Decoder Question

[Anonymous]

Hopefully someone in this forum can give me some clues to a decoder issue before I buy a replacement decoder or motor.

Here is the problem. I have a HO Rivarossi Challenger with an NCE D13SR decoder. Up until today it ran flawlessly. When I went to run it today, smoke came out of the tender (where the decoder is installed) and the Circuit Breaker on my Command 2000 tripped.

Upon inspection, I saw one of the small IC's had a burn mark on it. Since I have another NCE D13SR decoder that would not program, my wife, being the expert surface mount solderer that she is, swapped out the bad IC with one off the other decoder.

The engine ran fine for a couple minutes, then stopped dead. Since it was on the other side of my layout, I hit the reverse and the engine backed up perfectly. It won't go forward now, or if it does, it goes about 6 inches and stops. It backs up without a problem, for as long as I care to leave it run.

I have inspected the drivetrain for binding, there is none. The motor shaft turns freely in either direction. I have cleaned the wheels and contacts and inspected the lubrication. No problems found.

Anyone have any ideas?

By the way, all the other locos run jus fine.

Ray

[rrinker]

Is a portion of the motor or drivetrain moving when under power, such that it is making contact with something else and causing a short? For example, if the motor case is hot, even though you may have isolated the motor fromthe chassis and used a plastic screw, etc, if the motor twists to one side, maybe it touches the frame somewhere - but not when it twists to the other side in reverse. Or a drive wheel is lifting and contacting something. Either way it's a short between either both motor drive wires from the decoder, or one of the motor drive wires and one fo the rail connections. A short in the pickups, or before the decoder, would have stopped the loco dead and tripped the circuit breaker, but not fried the decoder. I would try running it with the boiler shell off, if possible, and see if you can spot any movement or contact. And here's a trick - try it with the lights off - room lights, AND headlight. Start moving forward, about the time it stops, you should see a spark somewhere if it is indeed shorting out. I don't know how many more times you'll get away with this before this decoder fries like the other one, or rather the same part lets go again, so make each attempt count.

--Randy

[Anonymous]

I now show my ignorance of things electrical. Many years ago MR carried an article about building the CTC-16, followed shortly by the upgraded version, the CTC-16e. These were the articles that gave impetus to the DCC controls of today. The reason I hold forth is because I did build the CTC-16e and still use it to control the locomotives on my layout. It works extremely well and has been virtually trouble free. I am limited to 32 locomotives operating at one time, but this is not a shortcoming on my layout. I did install a thing called the Modeltronics sound system. This is chuffing only, triggered by rotation of the drivers, with no other functions available. With all this preamble, I now ask my question. Among the electronically literate out there, I ask if it is at all possible to redo my system to use modern controllers and high zoot receivers so I can have the full array of sounds that are currently available? If the answer is no, I can live with it. If the answer might be yes, be advised I would prefer being able to make the conversion myself. I do take scratch building to an illogical extreme. Thanx for even considering my question. You need not tell me I am not in possession of a full deck, that fact is a given.

Tom

[rrinker]

Unfortunately, no. The DCC signals and CTC-16e signals are not compatible, so there is no way for the CTC-16 system to control DCC decoders, and no way for DCC throttles to control CTC-16 receivers. You'd have to replace everything.

[Anonymous]

rrinker

Your response is appreciated more than you might imagine. I understand the differences in the frequencies used in each system (CTC16e vs. DCC). I had just a sliver of hope that my old system could be rebuilt to embrace the the DCC frequencies. I know enough to understand the differences, but not knowledgeable enough in electronics to understand if it could be done and/or how to do it. To change the entire system at this point would require more effort than I am currently willing to give. Cost is not the problem, I am just focused on other aspects of work that needs to be completed on my layout. OK, I'm just to d--n lazy to make the change rigfht now. And, again, thanks for your timely response.

Tom