Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!carssdf!usenet
From: usenet@carssdf.UUCP (UseNet Id.)
Newsgroups: comp.unix.xenix
Subject: lightning damage, RS232
Keywords: lightning
Message-ID: <184@carssdf.UUCP>
Date: 10 Jul 89 01:41:29 GMT
Organization: C.A.R.S.,Middlesex,NJ
Lines: 47


Symtom: Lightning Storm nearby causes damage to one or both ends of the
data line.  Usually type '188 or '189 devices.  

I need some help to get through this summer.  Could anyone please email
(I will post summary) suggestions that have helped others, or explanations
to some of the following mythical tails that follow.

Plugging devices into orange outlets helps. :-)
 It helps even more if the ground (green) from these outlets is tied back
 to a central point and earth grounded there. (No connect to box/conduit)

 It would seem to me that this would only provide a superior return path
 for the induced charge in the data line to return to ground.

Question: Are we dealing with a magnetically induced current, or a capacitive,
  static pickup of some kind.

Using shielded data cables will ward off evil charges/inducements.
  Well, charges maby, but inducements, I don't think so.  If so, what
  do you do with the shield, besides connecting to pin 1 at each end
  and probably just generating a ground loop current, and about half
  the equip. I work with doesn't even have pin 1 connected.

Placing expensive ($50 each end) protection devices at each end will neutralize
  evil.  DO THESE WORK?  What are they? Ferite Beads, cap, diac, MOV?
  If they are necessary why not put the magic circuit on the Terminal or
  the CPU (Computone?) driver/receiver circuits.

Socket all the '188 & '189 devices, like WYSE does on their WY-60 terminal,
  but not yet the WY-995 mux board.  If in doubt, pop 'em out.  At about
  a dollar a piece they are cheaper than some fuses, and ignore the whole
  issue.

Turning off the system durring potential for lightning will help.  At
  least it is more humane, the system will never see it coming. :-)
  OR- Potential for latch up and thermal distruction of chip will be
  reduced?  (How should I know when I got my Clarkson degree in '71
  LS logic was not invented yet, RTL was the word and the computer was
  optically isolated.  We never saw it!)

I realy like the new modular telephone connector system for snapping together
a system, but am I just stretching out antenna waiting for disaster?  Does
anyone know where to get SHIELDED MODULAR CABLE?

Any help would be appreciated, John Watson, Middlesex, New Jersey
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