Circuit Overview:
SSM2031 HFO supplies signal to M112B1 sound chips which creates all waveforms to be modified through SSM2045 combo chip controlled by the digital interface. A neck bender/controller is available for this unit!
Service Tips:
I have finally repaired one of my DK-70 units. Since I can't find schematics here are a few tips. IC13 was the fault in mine. Pin8 should have the DAC output on it. pin 12 is the DAC inverting input of course and 11 is ground reference there. The offset output results in noise all the time as it drives the noise level open all the time.
I've also seen a dead M112B1 chip and it's summed signal output appears on the op amp nearby. Note the resistor packs..one is the pull up pack for the M112B1 outputs (7 of them) and then there are various sized capacitors to create different filters to be summed through the next resistor pack there to the op amp right by them on pin1. (A TL082). Enjoy!
Parts:
I've finally found a good source for the M112B1 chip! Ask if in need and I think I can get you around the 100 dollar minimum scenario. A guy is making cards for them now and see Sander's site for that info.
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