Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.2 9/5/84; site reed.UUCP
Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxt!houxm!vax135!cornell!uw-beaver!tektronix!reed!bart
From: bart@reed.UUCP (Bart Massey)
Newsgroups: net.micro.mac
Subject: Re: Comm./Modem Port Warning!
Message-ID: <2343@reed.UUCP>
Date: Mon, 20-Jan-86 03:41:02 EST
Article-I.D.: reed.2343
Posted: Mon Jan 20 03:41:02 1986
Date-Received: Wed, 22-Jan-86 04:28:44 EST
References: <527@decwrl.DEC.COM>
Organization: Reed College, Portland, Oregon
Lines: 24

> This afternoon I was plugging my Modem port into an extension RS-232 (DB25) 
> cable and, as  I fiddled with the plugs to get them to mate, noticed out of 
> the corner of my  eye  that  the  Mac's  screen  dimmed toward black at one 
> point.  I quickly realized  that this was due to a misallignment of the DB25 
> connectors, where, as I attempted to mate them, the grounded portion of the 
> female plug apparently shorted the +5 provided on the modem cable!!!!!
> 
> I was lucky in that (apparently, and  hopefully!)  no  damage was done, but 
> ***BE CAREFUL***, as I recall reading that the  current  is  NOT limited on 
> these pins.
> 
> Jeff

Better yet, I once thought that it was ok to build mac-mac cables with
the +5 pins connected together.  Big mistake, as we found out when we
realized that if one mac was on and the other off, the on one powers the
logic board of the off one through that 5-volt pin!!!!  You have been
warned...

				Bart Massey
				..tektronix!reed!bart

"Wait, why is that Mac drive whirring with the power turned off?"
"Must be the serial cable."