Glodark Audiophile Capacitor Page
You should measure the ESR of electrolytic capacitors to determine whether they need to be replaced. This can be carried out in-circuit provided that:
Capacitors have a temperature/time rating. For example 85'C/4000 means that a capacitor will withstand typically 85' Centigrade for 4000 hours before serious degradation sets in. Derate according to actual temperature. Don't be fooled by the temperature rating. A 105'C/2000 is no better than a 85'C/4000.
In equipment that runs warm in a centrally-heated room, you can expect a life of between 1 year and 6 years for electrolytic capacitors. (Work it out - how many years is 4000 hours?)
Most amps are over designed so they will tolerate quite severe degradation before the effects become audible. You could use an amp for a dozen years before you notice a problem.
Be *sure* to use the correct type of capacitor. There's no point in replacing an Ultra-low ESR capacitor in a power supply with a "high quality" one with "gold-plated wires" if it actually has a worse electrical or temperature/time specification!
However, for capacitors used in front-end circuits, low leakage is more important than low ESR so measure leakage current.
Send this page address - CLICK HERE - to a friend !