Generator issues

[Dave1]

26 generator was functioning in the car.
On this car I have rebuilt the drive train, so I thought it would be a good idea to go over the starter and generator.
The previous owner had gone through the generator as it has a new insulated brush plate. The field coils are not new, however they are not grounded . Checked the armature on a growler, this passed as well.
Found one for the field coil leads was bare, so I repaired it.
Assembled it and set the neutral position for the brush plate.
Bench tested it and it puts out 6.8 - 7.00 volts at 1100 rpm.
Installed in the car….. no output.
Removed the generator , bench tested , same results.
Re installed in the car, still no output??

[speedytinc]

No mention of the cutout. Did your bench tests include the cutout?
What was the output(amps) ?
How do you know it's not working on the car? Did you check with a modern ammeter @ the cutout & hot wire?
How many growler tests? You maybe checked for shorts, but what about opens?
Welcome to generator fun.

[Dave1]

Should have mentioned that I tested the output from the terminal post, no cutout involved.

[TXGOAT2]

Is the drive gear loose on the shaft? Gears in mesh? Did you try moving the third brush for higher output?

[Dave1]

I did all the tests suggested on the growler.
Did not do an amperage test on the bench,
My thinking ( maybe not correct) is if the generator is not producing any voltage , a amp test will not tell me much

[Dave1]

New generator gear, and yes the armature is turning.

[Dave1]

Yes tried to adjust the moveable brush

[Dave1]

Oops,….when I was bench testing I was turning the armature counter clockwise . When it is installed in the car it rotates clockwise .
Not sure what this tells me…..should I reverse the leads from the field coils and retest?

[speedytinc]

Oops,….when I was bench testing I was turning the armature counter clockwise . When it is installed in the car it rotates clockwise .
Not sure what this tells me…..should I reverse the leads from the field coils and retest?

Re-read the service manual generator repair.
Re-read the section on setting the null. the null setting determines the direction of rotation for setting during testing. Your bench test system should include a power source (6V?) & an ammeter between the cut out & battery source. The point is to set gen output. Thats amps.
You can also set the generator in with the in car method. I would recommend this since your bench testing method is lacking important elements.

[Jeff]

"Bench tested it and it puts out 6.8 - 7.00 volts at 1100 rpm."

It should read MUCH higher voltage than that. T gens are constant current, not voltage. They turn clockwise when looking directly at the gear. I stopped setting null point long ago. Ron Patterson's adjustment method is much more reliable.
If you're bench testing, set the brush plate rotation for 1A charge into a 6v battery with the 3rd brush pushed all the way away from you. Then, you can set the final charge rate once the brush plate is calibrated.

Jeff

[Dave1]

Where is Ron Patterson’s method posted?

[speedytinc]

"Bench tested it and it puts out 6.8 - 7.00 volts at 1100 rpm."

It should read MUCH higher voltage than that. T gens are constant current, not voltage. They turn clockwise when looking directly at the gear. I stopped setting null point long ago. Ron Patterson's adjustment method is much more reliable.
If you're bench testing, set the brush plate rotation for 1A charge into a 6v battery with the 3rd brush pushed all the way away from you. Then, you can set the final charge rate once the brush plate is calibrated.

Jeff

I also use Ron P's method on my bench tester. Much less aggravation to get a correct null setting leading to a correctly adjusted output.
Use the same method for in car adjusting also.

Above is the method as explained by Jeff.

[J1MGOLDEN]

Buy the book and read the setup procedure, Ron wrote a lot of it.

With the generator out of the engine, I noticed if you put an ammeter in line with a + voltage to the generator terminal and touch a bare spot on the case, the amps will be the same as the generator operating in the engine.

The test is recommended in the book, but not like mine.

[Woody23]

Hey Dave,

One more thing you could try:

With the generator installed in the car take the yellow/black wire that goes to the output of the cutout and touch the generator output post. This will both polarize and arc a bit when you touch it.

The arc will tell you if you have a good electrical path, just don’t do it with a VR installed. A diode or relay cutout is fine. If you don’t get any arc that tells you there is an issues with the electrical path.

I have seen this before and comes down to any issue in the car.

You can also take a headlamp bulb use the yellow/black wire to power and touch the generator body as a ground. If the path is good the bulb will be nice and bright. If it’s dim that confirms your car is the issue.

Hope that helps.

David Woods

[Mike Silbert]

Dave & Dave,

While shorting the generator used to be normal and common practice, I do not recommend it anymore.
Voltage regulators and diode conversions have been around too long and shorting them WILL cause damage.
Use the light bulb as a test load like Dave Woods described.

Too many cars and parts have changed hands plus some owners have forgotten they installed them.
I had trouble diagnosing a charging issue when the owner forgot they had a regulator and the battery was fully charged.
I hate ruining good parts for no good reason.
Mike

[Jeff]

Dave & Dave,

While shorting the generator used to be normal and common practice, I do not recommend it anymore.
Too many cars and parts have changed hands plus some owners have forgotten they installed them.
I had trouble diagnosing a charging issue when the owner forgot they had a regulator and the battery was fully charged.
I hate ruining good parts for no good reason.
Mike

VERY well said Mike. Of the 1000+ VRs I've sold the vast majority of the ones that have failed (a dozen or so) were due to owners "flashing" their generators. Even my warning label wasn't enough to save them!

[J1MGOLDEN]

When using the generator as a motor and connect the 6 volts to it, one of the statements in that blue book says the gear has to turn clockwise or the brush set is not properly aligned.

[J1MGOLDEN]

My point from the blue book:

Before applying current to the generator, try turning the armature shaft by hand to see that it turns freely. If it does, connect it to a battery to see if it will run as a motor.

Connect the Positive (+) lead of the battery to the generator terminal, and the negative (-) end to the generator case. It is preferable to use an ammeter in the circuit. When the negative wire is touched. to the case of the generator, it should run as a motor. If it runs and draws less than six amperes as indicated on the meter, the generator is probably in good condition, although the brushes may need resetting. If it draws a little higher than six amperes, take a piece. of fine sandpaper (600 grit or higher) and hold it against the commutator until a bright surface is attained. (Never use emery paper as the emery is a conductor and will short circuit the commutator.) If this does not bring the amperage down, there is probably a short or a ground.

[AndreFordT]

I was studying this post. What bothers me is the way the generator was bench tested by running it the wrong direction.

Did you tried to flash the generator and re-polarize the field?
Here is how I do it.
Take of the cutout.
Connect a test light between the generator out put and the frame of the car. A 21W 12V bulb will do the job.
Connect a wire on the + post of the battery. Don't use the yellow black wire. It is connected to the amp-meter. By flashing with this wire you risk to distroy the amp-meter .
Make the engine run at a brisk idle and flash the generator with the wire connected to the +post of the battery. Flash only 2seconds.
During the flash the test light should light up and should stay on. Speeding up the engine should make the light brighter.
Stop the engine, wait a moment and start up the engine. Now the light should light up right away.
If not your generator have a problem.
If yes, just put the cutout on the generator and connect the yellow black wire. Before connecting the wire test the voltage on the wire, it should be the battery voltage.
To set the brushes, Use a good amp-meter (not the amp-meter on the dash).
Connect the amp-meter between the generator out put and the +battery.
Set the third brush all the way down.
Loosen the four srews on the back of the generator the way you are able to move the brush holder bridge.
Make the engine run and turn the brush holder bridge till you read 1A on your amp-meter.
Tie the four screws. Now you can set the third brush to find the right current output (4A to 6A)on the amp-meter.

An other question.
How was the armature tested on the growler?
Was it just the magnetic test or did you also test the armature output on the growler?
Did you test for shorts or open windings?

Good luck
Andre
Belgium

[J1MGOLDEN]

Andre, my tester is a little simpler.