# Bypassing E unit on AC motor, AF locomotive



## Reckers

I thought I'd ask this question before I desperately need to: how do I bypass the e unit on an American Flyer (circa 1950) to see if the AC motor is working and the e-unit is the problem? T-Man, I read your dissertation on the Lionel, but three-wired can motor descriptions don't readily convert to two-railed AC.

Thanks!


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## T-Man

I rewired a 307 from the brushes. Each is connected to one end of the field wire and the front bulb. Touch each brush with a lead and off she runs.I need to see a diagram since there are 4 wires coming from the tender. I don't have time now to dissect my 300ac. You need two connections to test, one throught the coil, one through the armature. I wired mine in parrallel to test, years ago, beyond my memory.


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## Reckers

So, if i want a quick test, I could just touch the two transformer leads to the two brass tubes that hold the brushes? Don't do any dissection---here's a wiring diagram.

http://www.modeltrainforum.com/attachment.php?attachmentid=1946&d=1267968130


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## tjcruiser

Hey Reck,

Naive question ...

Are the e-units on old AF's similar to those on Lionel? Can you simply flip a toggle to turn the e-unit off, essentially bypassing it's functionality, getting power straight to the motor, itself?

(I'll bet it's more complicated than that, though ...)

TJ


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## T-Man

Jump two holes on each side with a wire, then attach the leads.I do not have this plug. Touching the brass won't work if the coil isn't connected.


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## Reckers

Tj,

I haven't got a clue. I've never worked on a Lionel and I'm not too bright, so there's a world of questions I'm too dumb to answer!


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## Reckers

T-Man, thanks! I'll tell my mother about you.


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## Stillakid

T-Man, thanks for posting that jumper diagram. Reckers was being nice, trying to help me get my old 302AC up and going again. What a guy

Tried the jumpers, no go. Since I've already got a new E-Unit coming, I think I'm going to set this aside for the next week or two. If I pick it up, and try one more thing that doesn't help, I can see her hitting the wall

I've got so many projects going on at the same time, I'm dizzy:laugh:

Anyway, thanks for the help, and I hope when I get ready to try again, you wouldn't mind me asking a bunch of, "Newbie" question

Jim


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## Reckers

Stillakid, if you can't get it fired up after the new e-unit goes in, send it to me and I'll look it over. I'm not too bright but I'm awfully lucky.


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## Stillakid

Reckers, thanks for the offer. I just might have to do that


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## T-Man

Make sure you have brush contacts and springs in the cans.

Current has to go through the motor and the coil. your choice, wire it in parrallel or series to test. If you have five wires you need to verify the right wiring.


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## Reckers

No problem. Let me know if I can help.


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## T-Man

I last ran the 300ac on mothers kitchen table over 30 years ago. I am a
little rusty on enuits. Remember, power comes from the tender. Ihave to dig out my s track and see how it looks with O gage!!!


I have yet to see ablock system to work two trains over the same area of track on different systems.


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## T-Man

I snapped some eunit pictures. They are similiar to Lionel with a drum. The coil looks like a whistle relay. I am not sure if it is power interuption or DC that activates it??? As I said before it has been a long time for me.


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## Reckers

T, if that is an AF, it's activated by power interruption. Works as follows:
1. Power is applied---this jerks the metal plunger up into the coil and holds it there.
2. Power discontinued: plunger falls from the coil, and it's weight advances the drum by one notch. Sequence is normally F-N-R-N.


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## T-Man

So to lock it, the lever holds it against the coil. Yes it is AF.


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## Stillakid

*Reckers/T-Man, By-Pass*

are the wires in the red circle connected? I'm not real bright when it comes to reading an electrical schematic

View attachment 2006


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## tjcruiser

Stillakid,

While I'll defer to T-Man and Reckers on the specifics of the motor circuit, I can tell you that that "jump" in the red circle is a standard way on electrical schematics to show that the wires are NOT connected. Think of it like a bridge overpass, with the wire going to "7-15V" running underneath the bridge.

TJ


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## T-Man

Stillakid said:


> are the wires in the red circle connected? I'm not real bright when it comes to reading an electrical schematic
> 
> View attachment 2006


The diagram shows the coil in series with the armature. Like most Lionel engines. You can run them in parrallel but this is simpler.


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## Stillakid

Thanks TJ/T-Man!
I'm getting ready for one more go at it. I'll also have a box and a roll of duct tape handy in case it doesn't work


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## Reckers

*LOL*....I doubt you'll need the tape or the box. You're gonna sort this thing out.


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## Stillakid

Just gave it a try.
"No Joy" 
The light came on very dimly. If I put my Tester leads on each side of the field, shouldn't I be getting "tone?" I test my e-units that way before rebuilding them.
I'm getting no tone!


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