capacitor replacement

[benni steinn]

Hello all,
I am doing a tube amp repair and am replacing capacitors first,
I have a electrolytic capacitor that has a value of 500 volts and 22 mfd,
now i cant locate a 22 mfd , only a 20 or 25 mfd
what is the best choice ? I am thinking the 25 mfd, better to go over value than under ?

Many Thanks, have a great day and Cheers !

 

[(*steve*)]

Either would be fine. Pick the one that fits the best. If either will fit, toss a coin. I vote for 25uF in that case.

 

[shrtrnd]

It's generally considered better to go over (the 25ufd).
Same with voltage, you can go over, but not under.

 

[Militoy]

Both the answers above are good - I'll only jump in to add that older lytic caps typically had very wide tolerances - especially on the upper end. As cap technology has advanced, newer caps tend to run much closer to their nominal rated values. Definitely go for the higher value - you are more likely to be closer to the original performance that way.