[SML] Fwd: DMX hardware

[Dan Sheehan]

digging a little deeper...

why did that 75176 device fail this way (resistive path to ground on
an input pin) ?

one quite likely possibility is an ESD zap, or electrical overstress,
on that pin
 with sufficient energy to do a partial meltdown of the ESD protection
diode clamp[s]

another, less likely, is corrosion (sometimes called "purple plague" )
 on the leadframe, inside the plastic DIP package;
 this has sometimes been a problem when bromine compounds have been
 added to the plastic to meet flame retardant specs

"Hobbit" said he was *going* to replace the suspect device,
not that he did.

 It's also possible that the path to ground was on the PC board under
the socket,
which could be likely if the board hadn't been properly cleaned after
flow solder

(In my day job I was an electronics test engineer for a major semiconductor
manufacturer, and was involved in a lot of failure analysis.
If this failure happened during product qualification, the FA lab
would dissolve away the plastic and look at the exposed device
with high powered microscopy)

Automobile manufacturers are quite concerned about stuff like this.

-- 
...Dan Sheehan
Fixer of things that break