K-Mark WP9019A1 (toy keyboard)

K-Mark
WP9019A1

small keyboard with 49 mini keys, programmable rhythm and accompaniment

Although this pretty red mini keyboard looks like one of the many My Music Center successors, the sound quality is much higher and it has 49 mini keys with 4 note polyphony, real accompaniment, programmable rhythms and sounds based on quite natural medium resolution samples featuring an astonishingly realistic piano.

I don't know the model name of this instrument, but only found the brand name(?) "K-MARK" (not K-Mart like the American shopping center) and the number "WP9019A1" on its PCB. (Even the sticker on the case back is only a piece of bare red paper.) Sound and behaviour of this instrument are very similar like the strange fullsize tablehooter Sankai 01504H (see there) although controls and CPU are different. I therefore only describe here the differences.

different main features:

49 mini keys
stereo (bassless and distorting 8cm speakers)
25 preset sounds {Piano, Epiano, Harpc, Celesta, Organ, Bell, MusicBox, Guitar, Eguitar, JazzGuitar, Bass, Violin, String, Harp, Trumpet, Tuba, Brass, Ebrass, Sax, Clarinet, Flute, Banjo, Cello, Oboe, Pipe}
10 preset rhythms {Ballad, Disco, Funk, Cha - Cha, Fussion, Pop Bossa, Slow waltz, Polka, March, Dance}
effect buttons {echo, vibrato, chorus} (chorus is mislabelled "reverb", not usable with rhythm)
5 drumpad buttons {base, snare, low cowbell, closed cymbal, open cymbal | high cowbell, rimshot, clap, shaker, low tom} (switchable between 2 drum set banks, also used as number buttons {1 .. 5} to select preset sounds & rhythms)
primitive sequencer (monophonic record/ play of 45 notes, no edit)
no pitchbend wheel, no "sync" button
CPU= "P901982" (big 27 pin rectangular COB module)
crystal clocked
2 demo melodies

(charleston piano tune)
Polly Wolly Doodle (by Boney M.?)

jacks for AC- adapter, headphone & microphone(?)

eastereggs:

transpose +/- button addable. (12 semitone steps, all higher. These don't transpose accompaniments and also don't function during rhythm.)
"synchro start" button addable.

modifications:

polarity protection diode added, AC- adapter jack polarity corrected.

transpose +/- buttons added.

notes:

The pretty case of this instrument looks like a piece of ars nouveau design inspired by historic Egyptian art. Sound and behaviour resemble much the big Sankai 01504H but the effect section has less flaws. The speakers sound here thinner and much more distorted, but unlike the Sankai 01504H here the volume can be set low enough. The drumpads here have 2 banks with each 5 percussion sounds (the Sankai has only 6 sounds). The single finger chord is misspelled "SINGER CHORD" here while the fingered chord is called "FINGER CHORD". The harpsichord is misspelled "Harpc" (it's not a harp, not a "c", just a harp-c...). The preset sounds are much like the Sankai (although more distorted), but regarding this toy size instrument particularly the quality of the sampled piano with its 4 split zones appears pretty impressive. The accompaniments strongly resemble the Elta KE-491.

The effect sounds of this instrument sound way less extreme than with the Sankai, which makes them more standard but also more boring. The "echo" is like with Sankai, but the vibrato has only normal depth and doesn't howl extremely in the bass range. Also the "reverb" here adds only a mild and slow stereo symphonic effect which mainly consists of panning with a small dose of phasing but with a way less extreme detuned chorus component. To use the 3 effect buttons, here first the "tone edit" button needs to be pressed (LED lit, doesn't work with rhythm).

The rhythms here are selected by entering a numbers with the drumpads and then pressing "start/ stop". The accompaniment is always turned off when the rhythm is stopped with that button, but unlike the Sankai, here a different rhythm can be selected without stopping accompaniment by entering its number. Confusing is that the LED at the "rhythm select" button is lit when a rhythm plays instead of indicating that this button is currently selected (i.e. drumpads enter rhythms numbers). Here also during rhythm most button presses make a beep, which is annoying during live performance. The drumpads here offer 2 banks of each 5 percussion samples (indicated by 2 LEDs) those can be used to program the user pattern of the custom drummer. While the "tempo" LED of the Sankai doesn't work, this instrument has even a chain of 3 green flashing LEDs (similar like e.g. Yamaha MK-100 or Fujitone 6A) to indicate the rhythm bars.

circuit bending details

The K-Mark WP9019A1 keyboard is based on the single chip CPU "P901982" (crystal clocked).

The clock crystal is hidden on the back of the CPU daughterboard (frequency unknown).

Unlike the 54 keys of the Sankai 01504H, this CPU supports only its 49 keys. Theoretically it might be that anywhere even a MIDI port could be added to this instrument, because my technically similar Sankai has a button labelled "PITCH/ MIDI" although it has no MIDI jacks too. (Due to the well responding 49 mini keys a MIDI output could be quite interesting, although the keyboard is not velocity sensitive.)

CPU pins count anticlockwise. from the lower left corner. The input lines are active-high, i.e. react on +Vs. Any functions can be triggered by a non- locking switch in series to a diode from one "out" to one "in" pin.

synchro & transpose button

The 'transpose' +/- buttons are connected from CPU pin 27 to pin 1, 2. An additional "synchro" button can be added from pin 27 to pin 8.

The 2 demo tunes are nicely arranged. The first song is a western style ragtime/ charleston piano tune with violin. The 2nd seems to be "Polly Wolly Doodle" ("Hooray, Hooray - It's the Holi- Holiday" known from the pop band Boney M) with a jazzy oboe improvisation.

The direct predecessor of this instrument (same case but no accompaniment etc.) was apparently the Quelle 496.996 0 keyboard.

Question: Does anybody know the original trade name of the K-Mark WP9019A1 keyboard? I saw this apparently quite rare thing only a few times on eBay (I bought mine before the Sankai 01504H), but yet never with a model name.

*removal of these screws voids warranty...*

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