This is a glitch/random bend by Finlay Shakespeare  http://www.futuresoundsystems.co.nr .
The mod was originally done on the casio sa1 but it should work with all the sa-serie.

Here is another random/glitch mod I found in a couple of forums:

The Yamaha PSS 390 is the “toy keyboard” claimed to have the better and best sounding FM synth engine in the toy range.
It has 100 tones that can be widely modified with the tone controls, instead of button +/- it features sliders to edit the synth parameters.
The only lack is the midi control that however  can be added by retrofit.
It can be seen in action in the videos of the band “the Apparat Organ Quartet”.

Doing some circuit bending on my casio keyboards  I collected some useful schematics to “safe-bend” the casio sa serie (sa 1 2 5 8 10 20 etc).
The main mod is the one from Casperelectronics that adds interesting bends as the “glitch/randomizer” , “feedback” , “5th add”, “pitch shift” and the classic “power crash”.

In the forum www.circuitbenders.co.uk I found another scheme based on the casper mod but with some adds.

A song made with Ableton Live and the Casiotone MT45 with realtime recording and looping.
Really fun!