Chris,
I've been thinking about your problem, in fact, I took a look a the electrical
diagram in Bentleys yesterday, but the kids wouldn't afford me the time to
reply.
> At any rate, I'm planning to put in a new generator tonight and see what
> happens. But I sure would like to understand this better. Pat?
My guess is that you don't need a new generator. My experience has been that
brushes and bearings are the typical generator faults. Assuming the brushes
are good, (at least 3/8" long), the commutator is clean (if not, clean it up
carefully with #300 paper), all internal connections are tight, and the field
has continuity and is not shorted to the case, your problem most likely is
with the regulator or a bad connection.
> This morning I did the voltage test on the generator - pulled off the D
> and F leads, shorted them together. Hooked the voltmeter to that and
> the case of the generator. Run the engine, get about 0.1v output.
> Great, seems like the generator is toast, the manual suggests that the
> field winding is at fault.
This test relies on residual magnetism in the field pole pieces, and so isn't
very reliable, especially if the regulator has been misbehaving ... um, just
had a thought: A 'dynamo' charging system like the TR2-4's relies on this
residual to "bootstrap" the system on start up. The initial generator output
due to the residual is what pulls in the cutout in the regulator after the
engine starts. The soft iron pole pieces become magnetized very easily to
affect this, but this means that they can also be demagnetized easily. Try
the voltage test again, but first "polarise" the generator by connecting a
wire to the battery hot lead and "sparking" the field terminal with the other
end of the wire.
> The cutout shunt coil seems fine - reads about 50 ohms.
>
> Now, if I trip the cutout manually, it stays closed, and the ammeter
> indicates that the battery is getting charged. But I can't get the
> cutout to close electromagnetically, even with my test lamp trick. This
> makes me think that the generator is partially toast - but that it is
> willing to generate into a heavy load.
No. If the generator charges *at all* it's not even slightly toasted.
Dave Agnew's suggestion of "motoring" the generator is a good one. Try it a
couple of times. The generator should start to spin by itself each time.
If you ever have to spin it by hand to get it started, then you have bad
commutator segments and/or open armature windings.
> Most recent trick - the "ignition warning" lamp doesn't come on at all,
> even with the engine shut off. This *could* be a lamp fault, [...]
If the "motoring" or voltage tests check out, it's a lamp problem.
I'll look a little closer at the regulator itself tonight. There's usually a
shunt resistor that's used in determining the charge rate based on the battery
voltage. If this was open or out of tolerance, you'd get flakey operation.
I'll have to look to see if this could cause your car's "stupid charging
tricks..."
Good luck!
Pat Vilbrandt Fluke Corporation Everett, Washington USA
pwv@tc.fluke.COM or: { uunet, uw-beaver, sun, microsoft }!fluke!pwv
From rwg1@cornell.edu Tue Sep 11 11:59:59 2001
From: (Roger Garnett) rwg1@cornell.edu
To: (British Cars) british-cars@autox.team.net
Date: Tue, 21 Dec 1993 14:21:53
Subject: Re: MGTC book
> Rob Reilly writes >
>
> > I read that book in high school too. The title is "The Red Car"
A true classic. I have both a hard cover and a soft cover copies. Really
hits the nail on the head about the emergence of Sports cars and racing in
the USA. Tilly is actually reading it this week for the first time...
Phile writes: (many details)
> How is that for a book I read about 35 years ago? I was just coming out
> of my submarine phase and hitting cars.
Pretty strong memories...
> The Fast Green Car (Morgan, SCCA racing)
I'm not sure if I have that one, but I do have several other similar
vintage & theme books.
> The Red, Red, Roadster (ALFA, rallying) which was serialized in Boy's Life
I had this one, gave it to Rich Welty (Alfa and driving school mail lists)
and Allison due to Alfa content. Really sould find another copy tho.
Roger- a small collection of automotive books, still under 500 -Garnett
(Index? Yea, right. If I can just get some rooms finished so I can unpack
them again, I could see what I've got!)
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