Blue esr mester low readings

[yo0]

hello, i recently buy a Blue esr meter, i assembly it, calibrate it, run test procedure (.8.8) was ok, testing several resistors all with good readings, low battery warning adjust was ok too, also check all resistors with dmm before install and double check all parts, places and orientation for install in pcb. well as i write before test procedure shows .8.8 and no error codes but... if a test old capacitors for example a pair of 30 years old 10000 uf 50 volts nichicons i pulled from a old Marantz receiver gives me abnormal low reading = 0.02 ohms, almost same as a brand new Panasonic 10000uf/80v 0.01 ohms, i tested a bunch of several sizes old used caps and all shows abnormal low readings 0.0X ohms, just a really severe bulged cap give me 1.3 ohms, any idea?


any help or opinions will be appreciated.


best regards

Pio
Mexico

[WB7ODYFred]

Re: Blue esr mester low readings

You are measuring the ESR Effective Series Resistance, Pio. You have performed some good testing to understand what your ESR meter outputs under good condition for capacitor under test. 0.02, 0.08, 0.2 are good numbers. Yes a bad severely bulged cap gives me 1.3 ohms.
I work on ATX Power Supply Units good electrolytic capacitors have low ESR, when they bulge or are bad they have ESRs 0.8 or 1.X and above. Think of high frequency AC current, low ESR low heat generated. High ESR high heat generated. Power = I squared R = curent x current x resistance.
Conclusion: Low ESR is good in power supplies. When the dialectric dries out the ESR goes up. Yet, Some of the smaller 10-100UF capacitors have 1.0 - 2.0 ohm ESR and are still good functionally. 470uf at 6.3V might have an 0.06 ohm ESR.

So learn as you go, Pio. You are have the basics down pat and are doing fine. Go out and fix some equipment. That ESR meter will make your job easy to quickly test capacitors from the solder side of the circuit board. If a large filtering capacitor has a high ESR, change it out. Greetings from Oregon, Fred

[yo0]

Re: Blue esr mester low readings

You are measuring the ESR Effective Series Resistance, Pio. You have performed some good testing to understand what your ESR meter outputs under good condition for capacitor under test. 0.02, 0.08, 0.2 are good numbers. Yes a bad severely bulged cap gives me 1.3 ohms.
I work on ATX Power Supply Units good electrolytic capacitors have low ESR, when they bulge or are bad they have ESRs 0.8 or 1.X and above. Think of high frequency AC current, low ESR low heat generated. High ESR high heat generated. Power = I squared R = curent x current x resistance.
Conclusion: Low ESR is good in power supplies. When the dialectric dries out the ESR goes up. Yet, Some of the smaller 10-100UF capacitors have 1.0 - 2.0 ohm ESR and are still good functionally. 470uf at 6.3V might have an 0.06 ohm ESR.

So learn as you go, Pio. You are have the basics down pat and are doing fine. Go out and fix some equipment. That ESR meter will make your job easy to quickly test capacitors from the solder side of the circuit board. If a large filtering capacitor has a high ESR, change it out. Greetings from Oregon, Fred

thank you very much for your comments, the intention of the original post is i was expecting higher readings in the old used caps, that make me think there is a problem with the meter, maybe defective or damaged part(s)?

for example, can be an used 30 years old cap still good?


best regards


Pio

[Kiriakos GR]

Re: Blue esr mester low readings

Electrolytic cap's life is measured by: working hours / to specific temperature range.
Therefore the unemployed cap which is just soldered it does not get effected by aging.

From the other hand, every cap model has one specific test frequency chosen by the manufacturer, if your meter is unable to test the cap at the suggested frequency the ESR reading would be totally inaccurate.

If the cap is too old and there is no posted public specifications, then you are unable to compare it and make your mind about it by just measuring ESR.

The LCR meters are capable for more measurements and the D (dissipation factor ) gives a more realistic picture according to test frequency's , and so even with out given specifications you can tell in which application the spesific cap it can serve.

Bottom line, you must learn the limitations of your gadget, so to avoid using it at tasks that is not capable to perform.