Products > Test Equipment
LCR vs ESR meter for in-circuit testing of electrolytic cap
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kripton2035:
You can't have any meter that measures precise esr or capacitance in circuit. you can only be close to.
I check the esr with Jay_diddy esr meter adapter I made with a digital display. only for magnitude order
if I read a high esr , then I grab the de5000 to measure capacitance, which can be close but never the real one
if the esr is too high, and the capacitance not the one marked on the cap I'm testing, then I desoldier the cap and measure it with the de5000
then only I get a precise value of the cap.
the in circuit method is there to narrow the bad caps, not to measure precisely.
I could do all of this with the de5000, but the jay_diddy esr meter is protected for charged caps, not the de5000...
HalFoster:
It hasn't been mentioned yet but, depending on the function of the capacitor in the circuit, the capacitors leakage can be vastly more important than ESR (usually not critical itself other than high DV/DT circuits such as a SMPS) and even the capacitance value itself.  Of course it is something that has to be measured out of circuit...

Hal
HalFoster:
I'll also chip in and give another recommendation for the DE5000 - very capable and accurate for the price.  Just make sure to make a set of Kelvin leads for it.
TimFox:
As mentioned earlier, one must be careful (and read the instructions) with the DE5000 to be sure that any capacitor being measured has been fully discharged before connecting to the meter, since it is not well protected against external voltage.
I built several test fixtures that included a low-resistance switch to short the terminals, for use in the "calibration" routine, that serve to discharge an external capacitor.
However, I would not recommend it for clumsy use in troubleshooting a complex circuit:  that is not what it was designed for.
indman:

--- Quote from: kripton2035 on September 11, 2023, 06:35:57 pm ---the in circuit method is there to narrow the bad caps, not to measure precisely.
I could do all of this with the de5000, but the jay_diddy esr meter is protected for charged caps, not the de5000...

--- End quote ---
Exactly so, that's why any experienced engineer understands that in-circuit analysis of elements can be only QUANTITATIVE evaluation but not QUALITY! Especially in complex circuits with many elements. And the availability of reliable overload protection allows for a quick assessment of the capacitors' condition without much hindrance or concern. This advantage outweighs all other characteristics in many cases.
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