If you can replace caps, i dont see why one couldnt build one of these. Probably turn out cheaper than a commercial unit and be plenty accurate for most of us troubleshooting. http://ludens.cl/Electron/esr/esr.html
On Sun, Dec 28, 2008 at 8:35 PM, Greg Michalski < [email protected]> wrote: > My experience has I admit been limited but useful for my purposes. I see > the math though of your tool and appreciate its importance - learned > something today :) Thanks! > > Greg > www.distinctperspectives.com > > -----Original Message----- > From: Gene Heskett [mailto:[email protected]] > Sent: Sunday, December 28, 2008 2:27 AM > To: Enhanced Machine Controller (EMC) > Subject: Re: [Emc-users] Bad motherboard capacitors? > > On Sunday 28 December 2008, Greg Michalski wrote: > >I've repaired no less than 2 dozen MOBOs of varying brands (Soyo, MSI, > Tyan, > >Dell, etc.) that all were simply in need of a capacitor or 6. Never > >bothered with a kit, just grabbed some from the 'Shack or the junk drawer > or > >tacked onto an order to Digi-Key or Mouser. Easiest way to diagnose a bad > >electrolytic is a bulge on the top of the caps, or in the worst case fluid > >on or around it. Most are usually in the power section (usually have a > >toroid bearby) but some were in varying locations causing the odd > behaviors > >you mention. > > > >Saved my tail on a MOBO based RAID situation where I'd have most likely > lost > >it all if I couldn't have gotten the board up again. They really aren't > >hard to replace, get the same MFD value and a voltage rating equal to or > >higher than the original (hopefully it didn't get too hot and melt the > >wrapper) and just like any soldering on a multi-layer board that has SMT > >components nearby, use the finest tip you have and medium heat for minimum > >time. > > > >If it's a dead board then the couple bucks are a no brainer. If you have > a > >decent multi-meter with capacitance metering, remove the suspect unit(s) > and > >check to see if they're ok or not. Got nothing to loose at that stage. > > I've not found those types of multimeters to be very informative, Greg. > They > will tell you that a cap marked 2200uf is only 1900uf ok, but that isn't > really germain to what they are supposed to do, and generally, a good 220uf > would function just as well although the ripple currents would soon destroy > the smaller valued capacitor. The multimeter is not looking at the most > important characteristic of a capacitor, its Equivalent Series Resistance. > > The capacitor wizard I've mentioned measures the capacitors ESR, at 100khz, > using a very low level drive so as not to temporarily heal a failing > capacitor, in circuit or out as long as the circuit is powered down. > Anything over .25 ohms in those big boys makes them suspect because they > are > > then allowing high frequency switching noises to stick their head up > looking > > for a bit of logic to screw up. > > In terms of keeping the digital stuff at a tv station working, that > nominally > $175 I spent for the wizard multiplied my productivity at restoring > operation > by a factor of at least 5. That is something you see as a plus on the P&L > sheet very easily. > > >Good subject to bring up. Curbside finds are prominent around me because > no > >one wants to wait for the biannual county electronics recycling drive to > >come around so they set them at the curb and usually someone like me comes > >along and snags them. $5 in caps can make for a nice Christmas gift to a > >digitally challenged relative :) > > Been there, done that. :) > > >HTH - as always YMMV :) > > > >Greg > >www.distinctperspectives.com > > > >-----Original Message----- > >From: Kent A. Reed [mailto:[email protected]] > >Sent: Sunday, December 28, 2008 12:14 AM > >To: [email protected] > >Subject: [Emc-users] Bad motherboard capacitors? > > > >Gentle persons: > > > >In part because of the need for a parallel port and in part because of > >the latency-inducing problems that seem to arise more often with recent > >chipsets, we EMC'ers often seek out older motherboards/cpus. > > > >I'm curious to know if anyone has run into the problem of bad capacitors > >on their older boards, in particular, with Nichicon capacitors. (see, > >for example, http://en.wikipedia.org/wiki/Capacitor_plague or > > > http://news.cnet.com/PCs-plagued-by-bad-capacitors/2100-1041_3-5942647.html > ) > > > >If bad caps always left the system as dead as a Norwegian Blue parrot, > >then they'd be easy to diagnose. Unfortunately, it is also possible for > >them to result in various headscratchingly odd behaviors in systems that > >seem as if they ought to be working, which is tough to diagnose. > > > >This problem is by no means found only with Dell Optiplex systems of a > >certain age, but Dell sold or leased so many to businesses that they're > >statistically the most likely brand to be bitched about. > > > >I know several on this list have mentioned their success with Dell > >Optiplex GX/SX 260/270/280 boxes coming off lease. These are great > >little machines, especially the SX boxes which I personally like on > >several counts, but I have found I have to be cautious buying them sight > >unseen. Sometimes machines that failed in service were recapped in the > >repair facility, more often the motherboard or the whole machine was > >simply replaced. Good or bad, many of these boards and machines have > >made their way inevitably to eBay and surplus-equipment channels. > > > >Let the buyer beware. Ask if the seller doesn't mention that motherboard > >capacitors are new, replaced, recapped, or somesuch. "Refurbished" may > >be an insufficient description since it could just mean they erased the > >disk drive and wiped the finger munge off the front panel. > > > >Fortunately, there is at least one enterprising person on the internet > >who sells capacitor sets for motherboards but you need a certain level > >of skill to do the job. > > > >Regards, > >Kent > > > >PS - if you've ever tried to bring vintage tube-type electronic gear > >back to life then you already know all about the need to replace > >electrolytic capacitors but you might not have expected digital > >computers newer than your car to have the same problem. > > > > > > >--------------------------------------------------------------------------- > - > >-- > >_______________________________________________ > >Emc-users mailing list > >[email protected] > >https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > >--------------------------------------------------------------------------- > - > >-- _______________________________________________ > >Emc-users mailing list > >[email protected] > >https://lists.sourceforge.net/lists/listinfo/emc-users > > > > -- > Cheers, Gene > "There are four boxes to be used in defense of liberty: > soap, ballot, jury, and ammo. Please use in that order." > -Ed Howdershelt (Author) > The Public is merely a multiplied "me." > -- Mark Twain > > > ---------------------------------------------------------------------------- > -- > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > ------------------------------------------------------------------------------ > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
