OC-3 Generator / Regulator Charging problems

Helping my Dad with an OC-3 dozer. He had a motor rebuild and we are putting it back together. The generator and regulator was part of the rebuild.

The guy who did the rebuild was setting very thing up to original Positive Ground 6 volt.

When we got it running, the amp meter showed discharge.

I've tried the polarization procedures that I have seen posted....but something is still not right.

Finally, with the tractor running, I have removed the wire connected to the BATT terminal on the Regulator. If I measure the output voltage on the BATT terminal, I read a Positive 6 volts....and not the Negative 6 volts. Is there a difference between Regulators and Generators for +6 and -6 systems????

HELP!!!!..... what are we doing wrong?????

Thanks for anything you folks can help with.

John

Thanks to all who have responded thus far....I think we almost figured it out.

We checked a few more things out and wanted to post them to see if we were on the right track.

1) After getting the engine running, we disconnected the battery. The generator / regulator setup is producing current because it will light the 6 volt lights on the dozer. But instead of reading the (-)6 volts, we read (+) 6 volts.

2) We pulled the belt and the 2 wires off the generator and applied (-) 6 volt battery to the Gen terminal to see if it would "motor". It did turn, but in the opposite direction that it would turn when connected to a running engine.

Items #1 & #2 still make me think that the field is polarized backwards.

Lastly we wanted to verify part numbers.

Generator : Delco-Remy Part# 1101853-254
Regulator : VR 851 6v POS

Are these parts the proper match for a Positive Ground 6 volt system??

Again, thanks to all for helping!!!!!

John

thanks, jeff (dads other son)

1) The ammeter connections are reversed.

2) The generator is not polarized. To do so, just short the "Batt" and "Gen" terminals at the regulator ever so briefly with a jumper.

3) The points in the regulator have been welded together by running the generator un-polarized. In time, this will also fry the generator. If either or both are damaged, they must be rebuilt. You can inspect the regulator's points yourself. The generator must come apart to check the condition of the armature.

Two things to keep in mind...

1) The "+" "-" stuff doesn't matter. The generator can work either way. It just has to match the battery connection.

2) The generator must be re-polarized every single time the generator is disconnected. Polarization does not persist.

We have tried the items you listed except for checking the internal of the generator....and still no luck.

Forgive the novice questions.....but I'm trying to understand this circuit better.

I understand that the generator can produce either a + or - charge depending on how it was polarized. Does a regulator have the same function? Is there such a thing as a positive and negative regulator, or does one do both polarities???

We are assuming that the generator rebuild was good....is it posiible that the Field and Gen terminals on the generator are crossed....and if so could that be the cause of our problem?

I think polarizing the generator is our problem....right now it's backwards.....and for whatever reason, the procedure you and others have stated isn't working.

Do you or anyone else have a circuit schematic of the regulator / generator circuit....or some website that might show it??? The manuals we have don't go into that detail.

Thanks again for any help!!!

John

1) The regulator, like the generator, works either way.

2) I've never seen a generator wired wrong internally but I guess it's possible.

3) Did you check the points in the regulator? If they are not opening and closing (welded together), that's why it won't polarize the generator.

4) If the armature has been damaged by running with the wrong polarity, it won't polarize and has to come apart to be repaired.

5) You can search the web using Google to find wiring diagrams for automotive generators.

Generator Article
Hope it will help.
Myron KY