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On eBay I had bought parts of a Casio Symphonytron. I don't own the entire stage organ system but only one CT-8000, the RC-1 accompaniment/drum machine and a defective MB-1 sequencer in very beaten up condition (full of scratches, dirt and glue residues), but no pedal board. It came without the CIDI (Casio's Infernal/Inferior/Internal/Instrument Digital Interface) cables, so I ordered 3 DIN14 cables for Atari ST floppy, those work perfectly with the RC-1 (with one keyboard it does key split accompaniment with arpeggio, and also the trio mode works). Like with Kawai MS20, when you set a preset sound on the keyboard it plays a short fanfare with it (always the same notes). How ever my MB-1 doesn't work at all (buttons don't respond and it makes sometimes a louder growing digital buzz); possibly the eprom is dead. Also CT-8000 and RC-1 contain (as the only Casio instruments I know) each a soldered eprom; I backed up all 3 to avoid data loss. Unfortunately my Symphonytron sequencer unit MB-1 is dead (does nothing, but plays note mess when touching the crystal etc.), so I am not sure if its eprom may have failed (dump does not change by reducing Vcc) or it might be still a bug by the lack of original CIDI port cables. - hardware details I have photographed all my Symphonytron PCBs from both sides. The multi-chip hardware is quite complex and particularly the RC-1 and MB-1 have several stacked PCBs in their crowded case. Fortunately there are are some pinout marks on them, those may help to decipher them. The MB-1 and CT-8000 both have the same CPU "NEC D8049C 364" (Intel MCS-48, I dumped its firmware) with sound IC "D931C 011". The RC-1 CPU is a "NEC D930G 011". So they are far relatives of the Casio CT-410V (MT-65) hardware class (minus the VCA, but with external ROM) which may help to research hidden functions of its chip set. I don't own the FK-1 pedal board, so I have no clue what is inside. Did you know that early Casio keyboards had a CPU compatible with Intel 8049? Unfortunately the "Willem Pro4 isp" eprommer had a way too weak power supply with tiny SMD transistors switching the voltages. One was burnt anyway, so I had to install bigger non-SMD ones to get the MCS-48 adapter to work. Casio "D8049C xxx" ICs need Vcc of at least 4.5V to read properly, which was impossible with the original transistors ans PSU (it gave only 4V even in 5.6V mode). I installed a 10kOhm resistor into the EA line to avoid damage by the +12V if the IC would not have supported it properly, and connected it to a 5kOhm potentiometer to vary the voltage, which I didn't need. (Too high EA voltage (15V) outputs only "00" while too low voltage (9V?) makes the CPU run its program and output garbage. At too low Vcc it repeats the first part of the rom again and again.) So I e.g. could read the firmware of the Symphonytron Casio CT-8000 cpu and Casio HT-6000 synth (its D80C48 seems to be a real CMOS IC that draws less current). Also MT-36,MT-40,MT-90/MT-200 and Casiotone 401 have such a CPU. - need service manual Eons ago I downloaded the complete Symphonytron user manual from an eBay link, but I have no schematics. Has anybody a service manual? Particularly I am interested in the MB-1 hardware, the official CIDI cable wiring (may the MB-1 only need a crossed wire somewhere?) and the pedal board (has anybody dumped the eprom?).