Ford 641 Charging Issue

WildcatFord · Oct 2, 2018

I have a Ford 641 with a charging light that won?t extinguish. Voltage regulator was recently replaced, and the charging system seemed to work for a few weeks.

Tried repolarizing the VR by shorting across the VR field and battery terminals, and the charging light went out for a little while, but started staying on again later in the day.

I can motor the generator, so I don?t suspect any issue with it.

Given that repolarizing seemed to solve the issue for a bit, I?m suspecting the replacement VR is bad. Any suggestions? Should I go ahead and shell out the cash for the NAPA ECH VR951?

TimInd · Oct 2, 2018

I can tell you that the foreign voltage made regulators are not reliable. I put a new one in about 18 months ago in my Ford 2000 diesel. Started it up this year, and no charge. I, like you, started to look at generator, etc. etc., since I knew the VR was not the problem, since it was almost new. Finally, I took the Generator and the regulator in to the NH dealer to test, and guess what, it was the VR. NH told me that they do not even buy foreign made VR's anymore, and instead they opt for a made in the USA supplier, which costs about twice a much. So....don't think the VR is not the problem just because it's new.

Bern · Oct 2, 2018

You don't polarize the VR, you polarize the generator.

Tim PloughNman Daley RIP · Oct 3, 2018

Yes, that is true, but can perform at the VR easily.

TPD

Tim PloughNman Daley RIP · Oct 3, 2018

Why was VR recently replaced? The early 9N-10000-A small generator, the NAA generator, and all others used up thru 1964 were the "B" Circuit Design. From '53 -'64, the VR is p/n FAG-10505-A. Polarizing a "B" Circuit Design generator is a different procedure than polarizing an "A" Circuit Design -see diagram. "A" Circuit = externally grounded field; "B" Circuit = internally grounded field. It sounds like you performed the process correctly so I'd verify if the entire wiring system is correct. You probably have something shorting to ground and/or improperly wired. Don't guess and keep replacing parts. Can we assume your setup is 6V/POS GND? 6V battery? 6-V coil? No ceramic resistor?

Tim *PloughNman* Daley(MI)

JMOR · Oct 3, 2018

(quoted from post at 06:25:40 10/03/18) Why was VR recently replaced? The early 9N-10000-A small generator, the NAA generator, and all others used up thru 1964 were the "B" Circuit Design. From '53 -'64, the VR is p/n FAG-10505-A. Polarizing a "B" Circuit Design generator is a different procedure than polarizing an "A" Circuit Design -see diagram. "A" Circuit = externally grounded field; "B" Circuit = internally grounded field. It sounds like you performed the process correctly so I'd verify if the entire wiring system is correct. You probably have something shorting to ground and/or improperly wired. Don't guess and keep replacing parts. Can we assume your setup is 6V/POS GND? 6V battery? 6-V coil? No ceramic resistor?

<center><img src="https://i.imgur.com/yfPvocUh.jpg"></center>

Tim *PloughNman* Daley(MI)

disagree that he performed the polarization correctly. He said he jumpered Field to Batt at VR. If he did that instead of removing Field wire from VR , as is shown on right in picture, the he put so much excess current thru the VR field contacts that it is likely toast now.

WildcatFord · Oct 3, 2018

The tractor was refurbished about 6 weeks ago, and the guy who did it replaced the VR.

I did short across terminals instead of removing wires, so I probably did that part wrong. Death by You Tube, I guess.

System is 6 V POS GND with 6 V battery and generator. I don?t think there is a ceramic resistor, but I?m not sure.

WildcatFord · Oct 3, 2018

Whoops. Didn?t see any of the infamous smoke, though.

JMOR · Oct 3, 2018

(quoted from post at 07:37:34 10/03/18) Whoops. Didn?t see any of the infamous smoke, though.

t would be somewhat dependent on the duration of the jumpering. Typical problem with polarizing the way you did it is too much current thru field contacts can weld the contacts closed and when that happens the generator will be maximum all the time (VR can't cut it back). As it sounds at this time that is not your problem. Running at fast idle, jumper the BATT to ARM terminals and see if that will make it charge. That bypasses the cut out function which connects/disconnects battery to generator. Don't leave this jumper in place more than a few seconds if engine is stopped or else the battery will be feeding current into stalled generator & that is bad for both generator & battery.

Sean in PA · Oct 3, 2018

System is 6 V POS GND with 6 V battery and generator. I don?t think there is a ceramic resistor, but I?m not sure.

A 6 volt system should not need a resistor in the ignition circuit except for, I believe, the N's with the front mount distributors.

WildcatFord · Oct 5, 2018

Confirmed that warning light is extinguished when BAT and
ARM terminals are jumpered at the VR when engine runs at
fast idle. Does this confirm bad VR? If so, any
recommendations on brand?

JMOR · Oct 6, 2018

(quoted from post at 20:47:39 10/05/18) Confirmed that warning light is extinguished when BAT and
ARM terminals are jumpered at the VR when engine runs at
fast idle. Does this confirm bad VR? If so, any
recommendations on brand?

ou could run with that conclusion, but before I invested in a new VR, I personally would verify that with the BATT shorted to ARM, that the genrator was actually charging the battery, by measuring battery voltage and looking for an increase running vs before starting voltage. And I would go a bit further and verify that there is voltage on the generator Field terminal during this running test. If both of these conditions are met, then generator is good and VR is faulty.

Ford 641 Charging Issue

WildcatFord

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Bern

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Tim PloughNman Daley RIP

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WildcatFord

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