There are a lot of sites/posts online with either audio or video of bent Casio SA2s. One site in specific has a lot of great, detailed information on the Casio series, and that is CasperElectronics‘s site. In fact, his site should be required reading by anyone looking to learn anything about hardware hacking.
That said, it is way more fun to explore an instrument than it is to read about it! Just doing what’s been done, or just following directions kills what makes HH such a joy — the thrill of the chase! The key to exploration is knowing how to sail (ahoy, amass those Sprogs n make fer thar swaggy!) and where to sail (say, is that the edge of the world? forward, ho!!!)
El MuCo prefers to lick-n-stick first, and read second (if at all…)
Here is the SA-2 with the top case off showing how it looks prior to having the case sealed up again. You will notice that work not described here as already been done. This is the problem with non-linear pictorial placement.
Here is a close up picture of the part of the circuit where bridging some of the resistors results in pleasing sonic/musical results. In the recording below, I was simply using a 4k resistor on 1 with a quick, light touch.
Click on it to see the 1024×728 version.
Here is a recording made tripping the resistors marked 1 & 2 above.
Here one can see the connections we’ve added in the form of wires soldered onto specific legs of the two integrated circuits. The white box at the left is the timing crystal. Note the black wires next to the timing circuit. These were soldered in place of a resistor which we removed because the wires were easier to “play” as indicated in the “tripping the resistors” comment above. Unfortunately, it turns out, pulling resistors from circuits and maintaining the overall resistance is not as easy as measuring the resistor and putting in a substitute elsewhere. As any electrical engineer (and now El MuCo) can tell you, length and thickness of the conductive materials will affect resistance.
Because we couldn’t fit the pots in the case, and there was already a dearth of space from all the wires, we decided to annex the control interface to another enclosure. In the below picture you can see the wires from the board running out through holes drilled in the case.
Here is the control module. The box is a standard Radio Shack project box with three bends, each with its own on/off switch.
We never put the keys (musical keyboard) back in the Casio case as it was deemed superfluous. One can find images of hacked SA-2s all over the web, many showing bends built-in to the original case. Our decisions were not purely aesthetic; we had a show in a week, and needed to get this thing wrapped up. Having said that, the modular approach is appealing for a number of reasons. We plan on cutting the wires to the module and building in an RCA patch bay. This way, the two units can be taken apart for transport.