Capacitor ESR

[roadrash]

I have been told the best way no be sure of a Visually good capacitors true condition is to measure its ESR. However I am still confused as there doesn't seem to any specific value of this. Some manufacturers data sheets for capacitors don't even give the ESR rating of thier capacitors. For example (1)
I have here a Nichon 25v 220uf electro cap that according to my GM328R component tester has the following values: Impedance 228.4 ohms, vlos 2% and a ESR:0.40 ohms. As i cannot find any specs on what a acceptable ESR should be How do I know whether this is a good or bad cap. Example 2 is a nichon 4700uf 10v electro cap and it tests are: uf=5293 uf, vlos=1.9% ESR=0.16 ohms. Are these caps good or bad? Some caps I have measured have impedance in the fractions of a ohm while others can be many ohms. Is there a rule or baseline for knowing when a cap is in tolerance and a acceptable usable condition.

[stj]

Re: Capacitor ESR

i suspect both those caps are fucked - specially the first one.

esr is only missing from datasheets of 85' general purpose caps.
for those, there are vague charts printed on early meters.
here's one.

[roadrash]

Re: Capacitor ESR

i suspect both those caps are fucked - specially the first one.

esr is only missing from datasheets of 85' general purpose caps.
for those, there are vague charts printed on early meters.
here's one.

Thanks that's very handy. Apologies I didn't notice the decimal point ahead of those ESR figures, I wish they would put a leading zero as the decimal pint is not easy seen so are these caps still U/S?

[stj]

Re: Capacitor ESR

if it's under an ohm it's probably o.k.
unless it's a low impedence type - then we need the datasheet.
you didnt say what series either of those caps are.

[roadrash]

Re: Capacitor ESR

if it's under an ohm it's probably o.k.
unless it's a low impedence type - then we need the data sheet.
you didn't say what series either of those caps are.

Thanks that's what I have been wanting to know ever since I got this tester was what is a good value of ESR. Not sure about this caps series but the caps are marked -40~+105c T N(M) Vent. I'm determined to learn this smps stuff repair and I must admit I'm starting to understand it now a bit better.

[stj]

Re: Capacitor ESR

http://www.paullinebarger.net/DS/Nichicon/

[roadrash]

Re: Capacitor ESR

http://www.paullinebarger.net/DS/Nichicon/

Wow thats great. So does that mean these are CY or CS series caps?

[stj]

Re: Capacitor ESR

i wouldnt know - you didnt upload a foto of them.

[roadrash]

Re: Capacitor ESR

i wouldnt know - you didnt upload a foto of them.

I was going by what the Temp specs were on the cap and finding a cap with the same rating. How are you identifying the Series? Here are some pics

[stj]

Re: Capacitor ESR

SXP series.
and it's what they call a "snap-in" terminal, large can type.
http://www.paullinebarger.net/DS/Rubycon/

i dont see it there, but a search will probably find it.

[stj]

Re: Capacitor ESR

btw, it's smoothing the mains,
so ESR is not important, but ripple-current is.
more is o.k. - less is bad.

[roadrash]

Re: Capacitor ESR

btw, it's smoothing the mains,
so ESR is not important, but ripple-current is
more is o.k. - less is bad.

I understand the reason for smoothing from all my swatting on SMPS I believe its rectified after this isn't it? So do you think these caps can be refitted or do they need replaced? They do look in perfect condition. I have replaced all the other caps including the one by the coloured label that was pointed out to me in my other "Amiga PSU" thread in the Power supply section of this forum.

[pfofit]

Re: Capacitor ESR

howdy.
Initially you were talking about specs measured on Nichicons but you showed a pic of a Rubycon.

Attached is an old copy of that SXP series, no esr data, but has ripple current spec dependent of physical size.

Typically the series is a 2 or 3 alpha numeric designation.
Esr will vary by series and manufacturer. Also is dependent on capacitance. temperature rating and physical size.
There is no hard fast rule, but experience will help.
Data sheets are necessary.

[roadrash]

Re: Capacitor ESR

howdy.
Initially you were talking about specs measured on Nichicons but you showed a pic of a Rubycon.

Yes your right, that was just a example cap I was using. I have these other 2 caps on this PSU I am doing that I am unsure need replacing and they are a perfect example of another Cap that looks perfect and I would like my ESR tester to tell me whether they are usable or not. I don't see the point of replacing caps that are OK and like STJ says are less likely to go bad anyway.