Lead Truck on MTH Premier F-7 Shorting

- check the red (hot) wire on the truck to ensure it is not close to and rubbing the frame.

- if the ground screw has a black oxide coating, remove it and file lightly the underside of the head to remove the coating, or just tighten it the best you can.

- check to see if the eyelets/wire crimps  for the hot and ground leads are touching.  May have to rotate one or both to have clearance.

- check to ensure the coupler wires (or any lighting wires) are not pinched between the motor mount and frame.

- in some early premier 2/3 rail trucks, the axle bearing fits poorly in tbe truck block (sloppy), preventing a good ground between the bearing and block.  I usually add a "U" shaped piece of shim material (brass) between the bearing and truck block.

If you send it to MTH under warranty, I'll be the one looking at it since I'm doing all the O gauge and Tinplate repairs.  Only two of us left there and I don't do HO!

John,

I'll take a look again. From this, I think the filing of the screw may be the easiest solution. With any luck, it will work. I'll update once I give that a try.

Marc

Hello,

I took some time and inspected the power connections from the truck to the rest of the locomotive. The screws were not coated and were fully metallic so I eliminated that possibility. Your other comment about the wire leads being in contact with the frame seemed to help, but once I got the shell back on the locomotive, the sparking resumed. With that in mind, why would the red wire simply being in contact with the frame cause a short? The red wire shows no damage and since it is insulated should not be conducting with the frame. To me, there is something else going on here.

The sparking resumes. As I work through this more and more, it seems the short is between the truck and frame. As a note, this is a PS3 locomotive. I get an electronic hum coming from the front end of the locomotive when I turn on the power. I do not get the same hum from the matching A-unit that I purchased at the same time.

Thanks again,

Marc

Sometimes it is hard to see a nick in the wire or heat shrink around the crimp on the eyelet.  Keep it away from the from the frame and let me know if the problem goes away.  I think you also posted this on Facebook.

Pictures would help.   At one time Weaver had a 3 axle truck that was an extension of the standard 2 axle drive system.  The third axle had blind drivers.  I have two of these models, one has steel blind wheels, the other plastic.   On a smaller O54 layout, the trucks flop-around enough to arc and spark.

The first instinct is to check for the positive wire grounding to the frame but common can also cause issues.

Try cleaning the black coating off of the wheels.  I have seen the trucks arc to the frame when there is poor ground.

Thought I would resurrect this to see if there was any resolution.  Thanks