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Wiring oddity

To: <peterz@merak.com>
Subject: Wiring oddity
From: "Sumner Weisman" <sweisman@gis.net>
Date: Sat, 4 Apr 1998 16:38:49 -0500
Cc: "Triumphs" <triumphs@Autox.Team.Net>
Peter,

Here's what I think is happening:
The radio case is connected to the chassis of the car.  Your ground return
in this radio is not electrically floating -- that is, it is grounded
directly to the case inside the radio.   So, current can now flow from the
positive terminal you have connected to power the memory and clock, 
through the radio, to the battery negative terminal.   In other words, you
have bypassed the new cutoff switch and current can take an end-run  to
chassis via the radio.  If this is true, then if you turn on something that
draws a lot of current, for example the starter, all that current will try
to return to the battery negative terminal through that skinny little wire,
which will burn open like a fuse, at minimum.  It may also damage your
radio.  However, if you're lucky, you have a fuse in series with the
positive terminal, and that will just open and protect everything.  That's
what it's there for!

Sumner Weisman
Framingham, Mass.
62 TR-3B

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