Ford 8N - Electrical problem. No juice and ammeter buried into negative side.

[Soundguy]

a bias resistor between field nd armature is not correct for a A circuit vreg... it is however correct for a B circuit reg.

there should be no resistors on the genny itself.

the genny should at least try to weakly motor from residual magentism in the field poles, with only arm and ground hooked up

 

[tmac196]

I will post some pictures of the Vreg when I get a chance, including views from the back and the guts of the unit. This may help identify the problem.

'Oyl - I do have a multitester, but it is digital/.

tmac

 

[tmac196]

Here are the pictures of the Vreg:



The first picture shows the terminals marked BAT ARM FLD going from left to right and on the reverse side there is a structure (resistor or ground?) connecting the case and what appears to be the FLD terminal.

These are the other pictures I took. Do any of these shed any light on my problem?



Thanks.

tmac

 

[Soundguy]

as i said. a bias resistor from ground to field is normal for a A circuit regulator.
your post #36 said otherwise.

 

[tmac196]

opps.. hit send too fast..


Anyways, best thing to do is start all hooked up then when the ammeter (alt meter ) is pegged to the left, lift the Grd wire from the Vreg. If it moves to the center, you've found the problem. If it stays, lift the Regulator (FLD) line and see if it moves. If it does, then the problem is again the Vreg. If not, there is a problem between the Vreg and the Generator. As I said above, the only difference (that I know of) between the first pic and the last is thast the Vreg is hooked back into the circuit. This points to either it being bad, again, or its wired incorrectly.

You could do more testing with a good sweep type VOM (non-digital) but I dont know if you have one..

Update:

Started the tractor with everything hooked up. Initially, the ammeter needle drifted aimlessly between the positive and negative side and finally drifted slowly to the positive side, but barely so. Once I lifted the ground line the ammeter zeroed and once the line was reconnected the needle drifted slightly negative and did not move again even if engine revved. The same occurred with each subsequent wire I lifted FLD ARM and BAT.

So what do you all make of these findings?

 

[Soundguy]

full field it when running at idle then increase rpm

 

[tmac196]

full field it when running at idle then increase rpm

Here is the setup for the full field test. FLD lead is disconnected and a ground jumper is connected to the field post:



At idle the ammeter shows a slight positive current:



With increased RPM:



However, once I reconnect the FLD wire to the gennie and reconnected the battery, the ammeter showed this:



If started and the engine is revved I noted this:



The situation seemed to temporarily rectify itself once I polarized the Vreg, but I attempted the full field test again after the polarization and the ammeter immediately pegged to the negative side again and, so far, I have been unable to reverse this problem.

The tractor ran fine if I pulled the leads off the battery, by the way. The problem seems to not be with the generator.


Sooo...these are the tea leaves, how do I read them?

 

[94BULLITT]

Is the battery installed positive ground?

In your last post did you mean you pulled the battery cables of while it is running?

 

[Midniteoyl]

PUt your ammeter (VOM) in line with the dash one and see what you get..

 

[tmac196]

Is the battery installed positive ground?

In your last post did you mean you pulled the battery cables of while it is running?

Yes. Positive ground 6V battery.

Yes. Pulled the cable off the negative lead of the battery and the tractor ran fine off the generator.