Did I Fry my new Voltage Regulator?

z145fergie · Jun 18, 2011

Installed new VR on my MF135 but forgot to polarize generator before starting engine - not showing any charge. I tried polarizing the gen anyway but the only way it will show a charge is when I ground the "FLD" terminal. Is VR bad? Any other thing to check? Thanks.
Z-

Owen Aaland · Jun 18, 2011

If the generator was off to be tested or the battery was reinstalled backwards you may have ruined the voltage regulator. If neither of those things occurred there is a good chance you did not damage the new regulator. If it has a removable cover you can check to see if you let the magic smoke out from the points and windings.

Check to make sure the voltage regulator is grounded. If it is mounted on an anti-vibration base make sure the ground wire is intact between the regulator and where the base attaches to the tractor.

gene bender · Jun 18, 2011

If you have to ground the field to make it charge the vr is the trouble. Ifn you ground the field and it doesent charge the gen is bad.

Janicholson · Jun 18, 2011

Make sure the VR is grounded securely, If it is not, it won"t charge automatically. Jim
This should help.
John T charging analysis

John T · Jun 19, 2011

If the battery didnt have its polarity reversed and the genny hadnt sat there for a longggggggggggg out of service time I dont see why the genny would have even needed Polarizing in the first place, although it dont hurt.

Its the Genny NOT the VR that needs and gets Polarized but the VR instructions always say to Polarize because if you install a new VR and start her and the genny happened to be at opposite polarity from the battery THEN YOU CAN FRY THE VR

Soooooooooo assuming you didnt change battery polarity and the genny hadnt been theree setting unused for a long timeeeeeeee I DONT SEE FAILUE TO POLARIZE AS THE CAUSE OF NON CHARGING NOW OR FOR TRASHING THE VR

I agree with Jim, MAKE SURE THE VR HAS A GOOD GROUND and check the connection from FLD on VR to the gennys FLD post. Just to be safe go ahead n polarize the genny before re starting.

PS some VR's are polarity sensitive, sure yours is okay for your battery polarity???

John T

Jon Hagen · Jun 19, 2011

I would guess the regulator was bad when you installed it or has a poor ground as others suggest.
Not polorizing the generator might have damaged the cut out contacts, but should not have affected the field control relay. The field control relay is what grounds the field coils and makes the generator charge at the correct voltage.
I would bet the problem is ditry / corroded field relay contacts or a poor regulator ground.

z145fergie · Jun 20, 2011

Here's what I found. Checked all wiring, connections and grounding. Still only showed just a slight charge even though battery was near complete discharge. I could ground the FLD terminal and effect significant charging. Took cover off VR and noticed a constant arcing between the contacts on the FLD relay (if that's the proper name for it). I could manually close the contacts and get a good proper charge. I ever so slightly increased the spring tension that allowed good contact closure and eliminated the arcing. Battery was near completely charged in about 20 min. of mowing. I was hesitant in making any internal adjustments but hopefully problem is resolved. Thanks for all help and suggestions. Any further comments welcomed.

Did I Fry my new Voltage Regulator?

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