Super stupid question, but this is an Athern. Did you pull the motor out and insulate under the motor? Atherns ground to the frame. If you didn't run an insulator tape under the motor, then you're shorted.
And another... Is she "backwards compatable?" aka, will it run on DC? Try it on DC, if she won't run there, then you've got it mis wired, or the motor's shorted to the chassis.
Are these RTR models or Blue box? If they have a circuit board on top of the motor, they are RTR. You simply need a decoder with a 9 pin plug, you remove the small square board that is plugged in to the 9 pin polug which stands off the circuit board on wires, and replace that small square board with the decoder. Nothing else needs to be done. They do NOT plug in to the 8 pin plug on the circuit board. It almost sounds as if you got a DH123AT decoder for older Blue Box Athearns and tried to install it using the decoder instructions - it won't work because there are some modifications to the pickup on a RTR model. RTR models are one of the easiest installs there is, remove shell, unplug board from 9 pin connector, plug in decoder - DONE.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Mike, out of curiosity, how were the locos running prior to your installation? I reserve only my best running locos for DCC installation.
Thanks, another of my mistakes. No, I am quite positive I did not flex the decoders .
He said flex, not flux. He was asking if you bent the boards as you were installing them, which could lead to breaks on the circuit board.
Jay
C-415 Build: https://imageshack.com/a/tShC/1
Other builds: https://imageshack.com/my/albums
I did put the tape on as directed but did not use any flux, should I? There was no soldering. I am not sure They were the right decoders, they are the same ones I used on my Atlas GP's and my Kato SD 40's and looked nothing like the light boards I removed. Thanks for the help, maybe we can figure it out. The decoders are the ones Digitrax said would fit.
Not sure what the # is but it is the plug and play, no pins, remove the old and slide in the new. I ought to have mentioned these are N scale. Thanks Mike
I have 2 Athren SD75's that installed Digitrax decoders in today and neither of them work. After installing the decoders and attempting to programing them (I am using Digitrax Super Chief) all they would is run on address 00 and no lights at all. It as if they still had the original light boards in them, they hum like a DC loco on a DCC track. Any help figuring out the problem would be appreciated. Thanks Mike