Page 8 of 31. Version 1.03 September 2012
Microbee Premium Plus+ | Construction Manual
4. Keyboard Frame & key switch assembly
The Microbee Premium Plus keyboard is made up of a number of parts which includes
individual mechanical key switches, key tops (caps), a metal keyboard frame and key switch
adapter PCBs. In planning and designing the Premium Plus, large efforts were made to try
and procure key switches that were the same physical form as the original ones. There was
no exact match to be found. Some came close (like the Cherry brand MX series) but were
cost prohibitive, others had non-suitable shaft styles and so on. All of the key switches that
we looked at also had different pin spacings & locations as well. While we could have
scrapped the existing stock of Premium series baseboards and made new ones to suit a
different style of switch, this was deemed to be wasteful & expensive. Seen as the Premium
Plus is a limited edition kit, the best solution was to provide a small adapter PCB for each of
the new key switches, so that the assembled switch would then suit the original PCBs. This
also made the solution suitable for people who want to replace the keyboard in other
Microbee models.
4.a Key switch assembly
Assembly of all of the key switch adapters & fitting them to the key switches takes quite an
amount of time. You can expect to spend 2 hours working through the whole lot of keys, so
have some patience & take a break when you need to because it is better to spend as much
time as it needs to do a great job rather than rushing it through. If done well, you will have
a decent keyboard for your Microbee that will last well. If you rush in assembling them, it is
likely that you will have keys that don’t work as well as they should.
In your kit, you will have a bag specifically of keyboard bits. This includes the key tops, key
switches, gold PCB pins, mounting hardware and so on. There is also a PCB supplied that
has 68 (64 needed, plus 4 spare) key switch adapter PCBs in a frame.
All of the individual adapter PCB’s are held
together in the frame with breakout tabs.
That is, on the edges of each PCB there is a
little bit of PCB material that connects one
PCB to another to hold all of them in the
frame while the board is being manufactured.
At these points there are very small holes
which provide a breaking point. If this point
is flexed, it will break apart & each individual
PCB will come away from the others. Refer to
the photo to the right which shows some of
the key switch adapter PCBs broken out from
the frame.
