Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!wuarchive!emory!att!att!fang!tarpit!bilver!bill
From: bill@bilver.uucp (Bill Vermillion)
Newsgroups: comp.dcom.modems
Subject: Re: Which is better to have?
Message-ID: <1991Apr24.154439.22034@bilver.uucp>
Date: 24 Apr 91 15:44:39 GMT
References: <7223.280D280F@zswamp.uucp> <1991Apr18.162946.29336@bilver.uucp> <3921.2812b277@hayes.uucp>
Organization: W. J. Vermillion - Winter Park, FL
Lines: 66

In article <3921.2812b277@hayes.uucp> tnixon@hayes.uucp writes:
>In article <1991Apr18.162946.29336@bilver.uucp>, bill@bilver.uucp
>(Bill Vermillion) writes: 
 
>> And if you get a lightning strike while you are connected to the phone
>> lines with an external modem, the only problem you are likely to have is a
>> dead modem - which brings this line
>> ...
>> If you have a lightning strike nearby when you have an internal modem
>> connected, you have just invited mother nature to be a guest in your
>> machine.
>> ...
>> Think of an external modem as a $200 fuse for a $5000 computer  :-)
>
>I specifically didn't include this widely-held view in my list of 
>advantages/disadvantages.  Why?  Because lighting is so 
>unpredictable and dangerous.  I've seen several cases of lighting 
>going THROUGH an external modem, arcing all around inside, and into 
>the computer through the EIA-232 cable, so I can't list "lighting 
>protection" as an advantage of external modems.  It may help a
>little, but it's no guarantee.  You need external protection,
>whether your modem is internal or external. 

I suspect you see more than your fair share of dead modems coming from
"south of YOUR border".

The last week we have had tremendous storms - almost on a continuing basis.

From experience - yes - lighthing will do strange and unpredictable things.

But in the largest majority of cases lightning strikes that induce voltages
into the phone system will damage a modem, but only seldom will they go
past that.

Locally, in my circle of acquaintences I have not seen a damaged computer
with an external modem.  The worst I have seen is the transceiver chips on
the serial port go too.

On the other hand one machine I know of had an internal modem.  It took out
the motherboard, the powersupply, the video display card, and the modem.

I have had three modems become inoperative because of lightning hits.  (not
too bad for operating 24 hours per/day for 10 years here in the lighthing
capitol of America).  Machines never faltered.

The last problem was induced voltage caused by a hit about 75 feet away
that stripped the bark to the ground on a 75 foot tall pine tree.

The Trailblazer stopped answering the phone, although it thought it was.
Turned out the problem was the relay that takes it on/off line.         

The phone lines have gas-discharge devices entering the house.   It's just
a rule of thumb in this area never to put in an internal.   Particularly if
you are going to be using it any amount of time.

Sometimes the first indication you have a storm in this area is the
thunder.  If you say not use it when there is chance of storms the best
thing is to unplug the modem in April and plug it back in in November.

Average is well over 150 thunderstorms per year in this area ( a strip about
200 miles wide from Tampa bay to Cape Canaveral)


-- 
Bill Vermillion - UUCP: uunet!tarpit!bilver!bill
                      : bill@bilver.UUCP