Inexplicable Short Circuit


Does the command station have different output settings? I use Digitrax and it has a switch for N, HO or O/G and leave it on the HO setting. I've had lots of derailments/shorts in the 20+ years I've been using it but no problems like you describe. If it's a short related to a derailment, the decoder shouldn't see the current, it would be flowing through the derailed wheel. What are the engines in question, you said they were new Genesis but didn't say what model? Have they been collecting dust or hair on the axles and slowly increasing the amount of current they need to move? That could also explain the circuit breaker issue if it was set to just above the current needed when they were brand new.

I checked the manual for my smart booster/command station, it says "track voltage setting" can be set to 12 or 13.8 volts. I took a look and it was set to 12 volts. I've been under the impression that there should be about 14 volts going to the track and seem to remember setting it accordingly when I set up the smart booster. Perhaps it got changed inadvertently. Could this, in whole or in part, be causing my problems?

I've also been looking into bus line sizes. I use 14 awg for my main bus line because I planned that it wouldn't be more than 40'. I haven't measured the bus line but it's very possible it ended up being longer than that. Should I be using 12 awg? Could that be part of the problem?

The engines: Athearn Genesis ATHG83115 ES44DC
Athearn Genesis ATHG65256 SD60E
Both with Tsunami 2 decoders.

What do you think about both engines being on the layout when one ran into an electrofrog turnout not properly aligned causing a short? The circuit breakers were removed at the time while I was trouble shooting (I thought the breakers were tripping when they shouldn't be, maybe this had something to do with the booster set at 12 volts). The short was present for at least a few seconds until I could flick the points.

The engines are both only months old and I don't think accumulated dust is the problem.

Thanks for your reply, I appreciate the help!

Paul
 
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Just found on nce website 12v is for n scale and 13.8 is for ho scale (I model ho). I wonder how much this had to do with my problems.
 
Probably not.

I just read on dccwiki that for bus line length of greater than 40' in ho scale 12-14 gauge wire should be used. If mine is longer than 40' It's not by very much so I don't think that is the problem either. If the output setting on the booster isn't the cause either than I am more convinced the decoders were damaged while subjected to the short circuit which happened without circuit breakers present to kill track power. I seem to remember reading that some Tsunami decoders are "sensitive".

While still stumbling through the darkness I think I will go forward (or maybe backward :)) by replacing the nce circuit breakers with the allegedly more reliable psx cbs. Then I will see if Athearn will fix these engines under warranty, if not it's going to cost me.

I'm not going to do anything immediately. Still waiting to see if I can gather more info.

KJD asked me some specific questions a couple of posts earlier and I tried to address them all so I'm curious to hear from him/her again.

Thanks to all for replying

Paul
 
Hi Paul, I don't really know what's going on, just guessing. I realize too my signature doesn't show up when on a mobile device, just on the PC. My limited understanding of electricity is struggling to figure out how the decoder could see more current than the load it is supplying to the motor, speaker and lights. That was why I asked about dust and hair, they could build up slow enough and cause an increase in current draw but a quick check of the bottom of the locomotives and it should be visible. Before we start worrying about tin whiskers, is there something else that could be increasing the current draw? It is also suspicious to me that multiple locos have the same problem. Is the BLI still running well? Did you try a reset of the Tsunami decoders?

I've had older Digitrax decoders, by older I mean I got them in the late 1990s, loose some of their programming when involved in a shorting derailment. Usually reprogramming the address fixed the issue for me. I also have newer Digitrax, NCE, TCS, ESU and Soundtraxx decoders but none of them have been affected by shorts.

As far as bus wires, a larger wire can carry more current and too small a wire will not carry enough to trip the circuit breaker. My layout just sort of happened, it is mostly some modules that used to go to shows but haven't now for 6 years already. When I first set it up, an intentional short wouldn't trip the breaker so I added more wires until it did. I just have a loop, about 70 HO coal hoppers around, and have some feeders connected to the modules' wiring as well as the few sections I've added to connect the modules. They all go back to a terminal strip and then a relatively heavy pair of wires goes to the command station. Because I had it, the longest wire run is actually a computer networking cable with 6 or 8 conductors. I stripped the ends and soldered half of them together for one "wire" and the other half for the other "wire".

The sum up is it doesn't have to be a 12 gauge wire, you can connect smaller parallel wires. I just added enough so an intentional short anywhere on the layout tripped the breaker. Maybe a single 12 ga wire is better but I had a lot of smaller gauge wire and no 12 ga so used what I had.

It is a puzzle though,
Another Paul, in Oregon.
 
Hi Paul, I don't really know what's going on, just guessing. I realize too my signature doesn't show up when on a mobile device, just on the PC. My limited understanding of electricity is struggling to figure out how the decoder could see more current than the load it is supplying to the motor, speaker and lights. That was why I asked about dust and hair, they could build up slow enough and cause an increase in current draw but a quick check of the bottom of the locomotives and it should be visible. Before we start worrying about tin whiskers, is there something else that could be increasing the current draw? It is also suspicious to me that multiple locos have the same problem. Is the BLI still running well? Did you try a reset of the Tsunami decoders?

I've had older Digitrax decoders, by older I mean I got them in the late 1990s, loose some of their programming when involved in a shorting derailment. Usually reprogramming the address fixed the issue for me. I also have newer Digitrax, NCE, TCS, ESU and Soundtraxx decoders but none of them have been affected by shorts.

As far as bus wires, a larger wire can carry more current and too small a wire will not carry enough to trip the circuit breaker. My layout just sort of happened, it is mostly some modules that used to go to shows but haven't now for 6 years already. When I first set it up, an intentional short wouldn't trip the breaker so I added more wires until it did. I just have a loop, about 70 HO coal hoppers around, and have some feeders connected to the modules' wiring as well as the few sections I've added to connect the modules. They all go back to a terminal strip and then a relatively heavy pair of wires goes to the command station. Because I had it, the longest wire run is actually a computer networking cable with 6 or 8 conductors. I stripped the ends and soldered half of them together for one "wire" and the other half for the other "wire".

The sum up is it doesn't have to be a 12 gauge wire, you can connect smaller parallel wires. I just added enough so an intentional short anywhere on the layout tripped the breaker. Maybe a single 12 ga wire is better but I had a lot of smaller gauge wire and no 12 ga so used what I had.

It is a puzzle though,
Another Paul, in Oregon.

Yes, the BLI still seems to be running fine. I reset cv 8 to 8 on one of the Tsunami decoders but no change. I didn't bother doing that to the other one but I will just for the heck of it. I'm also going to check youtube to see if there is another way to reset the decoder, a button on the decoder itself maybe? That is the case with the BLI engines.
 
Some what related to your problem of the shorting and the circuit breaker issues, I ad a short that was tripping the breaker in my Digitrax DB150. It happened for every DCC locomotive that I attempted to run. I searched for a reason for the shorting for over two full days.

The problem turned out to be a piece of .032 solder that was cut while I was repairing a section of flex-track and the solder was laying inside the rails and making contact on either side of the inside of the flex-track rails. This piece of solder was very hard to see in the reduced light levels.

I've run HO equipment on the N voltage selector on the DB 150 without any problems.

-Greg
 
Some what related to your problem of the shorting and the circuit breaker issues, I ad a short that was tripping the breaker in my Digitrax DB150. It happened for every DCC locomotive that I attempted to run. I searched for a reason for the shorting for over two full days.

The problem turned out to be a piece of .032 solder that was cut while I was repairing a section of flex-track and the solder was laying inside the rails and making contact on either side of the inside of the flex-track rails. This piece of solder was very hard to see in the reduced light levels.

I've run HO equipment on the N voltage selector on the DB 150 without any problems.

-Greg

I wish I could find something like that across the rails! Two other engines are running fine right now so the mystery continues... I'm just not sure what happened to the two Athearn engines.

I've emailed Athearn and am waiting to here back. Quite a bummer because those were my favorite engines.
 
While trying to figure out why I'm having these problems I found this video

Not sure if it has anything to do with my issues but It may and I found it interesting. I twisted my bus line wires about 3 times per foot but I dindn't know why I was doing it, I just heard it was recommended. However ,in some places my wires are not twisted tightly and are not close together as maybe they should be. I also don't have and RC filter at the ends of my bus lines.

I'm guessing NCE will recommend using an RC filter (snubber) since they manufacture one but I don't know what they'll say about twisted pairs or the use of speaker wire. I plan to contact NCE and ask.

Figured I'd share the video in case anyone's interested. Thanks

Paul
 



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