Timing is everything, amazing that this thread has appeared at the top of the hardware section the day after I finally got round to digging out my Amiga2000! Happily it's very much alive, and the battery - while starting to leak, hasn't done any damage (and is now in the bin).
I too have the A2090A card inside my A2K, hooked up to a Miniscribe 8425 disk which is making the most horrendous noises and giving me read/write errors ( I must confess, I had never heard of the ST-506 standard till I looked it up last night
)
So, thanks for the useful information! Looks like I'm on a mission to find either a SCSI HDD or a SCSI2SD myself.
@TommyE - if you are able to burn the relevant EPROMs, would you be willing to burn a second set I could purchase from you? No worries if not, just thinking my chances of finding a suitable drive under 256MB are rather slim