Ford NAA 12V not charging

[90Moneypit]

So it's a fix one thing find another kind of tractor it seems. After *ahem* fixing the fuel issue, found a leak in the radiator. Long story short, 2nd replacement radiator is holding coolant so that's fixed (for now at least). During the course of burping the radiator I decided to start checking gauges etc. to see what the next thing to fix was. Proofmeter has the needle broke off and sitting on the bottom of the gauge, oil pressure works (thankfully!) Temp never moved (already looked on here and see a potential fitment issue with the cheap temp gauge and how to avoid), and finally amperage gauge... It's sitting below zero. Hmm... volt meter not reading anything coming out of the wire. Belt a little loose so adjusted with no change. Look at the alternator itself and it's not a one wire AND there's nothing connected to the #1 or #2. Consulted myfordtractor.com for the diagram and went with the 5W bulb (194 bulb) route and made a quick harness since a non excited alt isn't going to put anything out, right? Well, still nothing. Bulb lights up when the key is on but even when I rev the engine beyond 1500 rpm, I'm not getting a charging voltage out of it. Is there anything else I've missed or is it time to buy a new alternator?

 

[90Moneypit]

Sorry I don't have different colored wire but I DID continuity tests on each wire to make sure they went to the correct side of the distribution block.

 

[John0829]

Did you make a connection from #2 to the battery post on the alternator? Post #1 must make contact with 12V to excite the alternator before it will charge, the best way to do this is to install an ignition switch that provides an accessory terminal. Connecting the #1 to the accessory terminal provides the 12V needed to excite the alternator and yet provides a break between the alternator and ignition coil when you shut off the key. If you do not have have this separation the voltage will continue to feed the ignition and you will not be able to shut the engine down. The light is suppose to accomplish this separation but I prefer the positive separation provided using the switch with accessory terminal.

If the alternator does not charge with the #1 post connected to the battery post and 12V connected to the #2 post then the alternator is probably defective. Get it tested at your local auto parts store.

 

[90Moneypit]

That's more or less the conclusion I came to. The only 'questionable' part of the current wiring that differed from the diagram online is how the amp meter is wired. It is not running directly to the terminal block with a jumper to meter, but directly to the meter with a jumper to the terminal block. With the meter being an untested part of the setup, is it possible that this could be enough to keep the alternator from exciting? Since the tractor was in a 'hey, it's at least starting and running as it is' state, I didn't want to start a complete rewire of everything. As it is, the coil is still running through a resistor pack and it's unknown to me if it's a 6V or a 12V coil... Sure, long term I'll probably cut and fab an entire new harness just so I know that everything is fresh, not crystalized, broken or otherwise hacked but with the wife staring hard over my buying it in the first place and the back 2 acres getting taller and taller by the day, I have to keep costs at a minimum for now. Even if that means packing a spare battery (yeah I'm a 12V battery hoarder with a de-sulfating 'repair mode' charger)on the floorboard or hidden in one of the nearby sheds. She made me turn most of them in before we moved cross country but I seem to have forgotten to turn a couple in and they made their way into the bed of my truck...

 

[EdGooding]

Is your amp meter the loop (inductive) or terminal type?

The presence of a resistor would indicate that you still have a 6v coil. You don't need it with the 12v coil - it will affect performance/running.

 

[John0829]

If your meter is a terminal type it must be between the battery and alternators battery terminal to indicate charge

 

[90Moneypit]

It looks to be the original meter with 2 terminals on it. I'm pretty sure that all the meters are more than likely 70 years old by the looks of them with some pretty severe fading. There's been some 'updating' to some of the wires in the past and even some of the 12V wires are showing some age while others look relatively new. The guy I bought it from had those hopes of restoring it as a parade tractor since other family members had parade tractors and he decided he liked golf better. The tractor was still (and is still) a bargain since it came with a 5' box blade and a seed spreader (not that I'll likely use the seed spreader) and it does run, lift, and output something to the pto. It's just going to be a work in progress, with emphasis on work. Paint and pretty will be along the lines of rust prevention and not presentation for me. Not that I don't want a nice looking tractor, I just don't want to get too upset when a branch scratches the paint or I bump into a fence post.

 

[EdGooding]

The factory ammeter was the loop type:

It looks to be the original meter with 2 terminals on it. I'm pretty sure that all the meters are more than likely 70 years old by the looks of them with some pretty severe fading.

 

[EdGooding]

Wiring for yours should look like this:

 

[90Moneypit]

I'll have to poke my head up under there but at first glance at these diagrams, the loop seems most likely. I hadn't considered the possibility of it looping though, only that the large wire went up to the gauge and there was a wire coming down from the gauge to the distribution block. It's the same color and gauge (red in this case but likely to have been replaced) going up and coming down. If the voltage regulator is still connected in this scenario, is that what might be causing the issue? To be a little clearer, the wiring I've seen looks like it's running from the armature on the rear of the alternator up to the ammeter and then down to the 'left' distribution block like in the 1st diagram and I added the circuit for the posts 1&2 to the distribution block with the 5w light bulb in place of the 1amp resistor.