Recapping Audio Equipment

Electrolytic capacitors (“caps”) are electronic components that perform a several important functions in amplifier and receiver circuits. Eliminating hum among other tasks. The electrolytic compound in a capacitor decays over time. A typical receiver has on approximately 30 to 40 separate electrolytic capacitors. Some of the largest receivers have over around twice that number of individual capacitors.

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.”

Symptoms included degraded performance in either channel or both, hum, sporadic noises, and eventually, failure to operate. In some cases, damage to other components that are irreplaceable can occur.

In the image to the right, the electrolytic capacitors are the larger blue cylinders. In some cases, you can actually see physical evidence that the capacitor has failed. The fact is that most of the time there is no visual indication of degradation or failure at all.

In our restoration process, we also replace key small signal transistors, as these also degrade over time due to heat cycling. If you would like to know more, or just need help falling asleep at night, here is some data on electrolytic capacitor reliability.