Siel DK70 / EX80/SX-500 -1985    Weight= 10 Lbs. Number Manufactured = ? MRP = $795

User Manual: Sander's Site
Reset Proceedures: N/A
Operating System code: dk70a.bin and dk70b.bin
MIDI or other control protocol: See Manual?
Software related Links: N/A
Patches or knob settings:
Circuit Overview: below
Scematics/Service Manual:
Common Service Issues/Tips: below
Parts Sources: Keys knobs semiconductors misc
Uncommon chips/modules used:M112B1 sound chip pdf available, SSM2045 VCF/combo, SSM2031 HFO, TDA1022 bbd
Modifications:Moogslayer (or not :-) )
General Info Links: Sander's Site

Circuit Overview:
     Very similar to Korg Poly800 in it's capabilities. To my amazement EX80 is module version as opposed to module of DK80 I'm told and SX-500 is Suzuki's rebadge. We have an SSM2031 HFO that supplies signal to M112B1 sound chips which creates all waveforms to be modified through SSM2045 combo VCF/VCA chip controlled by the digital interface. A neck bender/controller is available for this unit! Here is the pinout of DB9 connector for stage set according to my research:

1- Ground
2- 'wiper' for bender (not connected til pressed!) 1K to pin 11 IC19 4016 chip in DK70
3- Bottom of 10K bend potentiometer. 1K to ground in DK70
4- Vibrato switch. 10K pull up and 10K to Pin 1 IC10, 74HC32 in DK70
5- +5V
6- Shorts to pin 5 in bender neck. (Tells DK70 that bender is plugged in. Pin 12 IC19 via 1K resistor)
7- Top of 10K bend potentiometer. 1K to +5V in DK70
8- Damper switch. To ring of pedal in DK70
9- Multi-purpose switch. To tip of pedal in DK70

Note: there is a chorus using TDA1022 and when on the 'detune' is defeated. I'm not exactly sure why. Also I'm finally near working on the bender neck for these things. Mail me if you want to get on the list to know when they are available. It will feature a tilter instead of slide which allows fingers to stay on other functions. But also a flexible function generator lfo that will be controlled by the thumb but both pushing in and swaying! Allowing simultaneous control of two parameters like depth and speed! As well as a range switch for speed and one for waveshape.

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 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!

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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