Hello,
I am Thierry EPPHERRE from FRANCE and I have redrawn the complete SDS9 schematic from my own
second hand SDS9 some years ago.A very very big work......I also had the faulty ZN427 ADC !
If you need my schematic I can send it to you (perhaps you already have it!),I can also send binaries of sounds and software Eprom.
I will be really interested by your SDS9 test Eprom binarie....I would like to work again on my SDS9 that is not working as well as I think it should (my snare channel is not triggering very well and I had the same issue on another SDS9 I repaired for someone else sme years ago.)
See you soon
Thierry EPPHERRE