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Hello, Here, it's all about the NJM2069 and its MIDIbox Module. Here an old topic which is talking about too, I mention it too in the TIA Cartridge topic as a possible option for. First some words about the chip. Some of you already know it. It's present in some KORG products from the 80s, In Analog Hybrid Synths like the DW and EX series, DW-6000, DW-8000, and the Poly800... I've got the smallest one, the EX-800. You can find it too in Some samplers of the same brand, in the DSS-1 for example. The NJM2069 is Music Voicing System, like SSM brand used to say. Very close to the SSM2045, same functions but not the same tech. It's an OTA based LPF but it's not just a filter. It is composed of 4 VCA and 1 VCF Low Pass 4 Poles. 2 VCA are fixed on the VCF inputs named SIG1 and SIG2. 1 is used for the Resonance. The last VCA if fully independent. The VCF part has 3 Inputs: - SIG1 Signal 1 with VCA - SIG2 Signal 2 with VCA - VCF IN is a direct input to the VCF. 2 Outputs: - 2P, 2 poles Output - 4P, 4 poles Output and 5 CV Inputs - SIG1 Level - SIG2 Level - Freq Log - Freq Lin - Resonance The Independent VCA Has is own input and Output and 2 CV inputs, first is linear CV the other is labelled Log in some version and seems to be a bias on another and is finally not usable, i think. Here the function diagram and pinout. I didn't find too much documentation, no datasheet. And some written information on the internet are wrong. For example i read somewhere that the chip is not able to self oscillate! It's wrong! Mine on a bread board do it very well ;) Not too much data then i used the service manual of the Poly-800, DW-8000 and DSS-1 to prototype my board. And after some testing, analyze... Finally design a first PCB version. DDS-1 Service Manual DW-8000 Service Manual Poly-800 Service Manual ... Enough for today, i will continue later ;) ...