as long as we are sticking to the same type of capacitor (eg, tantalum, ceramic, mica, mylar, electrolytic...) size usually the only thing that increases as you increase its rated voltage. A physically larger capacitor might also have less ESR (equivalent series resistance) and larger and fatter leads will also have less resistance.
the only thing you should worry about is you are for example, replacing a tantalum capacitor with a mylar capacitor, as the ESR and ESL (equivalent series inductance) will vary with the materials used in the capacitor. electrolytics for example, have a higher ESR and leakage current compared to other types.
as far replacing what was a 10uf cap with a 22uf cap, it might be fine, but then you might potentially run into trouble. If all that was done on the later model was change that particular cap from 10uF to 22uf, then you're probably ok. but if they also changed that particular circuit that the cap was in, then the upgraded circuit probably required the extra capacitance, where as the older circuit with the 10uF cap could have been different. If that 10uf cap was electrolytic, you will probably be more likely to be ok, since electrolytics are usually only used to filter out AC and prevent sags or transients for a DC line.
I still have a lot to learn in this area, so if I am mistaken anywhere, hopefully no one will hesitate to correct me. :)
-Robby
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--- In TekScopes@..., Stefan Trethan <stefan_trethan@...> wrote:
Higher voltage is generally OK (even better) with electrolytics.
It may be different with ceramics, there are some dielectric materials
that have rotten voltage coefficient and the capacity will be way low
much below rated voltage.
Higher capacity depends on the circuit, if a later model uses more it
is most probably OK. There is a high tolerance on electrolytic caps
and circuits should not be too sensitive to the exact value anyway.
ST
On Wed, Jul 18, 2012 at 5:44 AM, doswoodman@...
<rgwood@...> wrote:
As I have shared before my electronics experience is some 20 years ago in the Navy and then some time working on consumer electronics in the later 80's. All the gear I worked on was not certifiable the way O'Scopes are.
Anyway, to the question. Are there any limits (beyond the obvious physical size, and economical limitations) when dealing with capacitors and suitable substitution? For example replacing a 10uf 25V capacitor with a 10uf 50V of suitable tolerance. Is size/money constraints the only thing keeping one from subbing a 10uf at 100V or 200V, or 1000MV <---got'a love taking things to the limit as that cap would likely be a large as a house as a guess ? --->
Along the same lines. If one is replacing a capacitor in a scope and scopes with later serial numbers show that the value has moved. i.e. a 10uf cap in the board but manual shows the value was upgraded to 22uf at some serial number after the one you have. Is the best sub another 10uf or a 22uf of suitable voltage in this situation?
Seams like this last part was touched on relatively recently. However, I could not find it with my search skills. Unfortunately my memory is not up to the task either.
I hope this is not to far off topic. Thank you as always for the bandwidth and replies.
Rob
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