bench testing a voltage regulator

any way to bench test or adjust a 6v pos ground v-regulator? bought a brand new one last year from case-ih and had it on the shelf. went to put it on my m, nada-zip-zilch. its a made in the usa, went thru john t's secret test proceedure, and the v-reg is the problem. genny will put out close to 25 amps with the field grounded. here is the varmint. maybe i should throw it around the shed a couple times and see if that helps. contacts are all clean and shiny

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Did you polarize the VR to the generator after installing it?

yup, followed john t's system check. here is a link to it
john ts super duper testing proceedure

For it to work it MUST have a good ground itself, you might wanan try a good jumper wire to insure its ground. Of course, the Genny needs correctly polarized otherwise you can harm the VR.

One of those relays is the Cutout, one of its contacts gets to the BAT terminal other to the GEN/ARM terminal. The other is the Field current control relay, one contact gets to the FLD terminal, the other gets to the ground connection via a wirewound resistor found somewhere on board.

To its case, the BAT terminal should read like an OPEN circuit........The GEN/ARM to case represents the shunt winding of the cutout, to case ground it may be like 20 to 40 ohms as my best guess,,,,,,,,The FLD terminal to case ground would be real low ohms if the field relay were in one position (high charge) and maybe 3 to 10 ohms best guess when the field relay is in the other position (low charge).

To bench test it you need a voltage source to see if the cutout closes ONLY when the voltage from case ground to GEN/ARM is higher then battery voltage...From FLD to case ground it will be near 0 ohms to maybe 3 to 10 ohms as batery voltage changes.

If it doesnt have any burned smell and the contacts are bright n shiny AND ITS WELL GROUNDED AND THE GENNY IS POLARIZED I wouldnt bet too much its bad???????????? Still either of its relay coils may be bad/open.

Some VR's are suitable for EITHER Pos or Neg ground while others are NOT, got any ideas on that????????

Still, if it charges ONLY by grounding the gennys FLD post but NOT otherwise, the VR is bad,,,,,,,,or not well grounded,,,,,,or the wires bad from FLD on Genny to FLD on VR

You need an accurate voltmeter and a voltage source to bench test it so you can vary the voltage and see what the relays do. The field relay can chatter to regulate while the cutout should be EITHER open when shes setting there and close ONLY when the voltage on GEN/ARM to ground is higher then the voltage from BAT to ground

It looks awfully good to be bad but they can be bad right out of the box, Id still look for wiring or grounds or polarity issues FIRST

PS it MUST be a VR for a Class A circuit, NOT a Class B like some Fords used ya know

John T

John T

Its the Genny that needs/gets Polarized to match battery polarity, NOT the VR, and if its started and the genny polarity is opposite the battery that can harm the VR which is why they always have those polarity warning labels on new VR's

John T

John T... Thanks SO much for verifying the fact that is the GENERATOR and NOT the VR that needs to be polarized!

Some guys REALLY have a tough time with that fact!

Yep I believe they get that impression because any new VR usually has that warning to POLARIZE ........

John T

When all else fails, the finger on the upper spring hanger trick will tell you if it just needs more tension on the spring on the regulator section, not the cutout. By forcing the points to close it should charge full if all the wiring inside the reg are ok. I use an ohm meter to check like John said to check continuity of the windings and points etc. If you have a full charged battery in tractor you can adjust the voltage with out special tools, just a good volt meter. Remember you will need to cycle cutout and recheck voltage and have cover on after final adjustment.