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Hi I have just joined after lurking a lot because I haven't found an answer that was specific enough for me.

I have a Soviet synthesizer (TOM 1501) and it has some odd defects such as clicking noises and sounds disappearing. I want to replace the capacitors in the power supply (only 8) to see if it solves the problem. It consists of three different types of electrolytic capacitors and I can easily find the two (2200uF/25V and 4700uF/16V), but I am having trouble finding one with 70uF/16V.

So I know that you can increase the voltage without it being a problem, but can you increase the capacitance? If yes, by how much?

It would be ideal for it to be axial but as long as it is big enough it can work.

The capacitors that are in the power supply right now are the infamous K50 from the Soviet Union, which are notoriously bad.

Thanks a lot

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  • \$\begingroup\$ Just a note that typical electrolytic cap tolerance is about +/-20%. So a 70uF cap could have been anywhere from 56 to 84uF when installed. The value also changes with age, temperature, applied voltage, perhaps even the phase of the moon... \$\endgroup\$
    – rdtsc
    Aug 17, 2018 at 21:49
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    \$\begingroup\$ @rdtsc ±20% is decent for a modern capacitor. The tolerances on a Soviet-era electrolytic were probably much worse. :) \$\endgroup\$
    – user39382
    Aug 17, 2018 at 22:22
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    \$\begingroup\$ The ones that are in it have 30% tolerance. but my final question is just: will a 100uF/25V do as a replacement for a 70uF/16V in a power supply on an old keyboard? \$\endgroup\$ Aug 17, 2018 at 23:03
  • \$\begingroup\$ Can i do that? Its all i need to know \$\endgroup\$ Aug 18, 2018 at 16:48

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Electrolytic capacitors in a power supply are probably being used for smoothing -- they are not precision components. 100 µF is a very common value, and is almost certainly close enough. 68 µF is quite common as well, as are 22 and 47 µF (which sum to 69 µF when used in parallel).

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  • \$\begingroup\$ So i can also change to a lower value? at least if its not too much lower? And great so i can just use a 100uF instead? assuming it fits in size Edit: Now i have found some from Nichicon with 100uF/25V. will they do? is it a good brand? \$\endgroup\$ Aug 17, 2018 at 21:06
  • \$\begingroup\$ In theory, yes. Most of the convenient values are higher, though. And yes, Nichicon is a reputable brand. \$\endgroup\$
    – user39382
    Aug 17, 2018 at 21:13
  • \$\begingroup\$ Thanks for the answers :) what do you mean by 'in theory'? \$\endgroup\$ Aug 17, 2018 at 21:23
  • \$\begingroup\$ maybe i misunderstood you. if the 100uF/25V swap for the old 70uF/16V is alright then i have no more questions \$\endgroup\$ Aug 17, 2018 at 21:29
  • \$\begingroup\$ @SørenHansen What duskwulff was saying is that in most cases a bigger smoothing capacitor is always better (except price). If it is used for some other function (not very likely in a PSU) then the answer reverts to it depends. \$\endgroup\$
    – KalleMP
    Aug 18, 2018 at 18:42

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