Excellent news for Ace Tone PS-1000 monosynth owners, there has been a significant increase in the amount of documentation available for servicing and adjustment of these capricious units.
Australian electronics tech and analog synth enthusiast, Richard Haller, has spent a great deal of time and effort reverse engineering two PS-1000s, resulting in a remarkably complete set of schematics, layout diagrams, circuit descriptions and adjustment procedures, all done from scratch.
The author has generously decided to make all of this freely available to the public, and so it is presented here with his authorization. Hopefully this will make it much easier for owners of faulty or unstable PS-1000s to get their units back to working condition.
Additionally, Richard’s very detailed circuit descriptions provide great insight into the architecture of various analog synth modules (PSU, EG, VCO, VCF, etc.), which makes for a very enlightening read for anyone wanting to understand their inner workings more deeply.
Overall, a well-researched, well-written series of documents that provide a wealth of information and a very interesting read for PS-1000 owners, analog synth fans and vintage technology aficionados. Great stuff!
Following is the author’s introduction (download link at bottom):
Author’s Note by Richard Haller
I don’t believe there are many PS-1000’s around. Many of those remaining may be unused, faulty or untunable.
No factory service documents appear to exist and to get one working at all is difficult, but to say, “it’s working as intended” is impossible without knowing what was originally intended. I’m also aware that professional repair has to be viewed as a balance between an item’s perceived value and the cost of repair. Without documentation, the “unrepairable” point is reached quickly.
The reverse engineering behind these documents was ultimately completed to provide information for professional or experienced enthusiast repair and to ascertain the design intentions with sufficient confidence and quantification to allow repair to the original operating standards.
The process began with the far more attainable desire to fix a hacked and fault ridden example I’d been given. Fortunately, I have the necessary experience, and after achieving some degree of success, I tackled the daunting task of generating accurate circuit diagrams and PCB overlays.
As work progressed, several functional aspects remained puzzling. I came to realise the Ace Tone engineers had approached many circuit designs in unconventional ways, so significantly that the process of understanding became less engineering and more an exercise in cultural anthropology.
This required an attempt at looking through 1970’s cherry-blossom-coloured glasses. I also had to remember this synth was made at a time when analog (or any) synthesis was evolving rapidly and that it was made for a specific market.
The general goals are obvious: make an affordable, portable, robust and versatile mono-synth with a layout suitable for organ-top playing. Given Ace’s field of combo organs, rhythm machines and amplifiers, I’d say the PS-1000 was intended for professional use.
It’s not too big a step to imagine them conjuring visions of ‘70s pool-side combos updating their renditions of ‘Tico Tico’ or ‘Quiet Village’ with sounds from that fabulous new instrument, the PS-1000 electronic synthesizer.
I came to the conclusion that rather than requiring, or even aspiring to, the brainiac precision of some contemporaries, many functions were provided for “effect”.
The resulting synthesizer then, has wide array of capabilities for a single oscillator mono synth; lots of routing possibilities and “electronic” features over what was becoming the standard, with a solid keyboard and dense control panel, all housed in a utilitarian but high quality travel case.
The conceptual architecture however, is that of a comparatively stable VCO surrounded by a host of loosely specified and in some cases highly temperature sensitive effectors.
In approaching the analysis I had to abandon my initial premise: That the engineers knew what they were doing meant predictable functionality and exact realization. I’d left out the intention. The engineers did know what they were doing, there are some ingenious circuits and remarkable efficiencies in the PS-1000 design, but at the cost of precision.
Yet it’s exactly this being accomplished by mostly discrete componentry that makes the PS-1000 so interesting in the 21st Century.
So in addition to obsessive determination, it was also retrospective respect for those engineers and their achievement that continued to provide inspiration for this detailed and at times exasperating work, and ultimately pass on the several hundred hours needed to achieve it.