Well,
I finally plucked up the courage to replace the remaining ICs in the sequencer section, this time soldering sockets first (which I wish I had done in the first place..)
And then, after replacing JP4 (turning the board over and over had led to a couple of the wires breaking, I ended up replacing the ribbon with a 5 pairs of wires), I switched it on and was delighted to see that I had what seemed to be a working sequencer!
Everything seems to be working correctly - init EEPROM, edit pattern, play track etc, apart from step 1 button either does not work or toggles on and off if I hold it down, hopefully this should be easy to fix.
Sooo... Although the sequencer section is working, it seems I'm going to have a lot of troubleshooting to do within the actual instruments - right now, instruments only sound if there is an accent on that step, and apart from the cowbell, cymbal, and open and closed hats, I get no noise at all out of any of the others.
The handclap makes a constant quiet noise if I have its volume up, and weirdy I get a constant quiet tone if I switch one of the tom switches to conga, and touch the metal of the switch.. Weird...
But at least I'm not at the dead end I was before though - I managed to have a quick little hi-hat jam to celebrate!
