Unplug decoder if 9pin or desolder wires from motor leads (orange and gray). Place chasis on track. Set multimeter to check continuity (I use one that beeps if there is a short). Touch 1 probe to a motor lead and the other to first one rail then the other. Repeat with other motor lead. No beeps no problem. I believe you will indicate a short if the decoder is plugged in because there is a path for current flow through the decoder. We are concerened only with current bypassing the decoder which is what causes the non-smoking HO locomotives to smoke.
Also verify your decoder isnt touching the frame anywhere. There is a lot of metal under the shell that your decoder may be touching. I wrapped mine in Kapton tape, as many of the folks here in the forums reccommend.
I just did 2 of them in about 30min. I used the provided board and harness to plug into a NCE D13SRJ. Probably could have put in a smaller decoder or replaced the board, but it was all I had on hand and I didnt feel like ripping out the provided board.
Thanks. I will give it a try.
I wired two up to the existing circuit board using Tsunami's. I had zero issues.
If I were you I would take the decoder out and connect the left and right pickup to the track and see if it still shorts by itself with a light + resistor attached to the headlight function. It wouldn't be the first time a decoder got it's insides messed up.
Don - Specializing in layout DC->DCC conversions
Modeling C&O transition era and steel industries There's Nothing Like Big Steam!
I am trying to install a TCS KAM4 decoder in this engine and would like to wire it directly. When I do this, I get a short. I have tried isolating the motor, but this doesn't help the issue. Any idea's or should I just try wiring it through the existing board as shown on the TCS website?