Farmall Super A, AV, 1939 - 1954
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8 posts • Page 1 of 1
Yippeee! I shined up every contact I could and replaced the distributor cap, spark plug wires, and spark plugs, and man it fires up slicker than deer guts on a door handle!
Now I need to get it to turn OFF ! I can't figure out from my Cub where the lamp goes in the wiring because it's all stuffed up under the hood and twisted together, it looks like it goes from the NEG side of the coil to something on the alternator.
I've only got two wires on my alternator, one of which goes to the NEG side of the coil, so I put it in-line there, but no joy.
With these "two wire" alternator setups, there's one wire for power, and one to excite the alternator at startup. The excite wire is the one you put the lamp in. It should also be switched.
Since the coil is also on the switch, the wire going to the NEG side of the coil is probably the right one.
You need to add a diode. What's happening is that the alternator is backfeeding through that wire into the coil, keeping the tractor running.
Oops, actually I was wrong, the alternator has a total of three wires, but one of them is a large wire that I assume goes into the ammeter.
The other two are small spade-type connectors labelled I believe 1 and 2.
I thought the lamp was supposed to do the same thing as a diode?
Yeah, the large wire goes to the ammeter, which is what charges the battery.
Maybe you don't have the alternator wired correctly? Even though there are three wire hookups, you should only have two wires running away from the alternator. The #2 post should be wired directly to the BAT terminal on the alternator.
Check out #6 in the list below. Even though it's for Hs and Ms, the concepts are the same even for Super As, and the part by the alternator is the same no matter what:
http://albums.photo.epson.com/j/AlbumIn ... 065733&f=0
Does the light come back on when you shut the tractor down? If so, and everything is wired correctly, you'll need to put a large diode in anyway. A regular incandescent lamp doesn't block flow of electricity in one direction.
The lamp comes on when I turn on the ignition switch, and then dims when the tractor is running... So I just took it out of the line.
I will trace the wires tomorrow, the large wire goes to the ammeter as you said, and then of the two spade-lug wires at the top (1 and 2), you are saying one should go to another connection on the alternator labelled BAT? I don't see such a connection on the alternator...
I got a brand new wiring harness in the mail today from CNG, but I'm not sure I want to get into all that now that the tractor is running so well (just not turning off.)
The tractor is wired the way it was when I got it, which is no indication whatsoever that it's correct
Hmm, OK, so from this I can see a few things...
First, the #2 wire does NOT go to the BAT terminal ! I will fix that immediately tomorrow!
Secondly, I had the lamp on the coil side of the ignition switch, instead of on the alternator side... Not sure if that matters, but I will hook that up per the diagram tomorrow as well.
Thirdly, I don't have the ballast resistor on there, but my coil is 12V and says it does not require an external resistor, so I think I'm OK?
Now I'm curious as to where the heck that #2 is going
I believe that a wire comes from the coil, and branches out to the #2 terminal, to the solenoid on the fuel line, and possibly somewhere else as well, but I'll have to go outside to look.
It's what I call a "Previous Owner Mess."
Maybe I will install that new wiring harness after all. The wiring on the tractor is the old fabric stuff and it's covered in years of grease and dust, and probably won't work all that well if it gets wet.
8 posts • Page 1 of 1
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