ESR and LCR Meter testing - Page 1
Forum section: electronics / beginners

author: funny718
author_rank: Contributor
timestamp: November 13, 2024, 08:20:47 pm
content: Hey all newbie here and trying to understand how to test ESR correctly using a RuoShui 4080 LCR meter. So what I'm having trouble understanding is when I test this cap which is 100uF, 25v the reading is as follow using 120hz frequencyI currently would like to recap a bose cinemate gs series ii and I have the service manual and all but and I suspect this cap 1x 100uF, EL, 85C, 25V, 20% part #177902-101EBamong others need to be replaced. I pulled the cap and set LCR to CS-ESR and frequency to 120hz, and thats my question how are you suppose to know which frequency 100khz, 100hz, 120hz I should set the meter for testing? do I need to change any other settings?

author: TimFox
author_rank: Super Contributor
timestamp: November 13, 2024, 09:20:06 pm
content: As always, "that depends".If the capacitor is a filter capacitor for a mains-powered rectifier (50 or 60 Hz), the relevant ESR would be at 100 or 120 Hz, respectively (not much different).If it is in a switching power supply, normally 10 kHz or 100 kHz settings would be used for the faster waveforms at the capacitor.The readings in your photo are perfectly reasonable: the capacitance is well within 20% spec and the ESR is believable.The reactance of 100 uF at 120 Hz is 13.3(capacitive).Catalog values of ESR at that capacitance and voltage range up to 2.8.Did you do the calibration with the same leads shorted that you used to connect to the capacitor?That is critical for ESR measurement on large capacitances.

author: RoGeorge
author_rank: Super Contributor
timestamp: November 14, 2024, 08:56:40 am
content: If the capacitor is used in a switching power supply (SMPS, most power supplies these days are SMPS) then use the 100kHz. If the caps are right after a diode bridge, so at mains 50/60Hz, then the capacitor will work at double of the, test it with 100Hz or 120Hz, depending of where you live. For USA is usually 60Hz.So, if the capacitor is after a mains or a transformer diode bridge, use 120Hz.If the capacitor is from a SMPS or some other area, use the 100kHz. If you know the capacitor is so called "Low ESR", then use the high frequency (100kHz). And if you have the datasheet for the capacitor model/series, then use whatever comes closer to the specs in the datasheet, so you can compare the results with the numbers in the datasheet. While ESR varies with frequency, the exact value doesn't matter much, ESR is always about being "in the ballpark of" whatever is specified in the datasheet. If the ESR as a few times more than that, then yes, replace that cap. But if the datasheet says 2.5 and you read 2.6 or 3 ohms or so, then it's OK. The capacitance however, has to be in the range indicated by the datasheet.After all, the test frequency doesn't matter much, so don't stress about that. I would probably use 100kHz all the time, because nowadays almost everything is SMPS and digital, using low ESR caps.Beware that these values are very sensitive to temperature. So, if you measure a capacitor immediatly after you desolder it, when it is still hot/warm, then it might measure OK even if that cap is bad. Wait for it to be at room temp when measuring, not hot. This is the reason why the devices that have caps with bad ESR will work apparently OK when warm, but they fail to start after you leave them unplugged for a few minutes (because in that time the device cools down to room temperature).When hot/warm, bad ESR and/or dried out caps perform much better, so the device might still work OK.Another thing, don't change the caps for "just in case". The ESR fail usually happens for capacitors used inside a SMPS, or in an area with a lot of heat, near power transistors/power diodes radiators for example. Most of the time (not always, but 90%+) low ESR damage is also accompanied by a capacitor bulge, or leftovers of electrolyte leakage on the PCB, and a much lower capacitance then nominal (when measured).In general, don't try to fix something if it works. With the shoddy supply chain of components these days, chances are the new capacitors will last less than the ones Bose used when they manufactured the device. "Better" is biggest enemy of good.

author: TERRA Operative
author_rank: Super Contributor
timestamp: November 14, 2024, 05:33:27 pm
content: According to the schematics included below, that capacitor appears to be C150 (schematic location D2 on page 5, and diagram location "PCB ASSY, DSP, PRIMARY PART NUMBER 318878-001S" on page, it looks like a simple bit of decoupling capacitance for the TDA8566TH power amp chips U150, U250 and U350.As it is on the DC +14V line it wouldn't need to be anything super special.The datasheets I can find don't actually list C150, C250 or C350 for some reason, but looking at other 100uF capacitors in the parts listing comes up with part number 306245-101EE which is a United Chemicon part that does exist.It turns out that part is an MVE series capacitor (datasheet included below). A completely standard capacitor with no particularly special qualities at all. Easy to replace.With a tan δ of 0.18 for that capacitor, you should expect an ESR of roughly about 2.4 ohms (measured at 120Hz), and it should be replaced with a part with 2.4 ohms or less of ESR, and at least 100mA/rms of ripple current or more.Your reading of 2.6 ohms is not unexpected for the age of the capacitor and is well withing the expected value. I wouldn't say it would be having a particularly bad effect on the operation of the circuit.If it does need replacement, I'd just use a quality brand with a reasonably low ESR and decent ripple current rating, it wouldn't be hard at all to find something suitable.What is the actual fault with the sound system anyway?

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: November 14, 2024, 09:32:04 pm
content: The Peak Instruments ESR meter manual covers the issue of frequency, see page 5 of the manual:http://www.peakelec.co.uk/downloads/esr70-user-guide-en.pdfSJ

author: u666sa
author_rank: Frequent Contributor
timestamp: November 15, 2024, 04:30:54 am
content: Quote from: funny718 on November 13, 2024, 08:20:47 pm100uF 25 volt should be 1.4 ohm or lower. You have a bad cap.Quote from: funny718 on November 13, 2024, 08:20:47 pmI had this one TV, older LCD panel, customer left them after I was unable to fix them. I had two of those. Problem was it would just not come up. First BIOS update helped. But then it just wouldn't come up. Voltages all checked good. All caps were pulled and capacitance measured with capacitance meter (not LCR). When I got my hantek LCR meter I checked cap the fed power to the CPU, and ESR was too high. Replaced that one cap, and it started working.Mind you. I did replace all the caps, including that one with news caps just in case. The new cap from the store had high ESR, and it wouldn't turn on.I check my ESR values at 400 hz. Small none electrolytic caps at 10 to 100 khz.I try to dumpster dive whenever I can. People throw out old tvs usually. So I pull caps off old TVs. Those caps have better ESR values than the caps from the store.

author: armandine2
author_rank: Frequent Contributor
timestamp: November 16, 2024, 02:27:29 pm
content: Re. ESR tables?I find my new MESR-100 esr meter's table confusing - some of the figures look suspect, in regard to the trend?

author: armandine2
author_rank: Frequent Contributor
timestamp: November 17, 2024, 03:58:27 pm
content: ...this explanation helps, from diode gone wild

author: faraday
author_rank: Regular Contributor
timestamp: December 12, 2024, 08:22:42 am
content: Quote from: armandine2 on November 16, 2024, 02:27:29 pmhere is table from my old trusty badcaps meter