Electrolyte caps are not solid state and they leak - likely the most common electronic failure. I have not heard of ceramic or polypropylene caps whine. OTOH co

Electrolyte caps are not solid state and they leak - likely the most common electronic failure. I have not heard of ceramic or polypropylene caps whine. OTOH coils are solid state and they are a lot more common to cause 'whine' than any type of capacitors.