LCR vs ESR meter for in-circuit testing of electrolytic cap  - Page 1
Forum section: electronics / testgear

author: RiRaRi
author_rank: Regular Contributor
timestamp: September 10, 2023, 04:12:56 pm
content: Hello. Which tool is better for in-circuit testing of e-caps? I was thinking about getting proper LCR like DER DE5000 but as i have seen more accurate are ESR meters like ESR70 from Peak if we are measuring in-circuit. Is that true?Sometimes ESR can not be accurate when in-circuit but still want to get the best tool for it.

author: KungFuJosh
author_rank: Super Contributor
timestamp: September 10, 2023, 05:35:28 pm
content: In-circuit testing is rarely simple, as there's often other things that will throw off your readings. That said, get both. The DE5000 is a great unit. Lots of people like the ESR70, though I don't have one (or want one). Personally, I prefer the Shannon Tweezers ST42.In any case, you still need to be careful about discharging things before testing, and aware of anything that might alter your test results.

author: RiRaRi
author_rank: Regular Contributor
timestamp: September 10, 2023, 05:41:51 pm
content: Understood. But why to get both if one will be enough?

author: Kean
author_rank: Unknown
timestamp: September 10, 2023, 05:44:28 pm
content: Quote from: RiRaRi on September 10, 2023, 05:41:51 pmSo you have two different results and don't know which one is correct!Clearly you need three different units, so you can take the average of the closest two...

author: RiRaRi
author_rank: Regular Contributor
timestamp: September 10, 2023, 05:54:05 pm
content: As i have seen on YT: DER DE 5000 can produce misleading results, and be completely off when in autorange. So i am not sure if thats good meter. Check EEVBLOG video about measuring ESR in-circuit.Which tool should be the best then and most accurate?

author: Kean
author_rank: Unknown
timestamp: September 10, 2023, 06:09:36 pm
content: The "best and most accurate" will be the one you understand the operation and limitations of, and thus only use it where appropriate.Get one that has good documentation, and lists suitability for the use you envisage.I personally have the Peak ESR70+, LCR40 (older), and LCR45 (newer). I also have a Tonghui TH2822C handheld LCR meter, and a CKT5000 bench LCR meter. All have their strengths.In circuit measurements are not generally that helpful in my experience. You need to review the surrounding circuit and consider how the measurement will be affected.Edit to add: the ESR70+ is the only one of those I have that I believe is suitable for use with in-circuit measurements, thanks to its low test voltage of +/-40mV. I will rarely use it for an in-circuit measurement though, as the parts I am testing are often out of a device that I don't have a schematic for.

author: TimFox
author_rank: Super Contributor
timestamp: September 10, 2023, 06:18:55 pm
content: Quote from: RiRaRi on September 10, 2023, 05:54:05 pmI don't believe the DER DE 5000 is designed for in-circuit ESR measurement, which is (at best) a non-trustworthy measurement.I have never had a misleading result from the DE 5000 on an isolated component, except at high frequencies where a capacitor is above its self-resonant frequency and the actual impedance is inductive.(The datasheet for the DE 5000 is explicit on ranges that work: measuring a small capacitor at lowest frequencies or a large capacitor at highest frequencies is out-of-spec.)

author: RiRaRi
author_rank: Regular Contributor
timestamp: September 10, 2023, 06:23:07 pm
content: Thank you. So it would be the best to use ESR70 for general testing in circuit just to have an idea if the cap might be bad. And if i suspect that cap is bad, then when pulled out it is best to test it with LCR like DER DE?

author: Kean
author_rank: Unknown
timestamp: September 10, 2023, 06:31:37 pm
content: If you just care about ESR and capacitance of electrolytic caps, then the ESR70 will do all you need.You will need something like the DE5000 if you want to make other measurements, as it is a full LCR meter.

author: RiRaRi
author_rank: Regular Contributor
timestamp: September 10, 2023, 08:47:24 pm
content: Yes, LCR is a lot more and deffinetly worth having. But who does better job for in-circuit testing caps: ESR meter like ESR70 or LCR like DER DE?

author: TimFox
author_rank: Super Contributor
timestamp: September 10, 2023, 08:56:31 pm
content: If the total circuit including the device under test is appropriate to the simple ESR meter, then by all means use it to get an indication.

author: Kean
author_rank: Unknown
timestamp: September 11, 2023, 03:19:02 am
content: An LCR meter will generally be designed for better accuracy rather than in-circuit measurement. ESR measurement is a special case.I didn't see any mention of in-circuit testing in the specs of the DE5000, but I may have missed it. I don't own one.

author: tautech
author_rank: Super Contributor
timestamp: September 11, 2023, 03:32:41 am
content: Quote from: KungFuJosh on September 10, 2023, 05:35:28 pmThis ^Best KISS cost effective solution.

author: Kean
author_rank: Unknown
timestamp: September 11, 2023, 04:00:19 am
content: I do like my Shannon tweezers, but they certainly wouldn't be the first thing (or even second/third) I'd think of using on suspect electrolytic caps.I fact, I'm not sure I've ever used them on an SMD electrolytic. They do get used a lot on small SMD parts, 0603 and 0402.Like the ESR70 they do have the benefit of selecting a very low test voltage.

author: tautech
author_rank: Super Contributor
timestamp: September 11, 2023, 04:22:18 am
content: Quote from: Kean on September 11, 2023, 04:00:19 amYou need use ST42 more and get to know them better.

author: indman
author_rank: Super Contributor
timestamp: September 11, 2023, 05:46:00 am
content: The device for in-circuit measurements of capacitors should have, in my opinion, the following characteristics:1. Have a convenient form factor so that capacitors can be easily tested at any point in the circuit.2. Have convenient readability of readings from the display even for people with not very good eyesight.3. Have simple circuitry with the element base available for repair, even better if it is assembled with your own hands.4. Have a reliable system of protection against overvoltage and residual voltage in the circuit.5. For a quick diagnosis of a suspicious element, it is quite enough to determine C and ESR, there is no need to use expensive LCR meters with delicate inputs without protection.I have DE-5000, XJW01, ST42 but I don't use them for in-circuit measurements, because I use a simple and reliable tool that has never let me down.

author: Kean
author_rank: Unknown
timestamp: September 11, 2023, 07:54:16 am
content: Quote from: tautech on September 11, 2023, 04:22:18 amIn what sense?I know they are pretty accurate, but I find the ergonomics aren't all that great for measuring larger parts. A good example is if you are measuring in-circuit and balancing a PCB attached by cables to a chassis. I'd find tweezers difficult to hold let alone read in that situation, and why I rarely measure in-circuit anyway.Just for reference, attached is a photo of a quick comparison of measuring a 330uF 16V SMD electrolytic with my CKT bench LCR, the Peak atlas ESR70+, and the Shannon Tweezers ST42.CKT5000: 297uF 330mohmESR70+: 306uF 200mohmST42: 298uF 341mohm(edited to fix typo in labels)The ESR70+ reads ESR a bit low, but that is because it measures at 100kHz whereas the others are set to measure at 100Hz (more appropriate for some random electro).The CKT5000 and ST42 are set for 100mV test voltage. The ESR70 uses about 80mV (+/-40mV). I didn't check, but I think those are all Vpp (and the manuals don't clarify).Further tests...ST42 set for 10kHz reads: 217uF 223mohm ... hmmm?CKT5000 set for 10kHz reads: 297uF 203mohmCKT5000 set for 100kHz gives invalid reading: -17uF 189mohm <- this is a good example of where knowing the instrument is importantESR70 Gold measures at 50kHz which might be better for accurate ESR on a bigger electro than 100kHz of the ESR70+. I just want to know order of magnitude to know if a cap deserves replacement. I am not using it for precision ESR measurement, because for that I'd use the bench LCR and a proper hands off test fixture.BTW, the CKT5000 is using correction data for my SMD test fixture where I was last measuring single digit pF 0402 capacitors.

author: tautech
author_rank: Super Contributor
timestamp: September 11, 2023, 10:15:19 am
content: Quote from: Kean on September 11, 2023, 07:54:16 amOne needs ask oneself how much accuracy is really necessary.One also needs remember every passive has a tolerance spec that we need factor into any measurement to determine if the passive is really faulty or just outta spec where the circuit/DUT won't operate as designed.I've been using SMD tweezers as my primary passive test device since ~2007 and as you can stretch their legs to 1"+ so most passive devices can be easy tested and for those that can't an extension wire fixes that.The Peak Atlas products have been of interest except for the fact you can solder wires on larger components the need for a test device with flying leads has never arisen as they are universally slower to use than one handed SMD tweezers.Any diagnostic technician should question every measurement so when something doesn't look right we first suspect the connection then the DUT itself < all occasions when probe or tweezer tips haven't penetrated oxides or conformal coatings....whom of us have never questioned a measurement ?YMMV but quality SMD LCR tweezers have been a godsend for all my electronic work as they provide quite sufficient accuracy and unsurpassed speed and ease of use.

author: RiRaRi
author_rank: Regular Contributor
timestamp: September 11, 2023, 03:34:06 pm
content: As i have seen new ESR70 gold measures at 50-100kHz. So you would say that LCR tweezers are more accurate for ESR then lets say ESR70 even for in-circuit?

author: alm
author_rank: Super Contributor
timestamp: September 11, 2023, 04:06:23 pm
content: Quote from: RiRaRi on September 11, 2023, 03:34:06 pmESR is frequency dependent, so you can't say a measurement at 100 Hz is more accurate than a measurement at 100 kHz. If anything, the latter is an easier measurement since the value will be higher. I'd say depending on your goal a measurement at the frequency specified in the data sheet (100/120 Hz, 10 kHz or 100 kHz depending on the intended applications), or the frequency it will be used at (100/120 Hz for a linear supply, but dozens of kHz for a switcher) is the most useful.For an in circuit ESR measurement accuracy is not something I care about. It's a ballpark measurement that's about orders of magnitude. For accurate measurements you want to measure out of circuit with a meter that can measure at multiple frequencies like the DE-5000.

author: RiRaRi
author_rank: Regular Contributor
timestamp: September 11, 2023, 04:40:28 pm
content: Thank you. That is good answer. I was thinking about getting DER DE5000 but as i can see it acctualy has a lot of problems and not consisted readings. Is there alternative?I think it would be the best to have ESR70 for in-circuit and proper LCR for out of circuit. Is there some better alternative to der dee but not as expensive as BK880?

author: Veteran68
author_rank: Frequent Contributor
timestamp: September 11, 2023, 04:59:38 pm
content: You keep implying the DE-5000 is unreliable. It is not. For what it is, you will really find no better instrument in its price range. There are comparable products in the same formfactor (Hantek 1830/Uni-T 622/EastTester 430 series) that provide a better UX and a few more parameters like additional test voltages & frequencies, but functionally they are all comparable to the DE-5000.As others keep pointing out, NOTHING will give you total accuracy for in-circuit measurements. You need to calibrate your expectations a bit. Exact accuracy should not be your goal, as measuring ESR is not an exact science, especially in-circuit. It's not like a voltmeter which if in spec will produce virtually the same result as any other in-spec voltmeter. Just look at the example measurements Kean posted above from a variety of instruments. You'll virtually never get the same result from different devices.The DE-5000 is more capable in terms of features and usefulness than the ESR70. Both have a purpose and are great if you can afford both, but if you can only buy one, the DE-5000 will serve you better overall.

author: TimFox
author_rank: Super Contributor
timestamp: September 11, 2023, 05:15:01 pm
content: "I was thinking about getting DER DE5000 but as i can see it acctualy has a lot of problems and not consisted readings."Why do you keep saying it has a lot of problems and inconsistent readings?Have you used one?I saw one whining complaint because it did not remember the previous setting when power was cycled--no big deal, since you need to "calibrate" the unit each time for accurate measurements (calibration here means compensate for the external test fixture or leads).I have one and think it is an excellent value for its low cost.Before retirement, I used an excellent bench LCR meter (QuadTech/IET 1730T) which is far more flexible,muchlarger and heavier, andmuch moreexpensive. It was better than the DE5000, as expected.

author: mawyatt
author_rank: Super Contributor
timestamp: September 11, 2023, 05:53:28 pm
content: Any instrument is going to give a different reading in-circuit vs DUT stand alone, simply because the other in-circuit components will draw some amount of residual test current and thus corrupt the in-circuit readings. All the test current is not going thru the intended component in-circuit whereas all the test current travels thru the component stand alone (discounting fixtures, cables and such).As Tim mentioned we also have the DE5000, and have compared it to our lab grade LCR meters, the Tonghui TH2830 and Hioki IM3536, and it's quite good, compares extremely well, and repeatable. Agree the UI is a little quirky, but for the performance/cost not going to complain!!The performance/cost is because of the use of a chip-set that takes care of most of the work an LCR needs to perform to make measurements, here if one studies the methods used for the measurements, one can glean quite a bit of understanding and appreciate what's going on and this will directly lead one to better, more reliable measurements.Best,

author: TimFox
author_rank: Super Contributor
timestamp: September 11, 2023, 06:01:18 pm
content: What is an in-circuit ESR meter?Essentially, it applies an AC voltage across two nodes on your PCB, assumes the capacitive reactance at the AC frequency is lower than the ESR, and measures the resulting current.What can go wrong?Well, what else is connected across those two nodes in the practical circuit?Do you know that the impedance of the rest of the circuit at that frequency is much larger than the capacitor's ESR, so the measured voltage is dominated by that ESR?Could be, in which case the ESR meter gives you a useful indication.

author: kripton2035
author_rank: Super Contributor
timestamp: September 11, 2023, 06:35:57 pm
content: 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 orderif I read a high esr , then I grab the de5000 to measure capacitance, which can be close but never the real oneif 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 de5000then 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...

author: HalFoster
author_rank: Frequent Contributor
timestamp: September 11, 2023, 06:44:22 pm
content: 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

author: HalFoster
author_rank: Frequent Contributor
timestamp: September 11, 2023, 06:47:12 pm
content: 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.

author: TimFox
author_rank: Super Contributor
timestamp: September 11, 2023, 07:13:20 pm
content: 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.

author: indman
author_rank: Super Contributor
timestamp: September 12, 2023, 01:50:55 pm
content: Quote from: kripton2035 on September 11, 2023, 06:35:57 pmExactly 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.

author: sonpul
author_rank: Regular Contributor
timestamp: September 12, 2023, 03:03:41 pm
content: 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.

author: Xruss
author_rank: Newbie
timestamp: October 08, 2023, 02:51:44 pm
content: Check it out, you'll love it.(EPILOGUE) Miron63 vs XJW01 vs MASTECH (MS8911). Test + comparison. In-circuit measurements!

author: Jwildesbr
author_rank: Newbie
timestamp: September 20, 2024, 05:33:03 pm
content: @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

author: TimFox
author_rank: Super Contributor
timestamp: September 20, 2024, 06:03:31 pm
content: Quote from: Jwildesbr on September 20, 2024, 05:33:03 pmI 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.

author: wraper
author_rank: Unknown
timestamp: September 20, 2024, 06:07:02 pm
content: Just set DE5000 to 100kHz resistance mode and you'll get ESR meter that works in circuit the same way as ESR70.