Posted by Sherman in Idaho [108.162.245.133] on Tuesday, December 20, 2016 at 13:05:07 :
In Reply to: Condenser: need help posted by WarEagle [108.162.237.73] on Tuesday, December 20, 2016 at 10:54:20 :
Don't know which is better or worse, but the old ones were a roll of paper and aluminum foil rolled up and stuffed into the can, filling the whole thing. The new ones that I've taken apart just have a standard capacitor, usually .22uF, like would be mounted on a PCB, inside the metal can. It's maybe 1/4 to 1/2" long, so the can is mostly empty. You could theoretically "rebuild" a bad one by opening the can and replacing the capacitor.
Longevity probably depends on the type and quality of capacitor used. The actual caps are cheap (a few cents) so you're mostly buying the packaging. If there's an issue with the life of the newer ones it's probably due to how they handle voltage surges. With the old foil-and-paper caps, especially the oil-filled ones, an arc between the foil "plates" would blow the foil away from the hole in the paper and you'd end up with very slightly diminished capacitance but no total failure. I suspect some of the new ones, being much more compact, fail more completely if there's an over-voltage arc, either shorting out or blowing pretty much all the metal out of the plates. Most are made of layers of metallized ceramic so there isn't much to work with.