300 not charging

I found the reason 300 was not charging was the alternator belt broke. I put a new belt on and it still not charging. The coil was heating up too hot to touch. I replaced w/12v. Running ok for now but not charging still. It's a DELCO. Also has a resistor on alternator. New coil is heating up also. What am I missing. Everything was good until belt broke. Voltage at battery is 12.2 V so I don't think alt is working.

Jumper the Number 2 terminal on the top edge to the big stud terminal after disconnecting what ever wire is there now. Try it if it works leave it alone as fixed.
With it stopped with that whit connecter pulled out, and the key on, check to see 12 volts in the connector that feeds terminal 1. If none it must have 12v there. To see if that is tha issue, start the tractor and jump 12 volts to that wire (connected to the alt) id still no charge, take the alt in to be tested. Jim

I cant quite follow all the wires on the picture. If thats a GM 10SI Alternator:

1) The small No 2 SENSE terminal should be wired to the big output stud which gets to the battery via the ammeter.

2) The small No 1 EXCITE Terminal should be wired to the input (From IGN switch NOT to coil) side of the Ignition Ballast Resistor. However, in series between the ballast input and the Alternators little No 1 Excite terminal, place a 10 ohm 5 watt resistor or diode to prevent coil feed back causing run on even if Ign is off.

3) Assuming thats a Neg ground Alternator as most are, the battery must be installed NEg ground.

4) An Ignition Ballast resistor normally runs fairly hot and on a 12 volt tractor you would have a 6 volt coil if the ballast is used.

5) If you have a 12 volt coil DO NOT USE THE BALLAST and the No 1 Excite terminal above wires (via the in line series resistor or diode) to the coils input (NOT to distributor) instead.

6) Even a 12 volt coil runs somewhat warm but NOT so hot you cant hold it. Sure its a 12 volt coil ??? If its labeled "12 volts for use with ballast" its a 6 volt coil and needs a ballast just like it says or it will ovberheat. A 12 volt coil may be labeled "12 volts" or "12 volts NOT for use with ballast" etc

Clear as mud???

John T

Well I'm not surprised that it's not charging.... It's wired completely wrong!!!

The big ceramic resistor on the alternator should be on the ignition coil. That resistor is what keeps the coil from getting hot! Why is it on the alternator?

The wire from the #2 terminal on the plug should be running to the BAT post on the back of the alternator.

There's probably a diode under that mess of electrical tape on the #2 wire. Move that to the #1 wire.

The way it's wired I would not be surprised if it STILL won't charge after you do all that, because the alternator has been burned out from being wired incorrectly.

That ballast resistor is not the one that drops voltage to the coil!!!!! It is there for the same reason as the light/diode/resister you guys are always discussing in these alternator conversions. It should be connected accordingly.

I would say that everything is wired correctly. It worked before so it shouldn't need a change in wiring to make it work now.

The wire on the battery terminal should go to the back of the ammeter.

The wire on the #1 terminal goes through a resistor and then should be connected to the switched side of the ignition switch or the switch side of the ignition resistor (or coil if it has a 12 volt coil).

The wire on the #2 terminal is most likely attached either to the ammeter or better yet at the starter switch where the battery cable is attached. Wiring it that way gives better control to charging voltage than having it connected to the battery terminal at the alternator. It controls the voltage at the battery after the electrical load instead of at the alternator before the load. For the most part the electrical load on these old tractor conversions is so small that the choice of how it is wired make no practical difference.

Testing involves checking for battery voltage at the alternator at both the battery terminal and the #2 terminal. The voltage must be there whether the ignition is on or off. The #1 terminal should have about 6 volts with the ignition switch on while the wire is connected to the alternator. With the wire removed from the alternator the voltage should equal battery voltage with the switch on. The voltage at the #1 terminal is not critical. The more voltage present when the alternator starts the lower the speed needs to be before it will begin to charge. With the resistor in place you will not get battery voltage at that terminal.

If you do have battery voltage at that terminal with the switch on, engine off, you have an open circuit in the brushes or rotor. To test the regulator find the D shaped hole in the back of the alternator and ground the little tab inside that hole to the case with the engine running. Grounding that tab bypasses the regulator and puts the alternator into full output mode.