The y have used Fairchild for their source.
If so, that explains the high rate of failure.
Years ago when at Intel, we disqualified Fairchild
as a source for parts because of the poor testing
and high failure rates.
Dwight
I seem to remember the 7474 that failed was actually a TI part, but
I'm not entirely sure now.
Something I forgot to note was that this instrument (the 4261A) was
actually manufactured for HP by Yokogawa, I'm not too sure where the
HP part ends and the Yokogawa begins, maybe it was designed by HP and
built by Yokogawa, or maybe the whole thing was a contracted design
for HP by Yokogawa.