Korg 900PS Preset synth

[LektroiD]

Hi, I recently managed to get my old Korg 900PS back from a friend, as it is, it's pretty useless, the sounds are weak, so I decided to open it up.

Inside there are 17 variable resistors, and a row of smaller preset resistors. They are all labelled up, most of the labelling is pretty obvious, such as cutoff freq, Q, a few less obvious, such as Balance, fC, etc, but there are more obscure labels on the smaller preset resistors, such as TP1.2, TP3, TP4, etc (Test Points?) these have been position fixed with paint, I'll get some pics up.

I was also thinking of making it semi modular, - similar to the MS range, as all the wiring is clearly listed on the board. As it is, the LFO (vibrato) & envelope seem to only control the VCO, it would be nice to have the option of routing the filter through them. I wouldn't mind putting CV/Gate sockets on too, but not sure where I would need to tap into the circuit.

I do have a bit of experience with electronics, but might possibly need a bit of guidance in some areas, and maybe a schematic if anyone knows where I can get one (preferably free). Basically any help will be appreciated.

Pics to follow...

[LektroiD]

There are a few more variable resistors under the control panel to the lower left of the machine, including a white noise level controller

[LektroiD]

Hmm, I had a feeling this forum would have been busier than this.

I take it there's somewhere else everyone goes for synth mods and circuit bends?

[elektro80]

You might try posting in the DIY subforum? What you are proposing here is not quite circuit bending by rather a breakout mod. Do you want me to move the post there?

[LektroiD]

[elektro80]

Actually, the Circuit Bending forum is inside the DIY structure and it seems we don´t have a subforum for the fuzzy stuff... hmm.. be patient and hopefully you will get some answers.

[LektroiD]

Hi, I think I found the forum, it's situated below all the sub forums. I've reposted this in there. You may want to remove this one, in the hope the new thread gets some more attention.

http://electro-music.com/forum/topic-28497.html

[nonymous]

I am not familiar with this korg, but this is definitely NOT circuit bending.

here is a definition from the man who coined the term:

"The creative short circuit, or the technique that I call circuit bending, is a form of hardware hacking or modding, but with two important differences. First, whereas hackers usually know something about electronics, you don't need any real knowledge of electronics to circuit-bend. Second, while most people hack an instrument with a particular goal in mind — such as increased frequency range or cleaner outputs — the circuit bender works improvisationally and has no idea where the trail will lead.

In circuit bending, the instrument shapes itself by telling the bender what it can do. In this way, circuit bending has turned the electronic circuit into an immediate “canvas”; a circuit is accessible at that moment to everyone for the creative act. No theoretical knowledge is required, and on the first occurrence of experimentation a one-of-a-kind instrument is created."

so all you have to do is start shorting things out, and not have any goal in mind - let the results of your experiments be your guide. if you want to circuit bend this korg, do so. circuit bending requires absolutely no help from others, although you should avoid anything that doesn't run on batteries. if you interested in a specific outcome, or if you are adding circuitry instead of shorting out what is there, you are not circuit bending. I think a lot of folks are finding that since circuit bending is becoming a trendy term, people are misunderstanding it more and more.

[LektroiD]

which is why this thread now needs to be deleted. With the kind suggestions from elektro80, there is now a duplicate thread in the correct area.

[nonymous]

P.S.
I was hoping this would allow more sharing of knowledge and understanding. just looking over the last few posts in this forum, it seems that lots of people are confused as to what circuit bending is.

it is not:

-adding cv to a toy
-fixing up the original wiring of a toy
-aided by schematics or diagrams
-adding trigger and gate outputs
-a clone of guitar pedal
-boost of the output volume

i think a lot of new people are getting the wrong idea about what circuit bending is, and it would be a great learning experience for them to have this forum be a more accurate resource.

[LektroiD]

Although I am aware of the principal of circuit bending, this was the closest forum I could see at the time. I couldn't find a better forum for my mod until elektro80 pointed out there is another forum hidden under the sub forum links.

Again, I'm new here, so I'm still getting used to the structure. Maybe there's an introduction forum I missed on my way in too

**Edit: Found the introduction forum: http://electro-music.com/forum/post-202513.html