When replacing capacitors is it okay to have a large discrepancy in voltage rating as long as it is rated to the same microfarad?

pyral · April 27, 2021

I am doing some recapping. The original capacitors were rated for 16 volt 10 microfarad. While I have 25 volt 10 microfarad capacitors that should work fine, I want to use my 50 volt 10 microfarad capacitors because they are closer to the original ones size, thus I don't have to have a gap below the capacitor when I solder it on.

I know that you can up the voltage, but this is over 3 times the voltage of the original capacitor. Can I still get away with a voltage this much greater than the original if the microfarad is still the same?

Also I'll add this on, is it normal for caps to get continuity as they get old? I was poking around with my multimeter and noticed that there was continuity between the two legs of the capacitors. They are 44 year old Rubycon capacitors, is that just an age thing?

greenhorn · April 27, 2021

AS you said the specified voltage should not be exceeded, staying below that is fine. The only thing I would keep in mind is that the new capacitors should have a similar series resistance to the old ones. You might get away with having a different value in some cases, it depends on how the circuit is designed.

As to the old capacitor: Yes, old capacitors can degrade, 44 years is a long time. Did you measure its capacitance and looks whether that value is still with the tolerance? Electrolytic capacitors can dry up, dielectrics can become damaged etc.

pyral · April 27, 2021

The circuit board is to a cassette deck. AFAIK the circuit board has exactly one chip on it, a Dolby NE545B for noise reduction, apart from that everything is accomplished through discrete/analog components (these are photos of the board if you want to see a bygone era of tech). I imagine that these aren't super sensitive.

Unfortunately my multimeter doesn't have the ability to measure capacitance. I'll probably recap it properly with new Rubycon caps that have a great track record if this deck indicates anything. For now I am just using what I got.