N_Cook wrote:

Old removed, tuned pin 20w socket , in place, easier to check continuity
etc, finish that tomorrow and push in NOS LS373.
Loads of black corrossion product on the pins of this IC and only this
one , no other TTL,4000 or analogue, whatever that means, outgassing
something ?. Cracked it open and frame metal was clean on the internal
pins I could see where free of encapsulant.
Texas Instruments, SN74LS373N, Malaysia 8206X if a batch problem.
Well, not clear if the original chip was in a socket.

There was a certain vintage of TI chips that had a silver plating that could
turn absolutely BLACK! These could certainly cause bad contacts in sockets,
but I think I've seen a couple times where it was so bad it got down and
isolated the pin from the through-hole in the board. I thought these were
before 1982, back in the mid-late 70's or so, but must have still been doing
that plating later. I'm pretty sure it didn't come from inside the chip,
but the effect of atmospheric sulfur on the silver plating.

Jon