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Subject: 861 electrical question

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Ozlander    Posted 03-21-2019 at 12:05:25 [URL] [DELETE]        [Reply] [No Email]  
  • 861 electrical question
  • My recently bought 861 still has a generator and 6 volt battery. It was installed with negative ground.
    Since I haven't messed with a generator in 40 years, my question is, is the voltage regulator now toast, or can I;
    1. Reinstall the battery with positive ground.
    2. Polarize the regulator with negative ground.

    Tractor had an oil pressure indicator problem, so I didn't run it much to check charging voltage.

    Tim Daley(MI)    Posted 03-22-2019 at 04:23:10 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 861 electrical question
  • One common misconception on Ford Tractors is polarization. It is the generator that gets polarized, not the VR. It is just easier to perform the task via the VR. It is also important to know which Circuit the generator is wired as. There is the "A" Circuit and the "B" Circuit. Polarizing each is different and if done incorrectly, you will smoke the generator. You would need to verify which via an internal inspection. I'm not 100% certain, so best to verify first but I believe the Hundred Series models would have a "B" Circuit design generator. The OEM early 9N-10000-A small generator used a VR, and was the "B" circuit design. The 9N-10000-B generator became an "A" circuit design with the cutout and A's were used up thru all N production, with the 8N reverting back to a VR. The NAA tractor generator went back to a "B" circuit design. If you have ay doubts, take the battery, VR, and generator to your trusty local starter/alternator shop guy who knows Ford Tractor electrical systems. He can test all components. A good battery is an essential component and he can bench test it faster and easier with his machine. The battery must sustain a full charge under load to be effective. Simply attaching a battery charger or a 'trickle' charger does not mean your battery is good. Specific gravity must be met and is checked with a hydrometer. When the tractor is idle, best to have the battery on a float charger like the DELTRAN Battery Tender Jr. (6V). This sketch JMOR modified may help:


    Tim Daley(MI)

    JMOR    Posted 03-21-2019 at 12:47:28 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 861 electrical question
  • If it works as is, leave well enough alone! Many VRs don't care about polarity. Can't speak for yours. It probably isn't original. You can do your #1, but not your #2, as VRs are not polarized, but generators are polarized and you will need to do that.

    Ozlander    Posted 03-21-2019 at 18:55:13 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 861 electrical question
  • Battery reads 6.3 sitting on bench.
    I meant polarize generator.

    It's tore down for painting and general fixing of years of little maintenance.
    I'll check the genny when it's back together.

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