lenses are inexpensive and easy to get, so a lack of the official objective lens isn't a showstopper.

[GterBeke]

For the Mantis Elite the turret is separately available. Partnumber is 202B0445.