[RodB]

Hi, there's a lot to consider when designing these circuits so you shouldn't have a lot of concern when replacing caps. A lot of people concentrate on replacing them with exact values but remember that these circuits are 60-80 years old and when they were designed components had a 20 percent tolerance. Standard values for caps are different today than 60 years, or more, ago. So, a 0.05 mfd cap in your chassis is now a 0.047 mfd and 0.02 mfd is 0.022 mfd. These are all within tolerance of circuit design. You'll pay more for exact values than getting replacement values.

Electrolytic caps are manufactured for low frequency applications thus have higher capacity. In the old days they were made of paper impregnated with an electrolyte which apparently increases the capacity.

When you buy poly film caps you can get them all at 630 volts and you'll save some money because that is the most common voltage and manufacturers see this and give a price break when they can make them in bulk quantities. Also, if you have to buy 6 or more of a certain value you might as well get ten and pay less.

Quite often you will find that someone has either substituted a cap with a different value or wired in the new cap across the old one. In this case stick with the schematic. Either practice does not fix the problem and causes confusion. If a circuit calls for a 400 volt electrolytic then that voltage would be the same or higher for the replacement. Remember, the higher the voltage, the greater the size.

Hope this shreds some light on capacitors.