Circuitbenders Forum > Synths & Samplers

Casio SA-1 & PT20

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Circuitbenders:
As far as i know you'll only see that jumper on an SA1 although i could be wrong and you might see it on other. If you're putting in a voltage drop crash pot i'd always wire it on the positive side of the supply. It doesn't matter which way round you wire a pot if its wired in line with the positive supply. The only difference it'd make is which way you have to turn the pot.

It shouldb't be that hard to trace the power rails on any cheap keyboard, just follow the circuit board traces from the power jack and/or the battery compartment until it gets to a component. Wiring in a pot before that point should probably give you a variable voltage input.

Getting hold of a multimeter might be helpful for tracking down the positive and negative rails if you have any difficulty.

computer at sea:

--- Quote ---i saw a photo of a 500k pot for POWERCRASH wired in a different place: the contact for the power supply jack.

--- End quote ---

A 500K pot will be about a zillion times too big.  Try a 500 ohm pot.

badbarcode:
hi guys

I found an interesting "decay" control for my SA-1

it's possible create very cool sounds using this  in combination with a distortion pot

Obi:
Hi guys

I am new to bending and the whole world of electronics in general and trying out a few SA-1s, following some of the great diagrams and tips here. Haven't had much luck yet, and just wanted to see if there were any general tips on how to diagnose problems. I appear to have killed one and the other two were bought 'untested and as seen'. I can get a few notes out of one before it, almost literally, coughs, chokes and dies. I can keep doing this by turning it off and on again, though it won't do it every time, but I can't get it to play more than a few notes. I haven't added any mods except add a line-out jack and battery pack. It doesn't look that great inside, and the battery coil is rusty.

Also, after the keys stop working, I can get various low hums and crackles by touching screwdrivers on the chip pins corresponding to glitch and other bends seen in the diagrams, so it's clearly still live and responsive in some way, but not providing any of the wonderful madness I got from the same glitch connections on the other one before it stopped working, so I don't know what the problem is with this one.

As I said, I'm trying to learn how everything works from scratch, so any suggestions for trouble shooting, much appreciated.

Cheers

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