In search of 4B3A Microswitch Keyswitches (for a restoration, not a keyboard collector!)

Ian Finder ian.finder at
Thu Jul 9 23:34:10 CDT 2020

I know what you guys are thinking- no, this isn't for a keyboard collection
or some modern build or some other nonsense like that.

I have a friend who is restoring a fairly interesting and historically
significant vintage computer- a and subject to what appears to be a
batch-related encapsulation failure on the proprietry hall effect sensors,
but could have been some other trauma, around a little over half of them
are bad.

The correct SD-series replacement switch would be the 4B3A-

*** These can allegedly be found on some of the Diablo printing terminals.**

It is possible other switches ending in ***A could be made to work with a
bit of labor and disassembly (swapping the fairly brittle sensors).

I am not a keyboard expert but I have learned that you can remove a key on
some of these microswitch keyboards and read the model fairly easily.

Please let me know if you have a lead on a donor for these switches. They
will be put to good use, and you can reply to me off list for more details.


- I

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