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Discussion Starter #1
Hello!

I need, if possible, some opinion regarding a problem with the assembly of a HO brass locomotive.

I bought an Alco Models/KMT EP-4 electric several years ago. It was recently painted with the NYNH & H scheme and had to be completely disassembled.

When proceeding with the assembly, I am experiencing a persistent short circuit and I am not able to identify the origin.

Apparently the problem arises when making the electrical connection of the motor with the bogies. The original motor is OK, and there is no short circuit in the mounted bogies when supported alone on the rails.

Is there (or was there) any Alco / KMT documentation of the model, such as an exploded view or an wiring diagram?

I will wait for an eventual feedback!

Thank you.
 

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Are one of the trucks swiveled 180deg from where it should be ? Look close at the wheel pickup/wiper arrangement..
 

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fairly simple -possible- answer ...
it's not possible [on this one] to get the trucks off by 180 degrees ..
what is possible, is that one [or more] individual wheelsets are in reversed position ..
they should all have the insulated portion to one side on the front truck, and to the other side on the rear truck, check the wheelsets themselves ..
 

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Discussion Starter #4
Hi, good night.

Well, first of all, many thanks by both answers.

Something wrong is occuring...

All the 6 wheelsets of the power trucks have insulated wheels on the both sides of the axles. I didn't find any identification or detail for insulated or not insulated side (?).

This information would be supplied by an user's manual...

When you support one complete truck assembly (power bogie + sideframe + guide bogie) over the tracks, there is no short circuit. When your support the second one together, no short circuit again.

The pickup assemblies are both installed in the same side of the tracks, the power trucks assembly is reverse between them, and both pickups are connected in the same motor pole.

The second pole is still not connected, because I must solve this problem first.

See the following pictures of this arrangement.

I will try to check more some details

Carlos
 

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Discussion Starter #5
Hi again,

I'm using now a multimeter and, in fact, the axles have one side insulated and the other isn't. Bad idea of KTM to use identical components in both sides of the axle without any identification! It would be very simple to press a mark in any place or the wheels.

Now I'm making a mark in each one and let's see what will happen...
 

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Discussion Starter #6
Good news!!!!!
After marking the wheels, the bogies were assembled according to your instructions and the engine is working!!!

Many thanks, my friends!

The EP-4 has a big motor indeed, but It seems the traction effort is smaller than I could immagine, in spite of the locomotive size and its brass body.

It's strange this kind of locomotive has only 8 wheel drive instead 12 wheel drive. The Frateschi 2+C-C+2 V8 model (the Brazilian version of EP-4) has 12 wheel drive, 2 motors and flywheels, in spite of the plastic quality used in its manufacturing.

Is it necessary to add some lead weights to increase the traction? Its train is 8 cars long (ACF 12 wheels heavyweight passenger cars)

Does somebody have this model of locomotive here in the community to share some experience with me?

Thank you very much

Carlos
 

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I think you have the one of the trucks reversed, as it appears that the power pickup is on the same side on both trucks?
 

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Thank you, Lemonhawk, this has been totally confounding me all along as I look at the pix! But now it's working! So I just wish someone would splain it!!! 😆
 

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Do you mean I was right, or that it just started working? I hate "just started working" means it will happen again. In the picture with just the cab removed the insulators are diagonally opposite, yet in later pictures it looks like you adjusted the insulator to the same side. I think that the insulators were originally correct and it's the truck that was reassembled with the power pickup on the wrong side. Thus each truck should be connected to a different brush, as you need both sides of the rail to go to individual brushes on the motor. I could be hopelessly wrong and the hole chassis could be electrically connected to the wheels opposite the side that has the pickup in the wheels. At least you have it working!
 

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Discussion Starter #10
Hi Lemonhawk and Cid.

Thank you for both feedbacks!

Lemonhawk, I think we are speaking the same language. Follow the text below and the diagram.

You can be sure that I was much more confused than you guys.

Just trying to explain, the locomotive was disassembled for the painting and, on that occasion, I did not memorize the layout of the original assembly/wiring . For this brass locomotive, things are certainly different compared to a traditional DC locomotive like many others I have.

Those white insulators in the first picture were, in fact, mounted diagonally, but the pickup assemblies just below were both on the same side of the locomotive. Unfortunately the picture is not clear enough to see these details.

The main mistake was the wrong assembly of the wheelsets, in which we can only know which side is insulated using a multimeter. There is no way to identify yourself otherwise.

Then, with the Aard information, all the 6 wheelsets insulated wheels are located in the same side of the locomotive and also in the same side of the pickup arrangements, where two wires are connected to one motor terminal.

In the other side (non insulated) two wires are connected to the locomotive mass (through reducers via axles contact of the other 6 wheels) and to the another motor terminal. One track side (+) supply energy for one motor terminal and the other (-) for the other terminal.

I understand this way would be the correct . Or not? The locomotive is working very nice.

I tried to resume the solution with this simple diagram:

542855


Assembly image is this:
 

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OK, so the chassis is one rail and the wires coming from the trucks are the pickups for the other rail. Actually this is better than having the pick up to each rail on seperate trucks. This way, with both rails being picked up by each truck, you can navigate thru an unpowered frog easier. So one brush is connected to the wires coming from the trucks and the other brush is just connected to the chassis. Great for DC operations, but maybe not so great for DCC conversion. If you're lucky just disconnecting the wire or strap from the brush to the chassis will isolate the motor. It does not appear that there any lights. Can't see in the pictures exactly how the other brush connects to the chassis, but that only needs to change if you want to convert it to DCC. Thanks for the reply and resolution!
 

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Discussion Starter #12
Hi Lemonhawk,

Very nice to receive your feedback. Thank you very much.

The wiring concept is exactly what you wrote, it's perfect!

I hope this image can help you about the wiring connections:

542864


The engine will receive lights very soon (warm white 3mm leds in both ends) and other details, including decals from
Microscale specific for this locomotive.

This energy supply option is normally used in almost all of my rooster (about 130 engines), but I have exceptions in some UK, European and Brazilian models (not Frateschi) - generally Ringfield type motors, instead cam motors.

DCC are wonderful, but it ins't in my plans. All my engines are DC.

I don't have a private HO layout, but there is a railroad model club with a very large HO layout in Sao Paulo where I can run my rarities. In fact, there are many insulated frogs switches there.

It was a pleasure to share this experience with you

Regards

Carlos
 
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