🚀 go-pugleaf

every pc tech who knows ne thing about pc's will tell you surges down phone
lines kill modems and sometimes entire pc's, so the dumb f@@@@ who keep
coming on here and saying that they don't need to re-train.

"Richard Unsworth" <richard@runsworth.freeserve.co.uk> wrote in message
news:bjars7$9ad$1@newsg4.svr.pol.co.uk...
> All I know is that many people I have spoken to while answering technical
> support lines have suffered blown modems due to a nearby lightning storm.
> eg. 1. It worked and connected 2. There was thunder and lightning nearby
3.
> It says 'No dial tone'.
> And this happened to my pc - I heard just one spectacular bang the April
> before last - I was about a mile and a half from home. The next day I
> switched on the pc - dead. Nothing. Having left my diagnostic brain at
work,
> it didn't dawn on me until a local child said 'Have you seen where the
> lightning blew the paving stone into the road?' This was sixty yards down
my
> street. Result? Modem, motherboard, memory, graphics card, sound card -
> every component attached directly to the motherboard was dead. w_tom can
say
> all he likes about electrical theory, but experience has shown me that
> lightning surges down the phone line blow modems up! After my own
> experience, I like to tell callers that the modem has acted as a fuse, and
> saved the rest of their P.C. - they seem to find this reassuring!
>
> "JAD" <jdemma25@eartink.net> wrote in message
> news:If__a.20585$vo2.8017@newsread1.news.atl.earthlink.net...
> > so tom  did lightning take out his modem?
> >
> >
> >
> > "w_tom" <w_tom1@hotmail.com> wrote in message
> > news:3F3C237C.7A74E7E9@hotmail.com...
> > > This discussion is cross posted to numerous newsgroups - not
> > > just a UK newsgroup.  Concept of breakdown voltages still
> > > apply on both sides of the pond.  For example isolation
> > > transformer in modem's DAA circuit may provide 2000 volts of
> > > galvanic isolation.  However destructive common mode surges
> > > are current sources.  That current will increase voltage, as
> > > necessary, to turn that transformer or optocoupler into a
> > > conductor. Either they provide isolation without damage, or
> > > they do not and become damaged as surge passes through.
> > > Through seeking what?  Earth ground.
> > >
> > >   Protector components do not sacrifice themselves to protect
> > > electronics.  Either destructive current flows through them or
> > > no current flows - no damage.  But again, destructive common
> > > mode surges cannot be stopped, blocked, filtered, or
> > > absorbed.  As in a flood, the dam will not stop a flood.  A
> > > dike will divert the flood, but only if the flood is shunted
> > > downstream.  Galvanic isolation works like a dike.  Only
> > > effective IF the surge has some other, non-destructive path
> > > downstream - to earth ground.  That is what the 'whole house'
> > > protector does; shunt the surge downstream to earth.
> > >
> > >   Appliances already have galvanic isolation.  But again, that
> > > internal protection will only be effective IF the surge is
> > > earthed before entering a building.  Appliances already have
> > > 'dikes' that will be overwhelmed if the surge is not earthed
> > > before entering the building.  Just as dikes work for the
> > > town.  If flood is not provided a downstream path, then 'dike'
> > > is acting like a dam - and is overwhelmed.
> > >
> > >   There are no sacrificial components in an effective
> > > protection system.  Even a thyristor based crowbar circuit is
> > > properly sized to shunt without damage.   A common mode
> > > transient either does nothing to the optocoupler OR creates a
> > > plasma path through that optocoupler.  A direct lightning
> > > strike is earthed without damage to transistors or the
> > > protector.  Protection is not difficult and performed so often
> > > that protector damage is not an option.  No sacrificial
> > > components are found or used in an effective protection
> > > system.
> > >
> > > www.ees-group.co.uk/downloads/Secondary%20Effects.pdf
> > > An interesting discussion, but where does this apply to
> > > anything posted here?  What numbers apply to this discussion?
> > >
> > >   We know how to protect everything from direct lightning
> > > strikes without damage even to the surge protectors.  Moreso,
> > > the protection is so inexpensive.  However plug-in protectors
> > > ARE expensive and not  effective protection - which is why
> > > they don't even claim to provide such protection.
> > >
> > >   Described in the previous post is how effective protection
> > > from direct lightning strikes is implemented - complete with
> > > products and where they can be purchased.  Even the
> > > www.ees-group.co.uk article does not dispute what was posted.
> > > Bottom line is this: a surge protector is only as effective as
> > > its earth ground.
> > >
> > >
> > > Nigel Kendrick wrote:
> > > > "w_tom" <w_tom1@usa.net> wrote in message
> > > > news:dfee1359.0308120333.5a970e26@posting.google.com...
> > > > > As soon as a read about 'fusible' components that protect other
> > > > components, then I know the poster does not have electrical
training.
> > > >
> > > > Actually, I'm an electronics engineer by training, including 4 years
> on
> > an
> > > > electronics engineering apprenticeship and a total of 6 years as an
> > > > electronics design engineer for visual systems for flight
simulators.
> > > >
> > > > > > either have a fusible transformer that 'sacrifices' itself in
the
> > event
> > > > of a surge in order to protect the PC,
> > > >
> > > > Instead of 'transformer', I should have written 'isolation circuit'.
> The
> > > > transformer isolation circuit in a modem includes components to damp
> > mild
> > > > surges - MOVs, gas arrestors, zener / avalanche diodes etc. These
will
> > fail
> > > > in the presence of *massive* surges but will often damp down
> potentially
> > > > damaging (to the PC) surges to safer levels.
> > > >
> > > > >   There is no sacrifical component to save electronics - except
> where
> > > > urban myth replaces electrical knowledge.
> > > >
> > > > Obviously not seen a crowbar circuit then--but that's off topic :-)
> > > >
> > > > > In the UK, this is different
> > > >
> > > > Freeserve is a UK ISP and so it would be safe to assume that all
> > discussion
> > > > points in this newsgroup should be based on UK conditions
> > > >
> > > > >   Furthermore the concept of breakdown voltage is totally unknow
to
> > > > > the poster.
> > > > > Even optocouplers have breakdown voltages typically starting at
2000
> > > > volts.
> > > >
> > > > Er, no it isn't but I wasn't specifically referring to breakdown or
> > > > flashover between the input and output of the opto isolator - a
surge
> on
> > the
> > > > input circuit will damage the opto isolator even if the applied emf
is
> > > > insufficient to flash over to the output side so, in effect, the
opto
> > > > isolator has sacrificed itself in order to protect other equipment.
> > > >
> > > > > Surge damage is easier in UK where even the phone line has no
'whole
> > > > house' protector.
> > > >
> > > > Exactly
> > > >
> > > > >
> > > > >   That claim of EMP induced surges is only another urban myth that
> > > > > falls flat on its face when the myth purveryor cannot provide
> numbers
> > > > > to support that claim.  Appliances have such good internal
> protection
> > > > > that only the direct strike causes damage.
> > > >
> > > > You want numbers - OK, read the following article which has data
> related
> > to
> > > > electromagnetic pulse damage caused by lightning.
> > > >
> > > > www.ees-group.co.uk/downloads/Secondary%20Effects.pdf
> > > >
> > > > NK
> >
> >
>
>