"larry moe 'n curly" wrote in message
ups.com...
Several months ago, a port on an NEC-based USB card failed (a
section
of its LM3526 power controller & overcurrent protection chip blew),
and
just recently the same happened to an ALI-based USB card. I'm
pretty
sure I didn't zap either card with high voltage because I always
touch
the outer metal shell of the USB connector to bare metal on the
computer case before plugging it in.

Each USB port has a 100-220 uF aluminum capacitor across its +5V and
ground lines, and the NEC-based card also had a ceramic chip
capacitor
in parallel. Is there anything I can change or add to protect USB
ports better? Does it help to use tantalum or low ESR aluminum
capacitors? I installed tantalums on my other USB cards just after
the
NEC card blew.

is this with various USB devices or one in particular? I have yet to
do harm to any USB port, on even my oldest machine. All kinds of
different devices- DC's, printers, keyboard/mice, speakers, sound
devices, USB LAN converters etc.