Electrolytic’ Capacitors may smooth out our ripples but they do need some TLC or they will blow your equipments main fuse. They do benefit from a regular top up of electricity but some are neglected and need a little bit of extra TLC to bring them back to life.
This short article is covering the poor neglected electrolytic capacitors that have not had an electron pass through them for a very long time and is to give you advice on giving them that extra TLC. More information on electrolytic capacitors can be found on the Wikipedia. While this topic is on unused equipment it is also relevant to New Old Stock capacitors recently bought.
Important!! There is controversy about using the methods in this article on switch mode power supplies. If your equipment has a switch mode power supply, then use at your own risk!
If a piece of equipment has not been used for some time that has a linear power supply, the electrolytic capacitors electrolyte deteriorates and can in fact blow the main fuse of the equipment straight away. Caution is required before switching on the equipment and a reduced voltage on power up usually helps.
A technique called re-forming is used to bring the capacitors back from the grave and all that is involved, is to apply a small voltage to start with and gradually over time increase the voltage till you reach the maximum voltage. On equipment this can be achieved by powering it up with a Variac transformer and slowly increasing the voltage over time. A quick method that can be used is to put the equipment in series with a 40 Watt light bulb and the same effect can be achieved though not as good as using the Variac Transformer. Basically what you are doing is using electricity to re-form the electrolyte dielectric see Wikipedia.
Warning! It’ is OK to start with reduced input but does not always guarantee ‘no bang or smoke’ !!