Recapping audio equipment

The black cylindrical objects with silver tops are electrolytic capacitors

Electrolytic Capacitors are the small black cylinders.

Electrolytic capacitors (“caps”) are electronic components that perform a critical function in amplifier and receiver circuits.   The electrolytic compound decays over time.   A typical receiver has almost 50 separate electrolytic caps.

Quoted directly from a manufacturer of electrolytic capacitors.  “The aluminum electrolytic capacitor has a limited life span. This occurs because the electrolyte in the element eventually dissipates.”

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The parts replaced during the rebuild of a Pioneer SX1050.  On several of the large black capacitors, you can clearly see that the sleeve has pulled back from the end.  This is due to heat from the electrical “leakage”.   

It is possible to isolate the failing capacitors in a circuit, but this is not only laborious, it is the beginning of a never ending loop of replacing one after the other when they are all 35 years old or older.  In our complete vintage component service, we replace all small electrolytics in the audio amplifier, often resulting in changing over 50 separate components, which means 100 desolder operations and 100 solder operations.  For mid century vintage audio, it is the only approach that makes sense.

If you would like to know more, or just need help falling asleep at night, here is some data on electrolytic capacitor reliability.