This is the marketed version of the first string machine prototypes by Ken Freeman. The CSS version has a vco/TOS combination which gives a "baseline" tone on each note. There are also two 12 high frequency oscillator "channels". Ch1 is only in the mix if Ensemble button is on. There are 6 oscillators that modulate various group combinations of the oscillators in ch1 and ch2 when the animator level is pulled up. A glide switch option jack allows for actuation of a preset pitch envelope that can modulate all the oscillators at once. All the generated tones that are active wind up on the buss circuit where they can be driven as keys are hit and according to how the balance control is set and the sustainer and high and low switches. Top boad has all oscillators, bottom all dividers and middle the buss circuitry. The LOw and HIGH buss under the keyboard have diodes that merge the keying of octaves so that when the Low only is turned on then you get normal sequence of triggers all the way up the keyboard. WHen High only is turned on the keying is offset up an octave and you actually run out of notes in the higher octave as a result which is ..yes a bit strange econo :-). But that's how they did it.
The first I worked on had dead TOS chips, missing dividers, and a bad opto-coupler for the volume control leaving a very bleak signal. Voltage must go through the jack of course to get to the light part of it but that was fine but always check it first. The metal can on the board above the power supply is the opto. One can temporarily just put a 33K resistor across the two front terminals on the board underneath to get signal around it. Also though the 13V for the pre-amps was down to 8V because of a bad transistor in the power supply. They use a TO92 case device to regulate there and I replaced with a 2N4401 as I recall and it worked great. The numbers on the transistors are not crossable near as I can tell.
Other units I worked on consistently had terrible solder jobs. Also a broken key switch spring and some rust on the bussbar where something got mosture on that end. Dividers seem to hold pretty well from what I can tell so far. I've seen one intermittent esr reading cap (4uF) that was causing rapid decay even w/sustain up on high C.
POTENTIAL CONFUSION WHEN READING DIAGRAMS! First they reversed the divider board's row assignments. The front row correlates to the front row of coil generators. Middle is the rear row of coil generators. And the rear is the TOS generated notes' dividers. ALSO note that those are opposite mouting direction of the front rows. The keyer board is correct. THe first note starts front right as it shows. Another error though is that they show the keyer board holding the 1K resistors, capacitors/10K resistors to ground and the diodes that merge signals from the three 'ranks'. In reality those parts are all on the divider board! That should save you some time scratching your head :-).
Of course the key bushings will be shot and I can supply those parts at very competative pricing.
I usually have most of the parts used in these. Including some original slider knobs at 5.00 each
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