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 Post subject: Re: ESR vs Leak testing Capacitors
PostPosted: Nov Sun 26, 2017 5:06 pm 
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Joined: Jun Sun 23, 2013 9:03 pm
Posts: 342
Location: Canandaigua, NY
The standard models are definitely an oversimplification. They address AC performance only, not DC leakage. They are valid for a single frequency only. I'm not sure what happens if you add a leakage component, but the model is then suited to only one amplitude.

The problem with any single test is that I've seen capacitors with problems in only one area, so you have to do a suite of tests to be sure of spotting them. Or just replace the cursed thing. I've seen both high and low capacitance with no relationship to leakage or losses. I've seen high losses with no relation to capacitance- other than the expected mathematical effect depending on the model you use. I've seen leakage sufficient to foul a circuit with no relationship to capacitance or dissipation factor. I've seen physical leakage and blown seals with perfect electrical performance, at least for a while.


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 Post subject: Re: ESR vs Leak testing Capacitors
PostPosted: Nov Sun 26, 2017 7:37 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 25
Location: Marquette, Michigan, USA
I collect and repair old transistor radios, mostly very early USA sets. They almost always have bad electrolytic caps in them, thankfully only a few, so I usually just change them all. Even the ones that aren't faulty yet will be at some time in the future. I even rebuild the original ones on the most valuable sets to preserve the original look. I have an ESR tester but have not become too adept at using it or interpreting the result, thus the decision to just change em all.
I have really only found one bad transistor in all the sets I have repaired, mostly just bad caps and things like dirty switches and corroded battery contacts, a few cold solder joints thrown in to make it interesting.

Bob S


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 Post subject: Re: ESR vs Leak testing Capacitors
PostPosted: Nov Sun 26, 2017 7:47 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 12378
Location: Omak,wa,usa
Hello guys
yes that one of the reasons i liked using my Sencore z-meter but mine stopped working I either need to fix it or replace it and am thinking of replacing it but one thing it applies full voltage to the caps for leakage


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 Post subject: Re: ESR vs Leak testing Capacitors
PostPosted: Nov Sun 26, 2017 9:33 pm 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 9400
Location: Powell River BC Canada
radiorich wrote:
Hello guys
yes that one of the reasons i liked using my Sencore z-meter but mine stopped working I either need to fix it or replace it and am thinking of replacing it but one thing it applies full voltage to the caps for leakage


There is a type of leakage testing that recognizes that dielectrics, especially where water is
involved, display memory. The short term memory, is the basis, of the next step in evaluating
the condition of the insulation.

Most of the industrial world depending on electric motors needs knowledge, acquired
over years, passed through generations of workers.

Most important motors are similar to the ones Tesla built.

You slide out the old staff, because of economics, and wonder why the Corps of Engineers
cannot make the pumps work properly during floods.

_________________
de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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