If they are identical except for packaging it doesn't matter too much.
Sometimes when looking for small lytics, and you can't find the exact match, try looking for a poly of the same value and voltage. MTF Likes stacked poly's for anything less than I think 4uf if he can fit them in.
Note that in the early 70's the value system that the manufacturers used changed to the present numbering system. It used to be whole numbers and .5 decimals. so changing overto the new system if you had a 20uf/15V you could look for a 22uf/16V, 22uf/20V or even go as high as 27uf/16V or 27uf/20V.
Most of the time it's recommended that you DO NOT go DOWN in value. With a 20% variance in capacitance in most current capacitors, you CAN go down in some cases. Say you have a 50uf/25V and need to replace it. 20% of 50uf is 10uf. so theoretically you can go DOWN to a 47uf (3%) or up to a 56uf(11%).
the following is as I understand it and is NOT intended to be "GOSPEL". More knowledgeable persons can and will correct this if it is inaccurate.
The voltage is the max working voltage the cap can safely handle. So a 20V can be safely increased to a 30 or 35v so there is some working voltage headroom. Surge voltage rating is more often than not 20-40% higher than working voltages. These occur on startup. So increasing the values on caps has it's rewards in a sense. You get a slightly increased working capacitance and at the same time the parts aren't being stressed at their limits.
Larry
Sometimes when looking for small lytics, and you can't find the exact match, try looking for a poly of the same value and voltage. MTF Likes stacked poly's for anything less than I think 4uf if he can fit them in.
Note that in the early 70's the value system that the manufacturers used changed to the present numbering system. It used to be whole numbers and .5 decimals. so changing overto the new system if you had a 20uf/15V you could look for a 22uf/16V, 22uf/20V or even go as high as 27uf/16V or 27uf/20V.
Most of the time it's recommended that you DO NOT go DOWN in value. With a 20% variance in capacitance in most current capacitors, you CAN go down in some cases. Say you have a 50uf/25V and need to replace it. 20% of 50uf is 10uf. so theoretically you can go DOWN to a 47uf (3%) or up to a 56uf(11%).
the following is as I understand it and is NOT intended to be "GOSPEL". More knowledgeable persons can and will correct this if it is inaccurate.
The voltage is the max working voltage the cap can safely handle. So a 20V can be safely increased to a 30 or 35v so there is some working voltage headroom. Surge voltage rating is more often than not 20-40% higher than working voltages. These occur on startup. So increasing the values on caps has it's rewards in a sense. You get a slightly increased working capacitance and at the same time the parts aren't being stressed at their limits.
Larry
