SR-16 as an output trigger - Stumped...

[ionia23]

Hello,  after much searching and experimenting I'm at a brick wall and asking for your advice/suggestions.

Pre-qualifier - If what I'm attempting to do has been a fool's crusade, I can accept that.

This isn't so much a bend for the purpose of altering sounds.  I'm attempting to modify an old SR-16 I had laying around to use as part of an analog trigger system.

I've been able to do a very basic 4-channel version of this.  Example:  A midi note-on is sent to the drum machine triggering whatever-drum-sound to happen.  The SR-16 allows you to map any of the drum pads to any of four audio outputs (Main L-R/Aux-LR).  use that signal to illumiate an LED.  From there it's an easy jump to use that to trigger, well, anything.   However, I got to thinking that it's possible that when a note-on is received it will cause specific pin(s) on the board to change state.  Theoretically, if I could find the right pins on any of the main chips, I could tap into those to have even more channels to use as triggers.

I could probably build a huge LED array and connect each one, pin for pin, to the various IC"s and watch the dataflow, but that's a very daunting project (which might not even work).

Since I've had a bear of a time finding datasheets for some of the IC's I"m at a loss.

I'm totally open to suggestions, and thank you all for your assistance in advance.

[Gordonjcp]

However, I got to thinking that it's possible that when a note-on is received it will cause specific pin(s) on the board to change state

No, it doesn't work that way.  When a note on message is received, the CPU tells the ASIC to start playing back a sample from a point in memory.  This is sent over the data bus, shared with the memory and IO.  There's no point where there's just a single pin that goes high for a particular drum trigger.

What you could do is get some sort of microcontroller like an AVR (step forward, the Arduino) and write a program to receive incoming MIDI and fire output pins based on the message, and drive that from the drum machine.