PPG Synthesizer 1002. Serviced by Stefan Hubner. Incredibly rare. One of maybe 10 left working in the world.
Early monophonic analog synthesizer by PPG. Distinctive for its sharp filter and unique oscillators (which we can confirm now we've tried it - see soundgasauctions on Instagram for some video). A precursor to the well-known PPG Wave series.
One key is broken along the bottom edge, this does not affect the functionality of the keyboard. Please see photos for more info.
OPERATIONAL STATUS: (A) Tested and working. Full service performed for the current owner by Stefan Hubner.
No guarantee or warranty implied. Operational status may change during shipping. See the main Buying Page for further important information.
Service Report by Stefan Hubner
PPG 1002 Synthesizer [no serial]: Several failures caused by a) broken/corroded rotary switches, b) intermittent/open electrolytic capacitors, c) broken solder connections. Defective parts were replaced, keyboard contacts cleaned and the unit was calibrated for tuning of both oscillators, wave shape and filter tracking after replacement of two intermittent trimpots. The mains wiring has been renewed and a short cable with a male IEC plug has been fitted. Jacks for CV, Gate and filter modulation have been added (see decription in email) and adjusted to 1V/oct."
The main issues with it were the broken (electrically most, mechnically some) rotary switches. Fortunately they are still made so I was able to replace them all with new ones. The next problem was a certain type of axial capacitor, all have dried up and started falling apart, some came out in two parts when desoldering. For continued stability I have replaced all electrolytics.
During calibration I had to swap two preset trimpots as they turned out to be intermittent.
The mains wiring has been re-done according to current safety expectations (not to say standards) including a "pig tail" cable with an IEC male plug for easier connection.
CV and Gate were never standard on the 1002 so the ones having it were all more or less hacks, especially when it comes to oscillator CV. One would expect 1V/octave with 0 volts at a defined note usually. For the 1002 without my modification this means you set the potentiometer on the back that usually came with CV in to track 1V per octave but then had to add an offset of something around 2 volts to reach the lowest C. My approach disconnects the keyboard instead of adding some external voltage somewhere and simulates exactly what the keyboard delivers starting at 0 volts for the lowest C. The connection is being made by a relay actuated by the contacts in the CV jack. By simulating the keyboard, all panel functions remain active on the external CV (glide, tune, modulation)
Trigger/Gate is a voltage input (V-Trig) working from 5V up.
The filter input only modulates the filter setting and is not intended to make the filter track, for this purpose you should rather use the panel knob that attaches the cutoff control to the keyboard CV.