Yamaha CS80

Jonathan,

Duplicating the logic is easy.  The big pain is the voltage.  The Yamaha uses 4000-series CMOS and runs all the digital logic at +8.5 / -6.5 -> 15 volt supply.  It’s offset above/below zero to interface with the analog circuits that run off +/- 15 volt.  No modern chips run at this high voltage.  Even 5-volt is history and 3.3-volt is only kept around for interfacing with older parts.  All the chip guts these days are running around 1-volt.   So, you end up needing tons of level-shifting chips to connect the Ardiuno (or FPGA) to the rest of the logic.  Most circuits I’ve seen use chips that were intended for converting RS-232 (also fairly extinct) like the MAX232.  The chips that were most commonly used won’t work anymore since they convert to +5v TTL.

 David


> On Jan 16, 2018, at 9:39 AM, jonathan4051@... [yamahacs80] <yamahacs80@yahoogroups.com> wrote:
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> 
> 
> Has anyone ever looked into modern alternatives for these fragile and rare 40-year old chips? I am wondering if it'd be possible to program an Arduino to handle key coding/assigning and D/A conversion on the KAS and KBC boards.
> Cheers,
> 
> Jonathan
>