PicDude wrote:
> Late last night, while building a 3-output power supply, a capacitor
> burned out (it just made a poof sound and the electrolyte leaked out)
> and it's totally baffling me.

Most likely possibility:  The capacitor was in backwards.  They do take it
for a while, then BOOM.  I know you said you checked this.  Check it again.
I still think it's the most likely explanation.

Second possibility:  The ripple current was way too high for the cap, which
heated it up and eventually caused it to explode.

> Also,
> can/should I test with the existing (blown) cap in place, or should I
> replace it first?

Definitely replace it.  It could look like an open, a short, or a toxic fume
generator.

> I know that switchers need a minimum load,

Not true.  Some commercial switching power supplies do indeed need a minimum
load, but this is not inherent to switchers, only particular
implementations.

> How would I determine the min load required?  The datasheet does
> not indicate how to determine this.

If it has a minimum load, this should be in the data sheet.  If the data
sheet doesn't mention it, then I would assume it has no minimum load
requirement.


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