w_tom said:
Incoming and outgoing currents on two AC wires is a
differential mode transient. First such transients are easily
stopped or made irrelevant by computer power supply. Power
supply contains layers of protection including isolation
transformers, optoisolators, and shunt devices that make
differential transients irrelevant. Second differential mode
are typically not the destructive transient.
As per usual with w_toms pontifications he has it all Arse about Face.
Defined is a typically destructive transient - lightning -
that would be common mode. Incoming on any one or all AC
electric wires. And yes, one incoming AC wire even bypasses
power supply to connect directly to motherboard and
peripherals.
This is fantasy this wire does not exist ! must be like w_toms wire
that directly connects between the AC mains and the Electronics in a
modem - he never identified that wire either !
The mother board does not connect directly to AC mains - hands up
everyone here who has received a serious belt while working on a PC?
Right now keep your hand up if the Power supply was not either Faulty
or it case open.
whats that ? no one has their hand up any more ?
w_tom must be wrong again ! - no surprises there.
Look for outgoing path elsewhere, such as mouse
cord hanging on baseboard heater, via network cable, or a most
common outgoing path - modem and phone line to earth ground.
And more Complete crap from this ignorant fool there is NO EARTH ON A
PHONE LINE. how much more simple could it get this is why the most
common path for Lightning damage is : Strike enters via phone Line and
exits to MEN earth.
Of course we have to bear in mind here that w_tom has a vested
interest in the sale of AC surge arrestors.
Again, this is common mode.
He cant even get common mode and differential right.
But to appreciate it (and what
ineffective protectors would have you not understand to make
their sales), the analyst's perspective must include cloud,
building, earth, and computer. Analysis only inside computer
is too myopic.
not true Lightning causes damage in the PC !
The most effective protection is that which makes the strike COMMON
MODE to the PC electronics it is a simple equation :
Power (heat this is the bit what causes damage) = Voltage * Current
in other words if we make the Voltage zero or common mode (ie common
to all the electronics in the PC) then it survives.
A destructive transient seeks earth ground.
One path to earth ground is via computer because transient was
not earthed before entering the building.
Not earthed ? I wonder which path it took to enter the building then?
Lets see now we have two possibilities here :
AC mains supply :
Earthed at every Main switchboard in the street
Connected together using relatively low impedance cabling typically
greater than 6mm square copper
Neutral is also tied to Earth
impedance between Active and Neutral is very, very low typically well
under 0.1 of an ohm.
Phone Line :
Not earthed at all
connected up using 0.25 mm square copper
Well I wonder which the most likely path for Lightning is ?
It aint rocket science.
I have personally seen Lightning damage which had travelled down 4 +
Kms of phone cable (after blowing the living shit out of the Lightning
protection connected to the cable)
Only now are we ready to identify that common mode transient
path, inside computer, to earth ground. There is no such
outgoing path through CPU or memory. One path may exist via
printer port - depending on how and where printer connects.
But to find those outgoing paths, analyst must include other
electrically conductive materials such as baseboard heat
pipes, vinyl or concrete flooring, etc.
The Path is actually very straight forward in this case :
In via the unearthed Phone line, Through the modem, across the
Motherboard .... and UP spook hill .... oops! sorry and straight to
MEN, Mains earth !
w_tom is of course desperately trying to encourage people to buy
'whole house protection' which is why he chooses to ignore the obvious
and basic pysics.
Some may talk about external modem damaged today. Then
serial port fails tomorrow. It is called overstress. Expect
an overstressed semiconductor to fail days or even months
later. This is why we identify the path that a common mode
transient would seek to earth ground. This is why any or all
three incoming AC wires are typically only the incoming
current path.
Crap! utter Crap! the AC mains is typically at best the outgoing Path
not the incoming path - if w_tom had a basic understanding of
Electricla theory he might understand that
Big difference between differential and common mode
transients. Since common mode transients are a typically
destructive type,
Crap!! Common mode spikes are ummm common mode therefore V = bugger
all and no damage occurs
then effective protection must be located at
the building service entrance; to earth that transient before
it can enter the building.
and into the sales spiel.....
Once inside a building, well, one
must spend significant time locating numerous potential paths
to earth ground through that Dell computer.
One obvious Path :
in via Phone line and out via the Mains earth - the fact that the PSU
has not failed strongly supports this argument...
Dont bother they are wrong.
ahh that would make the voltage 'common mode' according to w_tom logic
that should work - I wonder why it does not ? ;-)
what you mean you have to make the voltage differential ? well bugger
me! w_tom must be wrong after all ;-)
Regards
Richard Freeman
