Are these genuine nippon caps ? ( revisited, yet again ) - Page 1
Forum section: electronics / projects

author: Refrigerator
author_rank: Super Contributor
timestamp: February 02, 2015, 06:08:43 pm
content: Hey guys.I've got a cuick question because i wanted to get some capacitors for my power supply project and the most suitable place for me to buy is ebay, other places just charge ridiculous amounts for shipping.i've stumbled upon these two listings:http://www.ebay.com/itm/2PCS-AUDIO-Electrolytic-Capacitor-30-41mm-10000UF-63V-63V-10000UF/251121225080?_trksid=p2047675.c100009.m1982&_trkparms=aid%3D777000%26algo%3DABA.MBE%26ao%3D1%26asc%3D28796%26meid%3D9ce6ed717e664ff5be449e80047604f7%26pid%3D100009%26rk%3D1%26rkt%3D1%26mehot%3Dpp%26sd%3D260895770545http://www.ebay.com/itm/1-x-NIPPON-100V-10000UF-Electrolytic-Capacitor-35mmX51mm-B94-/260895770545?pt=LH_DefaultDomain_0&hash=item3cbe9987b1I'm not sure if they're genuine and after seeing counterfeit caps with little crappy caps bodged inside them just makes me feel paranoid.I'd like to hear your opinions before spending my money.Ps: the value i'm looking for is 10000µF, no less than 100V.

author: pickle9000
author_rank: Super Contributor
timestamp: February 02, 2015, 06:18:18 pm
content: The problem with a picture is that it may not be what is actually shipped.

author: mariush
author_rank: Super Contributor
timestamp: February 02, 2015, 06:20:50 pm
content: Have a look at Farnell :http://lt.farnell.com/or TME (http://tme.eu) or RS-Components (http://lt.rsdelivers.com/) . The shipping costs should be around 5 euro for these sites.The picture for that listing shows UCC KMH series, 10000uF @ 63v.The datasheet is here :http://media.digikey.com/pdf/Data%20Sheets/United%20Chemi-Con%20PDFs/KMH%20Series.pdfAs you can see, the only 10k uF 63v is shown as 35mm diameter x 50 mm height, not 31x40 as mentioned in the listing. The capacitors may be fake, or they may have been a custom batch for a company and they're extra stock. Either way, by the way they look, they're old and of dubious origin .. and they're not "audio", nothing audio about that series of capacitors from UCC.And like pickle says, you may not get what's shown in the picture.The only plus is they're cheap at $4.5 for two but who knows, it takes 2-3 weeks to arrive from china and they may arrive dented or smashed.

author: wraper
author_rank: Unknown
timestamp: February 02, 2015, 06:29:02 pm
content: 99% fake. Never buy large branded capacitors from China, elsewhere ebay not good too. Probably few trusted US ebay sellers. Heck, my friend even bought few fake Rubycons from Lemona (Lithuanian company). Rather buy Samwha (from TME) or some other lesser brand rather than those "Nippon Chemicon" if you want cheap.

author: Refrigerator
author_rank: Super Contributor
timestamp: February 02, 2015, 07:10:36 pm
content: Being on a tight budget ain't easy, even 5 € is alot to me.But yeah, i looked up the KMH series datasheet and both of them seem either fake or with wrong descriptions.The dimensions are not correct, the 100V 10k µF one should be 40x80 and the 63V one should be 35x50 but it looks like alot of people have bought those 63V ones and the seller still has good stats. Could they be selling off some older caps from some other product production run that was discontinued ?Well, i don't know. I am kinda tempted to try those 63V ones and "take one for the team".Ohh, i feel like this is not going to end well...

author: cosmicray
author_rank: Frequent Contributor
timestamp: February 02, 2015, 07:25:17 pm
content: One question you may want to ask yourself is, why would a seller of electronic components feel the need to run a private listing ? There may be perfectly valid reasons, but is strikes me as a warning sign.

author: wraper
author_rank: Unknown
timestamp: February 02, 2015, 08:10:15 pm
content: Quote from: Refrigerator on February 02, 2015, 07:10:36 pmBecause they work... at the beginning. Then bulge/leak after a few months - year. Too late for negative feedback. THERE ARE NO REAL CHEAP BRANDED CAPACITORS. Well, unless you can buy leftovers in bulk (like Toploser). Therefore decide if you want something very good but expensive, something medicore/acceptable like Samwha/Jamicon/Samxon at medium price or the cheap crap (even if it bears Nichicon, Rubycon or whatever name).

author: retiredcaps
author_rank: Super Contributor
timestamp: February 02, 2015, 08:39:12 pm
content: Quote from: wraper on February 02, 2015, 08:10:15 pmIn addition, even though the listing picture may look genuine, people may receive something slightly different and not notice. The ebay link provided only shows the side and not the top vent or bottom bung.Another reason why people leave positive feedback is that they might need the reciprocal positive feedback from the seller to boost their own ebay rating.BTW, ebay isn't the only place where counterfeit caps exist. I bought some caps from dx.com and what arrived were obviously fake. I bought it from dx.com as an experiment and was out $2 USD. Stick to the big name distributors like digikey, mouser, etc. Yes, you pay more $$ and I'm sympathetic to people's economic situation, but you should save up some $$ to get the real thing.

author: Refrigerator
author_rank: Super Contributor
timestamp: March 17, 2015, 01:53:08 pm
content: Well the "audio" caps arrived and guess what ? they don't look too fake, i actually think that they are genuine, just salvaged from other products and relabeled and i have reasons to think so :1) the capacitors have dust under them around the contacts.2) they have solder on the leads.3) they have the "K" shaped went on the top.4) they do seem to hold quite some charge.In case you're wondering how i checked the charge, i just connect my DMM and measure resistance and the time it takes to start measuring it, i have some genuine Rubycon 4700 µF caps as my reference, and the DMM reads 0 Ohm for a longer time than the 4700µF cap.The size of the cap ( 30mmx50mm ) indicates that if it is 63V then it could be a 6800 µF cap at max, which for my use is still usable.

author: Monkeh
author_rank: Super Contributor
timestamp: March 17, 2015, 02:09:30 pm
content: So you don't know what the actual capacitance is, you don't know what the voltage rating actually is, you have no idea how long they've been used and abused in another device, you don't even know if they're genuine Nippon, let alone which series they actually were.. and you're happy.

author: Refrigerator
author_rank: Super Contributor
timestamp: March 17, 2015, 02:28:26 pm
content: Quote from: Monkeh on March 17, 2015, 02:09:30 pmYeah, i know i'm weird like that.

author: wraper
author_rank: Unknown
timestamp: March 17, 2015, 02:32:17 pm
content: Quote from: Refrigerator on March 17, 2015, 01:53:08 pmLOL, "K" style vent is used in Rubycon capacitors, Not Nippon Chemicon, doesn't mean that they necessarily are genuine Rubycon capacitors. So you bought some relabeled used (probably 20 year old) crap and are happy with it. You don't know nor Capacitance, nor real Voltage rating. So yeah, I congratulate you with buying some fake used crap instead of buying genuine capacitors of lesser brand from some more reputable place.

author: wraper
author_rank: Unknown
timestamp: March 17, 2015, 03:27:25 pm
content: BTW if you are OK with lower capacitance, then why not just buy 4700 uF genuine capacitors for more than 2 times cheaper than 10 000 uF.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 17, 2015, 03:59:54 pm
content: Real test is when you stick 'em in an oven at 105C for 2000 hours while sinking 5A+ ripple and carrying rated voltage. If that causes about half of the test sample to fail, they're genuine.Tim

author: Refrigerator
author_rank: Super Contributor
timestamp: March 17, 2015, 04:16:32 pm
content: Quote from: wraper on March 17, 2015, 03:27:25 pmWell, a sucker is born every minute, so i might as well be that sucker, but never mind that, failing and loosing is the best way of learning. Next time i might look up to some of those cheaper alternatives.Anyone have any suggestions for such a cheap-ass like me ?

author: wraper
author_rank: Unknown
timestamp: March 17, 2015, 04:20:08 pm
content: Quote from: Refrigerator on March 17, 2015, 04:16:32 pmCheap-ass pays twice. Don't buy top components from shady places.

author: eneuro
author_rank: Super Contributor
timestamp: March 17, 2015, 04:49:55 pm
content: Quote from: Refrigerator on March 17, 2015, 01:53:08 pmLast time also had to test a few (two 50V 4700uF caps in parallel) which.... were reverse polarized for a few seconds from car starter battery 12V and guess what I've got using lets say strightforward method using derived capacitance formula based on charging this cap to some voltage 25V in my case and count time (~63s) when it drops to 1V with 21k loadhttps://www.eevblog.com/forum/projects/guess-what-will-happen-battery-desulfation-experiment/msg629209/#msg629209I was supprised that those caps surived reverse voltage and... it's capacitance is like another two brand new, so it looks like good capacitance doesn't tell you how such second hand caps were used, so of course no plans to buy caps on ebay after this experiment with reverse voltageDidn't desoldered them since they were mounted in prototype circuit and it seams to work as expected from circuit simulation, but of course marked them as reverse polarized to know if fail soon...

author: Refrigerator
author_rank: Super Contributor
timestamp: June 03, 2015, 08:22:47 am
content: I finally received the little mega328p component tester from eBay and tested the capacitors.I also took apart one capacitor and it was a real cap ( no smaller cap inside ), i'll post pics and more detailed info later.

author: Refrigerator
author_rank: Super Contributor
timestamp: June 03, 2015, 12:54:40 pm
content: So as i said i tested both of the caps and also took one apart to see it's guts.After i took the cap apart i epoxied both ends of the core to keep the electrolyte inside for future experiments.A couple photos of my setup.The esr might be a bit high but it could all be down to contact resistance.After i opened the cap i wanted to epoxy it right away but i couldn't find my epoxy so i dabbed some black paint over both ends, of course that didn't keep the electrolyte in too well but it gave me some time to find my epoxy, i wonder if i can take some other caps and squeeze their electrolyte out to put some in the big cap. In the end it was a pretty messy job that one but it's still functional, i might even use it somewhere just for the kicks.I'd say it was an interesting experience this one.

author: The Electrician
author_rank: Frequent Contributor
timestamp: June 03, 2015, 05:42:29 pm
content: I can't read the capacitance of the one you took apart. It looks like 0055 uF, or is it 8855 uF? That one also has the higher ESR.

author: Fungus
author_rank: Super Contributor
timestamp: June 03, 2015, 06:48:16 pm
content: Quote from: Refrigerator on March 17, 2015, 01:53:08 pmMy Fluke 27FM has a table in the manual for measuring capacitance using the resistance range. You set the range according to the capacitance you want to test and watch how long it takes the bar graph to reach full scale.

author: wraper
author_rank: Unknown
timestamp: June 03, 2015, 06:52:31 pm
content: Quote from: Refrigerator on June 03, 2015, 08:22:47 amUsually they just put a fake sleeve on some cheap Chinese cap. Putting another cap inside is too much hassle and doesn't make much sense.

author: Refrigerator
author_rank: Super Contributor
timestamp: June 03, 2015, 07:55:39 pm
content: Quote from: wraper on June 03, 2015, 06:52:31 pmWell i can still squeeze some life out of those suckers that's for sure.Now that i know that they're about 10mF i can check the can size with the Rubycon (K shape vent) voltage/capacitance/size table to find out what the voltage is.@The Electrician, the cap reads 8855uF and the ESR is higher because of the electrolyte that got out but it does still hold quite a charge.I'm actually quite surprised at how long those big caps stay good, i just took some late 80s vintage TVs and they had some 25V 4700µF caps of which all read good on capacitance and around 0.05 on ESR.

author: janoc
author_rank: Super Contributor
timestamp: June 03, 2015, 08:33:31 pm
content: Quote from: Refrigerator on June 03, 2015, 07:55:39 pmAnd how do you know those are actually Rubycons and not some other relabeled junk? The vent shape is not 100% identification. Don't be surprised if you actually try to use that voltage rating and the cap blows up in your face, because the rating didn't match the "hardware".