Roland's first export synthesizer product. This machine is heavily influenced it seems by the ARP Pro-Soloist and the like. I had errored in saying this machine used ROM chips like Pro-Soloist. Not sure where I got that. Anyway here's a good run down to give people some useful info:
PL-1: This board contains the power supply and noise source (open collector transistor) with conditioning for random note function, LFO's and delay, WAW envelope and gate generator circuitry.
VCO-1: This board is under the front panel. There are for some reason 2 'width' pots one on this board and one in series underneath so that it can be trimmed with or w/out removing the panel I suppose for convenience. This pot interacts with the circuitry that sets the voltage for the resistor ladder type keyboard.
The 'canned' FET amp combines with the portamento control and a capacitor to modulate the CV from the keyboard's buffer amp for portamento. THen the frequency trim, vibrato and some thermal correction mix into the vco circuitry using the uPA-41C transistor pair and a current source from the tune pot which goes through the thyrister circuit on the Pack #1 and to the transistor pair. I don't have a diagram of that handy but it's using that relationship with a capacitor to create the sawtooth waveform and the square comes out of the pack's transistor amplifier. This square wave goes right to the LM3216 divider on the FL-1 board below and also the high leg of the transpose switch whose common leg also goes to the divider chip's remaining 4 sections.
FL-4: Is far right under keyboard. Contains the divider chip LM3216. The VCO's signal directly feeds two chained dividers to produce two sub-octaves for the L-M-H octave select switch. Whatever of the three available frequences then is selected by that switch is sent to the remaining 4 chained dividers which produce footages 2'(undivided) , 4', 8', 16' and 32'. These footages are then filtered to produce the waveforms in the 'combinations'. They are also MIXED and filtered to produce the preset voicings. The switches on the front MUST have good return contacts because all of them must be up and contacting to allow the signals from the combination side to go through that chain of contacts to the VCF!
VCF-1: Left board under keyboard has the modulation summer and bias, input sense, balance and resonance trim controls. Pack#2 contains a diode ladder filter and Pack #3 is the vca.
AR-1: This board is in the middle under the keyboard. It contains 4 transistor arrays that interact to create the ADSR and a matrix lends voltages from mixing resistors attached logically to the various inputs from the switching to properly set the ADSR to be what it should be for the various types of sounds or the sliders which also interface to this board.
Lots of cleaning issues on these old units of course. On my first one everything just needed a lot of cleaning. I initially thought a problem on the VCF maybe as the presets all worked but no controls with them all up. The reason..is the signal goes through the return position of everyone of those switches of course. If some of them aren't contacting good on the up side then you get no signal. I may be scrapping the second one we got as it has no front panel, no sides and we need some of the switches and paddles to fix the good one and someone else already needs some. I may take the guts of that one and use it for part of a conglomerate synth I'm thinking of constructing here.
I have only the slider caps for these units in new remanufactured form. $3.75 each
I have a variety of parts that might help you on these as it appears Roland used many of the same parts those years. And also there are some discrete components that I usually stock.
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