# Rewinding a field



## dooper (Nov 9, 2015)

Hello All, Dooper here once again. I hope everyone is doing well.
A few years ago I successfully rewound a field. It still works today.
I have recently tried to do another one, and it ends up shorting and state to get hot and smoke.

Does anyone know what I am doing wrong?


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## AmFlyer (Mar 16, 2012)

Welcome back Dooper, glad you are still with us. Two questions, does the armature rotate when the field is overheating? Is it a 4 or five wire engine? I ask because the field must always be in series with the armature. If wired in parallel the low impedance of the field will look close to a short circuit to the track power. If you connect just the field across the transformer it will draw as much as 10A, which will overheat it. In series motors like the Gilbert, the back EMF of the rotating armature limits the current. That is why in a 4 wire engine the light and smoke unit are in parallel with the armature and in series with the field.


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## dooper (Nov 9, 2015)

AmFlyer said:


> Welcome back Dooper, glad you are still with us. Two questions, does the armature rotate when the field is overheating? Is it a 4 or five wire engine? I ask because the field must always be in series with the armature. If wired in parallel the low impedance of the field will look close to a short circuit to the track power. If you connect just the field across the transformer it will draw as much as 10A, which will overheat it. In series motors like the Gilbert, the back EMF of the rotating armature limits the current. That is why in a 4 wire engine the light and smoke unit are in parallel with the armature and in series with the field.


Thank you Tom. My problem might be the way I am testing it, just the two ends hooked up to a transformer. it shorts and heats. If I understand you, they should work if I use them in an engine? Remember, I can completely wire a house, but am not great with these small motors.


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## AmFlyer (Mar 16, 2012)

That is the problem. Never put just a field across the transformer. Test it with an ohm meter. It should read between 1.2 and 1.5 ohms.


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## dooper (Nov 9, 2015)

AmFlyer said:


> That is the problem. Never put just a field across the transformer. Test it with an ohm meter. It should read between 1.2 and 1.5 ohms.





AmFlyer said:


> That is the problem. Never put just a field across the transformer. Test it with an ohm meter. It should read between 1.2 and 1.5 ohms.


Thanks Tom. Tomorrow I will try that.


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## AmFlyer (Mar 16, 2012)

If the field resistance reads ok your rewound field will work in the engine. 
If you think house wiring is still simple you should see the computer driven, automated system in my next door neighbor’s house. There are three logic panels in the house each with 25 logic controllers to actuate the receivers at the controlled loads.


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## mopac (Feb 24, 2011)

Dooper, my friend, so glad to see you back here on the forum. Hope all is going well. I am doing fine now.
Last year I was in the hospital for pneumonia, dehydration, and falling. I have not fallen for months. The hospital started
talking about a nursing home for me. My son told them that 4 weeks before I was fine just find out why my dad is falling.
How are your trains running. Put that engine back together and then see how it is doing. I rewound a field of mine and it is working like a champ. I could not rewind as good as Gilbert did and ended up with about 15 feet of wire left over. Anymore and it was hitting the armature. This thing is a race car and runs cool. I have other fields but I wanted to see how I could do with a rewind. Very happy with it. I used the old wire. Good luck with yours and really glad to see you. Please do not stay away so long. Tom got cramden back this week. He was gone about as long as you were.


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## dooper (Nov 9, 2015)

mopac said:


> Dooper, my friend, so glad to see you back here on the forum. Hope all is going well. I am doing fine now.
> Last year I was in the hospital for pneumonia, dehydration, and falling. I have not fallen for months. The hospital started
> talking about a nursing home for me. My son told them that 4 weeks before I was fine just find out why my dad is falling.
> How are your trains running. Put that engine back together and then see how it is doing. I rewound a field of mine and it is working like a champ. I could not rewind as good as Gilbert did and ended up with about 15 feet of wire left over. Anymore and it was hitting the armature. This thing is a race car and runs cool. I have other fields but I wanted to see how I could do with a rewind. Very happy with it. I used the old wire. Good luck with yours and really glad to see you. Please do not stay away so long. Tom got cramden back this week. He was gone about as long as you were.


Thanks MoPac. I am glad you are doing better. At our ages, we need to take good care of ourselves. Last year, I lost two long time friends (they say that most of us can count your true friends on one hand) - these were two of those friends. I am old and cancer free, so I feel extremely happy. Had Omercron , chills for one night and felt slightly ill the next day. That was it. Stay healthy!
Al


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## dooper (Nov 9, 2015)

AmFlyer said:


> If the field resistance reads ok your rewound field will work in the engine.
> If you think house wiring is still simple you should see the computer driven, automated system in my next door neighbor’s house. There are three logic panels in the house each with 25 logic controllers to actuate the receivers at the controlled loads.


As you all know, I do not know much about electronics, but I could get your neighbors electricity to his controllers.

Thanks for the help. Now, I have 3 steamers I have been rewiring. As of now, when you supply electricity the light works, reverse units cycles properly, and the armature tries to turn but does not. Then the field starts smoking. I have triple checked my wiring and it seems correct. Any ideas anyone?


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## AmFlyer (Mar 16, 2012)

It sounds like a bad armature. I assume the armature turns freely if you move it manually. I do not know what engine you have but each armature winding should measure around 1.5 ohms between each pair of commutator segments. Each commutator segment to the worm gear shaft should be close to infinite ohms.
If the armature is bad replacements are available but there are many different part numbers and most do not interchange.


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## dooper (Nov 9, 2015)

AmFlyer said:


> It sounds like a bad armature. I assume the armature turns freely if you move it manually. I do not know what engine you have but each armature winding should measure around 1.5 ohms between each pair of commutator segments. Each commutator segment to the worm gear shaft should be close to infinite ohms.
> If the armature is bad replacements are available but there are many different part numbers and most do not interchange.
> [/QUOT Tom. Could this be happening to three engines at once?


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## AmFlyer (Mar 16, 2012)

Highly unlikely, I thought it was just one engine. I am being a bit facetious here, but the common mode failure could be dooper. A parallel rather than series armature and field will also cause this problem. What are the engine numbers?


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## AmFlyer (Mar 16, 2012)

Here are color augmented 4 wire and 5 wire steam engine wiring diagrams to check against.


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## dooper (Nov 9, 2015)

AmFlyer said:


> Highly unlikely, I thought it was just one engine. I am being a bit facetious here, but the common mode failure could be dooper. A parallel rather than series armature and field will also cause this problem. What are the engine numbers?


A 320, a circus engine, and any early six wheel engine.


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## dooper (Nov 9, 2015)

dooper said:


> A 320, a circus engine, and any early six wheel engine.


I have too many engines.


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## AmFlyer (Mar 16, 2012)

All with no smoke and an engine mounted reverse unit? Here is the wiring diagram for the engine mounted reverse unit.


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## mopac (Feb 24, 2011)

Thanks for posting the diagram with reverse unit in boiler Tom. I only have a couple like that. A Royal Bue at least. I have too many engines also. Most I have not serviced yet.


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## AmFlyer (Mar 16, 2012)

The 320 should also have the Reverse Unit in the tender.


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## flyernut (Oct 31, 2010)

I just serviced a 290 for a customer and that was the same problem. I ended up replacing the armature and brush bracket assembly, and it now runs like a scalded dog.


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## AmFlyer (Mar 16, 2012)

Flyernut, Dooper likely has three different motors in those three engines. The 320 has slotted style brushes, no oil slinger on the armature shaft. The Circus engine has shoulder style brushes and an oil slinger on the 1/16" longer armature shaft. No idea what motor is in the "early six wheel" engine without a production date or cab number. Since all of the three engines have the same problem it is possible there is a common wiring error made on reassembly. Could also be three bad armatures. Flyernut, you know better than all of us how important it is to fully clean all the parts, reassemble each motor with its correct parts, test it as you go, verify the wiring and that the Reverse Unit contact fingers are in the correct locations and that there are no shorts to the chassis.


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## flyernut (Oct 31, 2010)

AmFlyer said:


> Flyernut, Dooper likely has three different motors in those three engines. The 320 has slotted style brushes, no oil slinger on the armature shaft. The Circus engine has shoulder style brushes and an oil slinger on the 1/16" longer armature shaft. No idea what motor is in the "early six wheel" engine without a production date or cab number. Since all of the three engines have the same problem it is possible there is a common wiring error made on reassembly. Could also be three bad armatures. Flyernut, you know better than all of us how important it is to fully clean all the parts, reassemble each motor with its correct parts, test it as you go, verify the wiring and that the Reverse Unit contact fingers are in the correct locations and that there are no shorts to the chassis.


Thanks Tom.. Here's a picture of my multi-meter. I'm trying to test armatures with it, but I know I'm doing something wrong.. I'm not sure as to where I just have the dial turned to, Any help would be appreciated... I'm a idiot when it comes to things like this, so treat me as a new student in the classroom of multi-meters,lol..


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## AmFlyer (Mar 16, 2012)

First, turn the dial to the yellow "tone" position and touch the two leads together to produce the tone. This confirms the meter is properly working to measure resistance. Now select the white 200 setting immediately to the left of the yellow tone setting.and you are ready to measure the resistance.


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## dooper (Nov 9, 2015)

AmFlyer said:


> Flyernut, Dooper likely has three different motors in those three engines. The 320 has slotted style brushes, no oil slinger on the armature shaft. The Circus engine has shoulder style brushes and an oil slinger on the 1/16" longer armature shaft. No idea what motor is in the "early six wheel" engine without a production date or cab number. Since all of the three engines have the same problem it is possible there is a common wiring error made on reassembly. Could also be three bad armatures. Flyernut, you know better than all of us how important it is to fully clean all the parts, reassemble each motor with its correct parts, test it as you go, verify the wiring and that the Reverse Unit contact fingers are in the correct locations and that there are no shorts to the chassis.


I should have said a 302 instead of 320. Sorry I am responding so late but I have been out of town. I now have the 302 running very well for a while, and then it just stops. Jiggling the wires to look for a loose connection does not do any good. On several others, the armature wants to turn but won't. I have double checked the wiring and it is correct. I have also re-soldered all connections to be sure that I don't a cold soldered joint. Frustrating. So, I have four like this.


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## mopac (Feb 24, 2011)

I was going to tell you to check the side rods for binding but if it runs for a while its not the side rods.
You are losing electric some where. I had one and it was the brush cap. It could be anywhere. Its
some place you have not checked. Could be the strip that contacts the tender wheels, well the axles.
Could be the track. Does it stop same place every time? Could be a finger on the drum not solid
connection. Lots of places it could be. How do you get it to run again.


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## AmFlyer (Mar 16, 2012)

Running for a while until the motor gets hot, then stopping is a symptom of a commutator bar short. Most likely a bar to shaft short that takes several minutes of operation to show up.


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## dooper (Nov 9, 2015)

AmFlyer said:


> Running for a while until the motor gets hot, then stopping is a symptom of a commutator bar short. Most likely a bar to shaft short that takes several minutes of operation to show up.


Thank you both. Later today I will get myself frustrated again. Both ideas are plausible. As all the engines are shell-less , I had an opportunity to check the field of the one running and stopping and it was not. In one I had on the track I could see the commutator try to spin, it moved slightly, so it was trying to run. We shall see.


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## T-Man (May 16, 2008)

flyernut said:


> Thanks Tom.. Here's a picture of my multi-meter. I'm trying to test armatures with it, but I know I'm doing something wrong.. I'm not sure as to where I just have the dial turned to, Any help would be appreciated... I'm a idiot when it comes to things like this, so treat me as a new student in the classroom of multi-meters,lol..
> View attachment 578630


It is easy to measure ohms. Turn your dial 180 degrees to 200. That measures 1 to 200 ohms. to two or three digits. If there is a broken circuit the readout will be 0. Touch the two leads together to test. You can practice by measuring resistors. Reading the color code and then take a meter to them .


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## mopac (Feb 24, 2011)

Dooper, did you say the motor gets hot and then stops? Motor should not get hot.
If it gets hot try replacing the armature if you have another armature from another
motor. I did not see that you said motor was getting hot. I had a motor that got very hot but it still ran.
It had a bad armature. I can run the snot out of it and it stays cool now after replacing armature.
My engine also ran slow with the bad armature. You did not mention hot or slow running. I still
think you are losing electric contact somewhere. Bad armatures are rare.


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## AmFlyer (Mar 16, 2012)

Mopac, you and I are saying the same thing. As I tried to explain above, with an Ohm Meter it is possible to find bad armatures but it is not possible to confirm an armature is good. Several of the armature failure modes only show up after running the motor for a while. If one had a 1% precision, zero to 5 Ohm meter then the partial failure of the commutator bar connections might be detectable but it is not detectable with a 2%, zero to 200 Ohm meter. I suppose if someone wanted to really go crazy they could measure their armatures hot after operation with a Wheatstone Bridge. I would just buy some spare armatures to substitute.


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## mopac (Feb 24, 2011)

This will be easy with shell off. Get a non-metal object and when the engine stops
push in on the brush caps. Move them around the brush tubes. I have had this problem.

I agree a multi meter does not always tell you if armature is good or bad. A couple
spare armatures could be helpful. After I had a bad armature I ran across 2 brand
new armatures from an out of business train shop. I bought them both. LOL, bet
I will not ever need them since I bought them.

Also take tender shell off when your engine stops use a toothpick to push down on the
fingers in reverse unit with power to track on. Your problem may not be a solder problem but a contact problem. It is something simple, you just have to find it.

Good luck


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## mopac (Feb 24, 2011)

First time I replaced fingers in a reverse unit I did not bend down the fingers to make good contact with the drum and engine did not run at all. Live and learn.


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## TimmyD (Dec 6, 2021)

Hi Dooper, maybe this was already covered, but your track and pickup wheels are plenty clean on the engine that just stops? I have a few engines with dirty wheels, and some dirty track, and see that sometimes. I have also had issues where the engine side of the jack panel (female side) plugs loosened up so I had an intermittent connection to the tender. I messed with the wires for weeks before realizing I could just slightly squeeze the cavity shut with pliers, making the bullet connection snug again. 🤦‍♂️ Best of luck sir!


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## dooper (Nov 9, 2015)

Hello All. I did not have much time for the train room, but now I have only one 302 and my Circus engine to get moving again. I do like the idea that they are not getting full power. I will keep at it, maybe not tomorrow but later.


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