Smoke escaped my gennie

[Floats]

Hi Guys,
Your comments and advice will be appreciated.
Fitted a new battery a few days ago and all is well driving around town. Took her out on a long trip yesterday and after about 10 km the ampmeter drops down into the negative and we can smell electric smoke.
Couldnt stop right away but pulled off about 3 km later, too find the gennie very hot. Popped the cover ring and saw some smoke escaping. I then disconnected the gennie wire and returned home.
Please look at the picture below. The shellack insolation on the commutator end has over heated and flaked off.
Would you say the armature is cooked or will it still be OK?

[C26Pinelake]

Dont know the answer to the question by why did it take you 2 miles or 3 km to pull over instead of immediately once you smelled electrical burning ? Wayne

[Mike V. Florida]

Smoking electrical parts are NEVER good. You need to get the Armature tested to be sure. Could also be the field windings, you can check for continuity through the field coils by measuring resistance between the 3rd brush and the case, you should read 3-4 ohms.

you can also test the field windings with a 6 volt battery charger, and they should draw about 4 to 5 amps.

[Floats]

Tks Mike,
I'll report back when I'm done.

[Tom Wesenberg]

If the windings weren't cooked when you pulled over, you may have cooked them on the return drive with the wire OFF the generator. Since the stock Model A is an unregulated third brush generating system, when you disconnect the generator from the battery the voltage in the generator can reach as high as 40 volts, which will cook the windings.

If you must run the engine with the generator disconnected, then you must ground the generator output stud to keep the output at zero volts. If you have an electronic voltage regulator then that will keep the generator output at a safe level.

[Floats]

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OK Mike and Tom,
As I said before, new battery and charging rate seemed normal for a day or two.
This morning, removed and cleaned the gennie, commutator, brushes, bushes, contacts as well as the cutout contact points.
The genie motors when directly connected to the battery. Now back in the car and all connected.
Here goes
All OFF, the ammeter rests at -3
Ignition ON, ammeter goes down to -7
Ign + lights ON, ammeter down full scale to -20
OK, after start the needle goes from -7 to -6 and remains at -6 at any RPM.
Left the lights on for about 10 minutes in order to drain the battery a little however no change. After start the gauge settles at -6, no matter what RPM.
I also swaped the cutout with the one on my Chevy but no change.

[Tom Wesenberg]

Keep the battery charged up, as having a low charge is bad for the life of a lead/acid battery. Have you tried jumping across the two cutout terminals while the engine is at fast idle?

Also check the generator output stud voltage at fast idle. It should be higher than battery voltage.

One last check if you don't find the problem is to disconnect the wires from the output side of the cutout, then run a jumper wire from the cutout to the starter switch. Then measure the voltage stopped and at fast idle to see if it's charging.

[Floats]

TKS Tom,
Yep, the battery is charged up.
I have jumped across the cutout terminals, it gave a spark.
There is NO output at the back of the cutout from the gennie, however the gennie motored when powered up on the bench.

As there is no output from the gennie, I did not do the last test.