28 Aug
2015
28 Aug
'15
9:36 p.m.
On Fri, 28 Aug 2015 20:31:16 -0500 (CDT)
Tothwolf <tothwolf at concentric.net> wrote:
On Fri, 28 Aug 2015, Chuck Guzis wrote:
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"
On 08/28/2015 07:42 AM, Tothwolf wrote:
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. 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.