On Fri, 28 Aug 2015 20:31:16 -0500 (CDT) Tothwolf <tothw...@concentric.net> wrote:
> On Fri, 28 Aug 2015, Chuck Guzis wrote: > > On 08/28/2015 07:42 AM, Tothwolf wrote: > > > >> With all the different solder alloys I work with regularly, I have > >> to ask...what type of solder caused that sort of damage? Was it > >> the alloy itself, or did IBM use a flux which was too active and > >> then failed to clean away all the residue? If they used a > >> rosin-based flux, was it due to the specific activator used in the > >> flux? > > > > That's actually a little puzzling. 1401 core frames have survived > > well (got one in my desk drawer). You'd expect that the same > > process would be used for equipment that's pretty close to > > contemporary. > > I think I've answered my own question today while looking at a > datasheet for another type of solder. My guess is that the solder > they used did not contain any copper, and the tin in the solder IBM > used dissolved small amounts of the already very tiny copper wires, > creating a weak point where the wires were soldered to the terminals. > > Lyle, was there any discussion of possibly laser welding replacement > stubs of wire before the breaks that could then be re-soldered to the > terminals? That would seem to be a viable repair option, although it > would require special equipment. I was not on the Team that did the memory analysis and the ultimate "modern" replacement memory. However, when I joined the Team, I asked similar questions and was told that the core memory was literally "falling apart" and was not repairable. Lyle -- Lyle Bickley Bickley Consulting West Inc. http://bickleywest.com "Black holes are where God is dividing by zero"
