Any suggestions, please?

[Li Li]

On Fri, 2010-09-10 at 15:04 +0100, Dave Howorth wrote:
> Colin Law wrote:
> > I always think it is a bit of confidence trick selling electricity.
> > The supplier sends us electrons up one wire but we have to send them
> > back down the other so the supplier ends up with the same number of
> > electrons he started with, but we still have to pay.  It does not seem
> > right.
> 
> It's worse than that. The supplier basically just shakes the electrons
> at you, like tassels on a ????
> 
> According to <http://en.wikipedia.org/wiki/Electric_current>
> "For example, in a copper wire of cross-section 0.5 mm2, carrying a
> current of 5 A, the drift velocity of the electrons is of the order of a
> millimetre per second."
> 
> So in an AC circuit, the electron would get about 1/100 mm or 10 µm
> before it turned around and headed back the way it came.
> 
> I suppose the good news is that you get to keep your own electrons, that
> were inside your coffee maker the whole time.

Ha! But it's the push at the generator that you actually pay for, as
measured in coulombs * push in your meter.  Power engineers were taught
in my long ago time to think in terms of "holes" anyway, i.e. the
absence of electrons on the skin of the conductor.  So you are paying
big bucks for the power company to shove your holes around.  

Better stop now.

Basil: sorted = "sorted out," -- problem solved.  I don't think that's
an Americanism. 

I guess not, but it sure does look like a bum PSU.  You're right,
generally cheaper to just replace the thing and hope that there isn't
anything awful on the MB causing it to fail.  Any decent modern PSU will
have a "crowbar circuit" which should turn it off if it sees a dead
short.   

Do you have another PSU that you can substitute or another old MB that
you can test the suspect one on?  The cheap testers will give you *some*
idea (mainly if the power-good line is working).  I made a somewhat more
elaborate one for my own use which tells more but it could never be a
commercial product because it is very likely to start fires.  

We used to say "I'll just fix it the American way -- hang in parts until
it starts to work."



-- 
Lilly
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