ELMA tray keyboard with unmarked switches

Strg-F17

15 Oct 2017, 15:25

Hello,

I've been lurking around this forum for a while and I think it is time to break my silence. I picked up a rather strange board form Ebay a few days ago. It is an ELMA tray keyboard, intended to be built into a 19" server rack. ELMA still sells similar keyboards, as you can see here: http://www.elma.com/products/enclosures ... ys-detail/
ELMA01.jpeg
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Obviously the tray is missing and one of the mounts is broken off. The case is mostly made of steel panel except for the side parts with the mounts, which are made of cast iron. Knowing this it is no wonder this thing is really heavy: 2,2 kg! (For comparison: My Model M122 weighs 2,7 kg, a comparable G80-1800 is only 900g.)
ELMA02.jpeg
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Made in Switzerland. The board has a coiled cable with a standard 5-pin DIN AT connector. It is in working condition.
ELMA03.jpeg
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Cover removed. The layout is rather nice, even though the bottom row is a bit weird. But it has a 6,25 u space bar.
ELMA04.jpeg
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Alps mount switches. The amber one (return key) is an Omron B3G-S switch, the rest: no idea. There are no markings on them. Two of them have broken stems.
ELMA05.jpeg
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The PCB reveals that the board actually is a Costar CSK-7101N built into a sturdier case. Today ELMA uses G80-1800s for their tray keyboards.
ELMA06.jpeg
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The keycaps are pad-printed and very similar to those on a Chicony KB-5192 I own.

I've soldered out one ouf the switches, since i really wanted to know, what kind of switches these are, but there are absolutely no markings on them.
ELMA07.jpeg
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Underside with Omron-type pins.
ELMA08.jpeg
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Top view with broken stem.
ELMA09.jpeg
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Side view. The switches are clicky, but not every switch is still clicking.
ELMA10.jpeg
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Another side view.
ELMA11.jpeg
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Switch opened with actuation leaf at the top and click leaf at the bottom.
ELMA12.jpeg
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Opened switch from the side.
ELMA13.jpeg
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Switch disassembled. If you leave the click leaf away, you'll get a linear switch. Does anybody know these type of switch? Couldn't find anything in the wiki about those.

I'm not really sure what to do with this board. The case is awesome, but the switches are not my cup of tea. I'm not a big fan of clicky switches (except buckling springs) and these ones aren't anything outstanding. Maybe I will use the case and plate for a handwired custom build.

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Daniel Beardsmore

15 Oct 2017, 15:47

It's some kind of variant of "D-TRANS"/"D-TRNS", [wiki]alps.tw Type OD1[/wiki], which is something Costar are known to have used. Yours seems to have a thicker slider, but not the reversible base. (The reversible base in D-TRNS is likely to help with automated assembly, rather than for DPST.)

Strg-F17

29 Oct 2017, 15:35

Thank you, Daniel. So this is kind of a "new" variant of an alreday documented switch.

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