Jim,
It's a fairly simple electrical situation. There is continuity between the
power input wire of the radio (tied to +12v) and the radio's chassis. Since
there
is no current being drawn, there is nothing else to drop the 12 volts across
except the air gap between the radio chassis and the negative side of the power
source, whicjh happens to be connected to the car's body. The radio is acting
as
if it's a very high value resistor.
Bud Krueger (EE)
"James H. Nazarian, Ph.D." wrote:
> The car could be a reclassified '66, or the previous owners could have done a
> modification, or the title could have been lost and replaced by a newer one,
> etc.
>
> The question is still, "why does he measure 12 volts from the radio chassis to
> a car body ground?" He should be displaying 0.000 vDC. His reading indicates
> either an internal radio short, or a polarity error in the car. How is the
> battery connected? Is the + terminal connected to the starter or the chassis,
> or is it the negative terminal of the battery that is connected so?
>
> Jim
>
> Lawrie Alexander wrote:
>
> > Paul, I'm afraid your supposition is wrong. MGBs changed to negative ground
> > at the end of the 1967 model year.
> >
> > Lawrie
> > British Sportscar Center
> >
> > -----Original Message-----
> > From: Paul Nelson <ya632@victoria.tc.ca>
> > To: mistebar@juno.com <mistebar@juno.com>; MGS@autox.team.net
> > <MGS@autox.team.net>
> > Date: Friday, January 28, 2000 9:52 PM
> > Subject: Re: Radio
> >
> > >At 20:43 1/28/00 -0800, mistebar@juno.com wrote:
> > >>I was just going to do a simple project on our 1968 MGB-GT and put in a
> > >>radio. After seeing the comments, I think I need help. I replaced the old
> > >>radio with a new one using the same wiring. The light on the unit
> > >>"pulsates", but does not turn on. I don't know if the antenna is grounded
> > >>or not. When I touch the radio body with a voltmeter and ground it, there
> > >>is 12 volts. What am I doing wrong?
> > >
> > >
> > >Seems like the 68's were still positive ground, weren't they?
> > >Paul
> > >
> > >
--
Bud Krueger
http://home.ici.net/~bkrueger/
52TD
77MGB
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