30 Aug
2015
30 Aug
'15
6:01 p.m.
On Sun, 30 Aug 2015, ben wrote:
On 8/30/2015 6:32 PM, Tothwolf wrote:
My guess is that over time the thinned wires broke due to a combination of
vibration and thermal fatigue. Vibration while transporting the system to
CHM may well have been what ultimately caused them to break.
On page 5, they describe 0.0031" 40 AWG
magnet wire being reduced to
0.002" after soldering with 60/40 tin-lead solder. That 0.0011"
reduction is basically 1/3 of the diameter of the wire. This explains
the failures of the enamel wires in CHM's IBM 1620.
Copper erosion from tin is something I'd never really given a lot of
thought to, but it will certainly be something I keep in mind from now
on.
But is that the case? Would not heat induced failure be the real case
here as I suspect that a amp or two of current is flowing that now very
thin thread of wire? Digging though the doc's and a little calculation
clear this up.