Which Wiring Harness - Charging System?

homer14

Member
Hi a quick question and a little history.

8N side distributor late model 1951. Genny is a 8N1001 and regulator is a 8N10505C. Wiring to/from genny and regulator and what not is crap and i think i need a new harness to resolve my issue described below.

Question:

Which wiring harness will cover the charging system or should i buy my own wire (what gauges) and hand wire it myself? Is harness "8N14401C" for the charging system or do i need the expensive harness with diff part number?

History:

Last winter my battery was weak or dead all the time. During spring/summer it starts right up. This fall I was wondering exactly what to expect from the ammeter so I read up and realized i should be seeing some 1-20amp draw to the positive side while it is charging the battery. It never passes 1amp or 0 amps.

So i did some more reading and testing of my voltage regulator. I got to a particular test where i was to connect FLD to Ground and see if the ammeter jumps to full charge. It did! The next step in the PDF i was reading was to change the voltage regulator. So I did! I fired that puppy up all excited to see some draw and nothing. I repeated the FLD to Ground test with a wire and same thing, 20amp charge on ammeter. In fact, this time the ammeter jumped all over back and forth for a bit and finally stopped at 0amp after 5 min of jumping or sitting still at 0.

So i did some more reading.. Learned that i could adjust the voltage regulator armatures of the cutout and the regulator. But do i need to? I just bought a brand new one from this web site, isnt it spec? Plus, i opened the old one and noticed there is no screw to adjust it so id have to bend the tabs and want to avoid that.

This lead me to think maybe the wiring is bad? If so, then why would the FLD to ground jump spike my charge?

What are your opinions? Replacing wiring? Which harness? Could i just replace a few wires from the genny fld,arm,bat to the regulator instead and go buy some lesser priced wire at the hardware store of some specific gauge?

-Homer
 

One other thought. If my ammeter jumps to 20amps when i jumper a wire from the regulator FLD to a Ground (just touched a bolt somewhere down low) wouldnt that indicate that my voltage regulator is not grounded? This guess is because underneath the regulator there is an odd looking wire running from FLD to the voltage regulator chassis.

If yes, then what is the issue? the regulator is on dirt/paint or something.. or some wire is messed up somewhere?
 
"If my ammeter jumps to 20amps when i jumper a wire from the regulator FLD to a Ground (just touched a bolt somewhere down low) wouldnt that indicate that my voltage regulator is not grounded? This guess is because underneath the regulator there is an odd looking wire running from FLD to the voltage regulator chassis."

Far as Ive been told, the 8N uses a Class A Charging System, therefore:

If it ONLY charges if you dead ground the Gennys FLD, but NOT otherwise; A) The VR is bad or B) The VR isn't well grounded or C) The wires open from Gennys FLD to VR's FLD terminal.

Below is my Class A Charging Troubleshooting Procedure.

John T
John Ts Charging Troubleshooting
 
John,

Thanks for your time. Question on your Step #5?

You wrote: 5. With the tractor running, temporarily ground the Gens Field post to case. If she charges then, the VR may be bad, or a wires missing from VR"s Field post to the Field terminal on the VR, or the VR isnt well grounded.

Question: Did you mean a wires missing from the "GEN" Field post to the field terminal on the VR?
 
YES was talking about the wire from F on Genny to F or FLD on the VR, but that's usually not the problem, its usually the VR is bad or it isn't well grounded.

John T
 
(quoted from post at 11:21:47 10/23/14) YES was talking about the wire from F on Genny to F or FLD on the VR, but that's usually not the problem, its usually the VR is bad or it isn't well grounded.

John T

Hmm, could i just wire the VR base (via nut and loop) to a ground, or directly to the positive post on the battery then to accomplish that latter part?

This morning i left the fld from the VR to the batter positive post for a moment and the ammeter remained spiked full. The VR is brand new from this web site, just would be odd to have it be bad but i suppose it is possible.

I also bought a wiring harness this morning too but would like to return that if i can figure this out.
 
For sure if the VR isn't getting a good frame ground via its normal mount, you could run a known good ground (such as grounded battery post) jumper to the VR and see what happens. Of course, if the gennys field is kept constantly grounded you risk overcharging the battery.

John T
 
Well still stuck but I've now replaced the wiring harness and the VR. The wiring connections are REALLY good now. I polarized the VR using BAT/ARM jump.

I'm out of ideas. Do i need to polarize the generator too somehow or is the VR enough?

Should I run some special Generator tests or do we know the generator is good because the amps max when I do a FLD to Ground on the VR while its running?
 
"Do i need to polarize the generator too somehow or is the VR enough?"


The VR doesnt get or need Polarized, the genny does, but it can be done by jumping BAT over to GEN/ARM on the VR assuming all is in place and wired right and you should get that spark. Or just jump any hot ungrounded battery voltage source direct to ARM on the genny and get the spark. Either should work if all else is correct

"Should I run some special Generator tests or do we know the generator is good because the amps max when I do a FLD to Ground on the VR while its running?"

My Non Charging Troubleshooting procedure has a Motor Test to test a genny, but if the genny charges good when you dead ground its FLD post but NOT otherwise, the genny itself is okay so the problem is a bad or miswired VR, or VR isn't grounded, or the wires open from FLD on Genny to FLD on VR.

Sure you have the correct VR??? It has to be for your genny,,,,,,,,,,,,, and has to be okay for your ground (Pos or Neg),,,,,,,, and has to match your Charging System (Class A or Class B),,,,,,,,,,and has to be grounded.

best I can do not being there.

John T
John Ts Class A Charging
 
It's a late 8n (serial 400k+). Honestly I dont know what genny it has but have been assuming 8n10001 based on the FO-4 manual and online text along with that serial number. But the prior owner (2 years ago) might have modified things for all I know.

[genny]
Can i somehow identify the genny with a multi-meter perhaps or by looks? The field and ground terminals are hard to identify (no labels) but i read the insulated one (insulated with a vinyl washer or something maybe) is the field and the ground is the other.

If they were crossed would that break stuff or simply prevent it from charging? If its harmless to cross them them i could simply swap them and see what happens but I wouldnt ever do that unless i knew it was harmless. I believe they are correct as they are right now.

I dont think we need to do a motor test since we get a 20amp spike with jumpered wires right? The belt is nice and tight witht he 1/2 play and i cannot hand turn it by trying to turn the genny pully so it seems ok?

[VR]
The old one i took off is type "a" per the bottom print. I can open it too and validate that way i believe. The new VR is identical to the old one. So i think that is the correct VR 8n10505C for the genny assumption 8n10001 right?

The ground wire from the genny is connected to a bolt holding the VR to the frame. If i simply touch the back of the bolt (other side of frame where nut is and VR is not) to the FLD terminal on the VR i get the 20amp spike so i think that ground is good? Does that indicate anything else?
 
JOHN T...The gentleman wrote: "In fact, this time the ammeter jumped all over back and forth for a bit and finally stopped at 0amp after 5 min of jumping or sitting still at 0."

I'm not all that knowledgeable about this kind of stuff, but by what he's posted, I question if he hasn't damaged is VR...."finally stopped at 0 amp AFTER 5 min of jumping or sitting still at 0."

Please accept my apology if I'm wrong...just responding to what he wrote.
 
John, Snoop:

Before I go buy a "3rd" VR, this time from Orielly's for $60 made in America, is there any testing i can do with a multi-meter on the generator to clearly identify that its an 8N10001 type "a" generator before I purchase yet another Type "a" VR?

My wiring is brand new, the VR is brand new from this web site, ignition on shows slight amp pull. I think its wired right. I'm a bit ------ at the VR i just bought and it cant be returned because it has been used I believe.
 
Homer, I am NOT and Ford expert but I think Soundguy and other Ford board members have insured me an 8N uses a Class A Genny, ASK OVER ON THE FORD FORUM PAGE......

"Before I go buy a "3rd" VR, this time from Orielly's for $60 made in America, is there any testing i can do with a multi-meter on the generator to clearly identify that its an 8N10001 type "a" generator before I purchase yet another Type "a" VR?"

I can tell you this: If its a Class A Genny, the beginning of the first Field (has 2 in series, one on each side that splice together) CONNECTS TO THE INSULATED ARM POST or to that ungrounded brush which connects to the ARM post. And then the wire comes out of the first Field, splices to the second field on other side, and then it connects to an INSULATED post thru the case and out to the FLD post on the genny.

If its a Class B, the first field wires to again an insulated pass thru FLD post, then out to second field on other side, AND THEN CONNECTS TO THE CASE/FRAME OF THE GENNY.

Trouble with an ohm meter test is if the armature is in place and the brushes are in and against the commutator either genny terminal will read very low ohms to ground since one brush is grounded and the armature has very low resistance while the fields only have a few ohms. If you raise the brushes and put paper under them so they dont touch the commutator you can get some ohm readings that make some sense. Two fields in series may total in the range of 2 to 4 ohms while ohms thru the commutator is near zero LOOK AT THE DIAGRAM AND YOU CAN FIGURE OUT THE WIRING IF ITS AN A SYSTEM

If its a Class A VR, put one lead of ohmmeter on the case/frame ground, the other on BAT should read an OPEN circuit (approaches infinity ohms),,,,,,,,,,,The one that has very low ohms (zero to maybe a few) to case is FLD,,,,,,,,the one that has maybe 20 to 50 ohms is GEN/ARM.

I WOULD SUGGEST YOU CALL JIM GUIARNO at AGRI SERVICES IN NEW YORK at WWW.WIRINGHARNESSES.COM (tell him John T says Hi) and talk to him about the right VR for your Genny. I would trust him wayyyyyyyyyy more then O reillys. The counter guy likely has no idea about A or B systems nor which Ford used which. I think 8N was A while all other Fords were B so you may have the wrong one????

I have attached a simplified (NOT accurate but for illustration ONLY) of a Class A system, for a Class B one end of one field goes out the insulated FLD post and the end of the other field is internally grounded.

On the old Ford Flathead Class B gennys the ARM post is actually out the back plate NOT the round case side.

Again ifffffffffff its a Class A and if she charges with FLD grounded but NOT otherwise its a bad or wrong VR or its not grounded.......

Im runnin outa smarts here not being there...

John T
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Untitled URL Link
 
Ok some good news... The VR is not bad. I opened it, examined the points of soldering, put it back in with the cover off and started to attempt to adjust it per the FO-4 manual.

To me this mans FLD to Ground and full amp gauge could mean a few things right:

1 - bad ground to vr
2 - bad vr component inside vr
3 - uncalibrated vr (this is me i think, should the guides state this possibility?)

Anyhow... i'm having a hell of a time trying to calibrate it. I played with it for about an hour re-reading the FO-4 manual. I have some questions:

1. Is there a better VR tweaking guide for the type a 6v pos ground?

2. Should the VR points ever close? I cannot get mine to close no matter how fast or slow low the genny is running. Sometimes when I close it manually with gen slow i see voltage of 6.5-6.8 but when i leave it open the voltage never seems to go under 8v.

3. Can i not adjust the cutout until the vr is first calibrated so it opens and closes?

4. when adjusting the VR am i adjusting how much voltage is coming from the genny toward the cutout? If so, how do i detect what is coming from the genny at these points, leaving the points closed when it never goes below 8v?

I think im moving in the right direction and need only to tweak this VR some more.
 
Update:

I think I got it! Some things I've learned.. The screws on the back to adjust tension of the spring dont do enough. Tab bending has larger effects. Then the screws have some more fine effects later on once you're in the ball park. The VR's do not come very well calibrated from the manufacturer so they likely need to be tweaked and cannot just be dropped in and work, even if the FLD to Ground jump test spikes the ammeter (doesnt mean its bad necessarily).

It's not showing any amp draw now after diddling with the VR for an hour but thats because I think the battery happens to be charged at the moment..

I'm letting it drain a little and will test later today and followup.
 
Told ya I'm runnin outa smarts and without being there I cant answer too much more lol but can say this:

The VR works somewhat different with the cover off due to how it affects the magnetic field.

The Cutout Relay cant work (close) unless the VR is grounded with the genny because its the Shunt Winding portion of the relay that has to have a complete current path.

The Cutout relay only closes at a pre set (maybe adjustable) voltage which depends on the current flow through its "shunt" winding that's between the gennys ARM post and ground. It also has a heavy wire series winding that's in the circuit once its closed but the shunt winding is always there.

When you start bending tabs and tightening those small springs you better know what you're doing and how things are different if cap is on or off or else you may mess it up!!!

Sorry, Im not there and dont have your manual or the genny or VR specs, so this is about all I can do for you. I have tried to educate you on how things work and basic theory which may or may not have helped, but hey I've tried my best.

Good luck on getting her going

John T
 
2. Should the VR points ever close? I cannot get mine to close no matter how fast or slow low the genny is running. Sometimes when I close it manually with gen slow i see voltage of 6.5-6.8 but when i leave it open the voltage never seems to go under 8v.

I think you are confusing open and close. VR contacts closed will give same result as your jumper from FLD to ground gives,,,,,full output. VR contacts open will give a very, very minimal generator output.
 
I agree JMOR talking about the Field current control relay. I think they can chatter which yields something similar to "pulse width modulation". One position gives a dead ground for max high charge but the other the ground becomes resistive i.e. low charge. However unlike the 2 position ONLY manual light switch High/Low control they are more variable and precise as they can switch from one to the other. Correct me if Im wrong.

John T
 
(quoted from post at 16:56:13 10/24/14) I agree JMOR talking about the Field current control relay. I think they can chatter which yields something similar to "pulse width modulation". One position gives a dead ground for max high charge but the other the ground becomes resistive i.e. low charge. However unlike the 2 position ONLY manual light switch High/Low control they are more variable and precise as they can switch from one to the other. Correct me if Im wrong.

John T
o corrections here. Typically 3 modes: battery low (or much lighting load)=VR contacts closed 100% of time for max charge, battery full charged=VR contacts open 100% of time, battery in its normal state & light loads such a ignition= contacts constantly chattering/buzzing/switching on and off (characterized as puled width modulation), being closed greater part of time for greater charge & a lesser part of time for a lighter amount of charging. Typically perhaps 30 to 40HZ. Hold pocket transistor radio near VR wires or one lead of headphone to FLD & you can hear it if in switching mode.
 
Good summary of a VR's field current control system. And even if there's no field current flowing whatsoever, there's still some charge due to the small residual permanent magnetism in the soft iron field poles........

I think we have it, now if Billy Bob got it also???

John T
 
(quoted from post at 20:12:46 10/24/14) Good summary of a VR's field current control system. And even if there's no field current flowing whatsoever, there's still some charge due to the small residual permanent magnetism in the soft iron field poles........

I think we have it, now if Billy Bob got it also???

John T
won't say 100% on this one, but in my experience the residual alone is too small to make enough voltage to pull in the cut out, so no charge. It seems as though the residual is just enough to feed the field enough to bootstrap itself up to adequate voltage to pull in the cut out, so if you were to disconnect FLD at generator, I'm pretty confident that you will never see a charge.
 
VERY GOOD POINT JMOR (I love these kind of chats),,,,,,When I used the word some "charge" perhaps I should have chosen the word some "voltage". In my mind I was thinking as long as you're still rotating the armature (coils of wire) inside a magnetic field (the residual magnetism in the poles) you're inducing some "voltage" into the armature HOWEVER AS YOU POINT OUT it may not (but subject to RPM could) be enough to latch close the cutout relay. Of course, since the output is a function of field strength PLUS RPM, if a genny was turned fast enough (but just how fast???) Id guess the cutout relay might kick in even with FLD disconnected???

For info to others who may be reading this, if the gennys FLD post isn't connected to a ground, voltage on the ARM post doesnt cause a current flow through the field windings which greatly increases the strength of the magnetic field.

I guess if the soft iron field poles had enough residual magnetism the cutout relay might latch in but if its weak it would not WELL DUH. I have no specs or data or charts whatsoever to know if and when a cutout relay might pull in but it depends on the RPM as well as residual magnetic strength.

Thanks for the fun chat, I enjoy it but we are probably boring others lol

John T
 
John, JMOR and Snoop:

Thanks for your attention and help. This is resolved now. It was a learning experience for me and I think we should update step #5 of john's trouble shooting notes:

5. With the tractor running, temporarily ground the Gens Field post to case. If she charges then, the VR may be bad, or a wires missing from VR"s Field post to the Field terminal on the VR, or the VR isnt well grounded.

Add one more note to the last sentence. Or the VR and Cutout need internal adjustment of points and spring tension.

Step #6 from this other persons PDF guide should also mention the same thing. I found that one on google and the file name is Testing-Replacing-Polarizing-8N-Voltage-Regulator.pdf if you want to search.

Someone may save $40-60 on a VR that really isn't bad.

Either way, it was a pleasure getting expert help from you guys and a learning experience. It's always fun when you fix something and see it working again. Appreciate your help guys!

-Homer
 
I have no specs or data or charts whatsoever to know if and when a cutout relay might pull in but it depends on the RPM as well as residual magnetic strength.

The Ford FO-4 manual for 8n's has information on the cutin/cutout and VR voltage settings. I used it to fix mine once I realized my VR wasnt actually bad, rather miscalibrated out of the box new.
 

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