To clarify for those not familiar, the DH123AT decoder kit comes with replacement motor clips for the Athearn motor so, in theory, you don't need to frame isolate the motor, because the part of the clip that touches the frame is no longer there.
Of course, I personally am a belt and suspenders type guy, so I always cover the exposed contact point with liquid electrical tape as well to be extra sure.
In either case, you have a broken lead to track power. don't worry about the decoder being broken till you've fixed that.
How old is that blue-box Athearn? The ones I have use the frame ground for one side of the motor circuit. You have to separate the engine frame from the motor electrically. That's what Simon meant by "isolate the motor."
The broken wire may have saved you, but make sure that motor is isolated before you reconnect it.
It takes an iron man to play with a toy iron horse.
Something worth noting, Schmidly:
ALWAYS test out or program a decoder on the programming track rather than your mainline.
If you've inadvertently wired or installed the decoder incorrectly, you're less likely to blow on your programming track because the current levels are less.
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
Go with the obvious.
If you correctly installed it, isolated the motor and did the wiring correctly then the broken red wire may be the only issue. No red wire = no power as it is one of the rail pick up wires.
Simon Modelling CB&Q and Wabash See my slowly evolving layout on my picturetrail site http://www.picturetrail.com/simontrains and our videos at http://www.youtube.com/user/MrCrispybake?feature=mhum
Hi, I tried putting a Digitrax DH123AT into and old Atheran Blue Box which I thought I could do. However when I put the loco on the track to see If I had done a good job. The light came on when I pushed the button for the headlight then it went off and nothing worked. I cheeked the wiring and it seemed alright. then I then noticed that the red wire form the track pick-up had broken from the clip. Now I'm just wondering if maybe the decoder went bad or was it because the wire broke off. Any suggestions? this was my first try at decoder installation. At the moment I don't have any locos that I can switch out and test the decoder