A developer named Martin has just written a detailed post about the experience of reverse engineering the BKM-129x input board used in some Sony BVM monitors: https://immerhax.com/?p=422
The project is still in progress (the above picture is a mockup), but a complete board is currently in the works. If there’s any brave dev’s out there that want to try it now, you can load the current code on an Arduino Nano v3 and wire it into your BVM directly. The files are currently on his github: https://github.com/skumlos/bkm-129x-mcu/
While other input boards have been reverse-engineered in the past for other platforms, the Sony boards are often much more complex. Also, prices on all of these boards are going up, as they’re slowly getting more rare. Work like this is incredibly important to preserving these monitors and we all should take a moment to appreciate it.
Of course, Martin also spoke of the elusive BKM-68x card and tackling that project seems like it’s a ways off. Hopefully other developers can join the project and team up to eventually tackle that card…and maybe even add proper sync regeneration to fix the compatibility issues! This is all just wishful thinking of course and for now I’m just happy someone’s taking on a project like this.
I’ll buy one of these 129x replacements the moment they’re available and see how it performs in my 9″ BVM!