Resistor help

JD2840 · Jun 2, 2010

do i need a resistor on the exiter wire and in the place of the warning light as on this diagram? or do i need just on in one place? ive been told i need one on the exiterwire of the altinator but i also nowticed anoter on this diagram. its on a farmall H

Don Hopf · Jun 2, 2010

You'll need a resistor on the coil if the coil is 6 volts.

The other thing, could it be a diode?

If you have no warning light, you have to use the diode to stop the current flow thru the alternator when the tractor is not running.

JMOR · Jun 2, 2010

(quoted from post at 19:51:35 06/02/10) You'll need a resistor on the coil if the coil is 6 volts.

The other thing, could it be a diode?

If you have no warning light, you have to use the diode to stop the current flow thru the alternator when the tractor is not running.

The diode, warning light, or resistor or as GM did it, a warning light in parallel with a 10 ohm resistor, is there for the purpose of stopping the alternator from back feeding the ignition circuit from the Excite #1 alt terminal thus keeping the engine running & key is off. Has nothing to do with situation when engine not running, key off.

Don Hopf · Jun 2, 2010

The lamp will light up if the alternator is faulty. To light the lamp, the faulty alternator provides a ground/negative voltage on #1 terminal.The diode prevents the positive voltage of ignition switch from shorting out to ground.

Anonymous-0 · Jun 2, 2010

Got to missing somthing. How can it back feed when the ign.when the switch is off??

Anonymous-0 · Jun 2, 2010

Pls over look my comment. I will have to plead stuped but in my defence I was looking at a different drwing

JD2840 · Jun 2, 2010

i found out the tractor already has the needed diode. now i just have to unhook it all form the key and hook the old system back up. thanks for the help

John T · Jun 2, 2010

JD, I will try to explain this so you can figure it all out, here goes:

1) The "Warning Light" in the alternators excitation circuit serves two purposes.

a) Its ON to show the alternator isnt charging but OFF when she is (a charge indicator)

b) It keeps the alternator from backfeeding the coil so theres no run on i.e. it shuts OFF when the ignition is off.

NOW: If thats replaced with a 10 ohm resistor or a diode EITHER will prevent run on butttttttt you dont have the idiot light charge indicator

2) That other Resistor (before the coil) is an ignition ballast resistor. Its purpose is to drop 6 volts so on a 12 volt tractor you can still use a 6 volt coil. The other option is to use a coil rated for 12 volts on a 12 volt tractor whereby no ballast would be required

GOT IT??? If I missed anything hopefully the other gents will add to this. That diagram is for converting a 6 volt tractor to 12 volts and using an alternator versus the old generator. The ignition balalst is for when you keep and use the old 6 votl coil, so it drops 12 battery volts down to 6 for the 6 volt coil

John T

JD2840 · Jun 2, 2010

it already has the resister for the coil. but just to clear one more thing up,when the ammenter says that the batery is charging, wouldn't that also tell you its charging?

John T · Jun 2, 2010

Yep, if it has a working and correct wired ammeter, thats a darn good way to see if its charging and how much even. The "idiot light" is merely a charge/no charge go/no go indicator and doesnt tell you the amperage of charge or discharge

John T

JD2840 · Jun 2, 2010

ok well the ammeter dose work. thanks for the help

Resistor help

JD2840

Member

Don Hopf

Member

JMOR

Well-known Member

Don Hopf

Member

Anonymous-0

Well-known Member

Anonymous-0

Well-known Member

JD2840

Member

John T

Well-known Member

JD2840

Member

John T

Well-known Member

JD2840

Member

Similar threads