Any suggestions, please?

[Ric Moore]

On Fri, 2010-09-10 at 11:23 +0800, Christopher Chan wrote:
> On Friday, September 10, 2010 10:30 AM, Li Li wrote:
> > On Fri, 2010-09-10 at 08:24 +0800, Christopher Chan wrote:
> >> On Friday, September 10, 2010 03:40 AM, Li Li wrote:
> >>    My experience in places like that was that PSUs died more
> >>> often than in the lower voltage, higher amperage countries.
> >>>
> >>
> >> Power supplies today are all of the switching type. I'd put it to heat
> >> and humidity being the contributing factor rather than the voltage.
> >>
> > Yeah-but it's still winter and cool in the southern hemisphere.  The
> > predicted high for Friday at Sydney is only 20 degrees C and this is
> > almost exactly the average for the date.  I don't know where Basil
> > lives, but unless he's way up north around Darwin he doesn't know what
> > humidity is.   I remember all of the populous places in Oz as being
> > mighty dry, and that was nearly 40 years ago; I'm told it is worse now
> > and last (southern) summer's fires attest to that.
> >
> > I've seen lots and lots of switching power supplies die from
> > over-voltage, spikes and the like.  They can arc spectacularly.  Their
> > whole method of working is very high voltages (albeit at small
> > amperages) and high frequencies: this stresses the cheap components
> > found in most consumer grade PSUs.  Add in the usual house dust that
> > clogs them (anybody else notice that home PCs, even in the cleanest
> > houses, are far dirtier than office machines?), a thunderstorm or some
> > idiot hitting a power pole with a car causing an inductive spike and
> > pow!
> 
> Okay, I take back the part about high humidity and heat. However, low 
> humidity is exactly what will contribute to them arcs you are talking 
> about and of course, over-voltage. So it is not just the voltage alone.
> 
> 
> >
> > Now I'm interested: I'll ask people at my former employer if they have
> > any stats on PSU replacement frequencies, say in 100 V Japan and 250 V
> > Oz for comparable equipment.
> >
> 
> Yeah, me too because we use 220V here in Hong Kong and I am somehow 
> running at 310 (!!!) volts at home according to my digital multimeter. I 
> hope that is not true and that something is amiss about my multimeter 
> but then the previous occupier had recently had the mains replaced so...

Check both legs to ground and see if one of them isn't high. Usually
corrosion in the meter box, especially if you have aluminum wiring, can
be a large problem. Just look for a large ball of oxidized aluminum
around the terminals. Hopefully, your utility company will open it for
you as the power has to be turned off at the pole first.  Ric


-- 
My father, Victor Moore (Vic) used to say:
"There are two Great Sins in the world...
..the Sin of Ignorance, and the Sin of Stupidity.
Only the former may be overcome." R.I.P. Dad.
Linux user# 44256