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I'm looking into adding the Colored Light String product from Evan Designs to an old K-Line MP-15, but for obvious reasons I don't want to use the battery powered option, and would like to power it off the locomotive itself. This old MP-15 (given to me by a friend in a bad state, so I'm looking to repair and spruce it up to give away or donate) has one light in the front with two red wires, and one in the rear with two black wires. Can I simply splice the Christmas light string leads into the wiring for either of those lamps for power? Or is it preferred to tap into the wires directly connected to the roller? And I assume I would need the 9-18 V version of the string lights.

I have searched other threads, mostly this one here, so apologies if this was already addressed, but I did not see a comment that answered the question specific to my splicing for power question. This would be the first time I've touched the internals on a model train, but am okay with splicing and soldering as necessary with the right guidance. Also want to make sure this addition is done in a way that results in safe operation of the unit.

Thank you.


k-line diesel innards


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  • k-line diesel innards
Last edited by sinistar
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Any tips on the preferred wires to splice into to power the additional Christmas LED lights? Seems like the options are either tapping into wiring for one of the existing bulbs, or the red and black wires from one of the pickup rollers. I would be using the 9-18 V string option, so am not sure if anything extra would need to be added because the string is LEDs. Not too concerned about keeping them flicker-free if that helps.

Getting power straight form the power truck is the smartest way as some lamps electronically controlled and cannot supply the extra current.

As for extra components, I presume the Christmas lights are DC powered, therefore you would need an adequately sized bridge rectifier and possibly appropriately sized current limiting resistor. The sizing of these aforementioned components are contingent upon the electrical specifics of the Christmas string. Unfortunately, the website listing does not share much so you'll have to take some experienced based guesses or contact them for their recommendations.

Your solution, with their guidance, may actually turn out that you use the rectifier from Evan Designs and the 3V DC version of their Christmas Lights

Last edited by OGR CEO-PUBLISHER

Thank you for the response -- that helps with my confidence to proceed with something I know is old hat already to most people around here, especially as my research was mostly coming up with threads on upgrading incandescent to LED, so not quite like-for-like as far as I was concerned. 

I would imagine that the 9-18 volt option that's available for the colored string has the rectifier and resistor included, but I'll double check with them.

@sinistar posted:

I would imagine that the 9-18 volt option that's available for the colored string has the rectifier and resistor included, but I'll double check with them.

You would be very right to check with them and be sure the person you are speaking with understands that you are using a AC voltage source and that they understand the implications of such.

It would be great if their product information actually contained this information so we wouldn't be left guessing, presuming, hoping, or ultimately devastated when things don't work or burn up.

So at this point I have successfully added the color string lights from Evan Designs, and the old diesel switcher is now ready for Christmas. The light string options used: 26 LED version with Nano bulbs, and 9-18V ready. You might notice that one LED is not lit -- Evan Designs warns that they are delicate and to handle with care, so I guess I got one casualty during my install. Still looks good to me, and that string is glued down pretty good. And you can't really tell, but I swapped out the interior incandescent bulbs with LEDs, also from Evan Designs. Blue for the cab, and cool white up front.

Additionally, thanks to new e-unit from gunrunnerjohn, this locomotive now operates in both directions as intended. The replacement board was bigger than the original, but some time with a Dremel tool and mounting it on its side resolved that issue. 

Next, I will see if I can fit a sound board and speaker somewhere in there, and hopefully it will be a nice gift to a close friend.

MP-15 ED Xmas Lights


 xmas lights 3 rear


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  • MP-15 ED Xmas Lights
  • xmas lights 3 rear
Last edited by sinistar

Nice -- I would love to get one of the Christmas-themed MTH engines to complement the Halloween one I have. They have some really cool passenger cars with the Christmas LEDs as well.

Before this project, I had never done any repair or customization work on a model train, but this has been fun and not too difficult, just some patience to do things correctly.

Welp, Project Christmas K-Line MP-15 is pretty much done.


  • E-unit/reverse board replaced. Had to mount it on its side since it was wider than the original.
  • Sound board and ESU-type speaker added. Also had to mount on its side and remove several of the U-shaped plates (weights?) to fit properly. Glued the speaker to the backside of the sound board on its metal bracket, then glued the board's bracket to one of the plates. Still can be removed by removing the plate to service engine.
  • The horn sound is underwhelming and struggles to be heard against track noise, but the bell is pretty strong. Better than the previous condition though, where there were no sound effects at all.
  • Wiring for light string fed through hole in one of the smoke stacks, which I had to drill out. There's enough slack in the wiring to remove the body and service the engine.
  • Had to dremel bits here and there to get the hood to fit back on, and it's still a fairly tight fit.


Overall, a fun project and good learning experience.

top down view 1bSpeaker sideE-unit front side


Images (3)
  • top down view 1b
  • Speaker side
  • E-unit front side
Last edited by sinistar

Great job that looks nice with the lights. Evans makes some great lighting stuff. I use a lot of it on my trains. The LED bulbs for AC power to 18 volts works great.

I have been looking for light strings with much tighter spacing between the bulbs. I like how the MTH lighted cars and engines look with very closely spaced bulbs. 

I was trying to light up a CP Holiday train like the 2 real CP trains that run each year in Canada and US. I eventually settled on EL light strings with a solid color like the current real CP train uses.; Here are some past photos;

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