Jumping Locos!

[boblenon]

So today 7405 joined the list of locos that I have seen suddenly take off when track power is turned on. "Fortunately" it was in the engine terminal and only was trying to shove 5068 (least it didnt see the bottom of the turntable pit). I picked the unit up from the track and set it back - and it was no longer trying to run (I didnot cycle power).

Last week before the show I (as well as Walsh) saw Lakawana 954 do it twice in Syracuse - almost backing a cut of cars into CP-Wall.

The fact that 7405 stopped once I picked it up and set it back on the tracks indicates that there was no throttle with 7405 selected at a speed > 0. The other thing of note was the track power did not come on when I turned the layout on - but it should have... (I thought...)

I just tested it - If I turned the layout off with track power on, and turned it back on, the track power would initally come on with no moves. When I turned the track power off then the layout and turned it back on the track power was off - when I turned that on Mike's new CSX 2738 tried to speed off - until I cycled the track power.

This appears to not be 100% reproducable either :)

[Chris Stilson]

What if we set it up so track power is off untill told to be on. I think this is on Op-switch. That way if there is start up garbage that is making the locos take off then this might fix it. Then all you would need to do is turn track power on after you through the big switch on.

Chris

[Otto Vondrak]

Does the Digitrax System have a "Check Engine" light?

"I'm sorry sir, we weren't able to duplicate your problem. We don't think of it as a bug, it's most likely a super-special hidden feature. Enjoy!"

-otto-

[Mike Roque]

So today 7405 joined the list of locos that I have seen suddenly take off when track power is turned on.

I frequently see locomotives "lunge" forward (or backward; arbitrary) when the power is put on, but not take off. Interesting.

Last week [...] I [...] saw Lakawana 954 do it twice

[...]I just tested it [...] when I turned that on Mike's new CSX 2738 tried to speed off [...]. This appears to not be 100% reproducable either

The only thing I can think of is that 7405, 2738, and (I believe) 954 are all P2K. As such, I'm pretty sure they all have the same decoder installed (NCE's DA-SR).

I'm going to guess the problem is being caused by one of two things:

1. A problem with this particular decoder, or (more likely)...
2. The decoders are set to run on DC (if they were to be placed on a DC layout)

All DCC decoders have the ability to run DCC-only or DC/DCC in this way. There is a CV that controls whether they will respond to straight DC which is probably set for DC/DCC by default (IIRC).

I have heard about locomotives taking off like this when they are set for DC ops like this. Thus, in the past, I have disabled DC on all decoders for safety; should DC be applied to the tracks for some reason, the locos shouldn't take off.

I'm guessing that we're getting a spike of DC to the tracks on startup, and the engines with DC enabled are the ones that jump and/or take off.

I haven't disabled DC on the 2738 yet, so that could explain its behavior. I don't think I did it for 7405 or 954 either, so this is the most probable cause.

I'll take a look at this Tuesday night...

[Mike Walsh]

Lets not forget to do this!