Casio SA-21 some pictures and problems (edited)

Signal:Noise · June 06, 2006, 12:29:00 PM

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 · June 10, 2006, 03:32:00 AM

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 · June 10, 2006, 09:39:48 AM

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 · July 24, 2006, 09:37:42 PM

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 · July 26, 2006, 06:46:26 PM

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

Orangery · July 26, 2006, 10:59:01 PM

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 · July 26, 2006, 11:19:47 PM

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 · July 26, 2006, 11:36:42 PM

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.

goldenbaby · December 27, 2008, 06:46:29 AM

I alligatored up a 1k pot between the + of the battery box and the circuit. I'm not getting any crashes. I'll poke around for some other bends, but considering this the voltage crash is supposed to be the mother on this guy, I'd start there.

Could you repost your photos please?

goldenbaby · May 20, 2009, 06:37:03 AM

Bump ^^^

Dylan · May 20, 2009, 04:22:12 PM

Quote from: goldenbaby on December 27, 2008, 06:46:29 AM
I alligatored up a 1k pot between the + of the battery box and the circuit. I'm not getting any crashes. I'll poke around for some other bends, but considering this the voltage crash is supposed to be the mother on this guy, I'd start there.

Could you repost your photos please?

You're using a 1k? Try a 500ohm pot.

ne7 · May 21, 2009, 01:55:04 AM

i've got a sa-20 here which i'm fiddling with - try the volt drop with headphones plugged in - these things draw a lot more power to speakers (the sa20 has 2 so i'm assuming yours does too

than the other SA keyboards... taking the speakers offline (with a switch or by popping headphones in) seems to make the volt drop work a lot more reasonably like the other sa casio's

did a sa-35 recently this exact way...

oh yea and volt crash works way better on the sa1 etc without its speaker on...
hope that helps, worth a go eh? hehe

goldenbaby · May 25, 2009, 07:02:19 AM

Quote from: ne7 on May 21, 2009, 01:55:04 AM
i've got a sa-20 here which i'm fiddling with - try the volt drop with headphones plugged in - these things draw a lot more power to speakers (the sa20 has 2 so i'm assuming yours does too than the other SA keyboards... taking the speakers offline (with a switch or by popping headphones in) seems to make the volt drop work a lot more reasonably like the other sa casio's

did a sa-35 recently this exact way...

oh yea and volt crash works way better on the sa1 etc without its speaker on...
hope that helps, worth a go eh? hehe

And What Ohm of pot did you use? Pots under 1k here tend to cost over $10. Not sure I want to make that order online either, because there's nothing else I need with which I could combine the shipping.

ne7 · May 26, 2009, 04:29:01 AM

i always just use a 1k pot for those sorts of things (volt drain)
hope that helps!

i think someone elsewhere said that its pretty easy to wire up a pot and resistor in parallel to bring the value down tho...

Signal:Noise · June 13, 2009, 04:12:36 PM

Damn, I think I must have deleted the pictures from my web hosting...I can stick them back up if people are interested.