14 Jul
2003
14 Jul
'03
12:33 a.m.
Robert Krten wrote:
<snip>
:-)
In my case, the failure modes were as follows:
2 chips failed with: grounding the PRESET line caused the Q
to go high as expected, but when PRESET was left floating Q
went low. [DEC leaves the PRESET and CLEAR lines floating on
various modules, so I consider this a fair test].
1 chip failed with insufficient +5 on the Q (or bar-Q, forget
right at this instant) output. The measured output was something
like 1.6V.
<snip>
That sounds like a design flaw. Even with TTL, unused inputs should be
tied to somthing.
What was the fanout for the Q /Q on the fried output?
Jim Davis.