ARP String Ensemble Power Supply rebuild

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…

ARP String Ensemble Power Supply - before recapping

ARP String Ensemble Power Supply – before recapping

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!

ARP String Ensemble Power Supply - after recapping

ARP String Ensemble Power Supply – after recapping

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