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Generator Testing

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hondaracer2oo4

Member
I know that this has been discussed many times before but I would like to confirm with everyone the procedure for testing. I have a 1967 Case 430 Gas Positive Ground tractor. It has never charged the battery since I owned it. Started looking into the issue a few weeks ago. Started out by 'polarizing' the generator. That didn't change anything. I then removed the generator from the tractor and disassembled it. I found that the armature was bad I believe. When testing with the ohm meter I had continuity between the the Armature Stack and the commutator, the commutator and the armature shaft and the armature stack and the armature shaft. It appeared that from my reading that the armature was bad if I had continuity between everything. So I found a used generator and have received it. Can someone give me the procedure on bench testing with a jump pack, the generator has a large stud(I think that goes to the ARM) a small stud(the field?). This is positive ground so do I hook positive jump pack to the body of the generator then hook the negative to both the arm and field studs at the same time and it should spin?
 
Try it without any Field connection first. Many will spin like that. I don't know if your particular generator is the type A with externally grounded Field or type B with internally grounded Field. If type A you will need to ground field to case. If type B, you will need to apply power to Field, just as you apply power to Armature. HTH
 
So this is a Positive ground system so I assume I should put the positive to the case and the negative to the arm post and see if it spins. If it doesn't spin I should try hooking a jumper from the field stud(small stud I think?) to the case itself and again try with the positive to the case and the negative to the Arm post(Bigger stud). Lastly if neither of these work I should try positive to the case and negative to the field and arm studs at the same time?
 
The Ford FO-4 N series IT shop manual has a couple of pages, detailing how to test the starter and the generator. It lists what is wrong with each, based on the result of each test. Well worth the money for that alone.
 
Just take it to a gen shop and let them test it. You can put it in a vice then connect the pos lead to ground on the gen. With the A terminal hook other lead and with voltmeter on 6v spin the gen it should read something maybe only couple volts but that does mean it is good
 
Everyone on here can tell you how to this and that but your best would be a good old fashon gen / starter shop. Two minute test. They can also tell you how to check YOUR TRACTOR FIRST. Make sure you don't have problems.
 
Yes, positive to the case, negative to the ARM terminal but it will still motor if you put neg to ground and pos to the ARM terminal. Ground the F terminal to the case to make it motor if it isn't motoring already. You can do this whether you take it to a shop or not. The only way you will learn is to go ahead and do it. That's the way most of us shade tree mechanics learned.

If the genny motors it still might not be in top shape though if the commutator is dirty or the brushes are not making good contact. If the genny has a band you can remove, remove the band to expose the brushes and use a wooden dowel or something non-conductive to gently push each brush against the commutator while it is motoring. If it speeds up the brush isn't making good enough contact to enable the genny to put out full amps. Just another shade tree, red neck quick check you can do. In fact, the genny shop might do this first off before they tear it apart.
 
You test field-current draw and test total output. Field-current draw at 12 volts is 1.5 to 1.67 amps. Max output is 20 amps at 14 volts at 2300 RPM (gen RPM, not engine RPM).
 
Good questions Racer


1) Can someone give me the procedure on bench testing with a jump pack

My Troubleshooting Procedure linked below is usually performed on the tractor but a jump pack can serve as the tractors battery

2) "the generator has a large stud (I think that goes to the ARM) a small stud (the field?). This is positive ground so do I hook positive jump pack to the body of the generator then hook the negative to both the arm and field studs at the same time and it should spin?

For POS Ground the case/frame of the Genny attaches to + while - attaches to the ARM post. NOTE while the - attaches to the ARM post, the Field post is grounded to case/frame or unattached as described below

8. MOTOR TEST. You can Motor test the Gen. If its grounded (+ of your jump pack to case) and you remove the belt and apply hot battery voltage (- of your jump pack) direct to its ARM Post, it should motor n run well (Armature n Brushes and Commutator okay). Then if you ground the Field and it slows down some, the Fields probably good. If it passes BOTH those tests, it should charge, and if not, it may be a wiring or battery or grounding problem.

Heres my complete Troubleshooting Procedure. Its not exactly for your unit but if yours is a Class A ?? It can work

http://www.yesterdaystractors.com/cgi-bin/viewit.cgi?bd=jd&th=458743

John T
John Ts Troubleshooting
 
So I was able to test the generator to see if it motored today. What I found was that I hooked the negative of the jump pack to the ARM stud. I then jumped the FLD stud to the case of the generator. Then I hooked Positive on the jump pack to the generator. She spun up.

So that means that the generator is good I assume from what you guys have said. Now to testing the output of the Generator. I hooked the VR leads to the Arm and FLD studs. I then started up the tractor. I check voltage at Battery which was only 11.5 volts. So I went back down to the generator and using the volt meter on 20volt scale I tested between the Arm stud and ground and got 1.5 volts. I then tested between the FLD stud and ground and got the same 1.5 volts. Where do I go from here?
 
One other point is that when I motored up the Generator she did spin in the direction that the belt spins it when the tractor is running.
 
(quoted from post at 12:25:40 03/08/17) So I was able to test the generator to see if it motored today. What I found was that I hooked the negative of the jump pack to the ARM stud. I then jumped the FLD stud to the case of the generator. Then I hooked Positive on the jump pack to the generator. She spun up.

So that means that the generator is good I assume from what you guys have said. Now to testing the output of the Generator. I hooked the VR leads to the Arm and FLD studs. I then started up the tractor. I check voltage at Battery which was only 11.5 volts. So I went back down to the generator and using the volt meter on 20volt scale I tested between the Arm stud and ground and got 1.5 volts. I then tested between the FLD stud and ground and got the same 1.5 volts. Where do I go from here?
Click to expand...
hile connected as you describe & running, used a wire to ground the Field & look for a voltage increase. Y / N ?
 
(quoted from post at 12:33:28 03/08/17) Ok so Leave the generator hooked up to the VR. Then while running jumper the field stud to the frame and check voltage where?
Click to expand...
es, everything same as before & same meter connection (arm to gnd) as you said before.
 
Ok so I did it a little different than you said but this is what I did. I disconnected VR from Generator. I jumped FLD stud to the frame. Then I started the Tractor. I check the voltage between ARM stud and frame and got 33 volts. So it looks like it is putting out the right volts. Where to from here?
 
So I have a positive ground system. I found that the BAT terminal with the wire connected to it on the Voltage regulator has continuity to the Negative terminal on the Battery. It has no continuity to the Positive post on the battery.

That doesn't seem correct to me, I would think it should have a wire that goes directly from the BAT terminal on the VR to the Battery Positive post. Am I correct?
 
I opened up the Voltage Regulator to take a look. The VR looks to be newer and in very good shape externally and internally. What I found when I opened was with the tractor off the ARM and FLD coils where pulling the magnets together and the BAT coil magnet was open. I jumped a wire from the positive side of the battery(reverse polarity) to the case of the VR. I then started the tractor with the VR open to see if anything happened. Nothing was happening. I took a piece of wood and manually pushed the BAT coil magnets together, the voltage dropped at the battery to 11.6 from 11.86 which it sits and while the tractor is running. Not sure what this means but its apparent that the VR appears to not be doing what it is suppose to do. Not sure why as everything looks clean and unburned.
 
Is there a difference between an A TYPE Regulator and a B type regulator?

The only number I can find on this regulator is Fo25741. Google search came up with nothing.

I was able to get the generator to motor by jumping the field terminal to the chassis. Then hooking the ARM terminal to the battery ground(reverse polarity system) I believe this means I have an A type generator correct?

Is there a way to test whether the VR is a B or A type? I assume this could be my issue if it has a B type VR and is an A type generator.
 
(quoted from post at 13:17:56 03/08/17) So I have a positive ground system. I found that the BAT terminal with the wire connected to it on the Voltage regulator has continuity to the Negative terminal on the Battery. It has no continuity to the Positive post on the battery.

That doesn't seem correct to me, I would think it should have a wire that goes directly from the BAT terminal on the VR to the Battery Positive post. Am I correct?
Click to expand...
o, not correct. Since you have a positive ground system, the POS battery terminal goes to ground (chassis/engine).
 
So I should hook the BAT output on the VR to the positive on the battery which is hooked to ground? Do I just Jumper the VR BAT terminal to ground then?
 
(quoted from post at 14:17:42 03/08/17) Is there a difference between an A TYPE Regulator and a B type regulator?

The only number I can find on this regulator is Fo25741. Google search came up with nothing.

I was able to get the generator to motor by jumping the field terminal to the chassis. Then hooking the ARM terminal to the battery ground(reverse polarity system) I believe this means I have an A type generator correct?

Is there a way to test whether the VR is a B or A type? I assume this could be my issue if it has a B type VR and is an A type generator.
Click to expand...
f your VR has three terminals, all along one side, note the order . B-A-F will be type A and A-F-B will be type B. Observe with terminals facing you & read left to right. It appears the we have established that the generator is very likely type A. I think you are close to establishing that the Field contacts in VR are not making electrical contact even though they appear closed & touching, probably oxidized. Clean all contacts and try again.. Or you can verify by jumpering Field to chassis while running as I described a few post earlier (that you didn't perform).
 
So I just went out and looked at the Terminals. They go BAT-FIELD-ARM if looking at the VR with the Terminals facing down. That looks like it is a type B from what you have described meaning someone put the wrong VR on it then? So that means I need to get a TYPE A 12 volt regulator? I searched quick on Type A regulators and they list that the terminals are Light(I don't Have one of these) Battery, Field, Arm. Which is how mine is labeled so I am confused.
 
(quoted from post at 14:47:36 03/08/17) I also did try jumpering the Arm to the BAT terminals on the VR while the tractor was running and the Battery started charging.
Click to expand...
our statement above should be the absolute equal to this: " I took a piece of wood and manually pushed the BAT coil magnets together, the voltage dropped at the battery to 11.6 from 11.86 which it sits and while the tractor is running.".
So, ..........there is some confusion somewhere.???
 
Humm, so when I jumped the ARM to the BAT terminals on the VR I had also jumpered the FLD stud on the Generator to the Chassis. I was using this guide http://www.yesterdaystractors.com/cgi-bin/viewit.cgi?bd=jd&th=458743 Where it says for VR testing jump fld stud on Generator to chassis, then jump BAT to ARM on VR. When i did this I used a small 18 gauge wire to jump BAT to ARM and when I did this the wire got hot instantly and the DVM on the Battery started rising from 11.8 volts upwards very quickly so I immediately pulled off the BAT to ARM jumper.
 
(quoted from post at 15:05:25 03/08/17) Humm, so when I jumped the ARM to the BAT terminals on the VR I had also jumpered the FLD stud on the Generator to the Chassis. I was using this guide http://www.yesterdaystractors.com/cgi-bin/viewit.cgi?bd=jd&th=458743 Where it says for VR testing jump fld stud on Generator to chassis, then jump BAT to ARM on VR. When i did this I used a small 18 gauge wire to jump BAT to ARM and when I did this the wire got hot instantly and the DVM on the Battery started rising from 11.8 volts upwards very quickly so I immediately pulled off the BAT to ARM jumper.
Click to expand...
ntil proven otherwise, I am sticking to "field contacts are dirty/corroded/not making electrical contact even though they are touching".
 
So we have confirmed this is an A type generator though because the generator would only motor when I jumpered the field to the chassis correct? If so and my regulator goes battery field arm that means it is a type b regulator and I have. Type a generator so that means it won't work?
 
(quoted from post at 15:29:07 03/08/17) So we have confirmed this is an A type generator though because the generator would only motor when I jumpered the field to the chassis correct? If so and my regulator goes battery field arm that means it is a type b regulator and I have. Type a generator so that means it won't work?
Click to expand...
ll that you have said sounds correct. Just FYI, the difference in the 'A' & 'B' is that with the 'A', the VR grounds the generator field terminal for maximum output , whereas, with the 'B', the VR supplies voltage to the generator Field for maximum output.
 

But type b and type a voltage regulators aren't interchangeable right?

This replacement generator is used and is not the exact same as the original generator. Same mounting points etc but it is from an earlier model tractor. I guess it is possible that the original generator was a type b and was matched to the aftermarket type b regulator. Now that I have a type a I assume I just need to swap to a type a VR and not do any type of rewriting of the tractor?
 
Not interchangeable & no wiring changes needed. You have already polarized the generator by motoring it & verified by running it that it does make output, so don't chance ruining a new VR by doing any further polarizing.
 
Update, I reconfirmed that ground the field terminal on the generator produces 33 volts between the arm stud and chassis.

I went back to the VR again and this time grounded the field to chassis at the generator and hooked the BAT to ARM terminals togeather with jumper cables, the battery voltage did NOT increase like I previously thought. It went down to 11.6 just like when I pushed the BAT contacts togeather inside the VR. So I was wrong about that, it didnt start charging.

So this concludes that the VR is a B type and not able to do that job correct?
 
(quoted from post at 19:17:45 03/08/17) Update, I reconfirmed that ground the field terminal on the generator produces 33 volts between the arm stud and chassis.

I went back to the VR again and this time grounded the field to chassis at the generator and hooked the BAT to ARM terminals togeather with jumper cables, the battery voltage did NOT increase like I previously thought. It went down to 11.6 just like when I pushed the BAT contacts togeather inside the VR. So I was wrong about that, it didnt start charging.

So this concludes that the VR is a B type and not able to do that job correct?
Click to expand...
nce you did this (I went back to the VR again and this time grounded the field to chassis at the generator and hooked the BAT to ARM terminals togeather with jumper cables,), the VR isn't even involved.........so, it should show charging.
 
Hmm so what am I doing wrong here?

When field grounded to chassis and volt meter checked between arm stud and chassis I have 33 volts.

Leaving field grounded to chassis at generato(, field wire up to the vr disconnected)and arm wire still connected up to vr. I started the tractor, then connected arm stud to bat stud on the vr. I got no rise in voltage testing between the positive and negative terminals on the battery.

Should I try hooking a wire straight from bat terminal on vr to the negative post on the battery?

When I put the Dvm to resistance and touch the bat terminal on vr to - terminal on bat I get continuity so I know the wire isn't broken. When it leaves the bat terminal on vr it goes first to a fuse(which has continuity) then to the key switch I think, then to the lights and horn switches then heads down to the starter solenoid.
 
"Should I try hooking a wire straight from bat terminal on vr to the negative post on the battery? " You can try that. If still no joy, then direct from Battery neg terminal to generator Arm. Don't leave it connected that way after stopping engine though.
 
Alright I will give a try tomorrow hooking straight from Arm to Battery negative. What should my voltage reading be measure between the positive and negative on the battery when I do this?
 
(quoted from post at 21:24:09 03/08/17) Alright I will give a try tomorrow hooking straight from Arm to Battery negative. What should my voltage reading be measure between the positive and negative on the battery when I do this?
Click to expand...
ught to see at least a volt increase shortly & if run long enough it will go up in 14-15 volt range and if a long time, to point of over charging battery, you can see over 16.........not good for battery though.
 
Update

First test. Jump generator field to chassis. Jump generator arm straight to battery negative. Battery charges quickly, voltage jumps .10 every 5 seconds or so. I ran it to 13.5 before I stopped. So the generator does charge battery when I take the VR out of the equation.

Next test. Reconnect VR. Jumper from arm stud on VR to battery negative. Battery voltage drops.

Next test. Disconnect just arm from Vr with everything else connected. Battery voltage climbs slowly while running. Not sure what this means? Only ran it like that for about 30 seconds.

Next test. Checked power again from generator by disconnecting it from VR. Then jumped field to chassis. Started tractor and checked arm to chassis and got -33 volts. Is the negative correct because it's reverse polarity?
 
(quoted from post at 12:22:07 03/09/17) Update

First test. Jump generator field to chassis. Jump generator arm straight to battery negative. Battery charges quickly, voltage jumps .10 every 5 seconds or so. I ran it to 13.5 before I stopped. So the generator does charge battery when I take the VR out of the equation.

Next test. Reconnect VR. Jumper from arm stud on VR to battery negative. Battery voltage drops.

Next test. Disconnect just arm from Vr with everything else connected. Battery voltage climbs slowly while running. Not sure what this means? Only ran it like that for about 30 seconds.

Next test. Checked power again from generator by disconnecting it from VR. Then jumped field to chassis. Started tractor and checked arm to chassis and got -33 volts. Is the negative correct because it's reverse polarity?
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es, neg is correct with a positive grounded battery.

Sounds like you are still uncertain as to whether your reg is A or B. Look at back side if it to see if there is one or two resistors there. B 'usually' but not always have two, whereas A only one. two would be pretty good confirmation.

Other verifications you can do:
1) With VR on bench, use Ohmmeter to look for continuity between [u:445c8a2abb]ARM[/u:445c8a2abb] and Field. If present, continuity should be lost when you open the Field contacts & resume when contacts are again closed. They are normally closed.

2) With VR on bench, use Ohmmeter to look for continuity between VR [u:445c8a2abb]case[/u:445c8a2abb] and Field. If present, continuity should be lost when you open the Field contacts & resume when contacts are again closed. They are normally closed.
 
The VR has two resisters on the back

I feel confident at this point that the VR is a type b and th generator is a type a

I will order a type a. Any suggestions on a brand or model? Thank you again.
 
Not really, but Chrysler, Dodge, Plymouth in the years around 1956, 7, 8....appear to have used generators with numbers very much like the generator number that you posted. The cars were Negative ground & some old Chrysler VRs had polarity sensitive rectifiers inside them, so you would need to be sure whatever you buy doesn't care about polarity or that it is for Positive ground system. If all else fails, I fully expect that the VR for my 1962 Chevy C10 PU would do the job. Don't know about mounting hole alignment though.
 
Will this work?

http://www.oreillyauto.com/site/c/detail/BWD0/R159/02115.oap?year=1962&make=Chevrolet&model=C10%2BPanel%2BRWD&vi=1442224&ck=Search_02115_1442224_4533&pt=02115&ppt=C0330#compatibilityTab_
 
(quoted from post at 23:26:18 03/09/17) Will this work?

http://www.oreillyauto.com/site/c/detail/BWD0/R159/02115.oap?year=1962&make=Chevrolet&model=C10%2BPanel%2BRWD&vi=1442224&ck=Search_02115_1442224_4533&pt=02115&ppt=C0330#compatibilityTab_
Click to expand...
ot enough info there for me to commit.
 
http://ecatalog.smpcorp.com/bwd/#/vehicles/parts/num/R159?type=s

It says it fits chevy c10 60-62.

I think you said that your vr from your 61 c10? Would work.
 
boy I never would have imagined this would be so difficult to track down a voltage regulator.

There is so many voltage regulators out there and it shouldn't be so complicated to say I have a 12 volt generator that is a type a. This is the voltage regulator that goes with it...... very frustrating.
 
(quoted from post at 08:31:28 03/10/17) http://ecatalog.smpcorp.com/bwd/#/vehicles/parts/num/R159?type=s

It says it fits chevy c10 60-62.

I think you said that your vr from your 61 c10? Would work.
Click to expand...
ooks like that should work
 
You ought to verify your wiring. I say that because the results where you grounded the field and jumpered Batt to ARM should have charged the same as when you went straight from ARM to Battery Neg post.
 
When I take the arm and bat wires off the vr and connect them togeather it charges. When I leave them connected to
Vr and use a jumper wire between them it causes the voltage at bat to drop.
 
Thank you for the help. Picked up the bwd r129 today. It works. I put the dvm on the battery and as soon as I started the tractor the volts rose quickly from 11.9 to 14.3. Then slowly climbed up to 14.85-14.9 and ran in that range. I kicked the headlights on and it dropped to about 13.8 and stayed steady there. It appears that she's working like she is suppose to! Thanks again.
 
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