Quote:
Originally Posted by Eric H
I've restuffed a lot of late 40's capacitors, about 90% of them are dried up inside with the electrolyte turned to a white crystalline powder and the Aluminum foil is rotted and deteriorated. They often would still work to some extent, but no way were they okay.
Normally they would be damp to actually wet inside.
Low leakage is one part, but have you checked them for capacitance? I suspect the deteriorated ones have lost a lot.
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I have measured the capacitance and the capacitance has remained within 20%. Otherwise it would be replaced. Certainly the bad one that fail the reforming process appear deteriorated when opened.
But how do you define rotted aluminum with crystalline powder? I suppose we assume the crystalline is dried electrolyte? There is a chemical process within the can and I would expect the insides to appear messy. What is your evidence it is not supposed to look as it does? Or perhaps the question should be how does it differ from a newer capacitor?
I have also opened 1940's cans to restuff with new caps and found some moist and pliable. Would this mean that the capacitor had remained good? I am defining whether a capacitor is good or fails by capacitance, leakage and life test. Is yours the assumption if the capacitor is more than 30 years old, it must automatically be bad?