On Wednesday 16 July 2014 05:18:26 Mark Wendt did opine And Gene did reply: > On Wed, Jul 16, 2014 at 4:27 AM, Gene Heskett <ghesk...@wdtv.com> wrote: > > Does this scope also measure "ESR"? That is an often overlooked > > characteristic, but very real fault in electrolytic capacitors, much > > more prevalent in the lower voltage stuff. The higher voltage stuff > > can usually fix itself by re-welding the connections internally. > > Lower voltage, under 150 volt stuff can't. > > > > ESR stands for equivalent series resistance. Its caused by poor > > connections between the terminal leg you see, and the actual alu foil > > and electrolyte soaked kraft paper that is the capacitor itself. > > > > The only test tool I ever found that does a decent job of measuring > > this is called a "Capacitor Wizard", and sells for about 180-200 > > dollars on this side of the pond. Google for it. > > > > It uses an 85 millivolt signal to measure the capacitors resistance > > to a 100 khz signal, and anything over 2 ohms was either bad or > > going bad next week, change it. 85 millivolts so it didn't "fix" the > > bad cap. 100 khz so it largely ignored the size of the cap until you > > were down to less than 2 u-f. > > > > When I was the engineer fixing stuff at the tv station, it found bad > > caps, in circuit, in digital circuitry, where the average cap is the > > size of a pencil eraser, surface mounted, by the 3 lb coffee can > > full. It was the single most valuable tool I had to keep about 20 > > DVC-PRO video tape machines running well. > > > > That DVM that can measure capacitance, may well tell you that cap > > labeled 47 u-f is actually 44 u-f, but it won't tell you its pure > > crap because its internal resistance is well north of 10 ohms. > > > > [...] > > > > Cheers, Gene Heskett > > Gene, > > Here's a really good ESR checker, for a whole lot less (if you buy it > in kit form, takes less than an hour to solder and assemble): > > http://www.flippers.com/BlueEsr.html > > Mark
Interesting Mark. I saw one comment about its lack of static protection, and I noted it uses a 100 millivolt signal, doesn't say what frequency. The 100 millivolt can turn on some of the schotkey diodes in the various semiconductors which may effect ts accuracy. Also, the high priced model has a single cable probe that splits into two probes that are heavily gold plated to reduce the chance of a bad contact, and has an analogue taut band meter for instant response. I suppose the digitals 4 samples a second could be gotten used to. Given those limitations, its not that badly priced. At 80 bucks for the kit it should be a very helpful tool. But I'd see about getting a decent gold plate on the probes, AND hard wire them into the circuit, those banana like panel connectors can make a less than optimum connection at that low a voltage. > ----------------------------------------------------------------------- > ------- Want fast and easy access to all the code in your enterprise? > Index and search up to 200,000 lines of code with a free copy of Black > Duck Code Sight - the same software that powers the world's largest > code search on Ohloh, the Black Duck Open Hub! Try it now. > http://p.sf.net/sfu/bds > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> US V Castleman, SCOTUS, Mar 2014 is grounds for Impeaching SCOTUS ------------------------------------------------------------------------------ Want fast and easy access to all the code in your enterprise? Index and search up to 200,000 lines of code with a free copy of Black Duck Code Sight - the same software that powers the world's largest code search on Ohloh, the Black Duck Open Hub! Try it now. http://p.sf.net/sfu/bds _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
