It's a Yamaha CX5M with the built-in SFG-01 FM-synthesizer-unit.
I also got the YRM-103 DX7-Voicing Program. With this I can plug in my DX7 and edit the FM-sounds ;-)
Because the power supply was missing I took an external HD-supply with +12V / +5V and soldered it to the very special 13-pin-DIN-plug! With a Murata DC/DC converter I generate the -12V in the CX5M (on the board it generates -5V for the 3-voltage-DRAM's).
I built an audio-cable for the mini cassette recorder and now I'm able to load and save.
The SFG-01 sound-unit was easy to update to the SFG-05. I only needed to change the 16k ROM to the new 32k EPROM and add an extra wire for A14.
The CX5M uses the old TMS 9929 with 8 1-bit-DRAMs: