Jeff Liebermann wrote:


I've run into cute tricks like a big Lambda 12V power supply, that had
a 10 ohm resistor in series with the AC power lead. When the power
supply output finally stabilized, a relay would short out the 10 ohm
resistor so that full power could be delivered. That works great
until the relay contacts arced closed, causing the PS to suck full
current on startup and blowing the fuse. It took a while to find that
one.

Or, the resistor is on the DC side of the bridge, and they have an
SCR triggered by the startup of the switching supply to short the
resistor. If the SCR fails to turn on, the resistor goes up in
flames.

Jon