IBM 1620

Tothwolf tothwolf at
Fri Aug 28 09:42:42 CDT 2015

On Thu, 27 Aug 2015, Lyle Bickley wrote:

> The IBM 1620 at the CHM is a running computer. There were two teams that 
> worked on the 1620 at the CHM. The first Team got it running. 
> Unfortunately, IBM used the wrong kind of solder on the core memory and 
> so the wires of the core memory literally "dissolved".

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?

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