James - just noticed I typed '.05v' instead of '.5v', so it looks like your
field winding is faulty, particularly as it measures 0.5 ohms instead of
6ohms which is what my manual for an MGB says as well (there will be little
difference in design and spec for cars of a similar era with similar
electrical loads, the huge disparity in cost probably reflects rarity). The
yoke is the metal former it is wound on, at ground potential, i.e. same as a
mounting 'ear'. Quite possibly the insulation has broken down between turns
of the field winding, in which case it needs professional repair or
replacement.
PaulH.
----- Original Message -----
From: James Nazarian Jr <James.Nazarian@Colorado.EDU>
To: <paul.hunt1@virgin.net>
Cc: <mgs@autox.team.net>
Sent: Monday, July 31, 2000 7:35 PM
Subject: Re: generators and pos ground
> well, when connecting D,F terminals together we get .57 volts with no
> change whatsoever when increasing RPM. The manual said to check field
> coil between field coil terminal and generator yoke (don't actually know
> what that is, but assumed it to be mounting ear on generator) of the
> 6ohms expected we got .5 Couldn't say anything for the warning light
> since we have only had the car 1 week and I hadn't seen it on it may not
> be working. While I am thinking of it, this is a 1098 motor, not the 948
> that belongs in this car, your directions seemed like a quote from the
> shop manual, presumably this all holds true for the 1098 as well as 948
> but should the resistance in the field coil be any different? The nice
> bit is that the generator for 1098 is $65 while the one for the 948 is
> $200. Thanks for the help.
>
> James Nazarian
> '71 B roadster
> '71 BGT ever so slowly turning into a V8
> '63 Buick 215
>
> "Aerodynamics are for people who cannot build engines"
> Enzo Ferrari
>
> On Fri, 28 Jul 2000 paul.hunt1@virgin.net wrote:
>
> > Start the car and monitor the voltage on the brown circuit. You should
see
> > better than 12.7v, and hopefully around 14v if the system is charging,
less
> > than 12.7 if not.
> >
> > If not, disconnect the wiring from the D and F terminals on the
generator.
> > Connect the two terminals together, and connect a voltmeter from that
> > connection to ground. Start the car BUT DO NOT REV IT. Slowly increase
the
> > revs while watching the voltmeter. Do not exceed 20v, this should
happen
> > before 1000 rpm. Do not rev the engine to achieve 20v. If this test is
OK
> > the generator itself is good, the problem might be in the control box.
> >
> > If you only .05v to 1v the field winding may be faulty. If you only see
> > about 4v to 5v the armature winding may be faulty.
> >
> > The cut-out relay in the control box should operate when the generator
is
> > putting out between 12.7 and 13v, this should connect charging voltage
from
> > the D terminal to the B terminal, and incidentally extinguish the
ignition
> > warning light. This light should come on when you first turn on the
> > ignition and go off when the system is charging. If the warning light
does
> > not work then shame on you, and that's what you get for ignoring it.
> >
> > PaulH.
> >
> > ----- Original Message -----
> > From: James Nazarian Jr <James.Nazarian@Colorado.EDU>
> > To: <mgs@autox.team.net>
> > Sent: Thursday, July 27, 2000 8:35 PM
> > Subject: generators and pos ground
> >
> >
> > > How does one go about testing a generator
> > > and what quantity of juice should it be producing. I know on a B you
want
> > > to see about 14.5 volts on a well charging car, but how about on a
bugeye
> > > with a generator?
> >
> >
>
>
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