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
