Hi, in general, when replacing capacitors, which values (be it capacitance, voltage, ripple current, leak current, ESR, e.t.c.) must be followed and which ones are ok to be different?
This mostly depends on the particular circuit. However, if the part will fit physically, a higher voltage rating will be ok.
Also, a tighter tolerance of capacitance value is ok, a higher ripple current rating is ok, a higher temperature rating is ok,
and lower leakage is ok. All of these options would generally increase the part's cost.
Also, a tighter tolerance of capacitance value is ok, a higher ripple current rating is ok, a higher temperature rating is ok,
and lower leakage is ok. All of these options would generally increase the part's cost.
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Thank you, just to check, when you say "tighter tolerance", does it mean higher capacitance value?
For example, if the original was rated as +10%/-10% tolerance (in the capacitance value in uF),
then +5%/-5% tolerance would be ok, though perhaps more expensive.
A tighter tolerance for a replacement part could then actually have a slightly smaller total capacitance in uF,
since the original could be 10% higher than rated, while the replacement could only be 5% higher than rated.
In many circuits this would be better, since the actual value in uF can be important, rather than just more uF.
then +5%/-5% tolerance would be ok, though perhaps more expensive.
A tighter tolerance for a replacement part could then actually have a slightly smaller total capacitance in uF,
since the original could be 10% higher than rated, while the replacement could only be 5% higher than rated.
In many circuits this would be better, since the actual value in uF can be important, rather than just more uF.
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Ah thank you, I see. So in other words, assuming all other factors equal, as long the replacement capacitor has the same or higher range of capacitance (determined by the rated capacitance and tolerance levels) compared to the original capacitor, there should be no issue?
I think that conclusion is a bit simplistic. As alluded to in the first reply, it depends on the circuit.
Increasing the value of power supply filter capacitors is generally okay, within reason. Too large an increase (even if it fits physically) may stress the transformer and rectifiers due to the huge current in-rush on start-up.
Capacitors in speaker crossovers should remain the same nominal capacitance to avoid changing the crossover points. Bigger is not better in this situation, but you may note improvements by upgrading the dielectric type.
Other circuits which are frequency controlling, or frequency dependent, should not have their capacitance values changed. This would include applications such as active filters, tuners, etc.
Capacitor upgrades must be done carefully, and with at least some knowledge of the capacitor's purpose, or function, in the particular circuit. If you're not sure, leave it alone.
Increasing the value of power supply filter capacitors is generally okay, within reason. Too large an increase (even if it fits physically) may stress the transformer and rectifiers due to the huge current in-rush on start-up.
Capacitors in speaker crossovers should remain the same nominal capacitance to avoid changing the crossover points. Bigger is not better in this situation, but you may note improvements by upgrading the dielectric type.
Other circuits which are frequency controlling, or frequency dependent, should not have their capacitance values changed. This would include applications such as active filters, tuners, etc.
Capacitor upgrades must be done carefully, and with at least some knowledge of the capacitor's purpose, or function, in the particular circuit. If you're not sure, leave it alone.
To replace a part with a different part (including capacitors), you really have to reverse engineer the circuit
to some extent, to determine the requirements for the part. Among others, these requirements could
include voltage, current, power, value tolerance, physical dimensions, footprint, pinout, temperature, humidity,
ESR, inductance, thermal drift, stability, etc. Some aspects could be critical to the proper functioning of
the circuit, and some not.
to some extent, to determine the requirements for the part. Among others, these requirements could
include voltage, current, power, value tolerance, physical dimensions, footprint, pinout, temperature, humidity,
ESR, inductance, thermal drift, stability, etc. Some aspects could be critical to the proper functioning of
the circuit, and some not.
Thank you AcoustatAnswerMan and rayma, am I right to say that at the very least, I should look into the datasheets of the components connected to the capacitors?
Also where can I learn more about how different capacitors affect different parts of the circuit?
For context, this question of replacing capacitors came to me when I was reading the tweak guides of replacing capacitors in the JBL LSR 305; I was wondering how those values for the new capacitors got derived. Also, I was looking into replacing the capacitors with known brands but some value combinations are not available at the shops I am going to
Also where can I learn more about how different capacitors affect different parts of the circuit?
For context, this question of replacing capacitors came to me when I was reading the tweak guides of replacing capacitors in the JBL LSR 305; I was wondering how those values for the new capacitors got derived. Also, I was looking into replacing the capacitors with known brands but some value combinations are not available at the shops I am going to
For speakers, the capacitors must be nonpolar types. Other than that, you can't really know what
the original designer of the speaker considered important. The ESR could have been part of the design,
for example. The uF value could be critical, or the current capability.
You could read an introductory electronics text, and go on from there.
the original designer of the speaker considered important. The ESR could have been part of the design,
for example. The uF value could be critical, or the current capability.
You could read an introductory electronics text, and go on from there.
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Than you, you got a good point. At the very least, I want to replace those capacitors that are from unknown origins/brands with those from brands that I know to sound good (or at least have datasheets)
It really needs some additional specifics and there are a million and one possibilities based on the vague question that was asked.
I would search for the specific situation and then make conclusions based on others experiences along with more searching and learning regarding the issues that come up from the previous searching (ie. inductance, resonant circuits, esr profiles, temperature coefficients, etc.).
I would search for the specific situation and then make conclusions based on others experiences along with more searching and learning regarding the issues that come up from the previous searching (ie. inductance, resonant circuits, esr profiles, temperature coefficients, etc.).