Ammeter vibrates

It's on a Allis's Delco 6V postive ground, not a Farmall, but I post around here more often, and suspect it should behave the same.

The cut-out was allowing full charge all the time, the acid in the battery box indicated it had been going out for a while (not used for any work though so it's hard to notice charging issues), but the old battery had paid it's years anyway, so it has a new one now.

I could have ordered a cutout, but a VR upgrade was available and seemed to me a good choice for optimal battery life.

I connected the B and L as the wiring harness only provides one wire, but this made little or no difference from just B.

Now the perplexing part; it charges fine and seems to regulate, but about 75% of the time (now this is only 10 minutes or so, and never drove an inch) it vibrates wildly - about on center with the charge rate, but nasty swings at a high frequency.

Shorting the field back to ground, it settles just fine; though plenty high.

I'm going to see if the base just isn't taking a good ground - any other ideas?

Far as I know the generator has never been rebuilt, so nasty brushes or something inside may be up too, but I'm taking it to a threshing show this weekend and was hoping for something that I don't need to order parts.

Another part perplexing me and maybe even the missing link here:

the VR came with a large resistor packed in the same box. First thought was it was included for 12V converts, but it's a 6V regulator - so maybe it is required somewhere - but then where?

A "Jumpy" ammeter can be caused GENERALLY by any or more of the following:

Worn short genny brushes

Weak or stuck genny brush hold down spring
assemblys

The gennys commutator bars need the mica
seperation insulators cut down

Carboned or oiled up genny commutator

Burned or carboned VR relay contacts

Bad/resistive VR ground

A loose or carboned wiring connection or ground


HOWEVER MORE TO YOUR SPECIFIC PROBLEM: The part about dead grounding the field making her settle points toward a VR relay contact problem (carboned or have oil or residue on them CLEAN THEM) or the VR itself isnt well grounded CHECK THE VR's GROUND !!!!!!!!!

On that new VR I would GENTLY give the relay contacts a good contact cleaning and non abrasivley clean/buff/polish them and dry them

John T

The instructions that came with the reg will tell you that the resistor goes on the field terminal of the regulator.

not to be snotty, but then where does the other end ofthe resistor go? Inquiring minds wqant to know.LOL CC

(quoted from post at 09:13:09 08/07/09) not to be snotty, but then where does the other end ofthe resistor go? Inquiring minds wqant to know.LOL CC

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Thanks Gene! Good question Chuck! I presume then the genny's field terminal wires to it? There is already a "resitance coil" under the unit going to the field coil.

It's a domestic made unit, but I'm not sure whether Wells is a good brand or not. A VR617; the instructions were near worthless: roughly quoting "hook wires to same terminals as previous regulator" doesn't tell too much! Then again, I have been known to miss the obvious when reading instructions.

I'll give it a try, but John may have hit on a couple good points.

BTW, thanks John T for such a detailed answer; I'm guessing I have a couple issues (less than perfect internals, and perhaps tempermental contacts in the VR too) really agravating each other. Unless, the resistor puts it over the edge, I'll clean up the contacts in the VR, and then guess pull it apart and hope a little elbow grease is all it wants.

Thanks everyone!

Re-read the instructions, or lack thereof, and still see no mention of the resistor - seems that would kill a full charge scenario, unless it's wired in parallel and then the gen is never completely off.

It's OHMITE 714029: 1 ohm 10%. Theres a 0350 designation too, that doesn't mean anything to me; regardless, I'm still wondering if it's intended as an ignition resistor?

Brushes weren't too bad, but definitely trailing some crap, so cleaned up. Helped little if at all.

Took cover off regulator: throwing an arc between the relay [above the field connection] contacts. Cleaned up both relays with isopropyl on computer paper - no change.

Almost like it needs a capacitor, but then I never did find a good place to put that extra resistor either.

Still perplexed here! :?

(quoted from post at 15:00:50 08/07/09) Brushes weren't too bad, but definitely trailing some crap, so cleaned up. Helped little if at all.

Took cover off regulator: throwing an arc between the relay [above the field connection] contacts. Cleaned up both relays with isopropyl on computer paper - no change.

Almost like it needs a capacitor, but then I never did find a good place to put that extra resistor either.

Still perplexed here! :?

Click to expand...

I might be wrong here, but I doubt that the resistor belongs between Field & ground. One ohm in this position would cause the generator to output about a quarter to one-half its rated output (depending of specific field coils) at all times, thus rendering the regulator function pretty much useless. Still offer a little control in the upper end of range, but most likely still overcharge the battery.
Where does the resistor go, I do not know. Here is a bit of speculation:
My 6v gen experience tells me that thee are two large groupings of 6v field coils, one around 1.5 ohms & the other around 3 ohms. If the resistor were placed in series (one end to reg fld terminal & other to gen fld terminal, then the result would be smaller fld current both when VR contacts closed & when open, thus a smaller swing between max & min charge. If the reg is designed for a 3 ohm gen, then perhaps the resistor is necessary for a 1.5 ohm gen? Like I said, speculation, but it cost very little to try. Hopefully, someone can top speculation with hard fact.

Thanks JMOR! I'm quite open to hard facts, educated speculation, or even wild guesses!

I put the resistor in series to the field connection and it served my purpose today, but it definitely does not belong there. With this configuration I get (as you noted) partial output that follows RPMs more than need - but I like 5 (+/- 5 depending on RPMs; of course "negative charge" with lights) better than 10 to 20 constant, or 0.

I noticed a couple other orange ones with the same VR and no resistor; I didn't get a chance to ask the owners how it performed, but I presume OK. With the original cutout, the field is just dead grounded. Perhaps my generator's internals are more fickle than my quick teardown and looksee indicated. Or maybe I got a messed up VR, or perhaps I just need to tinker with it a bit more (with the resistor, I set the VR contact "heavy" and pretty much letting the resistor keep it off max) to get it right.

(quoted from post at 19:51:54 08/08/09)
Thanks JMOR! I'm quite open to hard facts, educated speculation, or even wild guesses!

I put the resistor in series to the field connection and it served my purpose today, but it definitely does not belong there. With this configuration I get (as you noted) partial output that follows RPMs more than need - but I like 5 (+/- 5 depending on RPMs; of course "negative charge" with lights) better than 10 to 20 constant, or 0.

I noticed a couple other orange ones with the same VR and no resistor; I didn't get a chance to ask the owners how it performed, but I presume OK. With the original cutout, the field is just dead grounded. Perhaps my generator's internals are more fickle than my quick teardown and looksee indicated. Or maybe I got a messed up VR, or perhaps I just need to tinker with it a bit more (with the resistor, I set the VR contact "heavy" and pretty much letting the resistor keep it off max) to get it right.

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hanks for the feedback. Wish I could help you more. Your generator isn't a 3 brush, with the 3rd being adjustable is it?

Your generator isn't a 3 brush, with the 3rd being adjustable is it?

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Yes it is a three brush: Delco 101357.

I thought these were fixed; however, may be wrong. I was talking with a fellow today, who noted there was an easy adjustment in them allowing 12V conversion without changing the genny - that noted, I'm not positive he had the same model generators as he didn't bring any of his tractors to the event.

(quoted from post at 22:00:47 08/08/09)

Your generator isn't a 3 brush, with the 3rd being adjustable is it?

Click to expand...

Yes it is a three brush: Delco 101357.

I thought these were fixed; however, may be wrong. I was talking with a fellow today, who noted there was an easy adjustment in them allowing 12V conversion without changing the genny - that noted, I'm not positive he had the same model generators as he didn't bring any of his tractors to the event.

Click to expand...

t may be fixed position. Just a thought, as something to look at.