Esr meter - the capabilities to check beyond electrolytic capacitor
There is something good about esr meter because besides electrolytic capacitor it can be use to measure other type of capacitors such as the non polarity capacitor. From esr meter specification, it is usually mentioned only checking the electrolytic type. When i began to experiment with the Dick Smith ESR Meter i found that it have the capabilities to check other type of capacitors as well.
However it is limited to checking capacitor in the higher value only such as .1uf(104), .22uf(224), 1uf(105) and etc. Lower capacitance value don't get any reading from the esr meter due to it can only read until 99 ohms. Perhaps other esr meter such as the B & K esr meter have the range to check it.
You will even be surprised to see that the dick smith esr meter can check the non-polarity capacitor in-circuit (without removing the cap).
True case example-Monitor came in with display jumping horizontally. You can see a bunch of horizontal black lines across the top display (picture). From experienced it will tell you that vertical section have problem. I begin to troubleshoot the vertical section. Supply voltage checked ok, vertical driver and oscillator IC replaced, all components connected or nearby vertical driver and oscillator ic have been checked ok. By the way I used digital capacitance meter to check the non-polarity cap and esr meter to check the electrolytic cap. The problem is still there and can't be solve!
When i use Dick Smith ESR Meter to compare the esr value of a non-polarity capacitor located near the vertical driver ic, i noticed that there is a big different in the esr value. The good esr value for a .22uf non-polarity cap is between 6.5 to 7 ohm but the spoilt one have a value of 14 ohm! Almost double the value, that's why the display jump. The good thing is i discovered the culprit while the capacitor still in the circuit which mean this esr meter can check non-polarity cap in-circuit. However my recommendation for you is to solder out one leg and check unless you already have the experienced in checking components on board. Replacing the cap solved the display problem.
Conclusion-In order to accurately test a non-polarity capacitor, besides checking the capacitance value and using analog meter to check the charge and discharge to see if it has develop any short circuit when under load, you are also required to check the esr value as well.
Jestine Yong is a electronic repairer and a writer. For more information about electronic repair please visit his website at http://www.noahtec.com/electronic-repair-articles.htm
Article Source: Messaggiamo.Com
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