Superb Sound EK-922

Superb Sound EK-922

This ultra-rare instrument from 1993 (PCB date) appears to be a direct predecessor of MC-2 hardware, because although it has a very similar control panel, it contains a Zilog brand CPU with fewer pins (much like the rare HBATEC, which was a MC-3 predecessor).

Unfortunately my EK-922 specimen (from fleamarket) is completely brain dead; it makes no sound anymore and only the CPU runs very hot (like my initially as dead and quite similar Fujiyama KS-37 - likely the previous owner confused power supply polarity), thus I don't know how it had sounded.

main features:

37 midsize keys
2 built-in speakers
main & rhythm volume slider
8 OBS preset sounds {piano, e-guitar, harpsichord, musicbox, clarinet, violin, banjo, oboe}
8 OBS preset rhythms {march, bossanova, pops, disco, rhumba, 16beat, waltz, slowrock}
sustain & vibrato buttons
tempo +/ - buttons
primitive sequencer {"record", "play/ stop"} (no edit)
3 plastic drumpad buttons (icons show base, hihat, snare)
programmable rhythm pattern ("program" & "play/ space" buttons)
accompaniment ("chord/ off" button, case writing "auto bass chord")
simple analogue(?) percussion
CPU= "Zilog R904, Z0860008PSC, SZJL-W30, 9334 N1" (28 pin DIL, crystal clocked @ 7.7692 MHz)
demo button
jacks for microphone & 9V DC power supply

This instrument was released by the obscure brand "Superb Sound Audio Products" (which also released the awful My Music Center variant EK-91DX and some fairly well working FM keyboards). The case style was blatantly copied from Casio SA-21, but is noticeably bigger. Although all 8 sounds and 8 rhythms have OBS buttons, their buttons are labelled with numbers those meaning is listed on the control panel to imitate the case style of modern soundbank keyboards. The EK-922 is ultra-rare; I never saw another one.

The small PCB contains quite much analogue stuff, similar like my MC-2 instruments although the CPU has less pins. The green writing on the beige PCB top looks like copied from something hand written, thus it was likely designed without computer. On the keys and panel PCB back is the small number "93.1.8", which may be the manufacturing date.

The EK-922 was possibly a direct predecessor of the MC-2 hardware class, or at least of some Angeltone stuff that is known to use Zilog microcontrollers. But the software number(?) "R904" does not resemble the "KZ#" numbers of Angeltone CPUs. The only other keyboard with 28 pin Zilog CPU (KZ283) I know is the HBATEC.

Help me!: Please tell me which sounds and demo melody the Superb Sound EK-922 had. Are there any other keyboards with the same CPU?

*removal of these screws voids warranty...*

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