All the keyboard I tested so far are genuine PS/2 keyboards.
I tested all first using an old WIndows XP Athlon FX64 computer fitted with a PS/2 keyboard socket.
So, now some new interesting results: Today I came back from office with a set of 6 Dell PS/2 AZERTY keyboards, 5 of them with the same formfactor as the one I already have and which fails with Lyra 3.
I started with the keyboard I borrowed to my friend (as mentionned in my previous message) and everything worked flawlessly as it did last time.
Then I started to test one by one the "new" Dell keyboards.
Strangely the first 4 keyboards worked fine (I hotplug the keyboard on Lyra 3 without swiching off the Amiga 2000, is it bad ?).
While I was testing fine the fith keyboard, suddenly the green lights (CAPS LOCK, NUM LOCK, ...) switched off and the keyboard was no longer responding ! I then tried to connect one by one the previous 4 keyboards but none of them worked !!
I plugged the keyboard from my friend which already worked fine but each time I tried to connect one of the Dell keyboards, it fails.
I keep trying mixing connections of "my friend's keyboard" and "Dell keyboards". From time to time, randomly, Dell keyboards seem to working fine again as if connecting "my friend's keyboard" resync something.
With one of them especially when I connect it no CAPS LOCK/NUM LOCK lights up ... until I hit one key ! No to mention, this keyboard has a little different form factor compared with the others (but is also a DELL Keyboard).
Thanks for the link to Thomas page, I'll have a look to it shortly.