Failed ICs and components

Mattis Lind mattislind at
Thu Feb 12 02:19:48 CST 2015

When I was repairing my HP9810 ( I replaced 13
TTL ICs. 12 out of 13 were National Semiconductor, one was Signetics. There
were all sorts of TTL types, 7400, 7402, 74H40, 74H53, 7474 etc. I sent 6
to Marc Verdiell that X-rayed them but there were no apparent fault visible
from those X-rays. I still have six or seven left that I can send to you if
you like. They are all manufactured around 1972.

2015-02-11 23:57 GMT+01:00 Kyle Owen <kylevowen at>:

> I am writing my master's thesis on accelerated life testing and would like
> to get a collection of parts to decap and experiment on. What prompted my
> study is a failed 7474 dual flip-flop in a PDP-8/E. As I later read (on
> here, I believe) was that the 7474s seem to fail in higher number than
> other 7400-series ICs. Is this because of a design flaw? I'm not sure
> (yet), but would like to find out.
> More recently, I saw a 680k 2W carbon resistor that read 1.3 meg out of
> circuit. As it turns out, it was in a high voltage portion of the circuit,
> and I suspect that electromigration caused its failure over time. Many of
> you are probably already aware that carbon resistors tend to increase in
> value as they age, though there are a few explanations too for that
> behavior, as I understand it.
> I would like to tie all of this together by researching older accelerated
> life testing schemes, examine how those parts actually fared, and see how
> current day models might be improved.
> If anyone has a collection of dead ICs (preferably those that have died
> inexplicably, and not by extreme overvoltage, for instance), I would like
> to talk to you about getting a few. If they are 7474s from Texas
> Instruments, ca. early 1970s, even better!
> Thanks in advance,
> Kyle

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