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Well, I just had my third board start to overheat since I
began using Tant Caps in them.
But, this time, I got better insight to what was
apparently causing it. There is no ON/OFF switch on the module - it is
designed to be ON from the time you turn your master switch on. This to
ensure that when you start your engine the module starts recording your fuel
burn.
Normally, I simply unplug the connector which removes the
power from the unit - with no problem.
However, this time when I was using an uncovered connector
with just two power wires connected for a temporary test. When I pulled
the connector, the power and ground lead made momentary contact - this
apparently caused a surge (voltage/current) that caused a chip to blow. I
had my finger on the heat sink for the voltage regulator and immediately felt it
start to heat up - so disconnected the power before things escalated. I do
have a 30 V schottky diode on the positive lead side to prevent reverse voltage
from damaging the circuit - So not certain what mechanism triggered the failure
mode- but it did.
I do recall reading in some of the studies on Tant
capacitors and some of you have mentioned that sudden surges in voltage can
cause failures - I believe I have verified that {:>). That
reinforces my decision to remove the Tant capacitors - Apparently they work well
under expected conditions but apparently do not have as much tolerance for
unexpected conditions.
Just thought I would mention my experience.
Ed
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