RSD-80 aka Yamaha D-85

another ebay finding

raw pcb

An old pcb with coils … this must be interesting. I could not find out much about this pcb, most probably it’s from a Yamaha D-85 organ. Labels like SDN, CY2, HB should make clear what it is – the sound generator for a drumcomputer. The plan: make the drumsounds accessible with a midi trigger interface and building a neat housing around it.

Additional electronics

Similar to many devices from Dr. Böhm this thing also entirely wanted a negative supply voltage (-12 V). My midi interface and the trigger converters needed -+12 V, i used a LS1054 for inverting.


Old case

By chance i had a fitting old case from another (failed) project. The connections to the outer world are minimalistic: 12V power supply, mono audio output with full level, Midi In – fixed notenumbers on channel 8.



The condition of the power supply voltages are lead to the frontpanel – at least something glowing to indicate the POWER ON state. Inside there are some fancy LEDs (orange, pink…) flashing on incoming triggers. After i while i finally realized i printed ‘RDS-80’ on the frontpanel while the PCB itself is labeled ‘RSD-80’, well.