The ARP String Ensemble we have in stock rolled off the factory line in 1974. Everything inside was original, including the power supply capacitors. The ARP/Solina String Ensemble uses an unregulated power supply, with the varying voltages being generated by rudimentary resistor voltage dividers. The filter capacitors in the original synth were 25V capacitors, on a 25VDC power supply. This is bad news on many levels, good design practice allows for a nice buffer between the expected circuit voltage and the capacitor voltage rating, to ensure the capacitors maximum voltage isn’t exceeded, as well as to provide for a longer life of the capacitor. A capacitor rated for 25V and run close to the maximum will last less than a capacitor rated for 50V and run at 25V…
So, we replaced all the capacitors in the power supply, with 50-63V rated capacitors. We switched to radial capacitors, since the quality of the radials are better than that of the axials, and selected capacitors with a higher 105°C rating. Now this string ensemble is good for another 40+ years!
