Could I have an explanation again, please?

S

Sarah Winfield

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Running my Stainz pulling 4 wagons round my track tonight everything was fine for 10 or 12 laps. Just the expected hesitation on the plastic frogs.

However, I then turned the locomotive through 180 degrees on the track to run in the opposite direction but it hadn't done half a lap when it stopped! The light was on but the locomotive wouldn't budge. I tried talking to it, even bribing it, and wiggling the track both in front and behind it but still no response. It was only if I moved it on a couple of feet would it spring into life.

Please would a member explain again how I can have power on the track but no response from the locomotive?

Thanks,

Sarah Winfield

PS. I appreciate this has been explained to me previously, so my apologies.
 
I know that JohnS overhauled the Stainz for you, Sarah, but I still wonder if the very old decoder that you have in it is really 100% working?
Why don't you put that loco aside for a while, and get some fun out of running the other three DCC locos that you have, all of which will have more modern decoders.....?

Jon.
 
So if the light is on, the loco is getting power... if it won't run then it's not the track (since you have proved power is on)

Next time this happens tip it over a bit (so 2 wheels on one side lose contact), wait a few seconds, and then let it back on the track.

Sounds like the motor has an issue or the decoder overheated. Interrupting power may reset the decoder.

Greg
 
Sarah, is your central station sitting in the sun? - I ask, as we are having (for us) very hot weather at the moment..
If the CS is marginal for driving large-scale anyway, the extra heat may be causing it problems??
 
Thank you PhilP.

I tend to run my layout in the evening when the sun is losing its heat and the track and my controller are in the shade.

I'm just trying to understand more about DCC.

SW
 
Power to the track but no loco movement (with loco lights on) means that the loco is not responding to a control signal to tell it to move.... so either the central station is not producing said control signal, or the loco's decoder is not responding to it.
One question - when the loco refuses to move in this manner, can you turn the lights on and off?

Jon.
 
Yes, Jon.

I think it is my track. I'm just trying to understand why I have power on the rails (about 20v AC as measured by my meter) but still the locomotive stops. Why? I understand the signal for the decoder is part of the AC voltage.

Can I have 20v AC on the rails but not enough digital signal to talk to the decoder?

All I'm trying to do is to understand.

SW
 
I am still a little bit suspicious of the decoder in your older Stainz..... I wish we could find out whether your other locos exhibit any similar problems on the same track?

Jon.
 
Reading the original post will help... she is running and it stops... So the CS was working and it stopped sending the commands, or the decoder decided to stop working, but still leave the light on.

Those older decoders weren't very sophisticated, so I don't think there is an overload sensor.

I suspect the command station, but if Sarah would just try a different loco when this happens, perhaps the endless conjecture could terminate and we could find a solution.
 
OK, I'll find time this morning to run my usual locomotive, the one John sorted for me. When it stops, I'll remove it from the track and replace it with one of my others.

In so doing, should I leave the controller where it is set?

SW

PS. You're being very patient. I have the advantage of being here and I believe it to be my track. I ask again, if I have 20V AC on the rails is it possible I have insufficient digital signal to control the locomotive's forward and reverse functions, please?
 
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At last a test proposed with another loco.

Do your locomotives all have the same chip number? If so turn the controller to stop then put the other Loco on the track and start it up.

If it has a different number you will need to put the controler to stop anyway to change to the other loco.

How I wish one of us lived near you, an hour with pretty well most of the forum guys would solve a lot of your issues at a stroke.
 
There's an old DCC saying I remember reading many years ago: "the signal IS the power". The DCC waveform varies with the digital signals being sent out - it's not modulated on top of some sort of regular AC wave. Your track may have a few dodgy joints which reduce the voltage a bit but the signal is still there. The symptoms seem to indicate a decoder problem, or possibly the command station is not sending commands to the loco's address.

Usually a command station regularly repeats the instructions for each loco it is controlling (in some systems the frequency of repetition can be adjusted). If a decoder loses power for a moment and then regains it, some decoders wait until a new instruction arrives while others resume based on the last instruction they had received.
 
One thing to bear in mind when you are running small locomotives on track that has not been pinned down to the trackbed is that the locomotive can rise up and lose contact with the track as it passes over the track..

Not all of my track is pinned down (it will be eventually when I get round to ballasting) and small locomotives sometimes pause or stop as they make their way round the track whereas large heavier locomotives have no problem.
 
I know some of you may be exasperated and well you might. It's also just as well none live close by as I would not be able to see them, so this is a sort of correspondence course which you partake in or like others you don't.

Believe me when I say I am learning. All the information helps me better understand DCC as opposed to DC.

A hypothetical situation. My layout is basically an oval. It has a few points but they are not the problem in and of themselves. Imagine the oval as a clock face with 12 at the top, 6 at the bottom etc. My controller is feeding the track at the 6 position.

If all my track joins are good then I should have no problems. If I separate the track at 12 presumably my locomotive will continue running because it is fed with power from 6 i.e in both direction?

Assume my track connections are not all 100%. If I separate the track again at 12 but the locomotive stops at 3, or 9, or somewhere else on the circuit what is that telling me please?

SW

I've had it running this morning with just one or two hesitations but it has not actually stop running. I'm pretty sure my problems is my track but asking my questions helps me understand the vagaries of DCC.
 
In the scenario you describe above, if the loco stops at 6 or 9 then there is a problem there. Either a bad joint or movement in the track like Keith refers to in post #16.
 
Your hypthetical situation is correct, power fed from position 6 will go in both directions and your loco will run around your circuit provided there are no breaks anywhere else.
 
Believe it or not this is how I started my garden railway. Track set out every time I wanted to run trains and put away afterwards. Had some small locomotives and no problem with the stopping and causing problems.

Then&Now01TheDecking.jpg

I started with a LGB Digital Start Set, followed the instructions, plugged it in and off I went, no problems whatsoever. Didn't worry myself about how dcc worked, I just wanted to run the trains.

Maybe everything worked because the decking was level so no ups and downs for the track.
 
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