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Re: ballast resister voltage drop - electrical guru needed

To: aribert <aribert@c3net.net>
Subject: Re: ballast resister voltage drop - electrical guru needed
From: George Richardson <gprtech@frontiernet.net>
Date: Mon, 09 Jul 2001 09:19:55 -0400
Cc: triumph list <triumphs@autox.team.net>
Organization: Merlin Group Inc.
References: <3B4979C2.420783FA@c3net.net>
Two things here:

First, use the MSD resistor. Don't worry about what Crane says.

Second, the Crane should be wired to take it's voltage from the vehicle
power source, *NOT* the positive side of a coil that's wired to a
resistor. Move the Crane positive wire to the positive side of the
resistor. 

I've put a Crane XR700 on my resistor equipped Stag, red wire to
resistor positive (away from coil), yellow wire to coil negative side,
and black wire to chassis ground.

aribert wrote:
> 
> My '71 GT6 has a Crane XR-700 ignition system.  With the engine
> running:  alternator voltage is 14.2v,  voltage into ballast resistor is
> 13.8v, voltage out of the resistor is 9.2v.  Ballast resistor reads 1.7
> ohm (catalog rated at 1.35 ohm).  My coil (MSD Blaster 2) reads 1.1 ohm
> across the terminals.  NOTE: both of my multimeters read 0.3 ohm thru
> the leads alone so all of the above resistances could be off.
> Additional electrical trivia: Blaster 2 coil came with a 0.8 ohm rated
> ballast resistor and Crane specs a 1.2 to 1.9 ohm resistor.
> 
> What could be causing such a large voltage drop?  Speaking to the people
> at Cranes tech line, the XR-700 likes to see 10 to 12v at the coil(+)
> terminal for their module - essentially 2v drop from charging voltage.

-- 
George Richardson
Wyvern - '57 Triumph TR3, TS15559LT -
http://www.merlingroupinc.com/tr3.htm
Griffin - '71 Triumph Stag - Daily Driver - when running!
Pikachu - '75 Triumph TR6 - undergoing repair
Kitty - '83 Jaguar XJ6 Vanden Plas - Waiting for engine overhaul

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