Running in locos as DC on DCC Wired Layout

[sholidom]

I don't suppose I'm the first person to raise this but I is there a simple way to run-in locos out of the box?  The main manufacturers strongly suggest running-in locos in DC before adding the chip.  I have a DC controller but my DCC layout is split into three sectors running through a NCE CP6 fuse board, which should be used only for DCC, and, in any case, I have 30-odd points and cross-overs, so that rules out wiring the DC controller through to the track - or does it?

 

The only options I can see are to purchase a rolling road or make up a separate running-in track but then I cannot be the first person to have had this situation crop up so what is the solution?   Suggestions, please!

 

 

[WIMorrison]

I run mine on a DC controller whilst sat on roller cradles - you cannot run a DC loco on DCC (despite what Lenz and some other manufacturers say, at least not if you want the loco to last)

 

I also use the DC controller with brass brushes to clean the wheels periodically by setting CV29 to allow DC running.

[grahame]

. . . . or buy yourself an oval of setrack - easy and cheap.

 

G.

[melmerby]

39 minutes ago, WIMorrison said:

 you cannot run a DC loco on DCC (despite what Lenz and some other manufacturers say, at least not if you want the loco to last

 

That's left over from the early days and I don't think anyone still suggests it is sensible with today's motors

It's probably OK with an XO4 or suchlike.

It'll still protest and get hot!

 

In case anyone is wondering it is done by changing the DCC waveform which is normally symmetrical and has (or should have) zero DC content in such a way that it is assymetrical thus having a DC component.

It still has lots of AC though which is not good for the motors.

 

Edited March 2, 2019 by melmerby

[Oldddudders]

Running a DC model on DCC is technically feasible, but the shrill noise from the motor when stationary tells you it ain’t comfy. Fine for briefly checking the loco runs forwards and backwards - say 10 seconds in each direction - but not wise beyond that.  

[johnb]

Well I don't usually run things in on DC or indeed at all most times. I choose to buy DCC ready stock, recently it's been Bachmann or Hornby EMUs and DMUs, I fit a decoder of my choice and then just operate them on the layout. I could run in on a rolling road, but only normally use that to check direction and steadiness. As an example I recently ran four Bachmann 2EPB EMUs that I had DCC fitted. at a show without any prior running in, I'd had most of them for a while and chipped them. They just came more or less straight from the box onto the layout, and ran happily all day. My layout is a terminus to fiddle yard one and is all of 13ft long.

 

Nothing  can run fast on a layout of that length so I didn't even notice any easing up that is reckoned to happen.

If I do get a DCC fitted item then any running in is on DCC. I automatically disable DC running when setting up stock.

 

Just to complete this saga, for the same show I recently chipped a Hornby DCC ready Class 25 I'd had for a while, it's running was all over the place when I tried it on a rolling road, so I simply cut off the capacitor and it ran perfectly with no CV twiddling.

 

I use a variety of 2 or 4 function chips usually in the around £20 range, TCS, Digitrax, some NCE, a couple of Lenz and recently some Zimo.

 

Maybe my overall approach is heresy to some, but it works for me!!

 

John

[34theletterbetweenB&D]

Never mind what the manufacturers may say, some low current running on DC has long been recognised as advantageous for the motor brushes. Hopefully you get a good polished patch on the brush and commutator contact areas, which will then not heat appreciably when asked to pass more current. Like wise all the pick up contact tracks get a chance to polish up for good contact while operating in undemanding conditions.

 

Seeing the mechanism perform 'unassisted' by back EMF powered by a simple DC supply like a resistance controller enables the owner to see whether the drive train is mechanically sound, and any less then satisfactory running to be rectified. Having the mechanism exercised forward and reverse around the sharpest curves it will negotiate - left and right - on the layout typically allows any running issues to be spotted and rectified. If the mechanism degrades in performance once the decoder is fitted, it's an easy test to remove the decoder and determine whether the mechanism unassisted outperforms the decoder.

 

Personally I would suggest a little planning on any layout that can support it, to have an isolated circuit which can be switched between DC, DCC programme and DCC power is advantageous on three counts:

convenience, so you are going to use it,

reduced handling of the loco once successfully decoder fitted,

keeps all the dirt from the new tyres on one defined piece of track.

 

[johnb]

Wheel cleaning, ah, some more heresy here! I use the Trix device that sits on the track and has wire brush top side, I just set the DCC id, set the controller to fast(ish), place the loco on wire brush and away we go!

Works for me is all I'll say.

John

[RAF96]

Length of circular track with a 9v block battery attached . Run at this voltage for 5 minutes each way by alternating loco direction on track until the battery dies. Also works for a rolling road if no DC controller.

[melmerby]

5 hours ago, Pete Darton said:

Odd question and suggestion by manufacturers. Surely running a motor under dcc or dc is the same thing. What happens and what do suppliers suggest if dcc chip is already fitted? 

 

My thought is that if the train comes ready to run on dc then what the manufacturer wants you to do is to check it works before adding the chip in case that adds a fault and then you think the fault is the model instead of the chip or you have damaged the train whilst installing.

When running in a new loco on DC most probably it will be getting pure DC

When running after fitting a decoder it will be getting pulse width modulated DC.

Slightly sticky mechanisms might not show up properly on DCC but will on pure DC

Edited March 2, 2019 by melmerby

[Junctionmad]

4 hours ago, 34theletterbetweenB&D said:

Never mind what the manufacturers may say, some low current running on DC has long been recognised as advantageous for the motor brushes. Hopefully you get a good polished patch on the brush and commutator contact areas, which will then not heat appreciably when asked to pass more current. Like wise all the pick up contact tracks get a chance to polish up for good contact while operating in undemanding conditions.

 

Seeing the mechanism perform 'unassisted' by back EMF powered by a simple DC supply like a resistance controller enables the owner to see whether the drive train is mechanically sound, and any less then satisfactory running to be rectified. Having the mechanism exercised forward and reverse around the sharpest curves it will negotiate - left and right - on the layout typically allows any running issues to be spotted and rectified. If the mechanism degrades in performance once the decoder is fitted, it's an easy test to remove the decoder and determine whether the mechanism unassisted outperforms the decoder.

 

Personally I would suggest a little planning on any layout that can support it, to have an isolated circuit which can be switched between DC, DCC programme and DCC power is advantageous on three counts:

convenience, so you are going to use it,

reduced handling of the loco once successfully decoder fitted,

keeps all the dirt from the new tyres on one defined piece of track.

 

I’m sorry , this is electrical voodoo 

 

firstly due to the high speed switching and motor inductance the net effect of PWM is in effect DC 

 

secondly by design many dc controllers are not pure dc , they are often only partly rectified to introduce an element of pulse a low speed 

 

thirdly resistance controllers are largely defunct 

 

fourthly , BEMF can be switched off in a DCC decoder 

 

I run my DCC locos from new immediately on DCC , it’s makes no difference 

[Crosland]

Ask yourself whether DCC fitted locos are "run in" on DC at the factory.

 

Better still, ask the manufacturers.

 

I haven't bothered in a long time. I no longer possess a DC controller. When building a new loco I put the chassis on a rolling road that sits on a short length of track driven by a decoder.

 

As Junctionmad says, a modern high frequency decoder, and the inductance of the motor, means that the motor is effectively seeing DC.

[sholidom]

Many thanks for the responses.  I've looked through the history on this subject and, as I suspected, the responses have been varied each time.

Like a couple of the respondants, I've wondered why it's recommended by both Farish and Dapol that their DCC products should be run-in on DC.  However, I'll take their word on the subject and so I've decided the simplest (and cheapest) solution is to set up another simple test track circuit that I can use both for DC runnning-in and DCC programming. 

[Jeff Smith]

Aren't most decoders dual function, ie can run on either DC or DCC.  It presumably recognizes what the power source is.

[WIMorrison]

2 minutes ago, Jeff Smith said:

Aren't most decoders dual function, ie can run on either DC or DCC.  It presumably recognizes what the power source is.

 

All decoders will run on pure DC but some reason (that I have never understood) many people disable the DC function in CV29. 

 

I always leave it switched on and have never had an issue leaving it switched on, and it makes cleaning wheels easier with my brass brushes for which I use an old Roco transfromer

[Phil S]

I suspect it is purely to 'limit their liability' - and also their 'responsibility' is to ensure it runs 'as supplied .... so without any dismantling (other than when Hornby added transit brackets to locos in the box...  will it work ?    Then add the decoder ... if it doesn't now work, they want to pass the buck to the decoder of your choice ....  but if, as with some wiring  errors manufacturers have made, the loco works on analogue without a decioder, but blows decoders .... that needs careful checking and fixing - examples include a Class 50- decoder 8 pin needed to be rotated 180 from marked position,  mirror image wiring has been seen -  a friend had a Bachmann dmu hand modified before sale to correct the pin wiring in the trailer... often the problem involves the 'blue' positive common wire pin position -  this may not reveal iself on a steam loco with no lighting   Some locos have  been wired with wires from the various pickups connected to adjacent pins - which are commoned by the blanking plug ... but not when that is replaced by a decoder 8-(

 

The only 'running in problems I can recall  was an unattended ! Dapol 155/156 jamming its gears ( grit or a moulding  pip?) and the motor then melted  the plastic mounting the motor shaft.  - and sligfhtly different - motor short on a new type Hornby power bogie caused by the motor's magnets attracting a piece of metal offcut ... shorting the adjacent, and unprotected motor terminal!!! .... problem avoidance .. put insulation over the magnet/ wire connections.

(or along time  ago with early v1 zero-1 decoders whic used triacs .. which did not turn off in time ... with much smoke.)

 

PS I strongly advocate the removal of all ancient controllers like H&M Clippers, duettes, dc60's etc   which output about 28V peak (100Hz full wave rectified)  at the labelled '12Vdc' ... NEVER try running a decoder-fitted loco on one of these, and expect it to behave properly

[Oldddudders]

30 minutes ago, WIMorrison said:

 

All decoders will run on pure DC but some reason (that I have never understood) many people disable the DC function in CV29. 

 

I always leave it switched on and have never had an issue leaving it switched on, and it makes cleaning wheels easier with my brass brushes for which I use an old Roco transfromer

Many of us learned long ago that a short-circuit can sometimes fool a decoder/motor into thinking it is running on full volts DC, hence it - or worse, they - take off at warpspeed with scope for damage. Disabling DC running in CV29 is free, and eminently reversible if the loco needs to run on a DC layout.  

[WIMorrison]

I have heard of this but in 15 years of DCC and short circuits I have yet to see it happen on my layout - and I have to say that people I know say that they have also heard that it happens but have also never experienced it.

 

I am happy to leave DC enabled on my locos

 

[ColinK]

I have a 3 foot long length of track on plank by my workbench wired to a old ZTC 511 controller.  This can be switched to either DC or DCC output.  To run in a loco in I put it on rollers on the length of track, switch the controller onto DC and run it for about 20 minutes in each direction.

 

Once thats done, I fit the decoder, switch the controller to DCC output, put the loco back on the track and run it up and down the track checking everything is OK.

 

The plank of track also comes in useful when cleaning wheels, checking coupling heights etc.

 

I replaced the ZTC unit on my layout with a NCE controller because I thought it was faulty as locos kept running away at full speed the first time I exhibited. I soon discovered that the controller was fine, it was something odd happening in the school where the exhibition was. The problem was solved by turning DC off on each decoder.

 

Unfortunatly my old ZTC 511 does not have the ability to read and change CVs up to 28.  I have to use my NCE controller to do this, either when the layout is errected (one siding can be switched to a programming track to do this), or more recently using a circle of secondhand setrack glued to a sheet of wood.  The reason for the circle is so I can tweak the CVs to get my locos accelerating and stopping at similar rates (There is a thread on this).

[Junctionmad]

The technical point is that there is virtually no difference at the motor end between DC and DCC in practice 

[johnb]

I have had this happen more than once, luckily I caught one and the other fetched up in the fiddle yard against the foam end stop. In neither case was the shorted loco affected by the run away, it was another that was nearby. I always disable DC  during the initial setup. Given the price of modern stock I am not willing to take the risk.

I don't use analogue DC on any of my layouts although I do retain an analogue controller for occasional use in testing friends stock.

 

John

[RAF96]

Another common cause of DCC signal ‘distortion’ is a controller that is set to run loco zero (analogue). Even if there isn’t one on track if loco zero has been selected (by accident?) and throttle applied then DC is sent to that (phantom) loco using a stretched zero bit value in the DCC signal.  For this reason to preclude the problem many controllers do not support loco zero and others have it disabled as default. If you don’t need it switch it off.

 

Edited March 3, 2019 by RAF96

[johnb]

1 hour ago, Junctionmad said:

The technical point is that there is virtually no difference at the motor end between DC and DCC in practice 

 

 If running DC enabled on a DCC fitted loco, the supply to the motor is through the chip anyway, so presumably any chip characteristics will also be sent to the motor. Or, does the chip effectively allow the DC to bypass its internal gubbins?

 

John

[michaelp]

Can I ask a question please, I wanted to run in a new Hornby 08 which is DCC ready but no decoder is fitted yet, my layout is DCC but the DCC power is disconnected and all other locos have been removed from the track, I connected my Hornby DC controller to the track the loco wheels just move a fraction in both directions and stop. I checked the loco with a 9V battery and the wheels rotate fine in both directions.

I don't know which model of DC controller I have on that it is a small Black Hornby controller with a Red switch that moves three 'notches' left and right with centre off position, it can be heard buzzing but the switch is switched either way the buzzing goes very faint. I have checked the output voltage and it reads pos 1  8V    pos 2  10V   and pos 3  14V in both directions.

Is it likely that the controller is damaged?

Any advice would be great

Thanks in advance

 

[Jeff Smith]

The chip rectifies the a.c. into d.c. And supplies the dc voltage as selected by the controller.  The dc is probably not pure dc as from a battery though.