15 Nov
2004
15 Nov
'04
10:06 a.m.
>>>> "Joe" == Joe R
<rigdonj(a)cfl.rr.com> writes:
Joe> Testing power supplies before powering up a system is just plain
Joe> paranoid! (And I'm trying to be polite here!) There are a
Joe> thousand parts in modern computers that can cause just as much
Joe> damage!!!!!!!!
I disagree -- at least in the case of linear regulator supplies, which
is what you'll normally find in a classic computer.
A very simple and very nasty failure in a linear regulator is a short
in the pass transistor. If that happens, you get a much higher output voltage, and there is no current limiting. It's a
fair bet that this
will fry a large fraction of the semiconductors in your system.
If the supply has a "crowbar overvoltage protection" circuit in it,
that's a different matter. But testing a linear supply is trivial.
So why not do it?
I'd rather not trust a protection device if I don't have to. Sure I like
crowbar circuits, and they have saved my chips a few times, but I don't
like to depend on them.
-tony