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Topic: alp death... dueling engineers (62 lines)
1) From: john roberts
First allow me to apologize to the rest of the list for this off-topic
debate. I was trying to throw an olive branch to Rick and not confuse the
original poster with apparently conflicting information. I repeat we are all
held to the same physical laws controlling how electronic devices behave.
The immediate consequence of a shorted diode is to present the power supply
reservoir capacitance directly across the transformer winding. Since large
capacitors look like a short to AC voltage, large ripple currents will flow
often leading to secondary failures if the transformer isn't adequately
fused.
Depending upon the rectifier topology, these large fault currents from a
shorted diode may flow through other diodes in the circuit. In the case of a
non-center tapped full wave bridge, the diodes opposite the shorted one will
each carry the full fault current for half the time. One conducting during
the positive half cycle, one during the negative half cycle. If the fault
persists long enough one or both of these can fail too (from over "current"
induced heating).
JR
PS: I won't bore the list with my full curriculum vitae but I've been
designing electronic circuits for a few tens of years. I have managed an
engineering department for a large music industry manufacturer and hold 8 US
Patents.


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