deskthority

I would like to reduce the size of some of my keyboards down from full size to TKL or smaller. I have no use for the numpad keys or function keys, and treat them as spare tyres: donor zones for harvesting usually pristine switches. However, certain switches - Futaba, Space Invader, Damped Alps - seem never or rarely to come in smaller boards. It looks like my options are then either to desolder a load of switches and mount them in a custom PCB and case, or take an existing board and cut it somehow down to size. For Alps, it seems the first option would be best - I've heard there is Alps-compatible stuff out there for building your own Alps board - but for Futaba and SI, I haven't heard of anything like that, so the second option beckons. Has anyone attempted a chop from full size to around 65%? I'm worried about buggering up the circuitry. What happens if a connection to an unwanted switch is severed - is that fine, or will it mess up the switches I'm keeping? Will the controller still work if a load of traces lead to nowhere - does this affect safe voltages, for instance? How dependent is this on the specific board I'm working on? I rarely open up keyboards, let alone attempt projects like this, hence my probably dense-sounding questions, but I just wanted to get a feel for how feasible and difficult something like this would be. Thanks in advance for any guidance!

To cut down a PC board you'll have to map out all the traces you'll be cutting to see what they do. That includes the switch matrix, and also anything else including power and ground. Many keyboards have the controller chip in the upper right, or in the gaps between the switch blocks, so that may prevent your idea from working on some models. Traces from switches being removed going nowhere shouldn't be a problem, and you can always cut them at the other end if you're worried about that. Traces going through the part of the board you're removing can be reconnected with jumper wires as necessary. Again you'll have to map out each one to determine if it's needed.