The drive resistor value (it's actually marked on it) is 9.5 ohm. That's all I
can contribute as that the only part I have.
I did see a schematic once (me thinks it must have been on the web) of one of
those and all it had was a couple of power transistors etc. So acting as a
pull-up would make sense. I'll scratch around and see if I turn it up again.
Alan
-----Original Message-----
From: "spitfires-owner@autox.team.net" <spitfires-owner@autox.team.net> on
behalf of "Donald H Locker" <dhl@chelseamsl.com>
Sent: Thu, 12 Sep 2002 11:12:43 -0400 (EDT)
To: "ptegler@cablespeed.com" <ptegler@cablespeed.com>
Cc: "bschwart@postoffice.pacbell.net" <bschwart@postoffice.pacbell.net>,
"spitfires@autox.team.net" <spitfires@autox.team.net>,
"triumphs@autox.team.net" <triumphs@autox.team.net>
Subject: Re: Distributor wiring
Thanks, Paul. I guess I don't have late enough schematics; none of
mine show that resistor. .... Oops. Just looked and my [factory]
book is MkIV, not MkIV/1500.
So, picking Haynes Brains, I see the "Drive Resistor," and it is only
sort-of connected across the distributor -- one lead (Green) connects
to ignition switch contact 3 via a White wire, one lead (White) goes
to the distributor, and a third lead (White/Blue) also goes to the
distributor. The diascratch makes it look like the White and
White/Blue leads attach to the distributor ground terminal.
The drive resistor is covered in Chapter 4, Section 15 (and mentioned
in Chapter 4, Section 2.) "Covered" is perhaps too generous a term --
"This is a remotely sited component of the ignition amplifier unit,
its purpose is to function as an essential requirement of the
amplifier transistors." i.e. you need one.
Since there are three terminals, one of which is electrically "hot,"
it would appear that it provides pullup or bias to a couple of devices
in the ignition amplifier. So, anyone willing to pull out an ohmmeter
and give us three resistance readings? With all wires disconnected
(please don't forget to label where they attach, 'cause I don't know!)
Green terminal to White terminal, Green Terminal to White/Blue
terminal and White to White/Blue? I'm just curious. And maybe even
voltage readings (to ground) from each terminal while the engine is
running. Again, just curiosity at this point.
Donald.
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