Farmall A generator- two different voltages

ccaissie · Apr 5, 2012

Hi:

Farmall A 6 volt battery. Picture of generator attached, one pole reads battery voltage, the other one, my finger pointing to it, reads erratically about 12V at idle, and up to 27 volts when at top rpm.

The battery is new, and reads 6.27 Volts, and seems to be diminishing, so I believe it's not charging

Any idea what is going on?

Janicholson · Apr 5, 2012

No picture, but the answer is likely to be that there is either a worn or sticky brush in the generator.
If it is a three brush gen, the two brushes that are opposite of each other provide output to the A post from one, and ground to the end frame on the other.
the third brush picks up voltage for the field, and the field is grounded through the light switch (if old non regulator system, or through the regulator to ground if regulator based system.
Brushes can hang up in the holders, or be worn and not touch reliably, or have broken springs or leads.
Charging Diagnosis John T

ccaissie · Apr 5, 2012

Adding the photo to the inquiry.

The original style bulbs are intact so it appears the system is still 6V.

I ws told the old style voltage regulators look like mine.

Bob M · Apr 5, 2012

Here's what I can tell from the photo:

1 - The wiring is cobbed together and in poor shape.

2 - The original mechanical cutout has been replaced by a solid state cutout (the rectangular can atop on the generator).

3 - The system appears to be wired wrong. The grounded generator field terminal has the generator is "running wild". Ie. there's no voltage control whatsoever. And 2 wires connected to one post of the cutout is incorrect (should be only a single wire on each cutout post).

It should be wired like this:

- Generator "A" to cutout "-"
- Cutout "+" to the ammeter.
- Generator "F" to the field resistor terminal on the light switch.

----

If I was mine I'd scrap the cutout and replace it with a voltage regulator for a Super A/C/H/M. Also replace the wiring harness. Or make your own harness per the diagram in the link - it's pretty simple.

Your generator and battery will thank you(!)
6 volt regulator wiring

gene bender · Apr 5, 2012

As Bob said get a new regulator just get hte Delce Remy # from the plate so you get the correct regulator as your gen probably has the adjustable third brush then wire it according to the instructions with the new one it should be for positive ground or you can get a new cut-out then wire the field to the sw.

ccaissie · Apr 5, 2012

Thanks for the replies. I replaced the funky wires, eliminated the light circuit for now, and it is putting out 7.5 volts.

I'll schedule a voltage regulator/ light circuit upgrade and relocate the wires next.

Thanks,
Colin

Farmall A generator- two different voltages

ccaissie

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Janicholson

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ccaissie

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Bob M

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gene bender

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ccaissie

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