I have just come back from my holiday so I'm
resuming my work on the project. First, I was advised to add 100 Ohm resistors
on the 4051 inputs to protect it from static electricity. I've updated the
Analogue Board schematics accordingly. I should mention that my test Analogue
Board is running fine without those resistors but to be on a safe side I'd
recommend to use them when you build your Analogue Board.