Casio SA-21 some pictures and problems (edited)

[Signal:Noise]

Seeing as various people have helped by posting details of their projects I thought I'd share some pictures and problems I've had.

First up, there doesn't appear to be a voltage crash bend, I followed the power input on the circuit but there doesn't seem to be a point where you can solder a pot across. If anyone can prove me wrong that'd be great. The tomne switch, high cut swith and the deep crash button mods are the same, but the deep crash button seems to be very hit and miss.



This picture shows the circuit board with teh smaller of the two chips, the wires from the two resistors are both connected to the 4th pin in from teh bottom right on teh chip, they go to a pair of 4k7 pots (lower value'd be better, but that's all i had) and create a high cut with ring mod/distortion and a distortion. the wire going to teh tone swithch can just be seen bottom left.



This picture shows the body contact points controlling pitch and the unconnected pots and bolts. Using these four controls makes the thing scream.



Detail of the deep crash and tone switch, like I said earlier, teh deep crash is a bit hit and miss, going to fish around a bit more tonight to see if i can find an alterantive.

[Circuitbenders]

Have you tried just soldering a 1K pot in line with the positive power input wire for the voltage drop crash?

More importantly, is there something wrong with teh H and E keys on your keyboard?

[Signal:Noise]

I realised after posting this that I could solder a pot from the positive power of the battery box, which I'll probably do today at some point.

Teh is a result of typing too quick and being too lazy to proof read. I do try and correct it most times but sometimes I forget.

[Orangery]

Hey... do you think this modification would work with a Casio SA-20 as the inside of this machine looks very similar to the one I just bought at a car boot for 50 pence.  It has some nice tones on it.

[Signal:Noise]

Yeah, i would of thought so, all teh sa series keyboards are fairly similar.

[Orangery]

OK, thanks... so did you get the voltage drop crash working on your machine?  Does it produce just a mish-mash of random sounds?

[Signal:Noise]

I was only able to get the voltage drop working with batteries, couldn't find a point that worked with both batteries and the power adapter.

[voodoolikeudoo]

In the 2nd pic theres a circuit trace leading from the red battery connection on the board to the corner pin of the chip at the bottom. Wouldn't cutting that trace and wiring in a pot produce a voltage drop crash that works from batteries or PSU?

or maybe not, its a bit difficult to see.