Generator question

B

BeerInaBag

Junior Member
first post, new to model A... New to generators instead of alternators, not new to working on old fords. So, I've done a search. My generator used to put out 2A if i jumped the cut out. I installed a new bearing and had a bushing made, and i installed new brushes. now i get 0 amps. tried jumping the cut out again. no go. it will motor slowly if battery is applied to it, as instructed to do first in every post...but now I'm stumped. Did I possibly wire the unit wrong? Do I have deeper issues?

its a 28 Sport Coupe with the long generator, not the compact powerhouse or whatever it was.....
 
Did you adjust the movable brushes? Your output is determined by the movable one, up or down.

From Les Andrews’s book: "To adjust the output charging rate, move the center brush up to the top of travel, then back down about 1/3 of its travel. Start the engine and check your reading running at a fast idle. Adjust the brush for a 10 amp charge. Move the brush up to decrease the amperage and down to increase amperage.”
 
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Battery voltage is set by the battery so there is no voltage regulator unless some one has installed a modern unit like the Fun Projects type. The three brush units are amperage output adjustable only as was mentioned. They originally had an electro-mechanical cut out to bring the generator on line. It may have that or it may have a modern diode replacement that looks like a cut out. The other possibility is that it may have the Fun Projects VR unit I mentioned previously which look like a cut out. There are other VRs that mount inside the generator but you should have found that if you opened it up.

If you polarized the pole shoes in there properly and put it back together at least as good as it came apart then it should generate. A person can bypass the cut out if that is what it has. A VR would have to be isolated (disconnected) to flash the field. The fun projects VRs are sensitive to battery disconnect and can be fried if the battery is disconnected while in operation. The OEM type cut outs or one of the diodes should pose no problem in this respect.

I hope you have a good ampere meter. Some of the reproductions are crap. Adjustment of the third brush should be done per the original instructions for the type of generator you have. It may need more than 2 amps. They are generally set at 10-amps but it would be a lot different if it has one of the voltage regulators.
 
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The Fun Projects regulator will be destroyed it you jumper the regulator/"cutout" or polarize the generator. Says so right in the installation instructions.

Same thing if battery polarity is changed.
 
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It has an original style cut out. The generator will not make enough amps to close the cut out. If i manually close it, it used to put out 2A. Now, after my new bearings and brushes, it puts out 0A, but will motor, very slowly if power is applied to it. Moving the 3rd brush has no effect on output. anyone have a diagram of where the wires go on the brushes? Maybe i mixed up my wires to my brushes. :eek:
 
This image might be hard to see but basically one brush goes to ground and the other to the output terminal. The third brush is connected to the first field windings which are then connected to the second field windings and then to ground.

Put some paper under all three brushes and then use you ohm meter to check to see if they are connected to the right places and, except for the grounded brush, not shorted to ground. The third brush should have a low resistance to ground, not zero, because it goes through the field windings. Then remove the paper from the two brushes and see if you get a very low resistance from the terminal to ground. It may be close to zero. You can also remove the ground from the second field winds to see if they are shorted to ground, with the paper under the third brush.
 

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It's hit or miss when you just replace bearings & brushes. The armature should be tested with a growler & checked for shorts. The field coils need to be tested for opens & proper Ohms reading. Wire or terminal shorts or opens should be confirmed as was mentioned. When the field is flashed, it magnetizes the pole shoes with proper polarity to the magnetic fields. This residual magnetism is what allows the generator to make enough current to close the circuit with the cut out switch and bring the generator on line.

The generator should motor as you mentioned but that doesn't mean that all is well with the internal parts. Verify everything or you can have problems like this. This will include a check of the wiring from the generator to the amp meter and the battery buss. Your cut out may be pulling a dirty set of points closed that won't allow current to pass.
 
nothing is shorted to ground, but i could not find any ohm specs. I have the 'large' wire from the stationary brush going to the output of the generator, and the smaller wire off the winding attaching to the moveable brush...that is where i fear i may have reversed the wires. Brushes make good contact. I'm just stumped as to how I made it worse..by adding new parts..only answer I have is that I screwed up!!
 
From spec I have collected--
motoring--4,75-5,0 amps at 6V, 350-400 rpm
field should be 4.75-5.0 amps @ 6V
I only have one generator at home to measure ohms, and I don't have the tools to check amp draw on it here, it measures 1 ohm, don't think that is correct though
 
BeerInaBag said:
nothing is shorted to ground, but i could not find any ohm specs. I have the 'large' wire from the stationary brush going to the output of the generator, and the smaller wire off the winding attaching to the moveable brush...that is where i fear i may have reversed the wires. Brushes make good contact. I'm just stumped as to how I made it worse..by adding new parts..only answer I have is that I screwed up!!
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Stationary brush to output, other stationary to ground. Movable brush to field.

Ohms are negligible. Should have some continuity to ground on all three brushes.
 
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The generator on my truck was full of mud dauber nests and cobwebs. I completely disassembled cleaned and tested field coils. I repaired insulation on the leads with linen cord and gave the fields a few coats of insulating varnish. I turned and undercut commutator and replaced bearings and brushes. I didn't have a growler to test armature. It wouldn't motor and I second guessed my wiring also. After confirming it was correct I figured I had a bad armature. I had a really rough generator off a $50 engine that had been stored outside. Turns out the armature in it was good so I'm back in business, it motors well now. I went ahead and turned and undercut the second armature as well. I also found a good used generator at a swap meet for $35 and it motors so I have a good spare also.
 
well, its wired right...brushes making good contact. but if i manually close the cut out, I used to get a 2A charge....now I get a 4a draw when I manually close the cutout with the car running...Any suggestions before I pay george moir for a new one?
 
If you have a local club, contact a member and ask for local help before you start throwing money at it. A more experienced on site examination might settle things. Or post your location in your sign-in. Somebody here might love right down the street from you.
 
700rpm said:
If you have a local club, contact a member and ask for local help before you start throwing money at it. A more experienced on site examination might settle things. Or post your location in your sign-in. Somebody here might love right down the street from you.
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Im in northern Alberta, Canada...Grande Prairie. Only club i found with a breif look was in Calgary and they seemed more of a spot on purist resto group, rather than leave the car to her scars and stories like I'm doing with this survivor..welded fenders, wooden roof and rust!!!
 
BeerInaBag said:
Im in northern Alberta, Canada...Grande Prairie. Only club i found with a breif look was in Calgary and they seemed more of a spot on purist resto group, rather than leave the car to her scars and stories like I'm doing with this survivor..welded fenders, wooden roof and rust!!!
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Well, that’s a different situation, for sure. This may be your best place for help after all. Good luck! :)
 
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ole gal in question. I ordered the genny from Moir, I would rather this ole gal wear out than sit around waiting for me to figure out how to fix her...now onto the windows(or lack thereof) and oil leaks!
 
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