Recapping from ESR of 0.1 to 0.01 ....is it worth the effort

quadklipsh

Super Member
Can someone enlighten me .....
Unfortunately all caps i sent to my tech are high esr value.
The amps he has done are all good ones.
Sansui au 9500.
Sansui au 607
Luxman L550X
Sony TA 1120
 
This can be true in case of high capacitance and higher voltage capacitors like with an amp's main filter caps, but it deserves a little intro...

A electrolytic capacitor in real life is not just a capacitor it's also a little resistor and a little inductor.
The amount of which a capacitor is also a resistor is relative to it's working voltage, capacitance and it's physical size (larger means it can dissipate more heat).
High ESR just means the capacitor is being more of a resistor, which also means it's doing more heat dissipation instead of energy storing.
In most cases it is a distinctive tell tale sign the electrolytic capacitor is near the end of it's life. In EC's this may be due to the dehydration / evaporation of the dielectric gel inside.
All electrolytic capacitors have an endurance (life span) specification attached to them in working hours at working voltage (at max temperature).

The difference between 0.1Ω and 0.01Ω when it comes to ESR is ten fold. It could be critical and make a huge difference, and
it could mean diddly squat. It all depends on the capacitance and working voltage of the capacitor in question.

I use some general and very old ESR charts which list the maximum allowed ESR values per capacitors (in ohms)

Take this with a grain of salt b/c it's pretty old, but use it for example's sake:

dTPaKUs.jpg


You can see that for a 100μF capacitor rated 10V, up to 2Ω of ESR is allowed.
For the same capacitance of 100μF but rated at 35V we're only allowed to have up to about half of the former value (1.1Ω)

Watch the big boys now...

For a 10,000μF mains filter capacitor rated at 63V we're only allowed to have 0.01Ω of ESR.
If we had 0.1Ω ESR for this cap, it would mean it's most likely trash already. Another example is a 1000μF capacitor rated at 35V,
which is allowed to have just a tad over 0.1Ω of ESR, so it would be OK for this one.

Modern electrolytic capacitors are way more advanced. The general purpose capacitor of today, is approaching the specs
of audio grade capacitors of the 70's, so all recommended max ESR values of today, are even lower than what appears
on this chart. Plus, these charts are total void if the mfgr datasheet provides different ESR specifications for the capacitor.
These are just general reference.

Look up a newer chart (lemme have a copy) and find out about the capacitors you sent to your tech. If you know the brand,
look up the datasheets, and find out the real allowed ESR for your caps. Your tech may be right... or not!
 
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