DCC for Athearn SD40T-2 problem

Model Railroader Electronics and DCC
1

I was at friends today and we put a TCS T4X plug-n-play into a Athearn Sd40T-2. I rewired the cab headlights with 2 470 ohm resistors to the hole next to the green wire. Now for the fun part when my friend programed the engine with decoder pro the Gyra light would only work when the headlight was off. When you turned on the headlight the gyra light went out. We both checked the wiring and it looks OK but we cannot get the headlight and the gyra light to work at the same time when the decoder is in the engine. When I put the decoder on my Loys Toys decoder tester the decoder worked perfectly the led for F1 flashed with the headlight on and did not turn off when the healight was on.

Now for the question am I looking at a hard wire job because the Athearn board has a problem?. It would be pretty easy with the way it is set up now I have done a few blue boxes and they all worked right and I think the new wiring system will make it easier.

Thanks for the help.

Scott O’Dell

2

The instruction on page 3 of the TCS Programming Advanced “X” Features might help. Go to the TCS web site and download this document if you don’t have it.

CV 51 controls the green function wire. A value of 39 sets the decoder for the gyra light to be on in both forward and reverse.

Do you have the blue decoder wire connected to both the regular headlight and the gyra ight? It is the positive voltage output to both lights.

3

A friend had some issues getting everything to work on his tunnel motors. We tried adding resistors, etc. Still wouldn’t work right.

The eventual solution was to pull out the factory board and use a TCS A6X decoder. This one has the 1.5 volt outputs on it. Mounted the board to the motor with double-sided tape. Hook up the lights to the appropriate outputs, program, and everything is good.