Godwin Digital Synthesizer

[bunker]

Hi there, I'm new to the forum and I hope this post is in the correct place!

I have a Godwin Digital Synthesizer built into my Godwin SC600 organ. The day after I took delivery the synth died or more precisely the oscillator died. At first I was expecting the synth to be built around the m110 chip that was used in other Italian synths of the time such as the Jen SX1000 and Siel Mono/Cruise. However on closer inspection the synth is made up of 9 seperate PC boards that slot into a motherboard. The basic features are Square/Sawtooth waveforms, LFO controlling vibrato, tremolo and filter, A Low Pass VCF, a High Pass filter (not VC), ADSR's for both VCA and VCF, repeat function, manual control of PWM, spring reverb and a crude form of aftertouch called sensitivity control which affects pitch and VCF. The only digital part seems to be the 8035 microprocessor which controls keyboard scanning, preset control and gate and trigger signals.

Ive poked around and when the board with the 8035 on is removed I get the frequencies that the schematic tells me I should be getting from the oscillator output on the Master Generator board. The oscillator looks to be built around 74132 logic chip and 4558 op amp which, I guess makes it a digital oscillator? With no 8035 however I have no gate or trigger hence no sound. When I replace the board the osc. freq. drops from the 200 odd kHz in the schematic down to About 1kHz. there is a wave form generator that is fed from the osc and this must divide the freq down to normal audio. The gate seems to be "stuck" but with no sound. The filter will self oscillate and the mod controls affect it as does the repeat function so im guessing its the 8035. There is A UV EPROM on the same board but my guess is that this is for storage of the preset patch controls and as all these seem to be okay, albeit with no sound, I dont think this is the problem.

I am still learning my was around repairing and building synths so please be gentle! I want to rehouse the synth in a custom case and modify it with maybe a VCO or two along side the 8035 osc. there are SSM 2020 and 2040 chips on the VCA/VCF/HPF board and there looks to be some scope to really mod this synth or maybe turn it into a fully analog instrument.

If anyone has any ideas or has even seen/played one of these before please let me know. I can see this baby in a cherry or oak case sat on stage being played!

Thanks,

Mark