Olivetti ET 121 unknown switches
Posted: 09 Jun 2022, 23:30
Today i disassembled an Olivetti ET 121 to try and convert it to usb, and after removing the pcb of the keyboard module i found out that it used switches very similiar to the ones in my Olivetti ET 111 which i posted here yesterday: viewtopic.php?t=27292
The main difference was that the domes on that keyboard where in 4 different sheets, while on this keyboard they were inside the discrete switches which are sandwitched between the pcb and the plate, but the sliders and top housings are identical. Also, on the other keyboards switches, after the tactile bump there was a bit of overtravel, but on these switches there is almost no overtravel at all. Another thing wich seemed odd to me is that there is an alps logo on the pcb, alongside the code: 11KE086A, while on the other keyboards pcb there is no alps logo anywhere, despite the two pcbs looking almost identical. Here is a picture of the pcb and the switches:
There is also another variant of these switches apparently, which is a double action switch: these were used for the spacebar, backspace and enter keys.
These are the disassembled switches:
I looked around to see if i could find these switches on the wiki but i couldn't find anything about them.
Update: i opened the other 3 Olivetti ET 121 i had and all of them had a different pcb, this time with an SMK logo on the back, alongside some markings near the diodes and the connector:
After removing the pcb i saw this:
The switches are identical to the other ones, the only difference is that the dome is now green instead of gray and the bottom housing black instead of white. Also, i don't know if it is because of the conditions of the board but these switches feel less tactile than the others, maybe the domes are of a different thickness?
This is the top side of the pcb.
As you can see, there is an SMK logo and code exactly where in the other pcb there was the alps logo.
Also, something i didn't notice on the other keyboard, there is some sort of dummy switch under the left shift key, supposedly used as a stabilizer:
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Update: i opened the other 3 Olivetti ET 121 i had and all of them had a different pcb, this time with an SMK logo on the back, alongside some markings near the diodes and the connector:
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Also, something i didn't notice on the other keyboard, there is some sort of dummy switch under the left shift key, supposedly used as a stabilizer:
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