Running in locos as DC on DCC Wired Layout

[Pete the Elaner]

10 hours ago, michaelp said:

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

 

You will not get much smoother DC than from a battery.

I am not familiar with that controller but I would expect it should be able to power a light engine 08. I would suspect it has a fault.

When measuring its output, you only have the load of the voltmeter. This is intentionally very low in order to affect the characteristics of the circuit as little as possible.

A motor provides much more load so the internal characteristics of the controller become far more significant. This is why a controller which produces 14v with an open circuit may only provide 10-11v for a train puling a heavy load.

 

 

 

As for the original question I have made a small test track which fits in the top tray of a toolbox. I was given Beatties controller in a bundle of hand-me-downs a few years ago. Its dial & switch look similar to what Gaugemaster use so I suspect this is where its origins lie. I keep this controller, a couple of rolling roads & a few useful spares in the toolbox itself.

Any new locos get run in for about an hour in each direction on here before getting chipped.

 

Any Issues? Occasionally. One which springs to mind was my Heljan Beyer-Garrett. One of its chassis was bent. My layout was still under construction at the time but my test track allowed me to identify this & return it immediately. Replacements were still available & I did not have the hassle of removing the chip again.

Some locos are a pain to chip, requiring work such as cutting the chassis block, which I assume will void any warranty. Surely it is better to determine that these are working before doing any work such as this?

[Pete the Elaner]

I have no idea how that duplicated. Duplicate removed.

 

Edited March 4, 2019 by Pete the Elaner

[Izzy]

14 hours 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. 

 

 

If a stay-alive if fitted there are some decoders where it is necessary for DC to be switched off for them to work. Hornby TTS and CT are two I know of and there may be others. I have only ever once had a runaway, for unknown reasons, but now always disable DC by default as a precaution. Since I never use it it’s no real hardship. At least the choice exists.

 

Izzy

[34theletterbetweenB&D]

On ‎03‎/‎03‎/‎2019 at 00:05, Junctionmad said:

I’m sorry , this is electrical voodoo ...

Actually, it is mechanical voodoo.

I want to ensure the mechanism is running as well as possible before the decoder is installed. This isn't compulsory, but I think it worthwhile.

[Art Dent]

5 hours ago, Izzy said:

 

If a stay-alive if fitted there are some decoders where it is necessary for DC to be switched off for them to work. Hornby TTS and CT are two I know of and there may be others. I have only ever once had a runaway, for unknown reasons, but now always disable DC by default as a precaution. Since I never use it it’s no real hardship. At least the choice exists.

 

Izzy

 

The 'around £10 a pop' Lais DCC decoders don't seem to play nice with stay-alives - even their own!

 

Art

[Hamburger]

Hi,

I'd like to have a look at some facts:

 

1. Running in is recommended to give the brushes a certain time to match its shape exactly to the dimensions of the collector/commutator.

2. For this it does not matter if you have smooth DC or pulsed DCC.

 

But:

3. When running in usually a lot of sparks are being caused ('brush fire').

4. This affects the surface of the collector in a negative way.

5. Causing sparks mainly depends on the applied voltage (and the shape of the brushes and the collector condition).

 

So,

6. a lower voltage gives less brush fire.

 

The Problem on DCC ist that

7. DCC works with a constant (higher) voltage which is pulsed,

Usually the motor gets a peak voltage which is just 1.4 volts below the DCC track voltage.

 

8. Using a DC device or a battery allows lower voltage at the motor.

9. That is the main reason.

 

If you manage to get your DCC output down to example 7 or 8 volts and the decoder is still working, everything is fine also on DCC.

If not, use a DC transformer.

 

Just for running in I also recommend to leave the capacitor as it is, also helps avoiding sparks.

 

Wolf

 

[michaelp]

37 minutes ago, Hamburger said:

Hi,

I'd like to have a look at some facts:

 

1. Running in is recommended to give the brushes a certain time to match its shape exactly to the dimensions of the collector/commutator.

2. For this it does not matter if you have smooth DC or pulsed DCC.

 

But:

3. When running in usually a lot of sparks are being caused ('brush fire').

4. This affects the surface of the collector in a negative way.

5. Causing sparks mainly depends on the applied voltage (and the shape of the brushes and the collector condition).

 

So,

6. a lower voltage gives less brush fire.

 

The Problem on DCC ist that

7. DCC works with a constant (higher) voltage which is pulsed,

Usually the motor gets a peak voltage which is just 1.4 volts below the DCC track voltage.

 

8. Using a DC device or a battery allows lower voltage at the motor.

9. That is the main reason.

 

If you manage to get your DCC output down to example 7 or 8 volts and the decoder is still working, everything is fine also on DCC.

If not, use a DC transformer.

 

Just for running in I also recommend to leave the capacitor as it is, also helps avoiding sparks.

 

Wolf

 

So if using a battery connected to a rolling road what size/type of battery would be required to give sufficient running in time?

[Jeff Smith]

12 minutes ago, Hamburger said:

The Problem on DCC ist that

7. DCC works with a constant (higher) voltage which is pulsed,

Usually the motor gets a peak voltage which is just 1.4 volts below the DCC track voltage.

 

So are you saying that the output to the motor is half-wave rectified?  If so I'm a little surprised as I would have thought this would be bad for motor life, but may explain why DCC is argued to be better for slow running, although this might just be better wheel/rail contact due to full voltage AC.....

 

My limited experience with 0n30 DC and DCC running showed no starting and slow running advantage for DCC.

[WIMorrison]

It is not halfwave rectified AC, it isn’t AC at all - if you look at this link then you will see what it looks like

 

https://www.nmra.org/sites/default/files/standards/sandrp/pdf/s-9.1_electrical_standards_2006.pdf

[Junctionmad]

23 hours ago, johnb said:

 

 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

Depends ,many decoders actually power up and control the loco on DC. You can often see this because the loco needs a higher initial DC voltage to move off then under  pure DC control 

 

( ie they still use pwm ) 

 

 

Edited March 4, 2019 by Junctionmad

[Junctionmad]

Firstly dcc typically use pwm , ie pulse width modulation 

 

this is typically at a quite high frequency usually these days above human hearing 

 

the nett effect combined with the motors inductance is basically a DC signal 

 

the commentary about “ sparks “ and new motors  is quite frankly electrical nonsense , the average energy under pwm is largely the same , the voltage is largely irrelevant 

 

the second thing is typical modern motors do not require a run on period 

 

what does tend to need is the mechanical arrangements on the loco itself 

 

it’s cares not a wit if it’s dc or dcc 

 

it’s an old wives tale with no basis in theory. 

 

Use dc , use dcc , both will run in the mechanics just fine

 

its always useful to have a dc controller handy when debugging dcc locos , but that’s a different thing entirely 

Edited March 4, 2019 by Junctionmad

[Butler Henderson]

On ‎02‎/‎03‎/‎2019 at 17:32, grahame said:

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

Does not last long if you are splitting it and reconnecting it - better is an oval of Kato Unitrack which is designed be broken up and reassembled. I run a loco one way then the other; then turn it round and repeat, all in equal time intervals equal in total to the recommended running in time. Should show up any faults, my Bachmann 7F failed to negotiate the curves in one direction as all the pick ups on one side were too compressed - did not affect its a running on the straight, and around the curve in the opposite direction. I make the end curves for OO models up from 45 degree 550mm radius curve leading to a 90 degree 490mm radii and then another 45 degree 550mm radii.  Needs 2 packs of 2-270 (490mm curves), 2 packs of 2-210 (550mm curves), a 2-151 feeder track and  at  least a pack of 2-141 straights to give a 369mm straight  between the curves - total price from Gaugemaster £67.75

Edited March 4, 2019 by Butler Henderson

[Junctionmad]

23 hours ago, Jeff Smith said:

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.

Not really , the voltage signal associated with dcc is correctly called a bipolar signal as from the perspective of the track the voltage swings about a “ nominal zero point “ ( which may or may not be gnd or 0 V ) 

 

some ( many ) command stations actually swing about Vsupply /2 

 

the decoder then then rectifies the dcc signal both to power itself and to supply a full bridge pwm controller 

 

to vary the “ energy “ supplied to the motor the duty cycle of the pwm is modified as required 

 

this is because other methods such as series pass control waste too much energy as heat and cause issues in such a small space ( leaving aside the loss of economy)

 

typically a dcc decoder operating under DC , does exactly the same thing , controlling the motor using pwm , except rather then receiving  speed  commands via  dcc , it uses the voltage value of the incoming feed to determine pwm duty cycle 

 

most of these microprocessor on the decoders can operate down to 1.8V So they can power up and control the loco from this point on 

 

in fact some decoders can do simulated momentum based on a preset CV while under DC control 

[Pete the Elaner]

27 minutes ago, Junctionmad said:

its always useful to have a dc controller handy when debugging dcc locos , but that’s a different thing entirely 

I thought that is what is really meant by 'running in on DC'. Ensure it works ok before fitting a decoder?

[sholidom]

Again, many thanks for all the responses and I'm greatly intrigued by the range of views.

 

I've decided to build and, indeed have already started, on a permanent test track on a shelf above my layout.  I have an old Gaugemaster DC controller that I can use for running-in (the subject of my original query) but I'm also setting it up with DCC input for programming which is going to be the next bit of faffing around once the chips are fitted.

 

It really would be very interesting to get the official line from manufacturers as to why they so strongly advise running-in in DC.

 

This is all a very far cry from the Triang Princess I had as a kid and writing as someone who got the lowest grade in Physics GCE and has only the most basic grasp of resistances and currents, the electrics have been proved a very "interesting" learning curve!    I have to be honest and confess that I've struggled a bit (lot?) with some of the explanations and teminology but I'm getting there.

 

And I've still got the programming of an ardhuino powered turntable to look forward to so that will no doubt be the subject of another crie de coeur in the future! 

 

 

[Junctionmad]

1 hour ago, Pete the Elaner said:

I thought that is what is really meant by 'running in on DC'. Ensure it works ok before fitting a decoder?

No , the process of running on a new loco is largely to “ bed “ in the loco specific mechanics , especially steam locos , model loco gearboxes and largely bush based bearings being relativeky crude mechanically ( not to mention all kettle specific valve gear stuff :D) 

 

this is is what needs bedding in not the actual electrical motor 

 

this makes no difference if you run in on dc or dcc 

 

the advantage of having access to a dc controller is when debugging a potentially troublesome dcc loco , ie to aid the “ process of elimination “ , so that you can remove the decoder and test the basic motor connections etc. 

 

A new loco shouldn’t need debugging at that level ( even if some unfortunately do) 

 

dave

Edited March 4, 2019 by Junctionmad

[Art Dent]

Just to toss in another spanner here ...

 

It is intriguing to hear comments about bedding in the brushes in the locomotive motor.

 

My son and I used to race 1/10 scale r/c touring cars using 7.2V NiCd (and then 7.2V NiMH) battery packs and the advice when getting a new motor was to connect the motor (like this > link) directly to the battery pack (i.e. no speed controller) and plunge the motor in a bucket of water (whilst running) for about 5 minutes.

 

Bear in mind that these battery packs contained a serious amount of energy - typically each 1.2V cell would store up to 4500mAh (that's 4.5Ah) of energy and the electronic speed controllers were capable of handling towards 150A (yes one hundred and fifty amps) at 7.2V.

 

Horrified at the idea, this was duly Googled and found to be OK and duly performed on a motor whenever run from new for the first time or after skimming the commutator and fitting new brushes. Quite daunting when you first try it.

 

Makes me wonder if this should be applied to our 12V loco motors 

 

Art

[Jeff Smith]

The process of running-in a mechanism, including motor brushes, is really to reduce any high spots and ensure the lubrication has coated all the running surfaces (except of course the motor brushes).  I used a Tenshodo on a project and out of the box it was very erratic but after about an hour of moderate speed no-load running was considerably improved.  This must be the pick-ups on the back of the wheels as the gears are I believe nylon.

[SRman]

Coming in a bit late on this topic: I have a rotary multi-pole switch feeding my programming track, with one of the pole pairs attached to a simple DC controller for running-in or testing purposes. In conjunction with a rolling road (mine is from DCC Concepts, but there are many alternatives), locos can be run-in on DC before fitting with a decoder then programming on the same track. Even as I type this, I have a loco running on the rolling road on DC power.

Not necessarily of relevance here, but maybe of interest to some, the other poles on the rotary switch are attached to:

• an NCE Power Cab - perfect for simple programming and setting up of decoders
• the main NCE Power Pro system - also good for programming, but not always as effective as the Power Cab, but can be used with the attached computer and JMRI Decoder Pro where more complex programming jobs are desired (e.g. function remapping)
• an ESU LokProgrammer - for reblowing or trouble-shooting ESU LokSound decoders, via the computer attached to it
• two isolated positions with no connections

This is probably over-complicated for most people's needs, but I find it works well for me and my own requirements.


Provender Store Progress 30-07-17 - 2 by Jeffrey Lynn, on Flickr


Edit: Of course, a much simpler solution would be to use a DPDT switch feeding the programming track either DCC or DC.

Edited March 5, 2019 by SRman
Adding extra info.

[Pete the Elaner]

9 hours ago, Art Dent said:

 

Bear in mind that these battery packs contained a serious amount of energy - typically each 1.2V cell would store up to 4500mAh (that's 4.5Ah) of energy and the electronic speed controllers were capable of handling towards 150A (yes one hundred and fifty amps) at 7.2V.

 

Horrified at the idea, this was duly Googled and found to be OK and duly performed on a motor whenever run from new for the first time or after skimming the commutator and fitting new brushes. Quite daunting when you first try it.

 

Makes me wonder if this should be applied to our 12V loco motors 

 

Art

Look up ohms law & relax!

 

The current in a circuit is determined by the supplied voltage & the total resistance in the circuit. It is not dependant on the supply's capacity.

If something goes wrong & you get a short circuit, then the resistance will reduce & you need some form of protection against the current being too high. The protector (circuit breaker or fuse) should always be the weakest part of the circuit.

[Crosland]

17 hours ago, WIMorrison said:

It is not halfwave rectified AC, it isn’t AC at all - if you look at this link then you will see what it looks like

 

https://www.nmra.org/sites/default/files/standards/sandrp/pdf/s-9.1_electrical_standards_2006.pdf

 

Can we please stop this nonsense.

 

DCC IS AC.

 

It just isn't a 50 or 60 Hz, sine wave at 120 or 240V (i.e. AC mains), which seems to greatly confuse our American cousins, and some others too, it seems.

 

DCC is a low voltage square wave of low kHz frequency. Half the time the current flows one way, half the time the current flows the other way. The current alternates. It is alternating current. It is AC.

 

If it looks like a duck, quacks like a duck, ...

[Crosland]

20 hours ago, Hamburger said:

Hi,

I'd like to have a look at some facts:

 

2. For this it does not matter if you have smooth DC or pulsed DCC.

 

7. DCC works with a constant (higher) voltage which is pulsed,

 

 

Sorry, but pulsed DC can be just as bad (or not) as the output of a DCC decoder, depending how the DC controller is generating the pulses.

 

In fact pulsed DC is more likely to be worse as it will be at a much lower frequency than the drive from a DCC decoder. The motor is more likely to react to the individual pulses.

 

[Sir TophamHatt]

I have about 20 locos/units.

Most new ones I buy aren't really run in that well, although I don't have that much of a layout to run them in with.

The only two I specifically ran in on DC were the Hattons 58XX (because of so many "dodgy" ones) and the Voyager (as it had been boxed for the previous 10 years untouched from new!).

 

All others will be run in on DCC... at my own risk as some would say.  However reading through the first few posts of advice that DC was better, there were no reasons given as to why.

My car manufacturer recommends BP petrol - I don't use BP petrol.

My dishwasher recommends Finish, but I don't use those tablets!

 

But until we have any quantifiable evidence DCC will make a loco/unit last for a shorter amount of time, specifically because it was run in using DCC, we'll never really know.  Some will think DC is a must, others won't care if it's DC or DCC, and others still won't bother running a unit in at all!

[Pete the Elaner]

5 minutes ago, Crosland said:

 

Can we please stop this nonsense.

 

DCC IS AC.

 

It just isn't a 50 or 60 Hz, sine wave at 120 or 240V (i.e. AC mains), which seems to greatly confuse our American cousins, and some others too, it seems.

 

DCC is a low voltage square wave of low kHz frequency. Half the time the current flows one way, half the time the current flows the other way. The current alternates. It is alternating current. It is AC.

 

If it looks like a duck, quacks like a duck, ...

I agree.

 

NMRA do not help matters though. You would think you can trust those who set the standards but I found this on their website:

"The DCC signal is an alternating DC waveform, which contains the digital information".

I wish they would take that rubbish down because the terms 'alternating' & 'DC' completely contradict each other. Current is either alternating or it is direct.

I read somewhere that some electrical engineers do not like a square wave described as AC, presumably because it confuses people into thinking it is a sine wave. I think they prefer to call it a bipolar signal.

A digital signal can be encoded within DC, but the DCC we all use does not work like this.

[Pete the Elaner]

8 minutes ago, Sir TophamHatt said:

I have about 20 locos/units.

Most new ones I buy aren't really run in that well, although I don't have that much of a layout to run them in with.

The only two I specifically ran in on DC were the Hattons 58XX (because of so many "dodgy" ones) and the Voyager (as it had been boxed for the previous 10 years untouched from new!).

 

All others will be run in on DCC... at my own risk as some would say.  However reading through the first few posts of advice that DC was better, there were no reasons given as to why.

My car manufacturer recommends BP petrol - I don't use BP petrol.

My dishwasher recommends Finish, but I don't use those tablets!

 

But until we have any quantifiable evidence DCC will make a loco/unit last for a shorter amount of time, specifically because it was run in using DCC, we'll never really know.  Some will think DC is a must, others won't care if it's DC or DCC, and others still won't bother running a unit in at all!

I don't see that it matters too much.

I have seen it mentioned that a decoder supplies PWM. Many DC controllers do too. I know that models often have a suppression capacitor but this is only to reduce interference with other devices. Decoders can be tweaked to cope with different motors anyway, which is similar to using a specific controller for a particular loco.

If a decoder is damaging to a fresh commutator, then surely it is also damaging to a not so fresh one?

 

If a brand new model ran poorly, would you take it back or try to fix it? I would take it back. I would not want to open it for a second time to remove the decoder I had just fitted, so I test it before taking it apart. Some models are a right pain to fit a decoder to, requiring some cutting which I am sure would void any warranty. This means I need the DC test box.

Once the DC test box is out, I may as well leave the loco running for a while longer to let the gears bed in.