Mitutoyo Micrometer Head Zero Switch Bypass Surgery
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  1. #1
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    Default Mitutoyo Micrometer Head Zero Switch Bypass Surgery

    Have two of the 164-162 2" micrometer heads on a toolmakers' scope. One zero switch wouldn't work at all (even when pressing the mangled silicone button with a probe), the other intermittently. I don't know why Mit puts those cheesy little silicone/conductive pad switches on a $800+ micrometer head (particularly on the zero switch that is used all the time); not only are they difficult to press when new because so small, they disintegrate after a while. And the ones these heads the conductive carbon is printed on the silicone, it's not even a separate conductive rubber pad (so the carbon wears off also). I can understand them in a caliper where size is an issue, and the zero isn't used continuously. Anyway, below is a switch-bypass method:
    a. remove battery cover and batteries (screw retaining the cover must come out to disassembl)
    b.pry off movable display module (it is electrically connected to the body with a spiral-ish flex-circuit and connector). The module snaps onto the body
    c. remove flex-circuit from module connector (mark flex and connector for orientation). This is a bit tricky, use a pair of small flat pliers to pull the flex out parallel to the connector (it takes a fair amount of force), and be careful not to twist the flex such that it tears. The connector has no latching mechanism, the flex is pushed directly into the connector.
    d)remove screws from metal bottom plate, remove plate
    e)remove pcb screws
    f)remove pcb (don't lose battery contacts)
    g)clean keypad, battery and conductive rubber pads with IPA and qtip
    h)mark housing for wire-exit location and dremel notch for wires to exit
    i)solder small wires to traces of "zero" keypad (will probably require microscope of magnification), route wires to edge of board.
    j)reverse assembly of pcb, and metal bottom plate, route wires thru notch
    k)solder wires to light-touch momentary switch, attach switch to module (I just used a piece of VHB tape)
    l)reinstall flex into connector (again sort of tricky, must align and use a fair amount of push force near connector, use flat jaw pliers)
    m)snap module back into body.

    This didn't take long at all, the biggest care and pain required is removing installing the flex-circuit into the connector. SO much easier to use, and has tactile feedback also. Cheers.
    img_7072.jpgimg_7073.jpgimg_7074.jpgimg_7076.jpgimg_7075.jpg

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  3. #2
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    couple more picturesimg_7077.jpgimg_7078.jpgimg_7080.jpgimg_7081.jpg

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    I actually tried to do the same fix on our scope.

    The pic showing the contacter pad (gold bars) that looks alot better than our did.

    Try cleaning/refurbishing the PAD not the contacter. In our scope the pad is a weird rubber thingy that deteriorated from use and outgassing. This damaged the contacter pad.

    You may also try contacting your local indicator repair shop to see if they can refurbish it.

    We had to replace the heads, so buckle up.

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    This fix works great, the micrometer heads are working fine. The soft touch button is much easier to use (and of course it works). Even if I could purchase a new keypad part, I'd rather have the button.

    The kepads on those are silicone, with a printed carbon ink to "short" the pattern on the PCB. That's a really cheap keypad, particularly using the carbon ink (less cheap, but still cheap ones use a solid conductive silicone pad bonded). So that cheapo ink wears off pretty easily, and once it wears off the key wont work (not to mention those tiny keys mechanically wear, and are hard to use). The two I repaired had that carbon ink transferred onto the pcb contact pad, I cleaned all of them off with IPA. That ink could also potentially short the pcb pad traces.
    Yea, I know those heads are $850, which makes it even more inexcusable they put a cheesy little unreliable, not-durable, hard to use keypad on them (especially on the "zero" key)--I mean that's throw-away cheap garbage level, like remote-controls and toys. The "data" switch actually has a pushbutton switch, not the cheesy silicone switches. Cheers
    (If you need a hand fixing yours, or want to get rid of them, drop me a PM).

  6. #5
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    This fix works great, the micrometer heads are working fine. The soft touch button is much easier to use (and of course it works). Even if I could purchase a new keypad part, I'd rather have the button.

    (If you need a hand fixing yours, or want to get rid of them, drop me a PM).
    They are in the "to do" bin. I'll probably try to get to them over the holidays.

    I am the entire tooling department, so I have a lot to do BEFORE then. But haven't forgotten them.

    I'm glad you were able to fix them.

  7. #6
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    Interesting post.

    That's the reason all of the remote controls to all my appliances crap out on the on-off button after about a year or two.

    Thanks for posting.

  8. Likes Bill in PA liked this post

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