• ALCO/KMT MODELS EP-4 BRASS LOCOMOTIVE SHORT CIRCUIT.

  • Discussion related to everything about model railroading, from layout design and planning, to reviews of related model tools and equipment. Discussion includes O, S, HO, N and Z, as well as narrow gauge topics. Also includes discussion of traditional "toy train" and "collector" topics such as Lionel, American Flyer, Marx, and others. Also includes discussion of outdoor garden railways and live steamers.
Discussion related to everything about model railroading, from layout design and planning, to reviews of related model tools and equipment. Discussion includes O, S, HO, N and Z, as well as narrow gauge topics. Also includes discussion of traditional "toy train" and "collector" topics such as Lionel, American Flyer, Marx, and others. Also includes discussion of outdoor garden railways and live steamers.
  by haberbeckbrandao
 
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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  by Backshophoss
 
Are there plans to install DCC with sound? Are the pans used as part of the power leads?
Isolate the motor from the frame , run direct wires to the Wheel and/or pans as needed.
  by jwhite07
 
Throwing a guess out there based on the angle of one of the pilot trucks in that photo - are the pilot trucks able to pivot 180°, and are they wired to be part of the power pick up? One or both may be "backwards" and thus causing the short.
  by haberbeckbrandao
 
Hi JWhite,

Many thanks by your opinion!

In fact, both pilot trucks do not have any pickup electrical connection with the chassis, then the problem was solved in other point of the locomotive: the axles of the power trucks.

I explain the solution in the next reply.

Carlos
  by haberbeckbrandao
 
Hi Backshophoss

Thank you very much for your suggestion.

I have no plans to install DCC or sound on this locomotive as I only use DC.
Pantographs were originally not intended to serve as a power pickup, but eventually they could.
I ended up getting help with the short circuit and after a careful investigation, the source of the problem was in the axles.
The axles do not have marks to identify the insulated wheels. You must use a multimeter.
In this locomotive the motor has isolated terminals, although it is screwed directly to the chassis.
The axles are in direct contact with the driving bogies through their bearings.
In this way, half of the 8 drive wheels have the same polarity as the chassis that is connected to one motor terminal.
The other half are insulated, and have an independent power pickup stripes directly connected to the other motor terminal.
I ended up making an assembly and wiring layout that I hope is clear enough to be understood (see the imagem below):

Image

These are the chassis after assembly. Red wires are connecting chassis mass to motor, blue wires connect insulated wheels to motor

Image
Image

If there are any questions, I am at your disposal

Carlos
  by Backshophoss
 
Man,that's an old motor on board,might help the power pack to swap a can motor replacement.
That old "Pittman" motor pulls an amp of power when running. gets quite warm to boot.
If possible,add power pickups to the center axle for running thru switch ladders
It's your model,these are just suggestions
  by jwhite07
 
Regardless of what's "under the hood", that is a beautiful model and I'm glad to hear you were able to identify and correct the electrical fault! Happy running!
  by haberbeckbrandao
 
Hi JWhite7,

Very nice your feedback. Thank you!

I'm also very happy to solve this problem. I have this locomotive for several years without painting, and I decided to paint it two months ago and I want to use this beautiful model during the years that I still have ahead.
Before its painting I have already formed all its train, with 8 heavyweight ACF passengers cars.
Every experience in life comes for our knowledge and learning, always. This is the magic of life!
Now I can repair similar models if I need.
I would like to thank you by your feedback. It's a pleasure to share this kind of experience with a hobby's friend from the US.

Regards and be well

Carlos
  by haberbeckbrandao
 
Hello Backshophoss

Suggestions are always welcome and I thank you for your considerations!

I don't live in the USA, and this locomotive cost me a lot, and it's difficult to get here, due to the exchange rate between our currencies.

Then, in this particular case, due to the rarity of this model here, I prefer that the engine remains original from the factory.

I think I don't need extra pickups in the power trucks, because both of them are connected to the motor. See the schematic diagram.

You're right. In fact, the motor is very old, but at the same time, its construction allows a lifetime operation. For me, this is the most important.

My model railroad club has DC controllers with 5A output. It is more than enough to power this motor, or even a combination of 5 old locomotives operating together, with no overload.

You may have noticed that I added two flywheels (Athearn) associated with A-Line # 12030 couplings to improve performance and torque at low speeds.

She doesn't have these items originally.

Many thanks by the sharing of ideas and suggestions, my friend.

Be well

Carlos