A person at our club has a Lifelike Proto-2000 SD9 unit that has a soundtrax decoder in it. This unit has been having problems on our club layout. We have solved several of these issues by powering frogs, jumpering point rails, etc. The one remaining problem is that the locomotive will be running fine for an apparent random amount of time and then will hesitate and either lurch forward for a split second and then return to normal speed, or it will hesitate and then take off in reverse at full speed.
Other locomotives on the layout are not effected when it does this.
Has anyone else experienced this behavior? We are bringing in the heavy guns for diagnosis (osccilloscopes) but were wondering if it was perhaps a known glitch.
Oh yeah, the DCC control is a Lenz System with the most current software upgrades.
I have a Digitrax system so I cannot really address your problem if it originates with the DCC system. But, your problem sounds like a signal problem to me. Does the event happen at the same place on the layout, or on similar curves, cross overs or turnouts? I have several Soundtraxx decoders in my locos and the only times they have acted strange, I have forgotten to dispatch/clear them from another throttle.
If the problem has a common denominator from one of the items mentioned above, beyond dispatching, look for loose or pinched wires when the trucks rotate. Also, you had to isolate the motor from the frame on some of the early PK2 locos, even though they were DCC ready. If the trucks turn too far you will get a short which scrambles the DCC signal and could produce the behavior you describe. Most such locos had a little tab on the side-frame that prevented the trucks from rotating too far. The tab was not scale, so it was often removed. Even with the tabs, over rotation of the truck is possible on transitions into a grade and on some tight radius turnouts or curves.
If none of the above possibilities are true, give Soundtraxx a call. Their people are always ready to help and they may have the answer already in hand.
I know nothing about that decoder, but if there is a CV to disable analog mode, I’d do it, to make sure that if it loses track of things it won’t decide to try to be analog. I don’t know if the DCC system you are using supports an analog loco, but if it doesn’t I’m not sure there is anything in the spec to necessarily ensure that a decoder in analog mode would not lose its mind.
I have never encountered a problem like this with any of the 10 or 15 SoundTraxx decoders I have used, which include their DSD, LC, and Tsunami.
It sounds to me like a short or loose wire to one of the P2K locomotive’s trucks is causing the decoder to lose power on an intermittent basis. Remove the locomotive shell and carefully check the wires to both trucks by gently tugging on them to insure that one is not loose or has come unsoldered from the pickup contacts within the truck. I have had that happen, but it didn’t effect the decoder in the way you describe.
Yeah, that would actually be my last guess because we have bunches of other locomotives that do not exhibit this behavior. I would think if it was the system, then multiple locos would be acting the same.
If there is a pattern we have not yet been able to discern it. It seems to be at totally random places. If it happens and we take the locomotive back to that exact spot it most often does not occur again.
This is what I am leaning toward. I had a BLI loco that something in the back truck would cause a short when it hit a bump or just vibrated the wrong way.