[sdiy] JRC 2090D anyone have specs? casio used these..

[Samppa Tolvanen]

Hi.

JRC 2090D is more likely a custom filter chip design for Casio.

I was involved in a modification, where cutoff and resonance of the
chip were brought under external CV control.

It turned HT-3000 into a different kind of animal with very brutal
filter sweeps and resonant zaps - highly recommended.

I can ask, if my friend still has the service manual pdf.

Samppa

p.s. I think one of the earlier Casiotones was even more of "a proper
analog" synth.. with that Knobby feelin'