[Elecraft] Anyone know this info about switching supplies?

[Dave Martin]

If a switcher had a component failure in the feedback loop it would go
full bore and probably produce twice its rated output voltage until it
totally failed, but none of these components are under much stress, so
it's unlikely to happen.  The failures are usually the switching
transistors or the rectifiers, which both run hot.  But these will
just kill the supply.  So we're pretty safe compared to a linear
supply whose pass transistors run hot and might short, passing the
total unregulated output voltage to the radio.

Dave  W5DHM

On Nov 6, 2007 10:35 AM, Tom Hammond <n0ss at embarqmail.com> wrote:
> Folks:
>
> A local discussion has 'erupted' regarding switching poser supplies and whether
> they can fail in an UNregulated (e.g. high) output voltage condition, or if
> when they fail will they (almost) always fail in a NO OUTPUT mode?
>
> I think this discussion may have been started as a result of a subject here on
> the reflector about overvoltage protection (OVP), but it's managed to take on
> a life of its own with respect to the MODES in which a switching P/S
> can/will fail.
>
> Anyone have enough real experience to express their thoughts on this subject.
>
> Must admit... I have no clue myself.  I've 'heard' that most switchers fail in
> the NO OUTPUT mode, but this is strictly hearsay.
>
> Let's try to get several responses and the let the subject drop before IT takes
> on a life of its own on the reflector and Eric has to step in... he's
> busy enough
> right now. <G>
>
> 73,
>
> Tom   N0SS
>
> _______________________________________________
> Elecraft mailing list
> Post to: Elecraft at mailman.qth.net
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
>  http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>