Yo Glenn,
The Alternator light is in series with the field winding of the Alternator.
The field winding needs to have 12 volts DC applied to it. When
the 12 volts is there, the field winding forms an electromagnetic.
When this magnetic turns it causes a voltage on the outer winding.
This is the voltage that eventually charges the battery.
Once the alternator begins turning, the charging voltage becomes enough
to power the field winding. Before this (when the alternator is not
turning)
the field winding power is supplied via the battery using the charging
light to complete the circuit.
All of this means that if the warning light is burned out, the field winding
will never become a magnet, and the alternator will never produce any
output.
Alternately (forgive me please) if the field winding has an open circuit
the same result will occur.
This is what happened to me. The OEM lucas alternator is so wimpy, it got
hot
enough to reflow the solder connections of the field coil and it openned up.
The only other thing that could happen is you lost the regulator, which
is the ground path for the field coil. You can find a replacement regulator
for little $$, but replacement with a bosch alternator is a better solution
in the long run.
Dan Master has some great drawings on the web showing the circuitry for
all of this stuff http://www.vtr.org/maintain/alternator-overview.html.
cheers
jayb
> -----Original Message-----
> From: owner-spitfires@autox.team.net
> [mailto:owner-spitfires@autox.team.net]On Behalf Of Glenn Trunnell
> Sent: Monday, March 22, 1999 4:15 PM
> To: Spitfires@autox.team.net
> Subject: Alternator warning light
>
>
>
> Hi,
>
> I know that this problem has been talked about before, but if
> someone could
> help me out I'd appreciate it. I noticed today that my alternator was not
> charging while looking for another problem, I had heard that if the
> warning light bulb was blown that this would happen. I checked the bulb
> and sure enough it was blown. I replaced the bulb, but I still don't get
> any output and the bulb does not light when I turn the key to the on
> position. I have 12 volts on the white wire through the bulb and at the
> brown and yellow wire at the alternator. I dob't see any path to ground
> though for the current to flow and light the bulb. If anyone
> could explain
> how this normally works I would appreciate it.
>
> Thanks,
> Glenn
>
>
>
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