Voltage Regulator

I am having some problems with voltage regulators. I have an Allis Chalmers C that i just put a new voltage regulator on and an Oliver 70 that I just put a new one on. Both of them were made in India and neither one charges worth a darn. They will both charge for just a couple seconds when I first start it and then they quit. Both of the generators are rebuilt and work great if I ground the field. I guess my questions is, are these VR really that much of a POS when the come from India or am I the only one that is having this problem? Thanks for the feedback!

I would need to look at the A-C wiring diagram but on the Oliver 70 do you still use the original style light switch as the field is grounded through the light switch. Are these 3 or 4 terminal regulators and how do you have them wired? Did you polarize the regulator? Start there. If the A-C used a cut out it will be like the Oliver. J.

Both of them had cutouts originaly I think. Both generators have an A and F terminal. I have 4 terminal voltage regulators. They are both wired with the A going to the GEN terminal, F to F terminal, and BAT to back of amp gauge which is hot.

Forgot to mention, I polorized both of them and neither one has the original light switch/resistor. They both just have a toggle switch for lights and the field terminal is connected right to the field terminal on the VR.

If she charges fine when you dead ground the gennys FLD post but NOT otherwise, the genny itself is okay so the problem is EITHER:

The VR is bad,,,,,,,,,The VR isnt compatible with your ground i.e. Pos or Neg,,,,,,,,,the VR isnt well grounded,,,,,,,,,the wires bad from FLD on Genny to the VR's FLD post.

On that 4 terminal VR it wires ARM/GEN to gennys ARM post,,,,,,FLD on VR to gennys FLD post,,,,,,,BAT wires up to Load side of ammeter,,,,,,LOAD terminal sends hot battery voltage to loads like lights n ignition. On many 4 terminal VR's the BAT LOAD FLD are together while the ARM/GEN is often on the bottom or one side by itself.

You should Polarize (if needed) the Generator BEFORE you start the tractor cuz if the gennys is polarized opposite the battery you may damage the VR

If I convert from a cutout relay and light switch charge control system to a VR I adjust the third brush for max charege if its a 3 brush adjustable genny.

Insure the VR is compatible with your ground,,,,,,,,,,,,Insure the VR is well grounded,,,,,,,,Polarize the Generator,,,,,see what happens

John T

JohnT, the VR is well grounded to good clean metal (took a test light and connected from it to the bat. and she lit up nice and bright, the VR states for POS or NEG ground, both have been polorized, and the 3rd brushes are set to MAX charge. Any other thoughts?

Gee, you already covered the bases and "usual suspects" lol. Sooooo Im back to if it charges fine with a dead grounded Genny FLD post (Says genny is okay) but NOT otherwise and the VR ground is good and the VR is compatible with your ground and the genny was polarized,,,,,,,,,,,that leaves a bad VR. Maybe the contacts just need cleaned??

Of course, the VR needs to be for a Class A charging system NOT class B like some Ford products used.

John T

JohnT, Thanks for the reply. Like I said, I am starting to think these particular VRs from India are pure junk. They are both new within the last 2 weeks so I doubt the contacts are dirty. Just to make sure I am right, to set the 3rd brush to max charge you rotate it in the direction the armature rotates right? If I am looking at the generator from the commutator end mounted on the tractor, I moved the 3rd brush all the way left.

To increase charge you move the adjustable brush CLOSER to the fixed brush HOWEVER NOT closer then 1.5 commutator bars (2.5 on some, cant tell you which gennys though)

Even a new VR can have some protective oil/coating on the relay contacts which may be a problem. If the cover can be easy removed Id run a clean dry thin cloth through the relay contacts

Im about of ideas here lol

John T
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JohnT, explain what you mean by FIXED brush. One brush connects to the ARM post, one connects to the field windings, and one is ground correct? I moved the 3rd brush (connected to field winding) closer to the one that connects to the ARM terminal? Is this wrong? I just always heard you turned them with the armature to increase output. Thanks for your help.

Is the BAT terminal connected to the load side or battery side of the ammeter? If its connected to the BAT side, any charge current will not flow through the ammeter. It should be connected to the load side.

Since nothing else seems to working, just something else to check on.

Keith

The BAT is connected to the load side. When I turn on the lights it will discharge and when I dead ground the field it shows charge so I know my gauge is hooked up right and working. If you have any other thoughts, they would be appreciated. Hate to think I just wasted 80 bucks on two junk regulators.

If you cant return those regulators for refund or exchange, you may just need to adjust the field relay spring a bit tighter. Adjusting the old vibrating contact regulators is a bit of a learned skill, but can be done quite easily with only a voltmeter. The cutout relay has the heavy wire windings in it's coil. The field relay that you need to adjust has the very small wire windings.
Disconnect a battery cable any time you install or remove a regulator cover, If you touch the cover to a Hot internal connection and the base, the regulator may be ruined by the short circuit. With the battery disconnected, your safe.
Always install the regulator cover before checking the final voltage setting. The battery must be fully charged and the regulator at operating temperature, so run it for 15 minutes before the final tweeking.
The steel cover changes the magnetic field in the regulator and can affect the voltage setting by 1/2 volt or more.

I love the new solid state regulators, 90% of generator / alternator troubles went away when the old mechanical regulators were replaced by solid state units.
BTW, there are several outfits making replacement solid state regulators for older 6 and 12V generator systems. Do a google search for "solid state generator regulator"

Check the voltage at the battery. Perhaps the ammeter drops because the battery is at full charge. If the voltage at the battery with the engine running is about 7.3 volts, consider that all is well and leave it alone.

NO its NOT wrong, its CORRECT

The one brush connects direct to the ARM post (I call it fixed, it dont move),,,,,,,,,the other adjustable brush connects to the Field winding (its close by the fixed ARM brush),,,,,,,,the one over on the other side is also fixed in place and its GROUNDED.

To increase charge rate you move the adjustable (Field) brush CLOSER to the fixed (ARM) brush.

John T