I've installed Soundtraxx Tsunami decoders in Athearn RTR's before but this one has me puzzled. I got this loco second hand and have no papers for it. I want to solve this conundrum before I buy a decoder for it and blow it. The Red arrows show the track pick up for the right side. This is the only wire running to the trucks. The green arrow shows a wire from the opposite side of the board, where the left track pickup wire should go. It looks to me like a ground because I can't seem to find anyway for the wheels to transfer power to the frame. The rear truck is the same minus the left pickup on the board, which is empty. The motor is isolated and the loco is DCC ready. What am I missing here?
The wires coming off the trucks “your red arrow” is one rail and the other rail is picked and sent through the frame and that is “your green arrow”. So these are your 2 power pickups.
I will be blunt about this issue. If you insist on working at this level, get your multimeter out and do a continuity check. If no meter, buy a couple of the below and a set of clip leads. I have been using three of these meters and clip leads for many years. When people say isolate the motor brushes, make sure the frame halves of the motor are not connected to the motor brushes. The motor terminals had no wires on them but there was continuity between the motor halves and the brushes. I have had a motor that was like that and the meter saved me from smoking the decoder. http://www.harborfreight.com/7-function-digital-multimeter-90899.html http://www.harborfreight.com/18-inch-low-voltage-multi-colored-test-leads-66717.html The meters do not measure AC current but in all the years of model railroading, I have never found that to be an issue. The meters compare very well to an expensive meter and the reading with my digital Oscilloscope. Rivet counters insist on a $200.00 meter. RIch
eagleman is correct, the older blueboxs, and this particular run of RTR's, used the frame as one conductor of electricity. The left hand (I want to say it's left, I could be wrong though) wheels pickup power and conduct it to the frame where the truck contacts the frame. Just install the decoder like normal, but leave one pickup from one end off (as it is in yours) because the frame will pickup power from both trucks at once, so there's no point of having a second wire.
I had a feeling it was frame fed I just couldn't see where it made contact. Thanks for all the replies.
