Hello everyone,
I've been poking around my SA-2 with the help of the knowledge found in this forum and a little of my own reasoning to discover a couple of bend points that will give you every feature of the Casio SA-1 using only one DPST switch (or two ordinary switches). The way it works is by mapping the hidden functions to the keyboard keys. I discovered this when I noticed that the hidden sound select switch mod also controls other things, and in fact the first eight keys all did something different, e.g. pressing Bb increases the tempo. There was a matrix of what happens if you connect one pin to another somewhere on this forum, and I discovered that it was redirecting all the signals from one pin to another. So, I altered the position of one wire to get to push buttons 6, 7, 8, 9 and 10. With it, I also got loads more features, which led me to think - if I connect both pins to different groups of notes on the keyboard, I'll get both sets of features. It worked! Yay! So, I believed that the community should hear of this discovery. So here it is:
Step 1: Solder a wire to pin 30 (all these pins are on the OKI chip). Solder another wire to pin 26.
Step 2: Solder these wires to the first set of pins on the DPST switch (or one switch).
Step 3: Solder a third wire to pin 29. Solder a fourth wire to pin 25.
Step 4: Solder these wires to the second set of pins on the DPST switch (or another switch).
Step 5: Turn on the switch (or both switches) and press the buttons according to the diagram below:
F: Button 1 (0 on SA-1)
F#: Button 2
G: Button 3
G#: Button 4
A: Button 5
A#: Tempo Up
B: Volume Up
C: Select Rhythm (a bit useless since it will automatically select Disco 1)
C#: Button 6
D: Button 7
D#: Button 8
E: Button 9
F: Button 10
F#: Stop Rhythm (good for dramatic contrast as it will play a note)
G: Tempo Down
G#: Volume Down
So, using the chart above, you can write them on the keyboard keys and have every function available to you, without loads of complex wiring and buttons clogging up case real estate best used for the wacky effects you can make with it.
Hope I was of use!