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From: gil@limbic.ssdl.com (Gil Kloepfer Jr.)
Newsgroups: comp.unix.sysv386
Subject: Re: internal Telebit, SCO Unix 3.2, 80 bytes/sec???
Summary: Oh yes, watch out for that lightnin'
Message-ID: <131@limbic.ssdl.com>
Date: 6 Jan 91 04:25:02 GMT
References: <24558@dime.cs.umass.edu> <130@limbic.ssdl.com> <5626@rsiatl.Dixie.Com>
Organization: Southwest Systems Development Labs, Houston, TX
Lines: 33

In article <5626@rsiatl.Dixie.Com> jgd@Dixie.Com (John G. DeArmond) writes:
>Plus, as KE4ZV (hi gary) can verify, an internal modem will conduct
>a lot of lightening into your machine and turn it back into silicon
>raw materials minus all the blue smoke.

Make that three...'cept not with a Telebit...

I recently had the unfortunate experience of one of those "one-hit-wonders"
which come without warning.  Nothing damaged on the electric lines, but
it fried a voice processor (3B1 Voice Power board), a serial board (the
modem survived, believe it or not), and a terminal connected to the
same serial board as the modem.

An interesting follow-up question is this:  There is a small amount of
lightning protection on the phone lines (usually of the carbon spark-gap
variety), which obviously don't eliminate the problem nearly enough
for sensitive electronic equipment.  I also know (and have preached)
that NOTHING can stop a good lightning strike from frying your computer,
except for unplugging it from the power and phone lines.  However, how
effective are a pair of MOV's from each leg of the phone line to ground?
(ie. ring-to-ground and tip-to-ground).  One problem with both the voice
power board (no MOVs) and the modem (only a MOV across ring and tip) was
the lack of adaquate means of sending the offending high-voltage surge
to ground.  After having my unfortunate experience, I made a little
phone-line surge suppressor as mentioned above...however I'm not too
sure of how effective it may be.  BTW: my device handles 4 phone lines,
and it is connected at the first available place I can attach it to the
phone line.
-- 
Gil Kloepfer, Jr.              gil@limbic.ssdl.com   ...!ames!limbic!gil 
Southwest Systems Development Labs (Div of ICUS)   Houston, Texas
"There are beautiful people I wish would have never opened their mouths,
because such ugliness oozes out."  Philosophy Prof. at NYIT