On Monday 14 August 2017 14:08:00 Les Newell wrote: > Hi Gene, > > Sorry it took me a while to respond. > > > Re-reading this, Les, I have to ask how old that VFD is? > > > > Anything over 4 or 5 years, I would expect that the capacitors would > > be suffering from poor ESR, which isn't a test feature available on > > a utility DVM with a microfarads test function. > > It is a few years old. The noise I was referring to was not from the > main switching transistors but rather from the internal logic power > supply. The reservoir caps may have a higher ESR than they originally > had but they are ginormous compared to what you would normally fit on > a switch mode PSU so their ESR is probably still much lower than most > SMPSs would see. Switching noise from the inverter with the spindle > running is much less that it's PSU noise. > > This inverter is one I bodged on because the original one failed. I > bought this inverter on eBay 'Fitted but never used'. Yeah, right. > Going by the accumulated dust it had done many hours on a woodworking > machine. > > I suspect the original failed due to dead caps. It started faulting > under heavy load then under light load and now won't even start the > spindle. To be fair I am subjecting the caps to a higher load they > they were designed for. The inverters were designed for 415V 3 phase > and I'm feeding them 415V single phase (I don't have 3 phase). > > I do have an LCR meter but I haven't got around to removing the > inverter and testing it. > > Les
That LCR meter will probably not detect high ESR until its boils your coffee bad. The 2 of the 10 dollar ones I bought were shipped Saturday night late. It will be interesting to check it out, I have several years experience with the Capacitor Wizard, it made it possible I could keep about 18 Dvc-Pro machines running at the tv station. Each one had at least 500 of Panasonics own brand of capacitors in it, they were smaller than anybody else micro versions, and a typical repair was maybe 2 of the 14 to 18 boards in it, testing the caps and replacing the shaky ones, per day. So it was often that the individual machine was on the bench for several days. Even with a 5x13" board in a Panavise frame, it was by the end of the day, back breaking work just from sitting there all bent over. 15 years later I still think thats the main reason I retired at 66.75 yo, still less than a year from maximum SS at 67.5 in those days. 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> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
