[Mgs] Change from Generator to 1-wire Alternator

[Paul Hunt]

Is this *really* a 1-wire i.e. no indicator wire?  Or what some people refer
to as a 1 wire which really is 1 output wire plus an indicator wire i.e. a
2-wire?

In either case it is fairly straightforward, but you will have to use the
Sprite diagrams to see how the original regulator connected to the rest of
the car i.e. confirm the colours used.  If the wires have been changed as
well then you will have to trace back what wires you *do* have to be sure
what you need to connect and which to leave disconnected (both ends!).

Going by the MGB there were 3 browns on the B terminal one of which went to
the solenoid to charge the battery, and the other two to the loads such as
the ignition switch, fusebox, lighting switch.  These three must remain
connected together, and the alternator output will be connected to them.  In
your case the two wires on A1 *probably* feed the loads, and A is connected
to the battery cable at the solenoid.

The should also be a dynamo field connection (brown/green, almost certainly
F on your regulator), a dynamo output connection (brown/yellow D), and a
warning light connection (brown/yellow) these last two connected together
(probably your two yellows), none of these are required with a true 1-wire
alt.  However the one from the warning light must either be taped up or the
bulb removed as it is live with the ignition on, although if it *does* short
to earth it will just cause the light to glow, it won't burn wiring.  With a
2-wire this last goes to the alternator indicator terminal.  It will almost 
certainly need the warning light connected to the indicator terminal as most 
alternators need this to start charging.

With 2 black wires on the E terminal I'm guessing that one connects to the
body and the other to some other component that still needs an earth, i.e.
the regulator terminal is being used as a 'daisy-chain' interconnection
point, so if the regulator is physically removed these two must remain
connected together.

Presumably the cut-off switch has facilities to disconnect the charging
system and ignition as well as the battery?  If so the alternator output
should go via one of these.  You may also need a different switch, those
intended for use with alternators usually have a resistor to ground on the
alternator wire to stop it going over-voltage and damaging itself if the
switch is turned off with the engine still spinning.  Alternatively you
could add a resistor to ground, you will have to do some research as to
value.

PaulH.

----- Original Message ----- 
> ...  But, this is pushing me into installing the mini 1-wire
> alternator I've had sitting on the parts shelf for a year.  I need to do
> some minor mods to get it to fit.  But, they're easy.  Problem is how to
> deal with the wires on the regulator.