On Jan 3, 2012, at 6:43 PM, faithie999 wrote: > None of the caps are visibly damaged, but I know that doesn't mean > that one or more aren't faulty.
Well, I don't know about that. At first, I bought the idea that a capacitor could be bad even if it didn't exhibit any signs of failure, i.e. leaking, bulging, tilting. But then I got to thinking about what caused the problem of bad caps for almost all of the world's electronics manufacturers who used caps from the manufacturer who stole the electrolyte recipe. The stolen recipe was missing a key ingredient: the stabilizer that prevented the electrolyte from boiling/overheating, which then caused the caps to become unstable and not be able to hold their voltage values. The worst caps even exploded, and I've seen a number of those. Just found one inside a 1 GHz Sept. 2004 eMac tonight, in fact. I also realized that the strongest recommendations to replace all caps irregardless of their visual condition came from people who were in the business of selling capacitor kits and soldering supplies. That's when I started replacing only those caps that looked bad, and suddenly my success rate climbed sharply upward. Of course, instead of replacing up to 27 caps on a board, I was replacing a half-dozen or so. That alone limited any damage -- hidden or not -- that might be done by removing caps unnecessarily. I've revisited a number of boards that have had only bad caps replaced in the last couple of years, and no more bad caps have appeared. So I've concluded that if one of the stolen-electrolyte-caps was going to go bad, it already has done so in the last 7 years or so. That doesn't mean the remaining stolen-recipe caps won't go bad in the future. Look at all the G5 iMacs that worked fine during and even after the official Apple bad-cap replacement program, then failed. But I suspect any original 2004-2005 or so stolen-recipe cap that's still in use would have failed by now if it were going to do so. Still, the main difficulty in replacing caps as a hobbyist -- advanced or otherwise -- is the lack of a proper professional-grade solder work station. It is godawful hard -- impossible I wager -- to get the no-lead high-temp solder Apple used in G5 iMacs to melt adequately during cap removal and replacement using consumer-grade soldering equipment. This causes "iffy" solder joints inside the holes, even if the solder adheres to the pads on the surface. HTH, Jim Scott -- You received this message because you are a member of G-Group, a group for those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs. The list FAQ is at http://lowendmac.com/lists/g-list.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/g3-5-list
