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Fiat tractor regulator

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Franc Zabkar

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May 17, 2003, 5:21:53 PM5/17/03
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I have a regulator out of a Fiat tractor (24V system) that was damaged
when the owner reversed one of the two 12V batteries. It is of the
vibrating contact type and has two diodes, both of which are faulty.
The circuit appears to be as follows:

470pF
|------ C --------|
|------ R --------|
| 139 ohm |
| | generator
| NC | field
| contact | Field winding
Gen + o--+-------/ --------+----o o-----FFFFF-----o o
|---- IIIII ---| | _|_
|---- VVVVV -| | |-|<|---| =
| | 1N4005 _|_ Gnd
|--- R ---| | = Gnd
_|_ 56 ohm |
= |
Gnd |
|
Bat + o-----|<|---------|
200V, 25A
diode

I'm only guessing that I have correctly identified the Gen+, Bat+, and
Field terminals, as I do not have access to the tractor or generator.
IIIII and VVVVV represent what I believe to be the current sense
(heavy gauge) and voltage sense (light gauge) windings of the
vibrating relay.

Could anyone confirm whether this drawing makes sense?


-- Franc Zabkar

Please remove one 's' from my address when replying by email.

Mr. Meval

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May 17, 2003, 10:45:08 PM5/17/03
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In message <ss6dcv0i3gj5s5dvj...@4ax.com>; Franc Zabkar wrote:


In these old things you can just replace the diodes and it should be fine
unless there is something severely burned. I don't think the vibrator would
be open but it's possible. If you have a meter just check the diodes, the
coil winding and the resistors.

Not sure what country you're in but there are available solid state generic
replacements. Oh, wait mechanicals:

You didn't state the tractor model nor the regulator part number but this
has a +12 and a +24 one listed for several Fiat tractors

One-winding positive excitation, for Bosch and M. Marelli alternators.
FIAT 643, 619, 697, 673;
JOHN DEERE 5010, 5020.
http://www.nosso.com.ar/spanish/product_pgs/regu_mecan02eng.htm

It also looks as if there may be Boche substitues for these, I just can't
seem to find them right now.

> diode

This appears correct, this appears to use the diodes for
steering/rectification.

> I'm only guessing that I have correctly identified the Gen+, Bat+, and
> Field terminals, as I do not have access to the tractor or generator.
> IIIII and VVVVV represent what I believe to be the current sense
> (heavy gauge) and voltage sense (light gauge) windings of the
> vibrating relay.

--
Some help:
http://www.repairfaq.org/REPAIR/F_Repair.html

Franc Zabkar

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May 18, 2003, 4:24:33 AM5/18/03
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On Sun, 18 May 2003 02:45:08 GMT, "Mr. Meval"
<mrm...@spam.earthlink.mapson.net> put finger to keyboard and
composed:

>In message <ss6dcv0i3gj5s5dvj...@4ax.com>; Franc Zabkar wrote:
>
>
>In these old things you can just replace the diodes and it should be fine
>unless there is something severely burned. I don't think the vibrator would
>be open but it's possible. If you have a meter just check the diodes, the
>coil winding and the resistors.

The relay contacts are pitted, and the 56 ohm wirewound resistor
measures open. The OC appears to be where the winding disappears
underneath the endcap. I'm betting that this was the original fault.
Such a fault would have caused the generator to overcharge the
battery.

>Not sure what country you're in but there are available solid state generic
>replacements. Oh, wait mechanicals:
>
>You didn't state the tractor model nor the regulator part number but this
>has a +12 and a +24 one listed for several Fiat tractors
>
>One-winding positive excitation, for Bosch and M. Marelli alternators.
>FIAT 643, 619, 697, 673;
>JOHN DEERE 5010, 5020.
>http://www.nosso.com.ar/spanish/product_pgs/regu_mecan02eng.htm
>
>It also looks as if there may be Boche substitues for these, I just can't
>seem to find them right now.

I have all the necessary parts so hopefully I won't be needing a
replacement unit. But thanks anyway.

>> diode
>
>This appears correct, this appears to use the diodes for
>steering/rectification.

I would think that the 1N4005 is a back emf suppression diode, while
the 25A diode (International Rectifier 4AF2) is there to prevent the
battery from discharging into the generator. The rectification would
be done by the generator's commutator.

>> I'm only guessing that I have correctly identified the Gen+, Bat+, and
>> Field terminals, as I do not have access to the tractor or generator.
>> IIIII and VVVVV represent what I believe to be the current sense
>> (heavy gauge) and voltage sense (light gauge) windings of the
>> vibrating relay.

Jim Adney

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May 18, 2003, 1:16:38 PM5/18/03
to

Looks pretty reasonable to me.

-
-----------------------------------------------
Jim Adney jad...@vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------

Mr. Meval

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May 18, 2003, 6:59:13 PM5/18/03
to
In message <bvfecv8s13sl2pav9...@4ax.com>; Franc Zabkar wrote:

>>This appears correct, this appears to use the diodes for
>>steering/rectification.
>
> I would think that the 1N4005 is a back emf suppression diode, while
> the 25A diode (International Rectifier 4AF2) is there to prevent the
> battery from discharging into the generator. The rectification would
> be done by the generator's commutator.

I keep thinking *alternator*, sorry. Yes, those did look to be steering
diodes, emf suppression in one case, blocking in the other.

Franc Zabkar

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May 19, 2003, 3:29:08 AM5/19/03
to
On Sun, 18 May 2003 22:59:13 GMT, "Mr. Meval"

<mrm...@spam.earthlink.mapson.net> put finger to keyboard and
composed:

>In message <bvfecv8s13sl2pav9...@4ax.com>; Franc Zabkar wrote:

I was stumped initially, too, until I stopped thinking "alternator".
BTW, this is my first generator job, hence the cautious approach.

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