DER EE DE-5000 capacitance measurement issues (vs. Fluke 287 & 177) - Page 1
Forum section: electronics / testgear

author: Ivan_s_Lab
author_rank: Newbie
timestamp: April 11, 2020, 10:44:57 pm
content: Greetings everybody, I wanted to get a decent budget LCR meter for my lab so I went with the DER EE DE-5000. However when I started using the meter I noticed a problem. I measured a few new Nichicon and Panasonic capacitors (220uF/35V)and I noticed that the meter was showing a value roughly 5-30% below the stated value - 180-210uF at 1kHz. I said to my self ok, there is +/- 20% tolerance on these. When I compaired the measurement to my main multimeter the Fluke 287 theresult was 229uF. I also tried with my backup meter the Fluke 177 because it was calibrated 6 months ago and the result was the same 229uF. I am off work for a few days but I have a Voltcraft LCR 4080 which I can use for comparison as well.Just to clarify this is how I proceeded with the measurements:For the DER EE DE-5000 I did the Open and Short calibration and I did the measurements both with the alligator clip guard, the tweezer guard and I also used some third party fine tip probes the results were the same. I also cycled through all of themeasurement frequencies and the closest I got was 221uF at 100Hz. The meter itself also feels a bit glitchy, when I tried to measure some 470uF/50V capacitors I had to re-insert and discharge the cap several times before I got a reading that seemedreasonable.Has anyone had this issue before and is there a workaround? The color of the meter seems a bit off as well. It like a deep shade of orange rather than a bright yellow. Could this be a counterfeit?I purchased the meter from here:https://www.ebay.co.uk/itm/DER-EE-DE-5000-Handheld-LCR-Meter-with-T-L21-TL-22-TL-23/164066879305?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649I still have the option to talk to the seller and resolve something if the meter is indeed faulty. Any and all suggestions are welcome. Thanks.PS I have been a fan of the EEVBlog channel and forum for many years now and finally I decided to join. I hope everybody is well in these challenging times.

author: masterx81
author_rank: Frequent Contributor
timestamp: April 12, 2020, 12:43:43 am
content: Did you know at what frequency the flukes tests the capacitors? I've also noticed this error comparing the deere to other meters, only for discover that the other meters were using different frequencies (less than 100hz). I have an 87iv and maybe i can compare, but i trust more the deere.For the glitches, also mine sometimes does weired things. Sometimes testing some capacitors in a batch i have to move from capacitance to auto and back to capacitance, or turning it off-on. Not much often, but happened.I've bought mine from akibashipping, that from what i've read is the best place to be sure to buy a genuine unit. From what i see, seem to me that your is the same as mine, also the brand of the battery is the same.

author: bob91343
author_rank: Super Contributor
timestamp: April 12, 2020, 01:47:59 am
content: Electrolytic capacitors aren't really capacitors. They are a magic mix of surreal chemicals and hype. Their ESL messes up measurements above the audio range, and causes erroneous readings when you least expect them.The first step is to learn by what method your instrument measures the capacitance. There are several ways to do it but they are mosly flawed. So it depends on your goals.Some meters measure by a bridge circuit or more correctly, by one of a number of possible brigge circuits. Others measure impedance without regard for parasitic parameters.So if you have a capacitor, ask yourself why you have it. Will it be filtering, bypass, time constant charging, or maybe something else. Then you can pick the appropriate measurement method.I have five or more capacitance measuring instruments and will use the one appropriate for the application. For filtering, for example, I care about impedance more than capacitance. For time constant charging I care about leakage and capacitance. And of course, voltage coefficient of capacitance.I realize this is more than you wanted to know, but I often will see how my instruments correlate in order to assess a component's suitability. I have one bridge that offers two measurement frequencies and more often than not it gives somewhat different results on large value capacitors. When I try to measure electrolytic units at high frequency I discover once again that these are worthless above the audio range and sometimes even within that range. Measuring equivalent parallel and series values will yield confusing results as well. What equivalent circuit do your units measure?

author: AVGresponding
author_rank: Super Contributor
timestamp: April 12, 2020, 02:49:42 am
content: What does the DE manual say about measuring frequency?My LCR 819 recommends 100-120Hz for capacitance over 1uF (excerpt attached below).I didn't have a 220uF conveniently to hand, but I did have a 100uF.At 1kHz it measures 93.617uF, and at 100Hz it measures 96.573uF.The biggest change however is in ESR; at 1kHz it's 0.2930 ohms, at 100Hz it's 0.5697 ohms.Ultimately I'd measure it at as close to the expected operating conditions as possible, remembering capacitance derates with voltage as well as frequency...

author: miken
author_rank: Regular Contributor
timestamp: April 12, 2020, 05:01:12 am
content: When you get an LCR meter you learn a lot of disturbing thingsLook at the datasheet for your capacitors. For example, Nichicon UPM. It says, Capacitance Tolerance: ±20% at 120Hz, 20°C. That's all that is promised.

author: bob91343
author_rank: Super Contributor
timestamp: April 12, 2020, 05:33:56 am
content: ESR probably doesn't change with frequency but most measurement techniques assume the capacitive reactance is zero so they measure impedance. That's why ESR comes out lower at higher frequency.A proper measurement of ESR would require resonating the capacitor at the test frequency but finding an inductor with high enough Q is not likely.Another way is to measure the capacitance and do the math to convert impedance into its vector components, assuming the measured 'ESR' is actually the real ESR in series with the capacitor, which it pretty much true. So the measured ESR is too high because it's in series with a capacitor (whose reactance increases at lower frequencies).

author: BravoV
author_rank: Super Contributor
timestamp: April 12, 2020, 06:13:10 am
content: Quote from: bob91343 on April 12, 2020, 05:33:56 amThese are the measurements made from probably 5 digits pricedWayne-Kerr 6440B LCR meter vs el.cheapo Mastech MS5308 (equiv. to DE-5000), watch the ESR of different caps at various frequencies.If you want more details about that comparisons ->HERE

author: J-R
author_rank: Super Contributor
timestamp: April 12, 2020, 06:34:06 am
content: https://www.digikey.com/eewiki/display/Motley/Non-Ideal+Properties+of+CapacitorsIn addition to the DE-5000, I also have the UEi DCM3 which uses three different frequencies depending on the range:820Hz - 2uF and below82Hz - 20uF8.2Hz - 200uF and above

author: masterx81
author_rank: Frequent Contributor
timestamp: April 12, 2020, 09:57:41 am
content: My fluke 87IV measure a 2200uF cap at a period of 2.5sec (0.4 hz), 47uF at a period of around 400ms (2.5hz). This is why the reading at 100hz of the deere is different.

author: PushUp
author_rank: Regular Contributor
timestamp: April 12, 2020, 12:39:47 pm
content: "TRX Bench" did some interesting videos about this "ESR"-topic:https://www.youtube.com/user/TRXBench/search?query=esr

author: AVGresponding
author_rank: Super Contributor
timestamp: April 12, 2020, 02:51:41 pm
content: Quote from: masterx81 on April 12, 2020, 09:57:41 amHandheld DMMs seem to have dynamic frequency ranging on this; try measuring the output with no capacitor connected.My UT139C puts out a 666Hz triangle wave (it's a bit skewed, as it's trying to be a ramp generator) open circuit, with that 100uF cap connected though it drops to something like 448mHz or so (was measuring it with my PM99 II, don't think the effect of the probe capacitance will be significant) and is a proper ramp.EDIT: @bob91343, if ESR genuinely doesn't change as a function of frequency, this would imply passive oscilloscope probes should have infinite bandwidth...

author: CDaniel
author_rank: Frequent Contributor
timestamp: April 12, 2020, 02:57:00 pm
content: This a well known issue for C>100uF . Multimeters use a simpler method for capacitance than LCR bridges ... and the calibration is done for non electrolytic capacitors , so fresh calibration means nothing .Basically the losses add to capacitance and appears to be higher .My multimeters also show higher capacitance for electrolytics than LCR meter , and there are differencies between different brands and models .

author: masterx81
author_rank: Frequent Contributor
timestamp: April 12, 2020, 03:30:26 pm
content: Quote from: AVGresponding on April 12, 2020, 02:51:41 pmWithout a cap it does a train of 45hz pulses, then pause, then restart. With 100nf it does a ramp of 24ms (41hz).For me it simply tries to charge the cap until a threshold is reached, then discharge it.

author: AVGresponding
author_rank: Super Contributor
timestamp: April 12, 2020, 03:34:03 pm
content: Quote from: masterx81 on April 12, 2020, 03:30:26 pmJust goes to show, there's more than one way to skin a cat... or get a decent approximation of capacitance!

author: masterx81
author_rank: Frequent Contributor
timestamp: April 12, 2020, 03:48:38 pm
content: At the end, it's best to trust a decent lcr over a multimeter.

author: J-R
author_rank: Super Contributor
timestamp: April 12, 2020, 09:35:52 pm
content: For the older UEi I mentioned the tester's output was trivial to observe, but the Fluke 287 and Brymen 869s appeared to use a somewhat more complex method even when selecting a manual range. With the Fluke 287 I did see some evidence of a 6Hz pulse.

author: markce
author_rank: Regular Contributor
timestamp: April 12, 2020, 10:13:17 pm
content: Hi Ivan,Tried to replicate your experiment.I used a new Nichicon PJ 220uF / 35V capacitor.It measured 217uF on my DER EE DE-5000 at 100Hz. Verified this with my Philips PM6302 RCL bridge, which indicated just below 220uF (217-218uF).At 1kHz the DE5000 measures 211uF for this capacitor.On my Fluke 175 DMM it is 226uF.Long story short: your DE-5000 seems Ok to me.

author: Mortymore
author_rank: Frequent Contributor
timestamp: April 12, 2020, 10:28:37 pm
content: Out of curiosity, I capture on scope the signals that came out of 2 Flukes when selected to measure capacitors, without any at the terminalsFluke 87 - max 5uFFluke 179 - max 10mF

author: masterx81
author_rank: Frequent Contributor
timestamp: April 12, 2020, 11:52:38 pm
content: When i've done the tests i was in autoranging with my 87-4. In any case the traces looks similar, excluding the different frequency (maybe because in different range).

author: CDaniel
author_rank: Frequent Contributor
timestamp: April 13, 2020, 06:14:07 am
content: The LCR bridge use a sine wave generator to measure the voltage/current through capacitor , multimeters just use DC current to charge/discharge and measure time , because of that any leakage fools the measurement and the capacitance appears to be higher . If a multimeter would use the LCR method than it could show ESR also ...

author: markce
author_rank: Regular Contributor
timestamp: April 13, 2020, 04:40:55 pm
content: QuoteYou can improve the DE5000 a lot by replacing the supplied alligator clips with a better capacitor fixture.

author: J-R
author_rank: Super Contributor
timestamp: April 13, 2020, 09:16:47 pm
content: I have not experience any issues with the TL-21 adapter using the included clips. I ran quite a few tests with various low value precision capacitors and resistors and found the capacitance accuracy was within 0.2pF and the resistance accuracy was within 0.003 Ohms.You do need to run the calibration process frequently if you are routing around down in those low values...

author: markce
author_rank: Regular Contributor
timestamp: April 14, 2020, 01:20:10 pm
content: You must have had clips from a lucky batch...(I did not).

author: AVGresponding
author_rank: Super Contributor
timestamp: April 14, 2020, 04:55:13 pm
content: Quote from: markce on April 14, 2020, 01:20:10 pmMan, that's ugly. Even my home made ones are nicer than that...

author: masterx81
author_rank: Frequent Contributor
timestamp: April 14, 2020, 05:25:06 pm
content: Mine had a short between shield and sensing wire, that was failing the calibration. 5 minute job to fix. In any case i've modded a tl-21 with cheap kelvin clips and i use them more.

author: markce
author_rank: Regular Contributor
timestamp: April 14, 2020, 07:42:55 pm
content: I've modified my TL-21 with a pair of Miyama test clips and some decent wire (stable 4-).No need for frequent recalibration anymore.

author: Ivan_s_Lab
author_rank: Newbie
timestamp: April 29, 2020, 10:25:03 pm
content: Ok it seems that I may have solved the mystery. A great man once said "Don't turn it on, take it apart!" so I decided to open the meter to see if there was anything noticeable. The glitchiness with the capacitor detection gave me clue that it may be some sort of contact issue. So I opened it up and in the words of the same great man "dry as a dead dingo's donger". The terminal joints were not that good. I re-flowed them and tried a cap straight in without any of the guards. Detection was much quicker and the measurements were more in range(I ll get back to those in a sec). But I didn't stop there I also decided to opened up the guards and there I found a much worse issue. The shielding that goes to the measurement wires was untangled inside of the guards and it was touching everywhere. It was the same situation both in the alligator clip guard and the tweezer guard. So I had 2 potential points of failure that might have been messing up my measurements. Now its working noticeably better. I have worked in a CEM that manufactured both PCBs and finished devices and sometimes things like this slip through the cracks but does not mean that the meter is bad. Very rarely someone will end up with a sour one.Regarding the measurements and I probably should have mentioned this in the initial post. My main concern was that the meter was showing brand new capacitors out of spec at 120Hz compared to the datasheet measurements at 120Hz.I believe that these are the caps that I have:https://uk.rs-online.com/web/p/aluminium-capacitors/1677803/And here is the datasheet:https://docs.rs-online.com/dcf7/0900766b813ecf20.pdfSo at 120Hz I was getting something like 160 -170uF and rarely up to 200uF before the repair. So now I'm getting a consistent 209uF at 120Hz vs 229uF with the Fluke. And a lot of people mentioned that the Fluke meters might have different measuring frequencies and measurement circuits which I though of as well. I compared the measurements to the Voltcraft LCR 4080 and the results were pretty much the same to the DE-5000. So I believe that the meter is fixed and working. If you get a new one and have similar issues then at lest open up the guards to see if everything is ok.

author: masterx81
author_rank: Frequent Contributor
timestamp: April 30, 2020, 08:39:10 am
content: Thanks for sharing... In any case i've seen some top tier caps far way off from the "theorical" value specified in the pdf at same frequency, but still within the +/-20% range of accuracy class.