HELP - MTH Premier Streamlined Santa Fe Blue Goose Coach Car - Wiring has melted - Thoughts/HELP

I'd just replace the wires.  FWIW, that most likely happened in a derailment when one of the pickup rollers sat on the outside rail for a spell before circuit protection kicked in.

 

Thank you so much for your response. A couple of questions though:

1. Out of curiosity, what does FWIW stand for?

2. What gauge wiring would you recommend and any tips or instructions on how to do this?

3. Is it safe to keep using the car, especially since it is running with a LED lighting board in place that doesn't require much power? Could the wire fail and cause a fire or melt the plastic of the underbody even more?

Thank you,
Chris

1. FWIW -- For What it's Worth
2. Depends on what you're connecting. Most modern passenger cars are using low-current lighting, so the wire should probably be something around 22-gauge. I would cut out the burnt section of the wire and replace it with a new section of wire. Make sure nothing gets pinched when screwing things down as this can create a potential short down the road. I like to refer to it as a "resistive short" which has just enough resistance to not trip a breaker, but causes heat to build up in the wire and melt the insulation.
3. LED lighting doesn't draw a lot of current, so that's not the problem. However, for the wiring in a car to melt, it sounds like the breaker in your transformer didn't trip properly and I'd be concerned about that, but if you had a pinched wire, the "resistive short" mentioned above might have been a factor. A Z-500 doesn't have that much power compared to other power supplies, but its maximum current though a thin or pinched wire can still burn the insulation.

 

My fix for passenger cars that I've done LED lighting upgrades for is to put a low value PTC between the two pickups.  That solves the problem of the wiring melting for derailments, and I haven't had any issues with those cars.  I have replaced the wiring in a number of cars I've gotten in for upgrades, as well as a couple of tenders with dual rollers that apparently derailed and suffered a similar fate.

Thank you all for the great advice. I will be replacing the wiring and I know it's not the transformer cutoff. I think the original factory wiring was damaged when the interior was screwed at the factory and the car derailed causing the short but the wiring burned. It's still working perfectly fine but I fear it might cause damage to the new led circuit board.

Oh, and is a ptc something do with have controls? Not sure what it is

Sorry, a PTC is a current limiting resettable fuse.  Here's an appropriate one for LED lighting in passenger cars.

 

http://www.digikey.com/product...90-4808-1-ND/1644689

Awesome! Thank you for the link! If you don't mind me asking, how do you connect it in the circuit? Just solder it to the two leads coming from the pick up rollers  then the wire continues on ?  Sorry I've never done much  electrical work before.

There are leads coming from each pickup roller.  You insert the PTC into the wire that connects these two together so that current flowing between the rollers has to go through the PTC.  You can connect the LED lighting supply on either side of the PTC (but NOT both sides), the current draw is too low to bother the PTC.