Capacitance tester meters - Page 1
Forum section: electronics / beginners

author: Greg65
author_rank: Contributor
timestamp: March 11, 2014, 01:02:57 am
content: Hiya everyone,I have a bit of a confusion here, maybe its a typical one that you have come across before.In my little experience of doing repairs to amplifiers, I have always been advised to change out the electrolyte PSU capacitors if they are over 10-15 years old for many of good reasons.So to reinforce I went and bought a couple of cheap testers that have pretty good reviews on the www. webz.After a while I collected and kept a few old capacitorsbut my query is? These capacitor meters tell me that every one of these capacitors are good to go even though some of them are over 40 years old.Here's one with a screw hole through it that was still inside an amp before replaced it and it reads good to go. LOL.any comments please

author: w2aew
author_rank: Super Contributor
timestamp: March 11, 2014, 03:30:16 am
content: Those meters read two different things about capacitors. One measures the ESR (equivalent series resistance), and the other measures the capacitance. These are two different parameters. Capacitors can have a good ESR but have a bad capacitance value, and vice versa.And, I would say that the vast majority of electrolytic capacitors that are 30-40 years old are still perfectly OK. Do old electrolytics have a higher failure rate than ceramic caps, resistors, etc. - sure. But, that doesn't mean that the majority of them out there are bad. So, the likelihood that if you've pulled caps out based purely on their age, then I'd guess that most of them are still good.

author: Shock
author_rank: Super Contributor
timestamp: March 11, 2014, 05:51:32 am
content: When servicing equipment there is a balance between m.t.f., preventative maintenance and cost.If you knew those capacitors were going to fail soon or were an inferior brand and they are cheap enough to replace you would do it.Especially if the owner is going to keep using the gear in operation for another 10 years. Leaking electrolytic caps can sometimes can cause PCB damage also.If it was a vintage piece of equipment and the value would decrease if you replaced components then you would just inspect and test them to see if they are in spec.The rest would be up to the person paying the bill.In addition to capacitance value and ESR (equivalent series resistance) there is also Q (quality factor) which is its efficiency at frequency or inversely the D.F. (dissipation factor).There is also IR (insulation resistance) which is the capacitors ability to withstand current leakage.Capacitance and ESR will get you by and Q or D.F. will show how well it's operating. So you can get really good picture if a capacitor is on it's way out or not.

author: mos6502
author_rank: Frequent Contributor
timestamp: March 11, 2014, 01:49:27 pm
content: Electrolytics wear due to high ripple currents (heating up the cap). That's essentially only in switching supplies. Caps used as mains filters or in linear applications aren't subjected to high ripple currents, so they will last a lot (that is aLOT) longer. I've seen 60 year old electrolytics that were perfectly fine. Replacing electrolytics for no reason is really stupid. It's a kind of cargo cult repair - "I fixed my PC motherboard by replacing the electrolytics so I can fix everything by replacing the electrolytics."Really, get an LCR meter so you can check all the parameters of a cap: D, C, ESR. Then you know for sure. And if it's good, no need to replace it.

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: March 11, 2014, 02:33:09 pm
content: Don't get pissed off , BUT another thread that had some good discussion ,And never answered the question - directly - some meters for testing capacitance ?I have been following a number of threads with the same theme and bought several meters / kitsThis is an example , not sure if I got it from this , payed less about $225 including shippinghttp://www.ebay.com/itm/300611462699?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649This one also but paid less -http://shop.anatekcorp.com/index.php?src=directory&view=products&srctype=detail&refno=2&category=Component%20AnalyzersAnother good sites for caps & testers -http://kripton2035.free.fr/esr-repository.htmlBeing a ham there is a lot of talk about reforming , haven't done it but did find a site a while back -http://archive.siliconchip.com.au/cms/A_112073/article.htmlNot finding a site for one of the most popular kits dangAnd it would seem that some of the measuring mentioned here like Q is left out of all of my links , I have come across Q meters and Q- multipliers at hamfests , haven't one of either yet .

author: mos6502
author_rank: Frequent Contributor
timestamp: March 11, 2014, 03:00:41 pm
content: Are you asking what meters can measure Q? Q is just 1/D (D being the dissipation factor). Q is normally used when talking about inductors and D when talking about caps.Anyway, since you have the MS5308 LCR meter, that one can display D, Q and ESR. Maybe time to read the manual?

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: March 11, 2014, 04:18:33 pm
content: Defiantly will have to read more , I have done a lot as far as housing AC construction , then even more in the auto repair bis.And got my ham lic. about 7-8 yrs. ago and that is the motivation to get deeper into AC/DC theory , repair & building .At the time I am focusing on RF and antenna theory .So just getting together a bench with lots of goodies , every hobby I have gotten into , I like to repair , build .I have lots of radio gear and repair equipment , maybe 2-3% was new and working , the other 97% was used and or not working , then just searching around learning to repair both radio equipment & test equipment .As far as the manual for the MS5308 , the manual is almost useless , but reading here I downloaded a manual for another tester that is spouse to work out the same as far as the manual goes .Right now I do not have enough space to setup a bench , let alone all the parts / components I have come across - another ham friend does scrapping mostly related to electrical , ham & test equipment .The stuff we scrapped that if I would have known more , would have made my storage issues even worse .And another issue / problem , getting started late at this , about 60 yrs. old , tuff to find sources to learn from and not able to find money & time to go to school at this late date .But it is fun

author: Shock
author_rank: Super Contributor
timestamp: March 12, 2014, 05:56:35 am
content: Quote from: mos6502 on March 11, 2014, 03:00:41 pmThey sell caps called "High Q" now but anyway

author: casinada
author_rank: Frequent Contributor
timestamp: March 12, 2014, 06:23:27 am
content: If you're going to remove the component out of the board to test it and the part is inexpensive, it will take the same time to put a new one, that is why is replaced.

author: Shock
author_rank: Super Contributor
timestamp: March 12, 2014, 07:13:08 am
content: Quote from: KD0CAC John on March 11, 2014, 02:33:09 pmWhat was the question? Were you asking the best meter for testing capacitors?There are many indicators if components are failing and most meters that take ESR and capacitance measurements will do the job fine.But some have a higher range and accuracy and more testing features that are intended more for batch testing than telling if a cap or two went bad in some circuit.Just like multimeters there is no piece of equipment that suits everyones needs.In case you haven't thought of this yet, if you are ever short of documentation google a way more expensive piece of equipment. Often they have comprehensive documentation explaining how the testing is performed and even some theory. It's a little easier than trying to piece the puzzle together. Also when checking tolerances component datasheets from reputable brands tell you all the important stuff and why the capacitor may be $2 vs 20c.