"w_tom" wrote in message
...
This is deception:
I like to tell callers that the modem has acted as a fuse,
and saved the rest of their P.C.
Lightning has traveled many miles through non-conductive
air. Is a silly little 'fuse' going to stop what miles of air
did not? Of course not. But basic technology also says a
fuse (response time 10 milliseconds) cannot possibly protect
from a surge (typically 100 microseconds). No fuse is
installed to provide such protection - as demonstrated twice
over.

First, surge passed through modem's off-hook relay circuit

You are starting to grasp the concept then .

and other components including motherboard ground plane.

well since we are being pedantic here try "heading for the Ground plane"

Only
then does something fail; typically a modem off-hook relay.

built in surge arrestors, Input and Output op-amps, Modem processor, Modem
PSU etc etc etc

Typical reason for so many computer peripherals damaged -
surge entered on AC electric and exited to earth ground via
other paths.

Damn just when I thought w_tom had grasped the concept. Once again w_tom
goes on with his fantasy that Lightning comes in via AC mains and exits via
the phone Line.

Lets see now applying a little bit of Basic Physics and electrical Theory we
have two Lines:

Phone Line:
No earth on either leg of the cable in fact a very high impedance path to
earth via the phone line maybe several kms away.
thin relatively high impedance wire with a DC resistance alone running to
tens of Ohms (which is why exchange damage is less common - but still
occours)

AC Mains:
typically runs multiple earthed Neutral that is multiple Earth points (in my
street about every 25 metres or so)
Relativily thick low impedance often multi strand cabling a fraction of an
ohm in impedance and with even the Active to Neutral path (via the
Transformer) giving a nice low impedance path to earth.

hmmmm no prizes for guessing which is the better path to earth here folks !

No damage can occur without both incoming and
outgoing path.

yep !

One traditional path that causes "No Dialtone
Detected" message is incoming on AC electric and outgoing on
phone line to earth ground.

BS! incoming Lightning coming in via the phone line blowing the living *^&t
out of the modem on the way through and exiting the far superior earth on
the AC mains

Damage that has often been
demonstrated by replacing off-hook PNP transistor; making
modem work again.

In the event of a distant strike maybe if you are lucky (but lets face it
who fixes modems nowadays ?)
in the event of a near or direct strike ... Forget it your modem is toast.

Surge damage is traceable to wires that entered building
without a connection to central earth ground. Modem never
acts like a fuse nor protected anything. That surge, as
taught in primary school science, first must have passed
through everything in a complete electric circuit. Many
forget primary school science when rationalizing about surge
damage. Many say the surge entered on phone line, damaged
modem and stopped -

Well almost more like Lightning entered modem via phone line and found nice
alternative paths to earth via AC mains - also via your PC motherboard if
you have an internal modem. But to all intents and purposes since it was
safely shunted to (mains) earth at this point and if it did no further
damage. it effectively dissapeared from the users view at this point.

a direct violation of primary school
science. It is that simple. Modem was damaged because surge
first took a complete circuit path through that computer - and
only then damaged something.

well if you are being a pedant it took a complete circuit path through that
computer and fried it en route.


Richard Unsworth wrote:
All I know is that many people I have spoken to while answering
technical
support lines have suffered blown modems due to a nearby lightning
storm.
eg. 1. It worked and connected 2. There was thunder and lightning nearby
3.
It says 'No dial tone'.
And this happened to my pc - I heard just one spectacular bang the April
before last - I was about a mile and a half from home. The next day I
switched on the pc - dead. Nothing. Having left my diagnostic brain at
work,
it didn't dawn on me until a local child said 'Have you seen where the
lightning blew the paving stone into the road?' This was sixty yards
down my
street.

Yep thats classified as a near strike

Result? Modem, motherboard, memory, graphics card, sound card -
every component attached directly to the motherboard was dead. w_tom can
say
all he likes about electrical theory,

I dunno why, he has a little trouble grasping basic electrical theory.

but experience has shown me that
lightning surges down the phone line blow modems up!

Yep that right and anyone else in the Comms/Data Comms industry would tell
you exactly the same thing.
two useful tips:
1) unplug the phone line from your modem/PC when not in use
2)use an external modem for preference - it is no guarantee but at least it
keeps lightning that one step further away from your PC

After my own
experience, I like to tell callers that the modem has acted as a fuse,
and
saved the rest of their P.C. - they seem to find this reassuring!

well while not strictly correct, I know what you mean.
Maybe for the sake of the pedants word it as : "your modem acted as a surge
arrestor and redirected the Lightning to the Mains earth"

Regards
Richard Freeman