Capacitor have shelf life!

[nike123]

Interesting reading.

http://hvacrfundamentals.blogspot.com/2010/10/are-your-capacitors-stale.html

[Quality]

I have experienced a lack duty from capacitors that have been stood for a long time but have also had success in restoring there performance by stricking the terminals with dc current

[BradC]

I have experienced a lack duty from capacitors that have been stood for a long time but have also had success in restoring there performance by stricking the terminals with dc current

Finally a topic I know about!

The correct way to "reform" an electrolytic capacitor is using constant current power supply. At first the cap will present a low resistance, and as the cap reforms it will slowly increase in resistance until it presents effectively an open circuit to DC at its working voltage. You need a pretty decent power supply to get near the working voltage of motor caps though.

This is a technique used *often* in the restoration of old Valve (tubes for you across the pond) equipment with high voltage electros in the power section. If you are unlucky enough to just plug a bit of gear in that has been sitting unused for years it's not uncommon to pop a cap or two. The smell is pretty foul.

The valve tech way of doing it is to very slowly increase the power supply voltage from 0 using a variac.