DCC trains struggling on new layout

[Michael1403]

Recently bought DCC controller and two trains second hand from a friend, trains showed slight stutter on his layout but adjusted after a few runs, one i took them home and changed my small layout to DCC the DC trains i had previously worked better than ever , very responsive and smooth too, but the two DCC trains kept stuttering and only worked on very small portions of the track... My friend says keep running them over and over until they adjust to my layout but they don't seem to be improving, what do i do? 

[RB51]

Have you made sure that the track and wheels are clean? Much more important with DCC as there is a data packet as well as power to be transferred between the rails and the motor.

 

Is there power all around the track? If you are relying on fishplates, or power cables soldered to fishplates, this could be part of your problem.

 

Your friend is talking about "running in" (like we used to do with cars) which only needs to be done on new locos to bed in the gears etc. If your locos are secondhand you shouldn't need to do this.

 

Let us know how you get on.

 

R-

[Yelrow]

Michael, , hi, with DCC clenliness, is  everything. Trains that run on DC track, will happily do so, on  old track, but DCC trains, will not.. Running them over and over again, will only make them worse, as wheels will become dirty... The other point is, depending on the size of your small layout, you need to consider, installing a BUS, that is 2 wires soldered in places to the track. Lot of past posts on this. I would, clean your Now DCCD track, with a Peco rubber, and check loco wheels, cleaning with turps/ cotton buds. Then try again. john 

[Michael1403]

I don't feel like it's a problem with parts of the layout being underpowered, as the trains struggle to work even when at the point where the track is being powered

But yes i will try and clean the wheels and track...

 

[RB51]

It certainly won't be wasted effort Michael, and if it isn't the complete solution you will be part way towards good running. R-

[96RAF]

You say your dc trains run even better on the dcc track.

 

word of caution, run them one at a time if you must but never leave them standing on the dcc track or they could burn out.

 

dcc locos will happily run on dc without any worries.

[DeeJayEye]

 I assume you are not still using the DC power connector. DCC requires a digital power connector or removal of the capacitor in the DC power connector.

[2e0dtoeric]

Do you have BOTH controllers connected at the same time?

That's a big nono. You will damage the DCC controller, and as said above, any dc loco's will be very quickly damaged by leaving them on the track while you are using DCC.

Very simply, the DCC controller is putting 16v AC on the track all the time, so any dc motors will be getting 16v on one winding, and buzzng furiously until the smoke gets out, after which they will be deceased.

Also - which power connector are you using to get the power from the controller to the track. If you use the dc one, the tv interference capacitor inside it will affect the DCC data signal. There's a simple cure - pop the cover off, and snip out the little component inside!

[Fishmanoz]

Easy to convert your DC power clip or power rail to DCC.  Just open the little black plastic box by flipping open the cover, then clip off the 2 metal legs of the capacitor and remove it.  Now close the cover and it will work with both DCC and DC.

[2e0dtoeric]

I put that! - There's a simple cure - pop the cover off, and snip out the little component inside!  😛

[Jimbo1707820979]

You say your dc trains run even better on the dcc track.

 

word of caution, run them one at a time if you must but never leave them standing on the dcc track or they could burn out.

 

 

Rob, would DC locos running on a DCC track with a Select controller be less likely to burn out than on a track with an Elite ? i.e. does the Elite put out a more powerful current ? Sorry the question may appear so elementary.

[Flashbang]

Hi

No, it wouldn't be any better regardless of the DCC system.

 

The problems occurs due to the frequency of the DCC applied to the rails. Typically around 8000 Hz to 10000 Hz

This is fed to the DC motor and while its stationary it is continually trying to move back and fore with the pulses at very high speed. It's only moving a fraction but the frequency is enough to cause the motor coils to heat. Eventually one of the coils will burn out rendering the whole motor unless. 

Hence the warnings to ideally not use address 0 (Zero) and never leave a DC loco stationary on DCC powered rails.

[96RAF]

The Elite runs on a 4amp power pack and the Select as delivered has a 1 amp supply, so yes there is less chance of damaging your DC locos on the Select lo-power supply but there is still enough current there to cause harm, so best avoided.

 

Just to paraphrase what the Select manual says:

 

The Select is internally protected at 4 amps so that it can use the Elite 4 amp supply. Overload protection is therefore with the 1 amp supply which upon detecting an overload will cut its output voltage. The Select will respond to reduced voltage by trying to reboot and the display may be corrupt.

 

The answer is if you are RUNNING a DC loco on DCC then it will be OK, but when it is standing it sees the full DCC voltage across part of the motor and it is likely to burn out as a result. YOu can tell it is not happy as it will buzz, whine or otherwise protest.

[Chrissaf]

The Brand and model of DCC controller makes not the slightest difference. The overheating issue is fundamental to the way that a DCC track signal is constructed. The DCC signal is an alternating square wave with a peak to peak voltage in the region of 28 volts, more or less the same on an Elite as it is on a Select.

.

DC support via a DCC controller works by stretching the digital signal either on the positive voltage side of the zero volt signal line (loco goes one way) or stretching the digital signal on the negative side of the zero volt signal line (loco goes the other way). When the digital signal pulse width is equal on both sides of the zero volt signal line the loco is stationary but the electric motor still has an alternating 28 volt signal across the motor windings making current flow equally and alternatively back and forth through it. This alternating current being equal means that the motor doesn't turn but the current is still flowing through it, building up heat. Since the motor is stationary there is little scope for air flow to aid cooling. Not only that, but as the DCC signal is about 28 volts peak to peak, this is a far higher voltage than a traditional DC Analogue controller output would be. The extra voltage generates higher currents, higher currents mean even more heat. The DCC signal is at full voltage permanently, thus the motor has NO respite periods to cool down that it would get in a DC Analogue environment.

.

The bottom line is that operating a DC loco on a DCC signal is a technical fudge. The controller is manipulating the DCC waveform shape to generate movement in the DC loco motor. The DCC controller is NOT applying DC current to the motor. The more time the Analogue DC loco remains stationary on a DCC (always live) track, then the higher the risk that the heat generated will start to damage the motor winding coils. This will be true irrespective of what DCC controller and power pack (i.e. 1 amp versus 4 amp) is being used.

[96RAF]

Just to reiterate what I said above, even if your DC loco was to pull enough current to 'trip' the Select lo-power supply protection then chances are your loco's motor would be cooked anyhow, so as I said before - best avoided.

[Chrissaf]

The Zero Bit Stretched DCC signal waveforms for running a DC loco on DCC can be seen on Oscilloscope traces here:

http://members.shaw.ca/sask.rail/dcc/DCC-waveforms/DCC_waveforms.html

[Jimbo1707820979]

Thanks, Gents. The situation is quite clear now. A few months ago I stopped buying any loco that was not DCC ready or fitted. Trouble is that in my first rush of enthusiasm I bought quite a number of analog locos, mostly second-hand, but still nice, and not available in digital guise.    If I run any of these now I never leave them standing on a live track and only run them for a few circuits.   Most are not worthwhile converting to DCC - 0-4-0's for example - or cannot be. Too old/ split-chassis etc. Also expensive, as I cannot do the coversion myself.

So this is probably the MAIN disadvantage of DCC and leaving Analog for DCC . Shall we call it "DEXIT" 😆  Thus beginners would be best to decide on DCC from the outset if they can afford it. As to listening for buzzes, whines or screeches ..... I will leave this to the Little Controller, who has already been advised of the burn-out dangers. Also feeling the loco for heating up. Bye for now.