bontempi system 5 plus GT509 In which i try to circuit bend the toy keys!

I got this keyboard with the intent to circuit bend after i one hit KO'd a sucky biltema-brand one. But then i liked the sound so much that i didn't wanna touch it for a few months! But now the time has come. xoxo, ~sixeye



OBJECT INFO "Tiny" battery powered keyboard thing, cyberyogi has written nicely about it here (archive link). But basically: 32 keys

8 bit

buncha fairly rich waves, fun envelopes

"chorus" which is layering of (often not the same) voices, reducing polyphony

"reverb" which i think is just envelope modification? maybe?

speaker, NO headphone/line jack

Main chip

A45025PH

WX 72AD9RW

COMUS2743381

Can't manage to find any info on it. Here's my attempt to find out what the pins do:

1: - 2: ? 3: ? 4: ? 5: ? 6: keys 7: keys 8: keys 9: keys 10: keys 11: keys 12: GROUND 13: ? 14: keys 15: keys 16: keys 17: keys 18: keys 19: keys 20: keys 21: keys 22: keys 23: keys 24: audio out 25: audio out 26: audio out 27: audio out 28: audio out 29: audio out 30: audio out 31: audio out 32: - 33: keys (numbers) 34: keys (numbers) 35: keys (numbers) 36: keys (numbers) 37: keys (numbers) 38: keys (numbers) 39: keys (numbers) 40: keys (numbers) 41: - 42: - 43: - 44: - 45: - 46: - 47: - 48: - 49: - 50: - 51: - 52: ? 53: GROUND 54: - 55: ? 56: - 57: ? 58: keys 59: keys 60: keys 61: keys 62: keys 63: keys 64: keys 65: keys 66: - (maybe, leads to unused pad i think) 67: - 68: - 69: ? 70: ? 71: ? 72: GROUND 73: keys 74: keys 75: keys 76: keys 77: keys 78: keys 79: keys 80: keys

First attempt: audio out

The thing lacks any output except a speaker, so i'd like to begin with adding one of those. Should be simple enough IMHO: add a jack parallel to the speaker, right?

Fucked that up somewhat by wiring it completely different:

What would happen is the speaker would be completely silent UNTIL i put in a cable and bridged the tip and sleeve.

In my defense, i was busy taking care of these noobs

Second attempt: audio out II

So as i had earlier somehow put the speaker between the jack and ground, i had to open up and remodel a bit, a few new wires and so on... but the problem stayed! What now? I though maybe i messed up which of the two original speaker connections was ground, but no, that was correct... then it dawned on me. I had just assumed which of the pins on the jack was the normal connection and which was the wire. Eh. I'm currently waiting for the iron to get hot so i can fix that. Yeaa boi. Figured it out. Also, the way i put this together meant i could try different resistors by the line out and find which one gave a nice volume. Turns out, 4.7K ohms did the trick! Incidentally, that might be the lowest value i've got, so 🤷‍♀️



You see! Clear as day!

The biggest problem i've had is that the thing relies on pressure to keep the keys spongy, and while at first glance it looks like there's a lot of room in the case, just a few wires can upset that pressure, making the keys stale and unplayable. So some effort has to be put toward making sure the cables are at reasonable places. Piece of shit, super boring and annoying, i hate it.

But yea! At this time, the thing works! 😎🐱😎🐱😎🐱😎

Audio example

Breaking out the bits

Because of the previously described thinness of these wires i need no new holes or anything, i'll just pull everything through the old ones.





So what happens is that i can reorder the bits in the output, and what that means in real life is i can make the sound be distorted, it's a kind of waveshaper (might have said that before but it's true), and that also fucks up the envelope and if i do it right it's just full volume for the entire duration of the sound.

It sounds better some times than others. Well well.

Pros

Bend electricity to your will like a puppet master

Hear unintended secret sounds

Cons

The creature is weakened

Breathe lead fumes into your body

Somehow the line out is broken again

Audio example

Bye