Yamaha PC-100

This is the instrument in its carry case.

The main voice preset sounds are cold and very bright and resemble simple 2 operator FM sounds; interesting is the cheesy "vibraphone" sound which has slow tremolo. The single finger accompaniment has a nice arpeggio. The rhythms employ blip percussion of quite unique electronic style with semi- metallic hissing cymbals (a bit like Casio SK-1) and may be interesting for tekkno. The original German retail price of the PC-100 was 990DM (about 445€).

main features:

• 44 midsize keys
• key lighting with 30 red & yellow LEDs above the main (non chord) keys
• slot with a tape head for reading PlayCards
• main voice polyphony 8 notes (only 4 with accompaniment)
• 10 semi- OBS preset sound {organ, trumpet, clarinet, piano, guitar | piccolo, violin, oboe, harpsichord, vibraphone} selected by 5 locking buttons + bank a switch button.
• 10 semi- OBS preset rhythms {march, waltz, jazz rock, swing, rhumba | disco, slow rock, 16 beat, bossanova, samba} selected by 5 locking buttons + bank a switch button.
• locking push button switches to select sounds and rhythms
• single finger accompaniment (manual organ chord with rhythm off)
• 2 switchable accompaniment variations per rhythm
• sustain, single finger chord & variation buttons
• master volume slider
• sliders for auto bass-, arpeggio- and rhythm volume (each 8 steps?)
• tempo slider
• transpose knob (-5..+6 semitones)
• sound generator layers 2 static digital waveforms with independent envelopes, which sounds quite bright and a bit harsh; with low notes sample aliasing gets audible. The trumpet, violin, oboe and piccolo have a delayed vibrato that fades in only after the sustain phase of the envelope begins.
• The drums sound like squarewave blips, the hihats sound somewhat metallic and may be shift register noise or a very low- res waveform sample.
• jacks for line out, AC adapter and analogue volume pedal

Above the keys are the key lighting LEDs. At the top is the PlayCard slot.

These are the key lighting control buttons. The round knob is for transpose.

This is a PlayCard; much like a MIDI file the data tape strip contains the music data.

eastereggs:

notes:

The "organ" is rather Hammond than church style; it quickly grows slightly duller during its percussive attack phase (likely by crossfading 2 waveforms). The "piano" sounds more like an electric than acoustic one and the bass range strongly resembles a gently picked nylon guitar; "harpsichord" sounds much more realistic. The "trumpet" sounds way too thin and harsh. "trumpet", "violin", and "oboe" have a delayed 7Hz vibrato. "guitar" attempts to be a bright acoustic one. The "vibraphone" has a strong and cheesy sounding 3Hz tremolo, includes sustain and ignores the sustain switch. All other sounds stop almost immediately after key release when sustain is not pressed.

The single finger chord mode employs an envelopeless electronic organ chord timbre, while the automatic accompaniment during rhythm plays a kind of piano chord made from the same waveform with decay envelope, combined with an e-bass. In manual chord mode the variation button toggles between a very bright and a less bright organ timbre or vice versa depending on the selected rhythm. (There are 2 chord timbres in total, those are also used by the accompaniments.)

A fullsize variant of the PC-100 was released in 1983 as Yamaha PC-1000 (49 keys, metallic with dark control panel, case style like Yamaha PS-55 but only 1 speaker, very rare). A white PC-100 variant with slide switches instead of push buttons was later released as Yamaha PC-50 (seen on eBay). 2 variants without PlayCard reader (and no key lighting) were made as Yamaha PS-400 and PS-300 (I read the manual). The black PS-400 had a chord sequencer, 4-bar rhythm variation switch and duet mode. The beige PS-300 (with beige carry case) has far less features; it has only 37 keys and 8 preset sounds and is missing many features like the chord sequencer, chord variation, transposer knob, duet mode and even lacks the arpeggio. (The Yamaha PS-500 looks identical and Yamaha PSS-401 seems to be a golden 44 keys variant of it.) These instruments were likely intended as digital successors of the analogue Yamaha PS-2 and PS-3. Also the Yamaha PS-200 from 1984 seems to be a black PS-300 variant with slide switches instead of push buttons and 3 built-in demo melodies. In 1984 the larger PlayCard keyboard Yamaha PCS-500 was released as successor of the PC-100; it featured 49 midsize keys, stereo symphonic (rotary speaker simulation), fingered chord and warmer sound, but unfortunately has no arpeggio anymore. A small PlayCard keyboard with only 32 keys and squarewave sound was released as Yamaha PCS-30. Later Yamaha released some ROM based key lighting instruments like e.g. the small TYU-30.

Yamaha MP-1

This keyboard was a close variant of the Yamaha PC-100, but instead of the PlayCard key lighting feature it had as the world only such midsize keyboard a built-in musical score printer.

This printer is a small plotter that draws music notes on a narrow paper strip using a small ball pen. It either prints immediately all played notes, or prints the recorded contents of an internal sequencer. There is also an additional duet mode and much like Yamaha PS-30 it has a stupid "4 bar" button switch that automatically inserts a rhythm fill-in every 4th bar; a manual fill-in button would have been much more useful here. Due to the strong similarity I only mention the differences to the PC-100 here.

different main features:

• neither PlayCard slot nor key lighting
• built-in musical score printer (draws notes on narrow paper strip using a small ball pen)
• button for automatic 4 bar fill-in
• duet mode
• sequencer (polyphonic)
• tuning trimmer
• complex multi-chip hardware: (according to Scott Nordlund)
• CPU1= "OKI MSM80C85A"
• CPU2= "Yamaha YM1034" (key/button scanning, controls sound IC)
• sound IC= "Yamaha YM1019"
• plotter CPU= "Hitachi HD44820A71"
• 3x SRAM= "Toshiba TC5516AFL" (each 2kB)
• RAM/ ROM controller?= "IG07806"

The PCB has a grid of empty test solder pads.

notes:

Question: Can anybody tell me what the original plotter ball pen for Yamaha MP-1 looks like? I want to replicate one.
 
 
With my Yamaha MP-1 someone had stuffed a cylindrical lump of tar- like dirt into the tuning trimmer hole. I first thought it was the remain of the plotter pen, but according to the instruction sticker on the plotter lid a ball pen was used for it. Someone e-mailed me that also his Yamaha PC-100 had the same sticky stick in its trimmer hole, and after a close look even at my PC-100 trimmer hole I discovered some black smeary stains from it. Thus it was apparently originally placed there by the manufacturer and not just stuffed in by a kid. Thus likely it was some kind of plug that was originally made of some wrongly mixed or accidentally unvulcanized rubber compound, that turned into pulp after few years. I only know that my Yamaha PS-20 and PS-30 had badly smearing dissolved black foam rubber pods at their case bottom. However I don't understand why anybody should plug a trimmer hole tight with a soft material at all. It might be that the case was painted after assembly (which makes very little sense) and the soft plug thus should protect the electronics against paint, and the manufacturer forgot to remove it.
 

removal of these screws voids warranty...
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