torbjorn |
Posted: Tue Mar 29, 2011 11:57 am Post subject: |
|
Do you know if the original capacitors also are low ESR? And do you know the purpose of those capacitors in the equipment? Typically, you should use low ESR caps where they are subjected to high ripple currents of high frequency - for instance in switched mode power supplies, DCDC converters, horizontal deflection of CRT monitors and televisions, inverters for welding or motor drives. But in case of audio equipment, smoothing of voltage from linear power supplies etc, then low ESR is of no use. Most capacitors that bulge when they fail are low-ESR (or, at least, the ripple currents are so large that low-ESR should have been used there). If you find out that a capacitor gets hot in operation, then it probably has too high ESR for the application. Remember that the cheapest low-ESR capacitors are in fact not much better than a good standard quality capacitor. The only difference is that the manufacturer has published a guaranteed value for the ESR of the low-ESR types, while the standard types only have a "typical" value stated. A sign of a good low-ESR capacitor is that the ESR value is stated at 100 kHz, not 120 Hz as for the types intended for linear power supplies etc. You should study the datasheet from the capacitor manufacturer and not rely on the reseller's webshop, as the latter are often full of typos and misunderstandings. |
|