Mis-marked generator??

Delco-Remy 6 volt generator on a friend"s C. At what I think is the Arm. post is a sunken triangle in the housing. At what should be the Field post is a sunken D and below this mark is a small A stamped in the housing. The ground is positive and at a fast idle will only charge 3 to 4 amps. Battery was almost dead when we started the tractor. Your thoughts --please.

The C should have a positive ground. You may need to have the generator rebuilt to get full charging ability. Be sure the fan belt and generator is fully tight and not slipping.

Polarity is not important. If the tractor charges at all, it is connected correctly. They do not care which terminal is ground if they are polarized correctly for that ground, and it is.
If it is setup to use a voltage regulator, the field terminal should go directly to the smaller terminal on the gen. If it goes other places, it is wrong. If it has no regulator, but has a 4 position light switch, LHDB, then it has a cutout relay with two terminals, and no regulator. The switch for the lights also controlls charge rate. L (the first position CCW on the Switch) is low charge and will be as you found, low amps to maintain the charge after it is charged up. The second position H is high charge, and will usually pump out more like 12 to 15 amps. The D position, and B positions are for lights and also cause high charge. Though the lights draw this down to maybe 4 or 5 amps into the battery.
If it has a regulator, and it is connected directly to the gen, the regulator may need adjusting (by a knowledgable elecrtical system tech), or replaced. Let us know how it turns out. JimN

Dr. Bert - A quick way to determine which generator terminal is which is to use an ohmmeter - either a VOM or DMM:

First disconnect the wiring from both generator terminals. Set the meter to the lowest resistance range, ground/hold one ohmmeter probe to the generator frame then touch the other probe each generator terminal in turn. The terminal reading almost zero resistance (usually 0.1 ohm or less) will be the A (armature). The other terminal will measure between about 1.5 and 4 ohms - it will be the F (field).

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Presuming the C has its original 3 brush generator, maximum current output can be changed by adjusting the 3rd (movable) brush position. The closer the 3rd brush is to the nearest fixed brush the more amps the generator will produce.

Hi
Just for my own info, don't laugh, my memory aint that good, but wasnt that near normal gen output at idle.
Thanks
Bob S.

At Low Idle the gen was not able to charge, and goes dormant. At about 1/3 throttle, it will charge some, at High Idle, it is full output. JimN

Generator is not a 3 brush generator. Does not have the 4 position light switch--in fact no lights at all. Looks like a simple cutout on the gen. When I stated a fast idle, read 1/2 throttle. Plan to clean and tighten all contacts and run the suggested tests. Thanks to all for the advise. Will post back with the results. PS Does anyone besides me find the markings on the generator a little strange?

There needs to be a method to adjust gen output. If it has no light switch, the F terminal must go some where. It needs a ground to make full output, Or it could be a "B" circuit generator. if it is, it will be getting battery voltage at the F terminal to make it go. Trace the wire from the Little terminal to see where it ends up. sense it is charging it can't be all bad! JimN

Doctor, let me jump in here with my friends the Bobster n the Jimster. Some of what youre saying isnt adding up for me. You say it appears to be a cutout but theres no LHBD light switch,,,,, its NOT a 3 brush genny,,,,,,,yet it still charges a few amps?????

We need to know if its indeed a cutout relay in which case as Bob points out there has to be some sort of Field ground somewhere?? (It may be permanently dead grounded or still grounded somewhere in the switch box, where does any wire go from the gennys FLD post??? ) If its instead a Voltage Regulator theres no light switch control needed.

In the meantime insure the belts good n tight and when shes running dead ground the gennys FLD post n see how she charges then. Such will tell us a lot. If grounding the fld makes her charge like 10 amps that tells us the genny itself is okay and we need to investigate the regulation system, be it a realy and light switch or a full fledged Voltage Regulator.

Also if the belt is a lil loose 3 to 4 amps may be all she can charge depending on which genny you have and how its regulated

WHERE IS THE GENNYS FLD POST CURRENTLY CONNECTED??????? HOW MANY TERMINALS AND ANY LABELS ON THE RELAY/REGULATOR????????????WHAT HAPPENS WHEN YOU DEAD GROUND THE GENNYS FLD POST


John T

Any chance the sunken triangle marking is a mal-formed "A"? I have seen some poor markings on generators. Is the original Delco tag still on it? If so, what are the stamped numbers and what color is the tag? Long shot, but if the number is still there, we may find a listing for it.

If it is in fact a cut-out system with no light switch, the charge rate is controlled by the wiring of the F terminal of the generator. Connect to the cut-out F for low charge and ground it to the generator housing for high charge.