HELP! N-Scale Tomix Thomas the Tank Engine Repair

Well it’s Christmas in July here so I broke out Dear Old Thomas so my son and I could enjoy a little run time with his best pal. I have set up a “small” loop of Kato Uni-Trak with an MRC1300 for power since my permanent layout is not yet permanant nor does it qualify as a layout.

Unfortunately, Dear Old Thomas is sick. I am hoping someone has had to do some maintanance on theirs and may be able to offer guidance with the repairs before I completely disect him. He is pretty much brand new. I bought him at auction last Christmas and ran him for no more than 10 hours before packing him up until the fall op sessions. Also, the other engines I am running all seem to respond to the throttle appropriately, Tommy’s wheels are clean, and I have cleaned the track just to rule out the obvious.

I placed him on the track and got no response to the throttle. A few wiggles got some sporatic motion. I took the plastic driver retaining clip loose, checked everything, added a drop of oil, but still nothing consistent. He will run great for a few short moments and then move very slowly at the same speed at any range on the throttle. Some times it’s only an issue in reverse. Some times he will only run in reverse.

I have successfully removed the shell and running boards without breaking anything (thank heavens). When I placed the bare chassis back on the rails, I felt a very noticable shock or electric current in my fingertips. I have never felt current from a motor before in 100’s, maybe 1000’s of repairs - although mostly HO. Based on this, I am inclined to believe that the frame or drivers are shorting out (I am guessing I detect the current due to enough oil residue on finger tips contacting a split frame motor). A quick inspection did not reveal any insulating washers between the frame halves and I have not yet broke out a meter to check continuity to confirm a short. I did not see any pickup strip

To paraphrase the old TV commercial: “Trains is trains” (remember “Parts is parts”?)

Go through the same procedures you would on any locomotive for locating a short. From your description of how Thomas is responding, I think you have either an intermittant short circuit or an intermittant dead short. The latter is my guess. Check continuity to determine the route power takes to the motor. You may discover that both halves of the frame are powered from their respective rails and you can feel current when you touch both halves of the frame with your fingers. The fact that you got a small shock doesn’t mean there is a short circuit, it just means power is getting to the frame.

Remember, only the scale is small, the physics are the same regardless of scale!

Hope you have success.

Darrell, shockingly quiet…for now