On Thu, 12 Dec 2013 14:11:32 -0500 "Goren Buckwalk" <goren.buckw...@mail.com> wrote:
> > Are three rusty capacitors and 3 bad slots just a coincidence? Thanks. > > The exactly matching numbers is a coincidence, but overall it isn't. Dying capacitors mean that the power rails they are attached to are no longer nice and clean and smooth, but contain voltage spikes and steps. When the voltage including these transients falls outside the range in which RAM (or anything else) works, then it starts causing errors. RAM draws quite a bit of current, and the higher the current, the worse the spikes, so removing RAM may well take the voltage back into the working range. The worse the capacitors get, the more you need to reduce the current taken to get things working again. Capacitors degrade prograssively rather than dying instantly, and you can't see the loss of capacity, so the number that are visibly damaged is a coincidence. They will all be on the way out. So yes, replacing the capacitors is the only option. And as has been said, it isn't a trivial job. It's easy in principle, but the board is thick and the holes aren't that much larger than the wires, and the wires are connected to large copper areas, so it's difficult to melt the solder. Too small an iron simply won't do the job at all, you want at least 50 Watts with a short bit or an equivalent hot-air rework tool. Having removed the capacitor, it may be even more difficult to remove the remaining solder from the holes, or at least enough to fit a new component. If you succeed in removing the dodgy capacitors, look around their positions to see if any electrolyte has leaked out, and if so, clean it up. It's water-soluble and corrosive, and generally eats copper and other materials, so don't leave it there, even if it looks dry. It *will* eat the PCB tracks nearby. Finally, these capacitors are chosen for very high ripple current ratings at high frequencies, so any replacements need to be designed to do this particular job. Obviously, use the same capacity and voltage rating (not larger in capacity, as that may over-stress the switching regulator which they work with, and not higher in voltage as it won't do any harm but you'll be trading that for ripple current) and preferably about the same physical size. The smaller the capacitor, the lower its ripple current rating will be. The ripple rating won't be marked on the capacitor, though you may be able to look up the model number in a datasheet. Just get the highest ripple current you can find for the voltage and capacitance and physical size, looking for figures quoted at tens or hundreds of kilohertz rather than 50/60Hz values. Capacitors designed for switching regulators won't usually have a 50Hz value quoted anyway. -- Joe -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/20131212220117.66ca0...@jretrading.com