01-02-2022, 12:01 AM
There always seems to be confusion regarding whether plastic cased tubular caps are actually paper caps in disguise, or really Mylar or Difilm in construction.
Here is an interesting article by someone who has dissected many different plastic tubular caps and made a chart of the various brands and their actual types of dielectric.
http://crasno.ca/articles/capdielectrics.htm
This is useful because in many cases, these caps may not need replacement if it can be determined that they are actually mylar film caps in a molded case. I have some NOS samples of these vintage molded Mylars from Sprague and Cornell Dubilier, and can confirm that they do measure as new with regard to leakage, capacitance and power factor.
Here is an interesting article by someone who has dissected many different plastic tubular caps and made a chart of the various brands and their actual types of dielectric.
http://crasno.ca/articles/capdielectrics.htm
This is useful because in many cases, these caps may not need replacement if it can be determined that they are actually mylar film caps in a molded case. I have some NOS samples of these vintage molded Mylars from Sprague and Cornell Dubilier, and can confirm that they do measure as new with regard to leakage, capacitance and power factor.