Pan Toys MC-7,
TrendLine MC 3700,
Fujiyama KS-37
squarewave keyboard with analogue rhythm & monophonic accompaniment

These keyboards belong to a very odd squarewave hardware class that was likely a predecessor of the Hing Hon EK-001 and possibly of MC-3. At the one hand it features accompaniment, programmable analogue rhythm and even a simple sequencer, but at the other hand the sound is plain squarewave with the most crude and primitive volume envelopes you can imagine, the whole thing is only 2 note polyphonic and the automatic accompaniment features neither chords nor a separate bass line but simply occupies the 2nd melody voice with a monophonic pattern.

But these instruments are nothing bad; they sound just in a sympathetical way artificial and puristic and have much similarity with music from historical videogames or simple Commodore C64 homecomputer compositions. Especially the accompaniments sound nicely cheesy and innocent.

(Note: This thing sounds quite nice, but don't buy one of these so far your only intention is to get a keyboard with faithfully imitated natural instrument timbres. Remember, this is a squarewave instrument and its sounds do not even remotely resemble what is written on its buttons, thus bought with wrong expectation it may disappoint you.)

Pan Toys MC-7

While the front panel of this instrument is labelled "MC-7", on the back of the case stands also the brand name "Pan Toys". This instrument was also released as Elite MC-7, GPM MC-7 and Levis MC-7 (seen on eBay). Besides that it is much bigger (midsize keys), the case design of this instrument resembles very much the Hing Hon EK-001, and indeed also a mini keys version of it was released as Elite MC 2000, Transtec 893 and Grand Prix KB 893 (seen on eBay), which case looks besides the different button layout exactly like my EK-001. A case variant of the MC 2000 with centered drumpads shaped like Casio SK-5 and SK-8 was released as Fujitone II and Monacor MC-2000A (see below).

main features:

(old eBay picture of my specimen.)


This is one of the keyboards I believe to have seen as the smallest "Fujitone" in shopping centers of my childhood; particularly I remember well how I mused about its lousy "xylophone" sound and the colourless drums at a time where the first Casio ToneBank keyboards (SA-20 etc.) appeared with lots of (at that time) very realistic sounding timbres.
The PCB of this instrument is rather small, and like the bizarre HBATEC it contains only a single digital IC (CPU) and lots of analogue stuff (mainly percussion). There are also many unused drill holes without traces on it; possibly a 4th percussion instrument was planned here because the CPU outputs a sort of drumroll pattern at an unconnected pin. Very unusual is that the keyboard matrix inputs of this CPU respond only on very low ohmed voltages (about 330 Ohm).

The sounds of the MC-7 are extremely odd, because the timbres are just plain squarewave with different pulse widths and so archaic, crude volume envelopes that even a Letron or Casio VL-1 sounds almost natural against it. When sustain is switched off, after releasing the key any sounds stop immediately with an audible click, and the sound presets itself also contain neither vibrato nor tremolo. The squarewave timbres are quite bright and have a somehow grainy purring texture; it is not zipper noise but rather an intermodulation with internal digital signals; it may be that the mandolin ring LFO is always running and somehow crosstalks into other preset sound those don't use it. When 2 notes are held, the timbre flutters with a strange irregular textures, which sounds quite interesting. Similar like the simple MC-11, this instrument permits (with some skill) to play extremely short, blipping notes those most modern keyboards would rather ignore or play too long. The "clarinet", "violin", "oboe" and even the "elec. guitar" are nothing but plain squarewave tones of different pulse widths without any envelope (i.e. a simple toot or beep like from a cash register or similar). The "piano" and "harpsichord" have a decay envelope, but with sustain enabled they ignore the key press duration. The "xylophone" is nothing else but a short beep (0.2s?) with sudden end click, which stops without sustain even earlier by releasing the key, but also with sustain it won't get any longer than its maximum length (which is much shorter than e.g. the "piano" or any of the continuous tone sustains). The "mandolin" of this little tablehooter even rings (about 8Hz), but like the latter it can also not be really prolonged by sustain. The sustain duration with other preset sounds corresponds to the held "piano" envelope.

Unlike the Letron and various similar squarewave keyboards, when OBS sound preset buttons are pressed with held down keys, this instrument does not immediately switch the timbre of the still sounding notes, but assigns the new selected sound either only to the next played notes or makes the held notes fade silent and then retriggers them with the new timbre. What exactly happens depends on the previous and new selected sound preset; e.g. a held "mandolin" note stops ringing as soon a different sound is selected. This can be used as a sound effect, although the behaviour can be difficult to predict.

Like the arpeggio of other instruments, the accompaniment can play in different keys despite it is monophonic; for this simply 1 or more keys in the left keyboard section have to be pressed, similar like a single finger chord (1 key= minor, 2 keys= major, 3 keys= 7th or the like). Although the accompaniment plays always with the currently selected main voice sound (including the vibrato setting), it uses no sustain. Rhythms can be switched immediately and always (re-)start from their 1st step as soon any OBS rhythm button is pressed. With some skill this can be uses as a realtime variation feature. The rhythm only employs 2 dull analogue drums (like muffled congas with short decay envelope) and a hihat. With my first MC-7 the hihat sounded quiet like hit with too little force. Later I bought another Pan Toys MC-7 (to gut out for repairing my rare Fujiyama KS-37), which hihat sounded noticeably louder with more percussive attack (like a brushed snare); possibly one had a broken electrolytic cap or different discrete components.

The monophonic sequencer is useless because it holds only 28 notes and works not together with rhythm. The "custom drummer" otherwise can be combined with the preset rhythm accompaniments, and even length of the drum pattern depends on the selected preset rhythm, thus it is a quite interesting feature that may be good for tekkno. (The analogue drums can be likely circuit- bent similar like I did with my HBATEC.)

The MC-7 has no sound output, even the lowest volume setting is quite loud and it generally sounds quite bright and a little harsh (analogue distortion?), but the timbre is still pleasant. (I didn't modify this tablehooter because I also own the TrendLine MC 3700.)

TrendLine MC 3700

This instrument is based on the same CPU like the MC-7, but has a different PCB. It sounds less harsh (e.g. the clarinet sounds more credible; likely it was built with different capacitor values). Also the drums sound different; they are more melodic here and particularly the high tom resembles more a muffled plastic pot and does not resemble at all a base drum like the MC-7 one. Very unusual is that this instrument has no master volume control, but only 2 separate "faders" for main voice and rhythm volumes, those behave totally independent (i.e. reducing the "main volume" does not also reduce the rhythm volume).
(This is an eBay picture, showing my specimen.)

different main features:

This instrument was also sold as Bestar MC 3700, Mundia MC-3700 MP180 and Kamosonic F1. The case design of this instruments has many style elements common with the MC-3 keyboard Tristar MC 3000 and the GPM MC-5000.

Fujiyama KS-37

Fujiyama KS-37

This was my first specimen that I found of the MC-2 hardware class (see Pan Toys MC-7). It was sold to me on flea market and seems to be very rare, but unfortunately it was completely brain- dead; apparently someone before me confused the AC- adapter polarity and though toasted it. The only still working parts were the amp and the transistorized analogue drum circuit. Later I repaired it with parts from a Pan Toys MC-7.

The case is brown and the speakers are left and right next to the keyboard instead of above it ( =>wastes space). It has 3 orange drum pad buttons and most other controls are similarly labelled like the Letron, but the keys are slightly longer than normal midsize keys.

different main features:

The slightly slanted side speakers are a well recognizable style element of this case; I believe to remember that old Fujitone keyboards featured them also. The drumpads have wrong icons {base, snare, open hihat}; genuinely they play [conga, bongo, close hihat}.




I later repaired the Fujiyama KS-37 with parts from a 2nd Pan Toys MC-7 that I bought for this on eBay. I soldered in a socket for the new CPU (40 pin socket + piece from another socket to get 42 pins), and at low voltage it indeed seemed to work, although there was plenty of mains hum from my unregulated AC- adapter. But when I increased the voltage (jack was labelled 9V), the CPU crashed and didn't start anymore for many minutes. I first thought I had toasted it - arrrg! - But after waiting about 30 minutes, at low voltage the instrument worked again. I examined the PCB and found out that the zener diode that together with a transistor was intended to regulate the CPU voltage was defective (open, took no effect) and thus the CPU got almost the full supply voltage instead of only 5V. Either the original CPU died by that faulty zener diode, or the confused polarity by the previous owner not only toasted the CPU but also the zener diode. I replaced it with the zener from that MC-7 to protect the CPU properly. It worked well now but there was still much mains hum because the GND line was wired very badly; the entire ground current of the supply voltage was drawn through the audio GND line at the volume potentiometers and thus caused a voltage drop. I separated both grounds and wired the audio and audio GND lines separately with a shielded cable to the amp section =>hum is gone. Initially also the left speaker had wrong polarity, but wiring it correctly didn't boost the bass response really much.
I first hoped this rare instrument had different analogue percussion (and made use of the mysterious 4th drum output of the CPU), but it doesn't differ that much from MC-7.  The 2 drums are quite dull with short envelope; the higher one (bongo or high tom) sounds like a muffled plop noise that reminds to opening a plastic bottle. At higher volume setting the drums distort and thus get more percussive. Despite like with other MC-2 variants the power LED is mislabelled "tempo" and has a separate lead to the main PCB, here it doesn't flash but the unlabelled LED above the "accomp" button flashes instead. Bizarre is also that on the button names are printed on the back of the control panel PCB, but many of them differ from the actual control panel writing and they have plenty of Engrish misspellings.

The Fujiyama KS-37 looks quite much like what I remember from my childhood as a "Fujitone". I would love to find one of these first Fujitones (not a Fujitone IIIb but a really old one). A variant of the Fujiyama KS-37 with similar case but more rectangular speakers and drumpads was apparently released in China with the brand name Tongmei (not Yongmei, seen on eBay).

These are some pictures and model names I found on eBay:
Transtec 893

same case:
Elite MC 2000
Gran Prix KB 893

This was the direct predecessor of the Hing Hon EK-001.

Fujitone 2 (Fujitone II)

same case:
Kazama EK-828 CP
Monacor MC-2000A

Instruments of this hardware class can be recognized by the combined power & tempo LED (i.e. the power LED is labelled "tempo"), the presence of 8 OBS rhythms and 8 OBS sounds, 3 drumpads with 2 custom drummer buttons and the sequencer "record" and "play/ stop" buttons. Regarding the CPU type label, also a variant called "MC-2" may exist, which appears to be the genuine name of this hardware class (e.g. MC-3 keyboards (like Letron MC-3) also have "MC-3" in their CPU name). A possible direct predecessor of the MC-2 hardware class was the Superb Sound EK-922. A possible successor was the Elite MC2200. Another keyboard with similarly cheesy monophonic accompaniment and analogue rhythm is the nice Casio MT-40.

 removal of these screws voids warranty...    
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