LCR vs ESR meter for in-circuit testing of electrolytic cap

[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]

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...

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.

[sonpul]

Two diodes of different polarities connected in parallel with the DE5000 tweezers protect the device and do not interfere with measuring and testing in-circuit capacitors from .47uF to maximum.

[Xruss]

Check it out, you'll love it.
(EPILOGUE) Miron63 vs XJW01 vs MASTECH (MS8911). Test + comparison. In-circuit measurements!

[Jwildesbr]

@TimFox Can you share your experience with Quadtech 1730T?
Because we have 3 units of this model and can not measure pico farads capacitors well.

Best regards,

JFarias

[TimFox]

@TimFox Can you share your experience with Quadtech 1730T?
Because we have 3 units of this model and can not measure pico farads capacitors well.

Best regards,

JFarias

I have been retired from that job for 10 years, so this is from memory:
To measure small capacitors, we built a shielded box with four BNCs for the connections to the 1730 (not "T" model) through short coax cables, with appropriate connections for the devices under test (photodiodes in our case) inside the box.
We did the open and short calibrations at the frequency range of interest at the device connections inside the box.
For our application, we almost always had capacitances > 10 pF.

[wraper]

Just set DE5000 to 100kHz resistance mode and you'll get ESR meter that works in circuit the same way as ESR70.