DCC install in Athearn F7 B units?

[Anonymous]

I have been installing NCE D13SR decoders in my Athearn fleet. All has gone well until I did my first F7B unit. I am not doing anything special or advanced, just basic hard wiring. The only difference between an A and a B is the lighting. No lights on the B. Do I need to wire the B units different than the A's ? My B units wont run at all. Not on DC, not on DCC.
I have the black to frame, orange to top of motor, gray to bottom of motor, and red to the metal tab for the trucks. On the A units, the blue goes directly to the headlight. What do I need to do???? HEEEELLLLLPPPP!!!
Thanks,
Tim

[rrinker]

You DID isolate the motor, right? And make sure the unused wires (blue, white, yellow for lights) aren't touching anything. Otherwise, there are no differences between a powered B unit and an A unit, other than no headlight.

--Randy

[Anonymous]

Yep, motor is isolated and everything is hooked up like the A units. I even thought I might have a bad decoder and replaced it, but it still won't work. I am at a loss. I have 6 other Athearn units with decoders and they all work perfectly.

[mcouvillion]

Tim,

Take the motor out of the B unit and run it on the bench, hooked up directly to a transformer. Does it run? If it won't run on the bench, it won't run on a decoder.

Get rid of the Athearn metal clips and hardwire the decoder to the frame and solder wires to the pickups that the clip usually rubs against. I usually break off most of the pickup, leaving only enough to easily solder to, to give me more room in the shell and a better electrical connection. Sounds like your wiring is OK, but my guess is you have a bad motor or electrical connection at the motor. Check to see if the brushes and brush springs are in the motor. Maybe not!!!!

Mark C.

[Anonymous]

When you put your loco with decoder installed on the programming track, can you read back the loco address (assuming your dcc system can do that) ? I found a few soldering problems with decoders I installed this way... Sometimes it would let me "program" the decoder, but when I tried to run the loco on the main, it wouldn't do anything. Came to find out I had a wire loose.

[rrinker]

This brings up a good point for EVERYONE: If your DCC system supports a separate programming track - ALWAYS test a new install on the programming track FIRST. If you can't access the decoder on the programming track, do NOT put it on the main. The programming track is current limited and is far less likely to fry a decoder that's been wired with a short somewhere.

--Randy

[Anonymous]

Thanks for the replies. I was out for a bit. I already had the loco hardwired, and everything was EXACTLY the same as my others that run with no problems. Turns out the frame wasn't grounding on the trucks. I had to remove the paint from the bottom of the frame where it rides on the trucks. Now, everything is fine. The only thing I don't understand is WHY the frame is painted there when the MFG knows that is where electrical contact is required? Oh well, at least it's right now.