>> [...] there migth be excessiveripple on one of
the power lines.
Have you put a 'scope on the power liens to check
for ripple?
Don't have a 'scope yet. [...]
I am tryign to think if
there's any way you could find the fault with
just a multimeter...
Well, if the meter has an AC setting, you can hook it up with a
middling-large series capacitor, er, condenser, to measure the ripple
on the power rail fairly directly. (What counts as "middling-large"
depends on the frequency of the expected ripple and the impedance of
the meter - you want the cap's impedance at the frequencies in question
to be small compared to the meter's. Depending on the meter's design,
you may also need a DC path somewhere.)
Mouse