Analogue-sequencer

> When sending the sysex file  I get a "Bad block!X" message on 
> my display...

Any chance you have a midi loop ?
P3 sends a sysex 'acknowledge' for each code block it receives - if this
loops back through and P3 sees it, it will display bad block.

If that isn't the problem, it could be the opto-isolator. Some 6N139s work
OK for short midi messages (notes etc.) but during a longer sysex block,
their output seems to latch up somehow. I'm going to switch to 6N137s for
the next run.
You can usually get a dodgy 6N139 working by removing R3.

Cheers,
Colin f