DCC in kits

[sundodger]

Is it straight forward for putting DCC In kit build locos ie disconnect wires from motor put chip in reconnect to motor. Or do I have to do anything else,

[SRman]

Your question is very vague indeed. It depends on a heap of factors, the main one being that the motor brushes are totally isolated from the chassis. You don't specify what sot of kit you are referring to - steam, diesel, electric outline, and so on.

Diesels and electrics may be motorised with power bogies or with central motors driving through cardan shafts. The electrical arrangements may vary widely between these types. Steam locomotives may be built with live chassis providing half of the electrical path between track and brush.

 

To convert any of these to DCC, you must ensure the brushes are completely isolated from any feeds from the tracks. Orange and grey wires go from decoder to brush. Red and black wires go from decoder to wheels/track feeds - convention says that the red wire goes to the right-hand track feed when the loco or unit is facing forwards.

[Brian]

You should always check by testing if necessary that once all the wires on the motor are removed there is no connection between the two motor wiring tags and any metal of the chassis or to any wheels.

If there is a connection this must be removed before fitting and powering up a decoder. Failure to remove a connection would result in the decoder immediately blowing upon DCC being applied.

[34theletterbetweenB&D]

All the above advice is correct.

 

In principle, if it is a satisfactorily operating 12V DC model, then conversion to DCC is straightforward. Since there is usually a wired connection to each motor brush, isolating the motor from the rails and interposing a decoder is simple, but it is not this aspect that leads to problems.

 

In practise, you may be faced with a complete PITA, but this will very much depend on any or all of: the design of the prototype, design of the kit, materials and parts used in the kit.

 

The reason for this is that DC is tolerant of brief short circuits, DCC is not.

 

An all metal construction - typical of a great many kits - is a fruitful potential location for such short circuits. I have exceedingly satisfactory all metal kit models running on DCC; and a couple which are non-stop problem children because despite brass construction for thin cross sections, the loco design puts tyres just a hairs breadth from metal surfaces which have to be present for a realistic model. What insulation can be got into the limited space available without intruding on appearance is applied; but sooner or later the wheels machine their way through, there is a spark, and the DCC system trips out. To make these into wholly satisfactory running models would require either substituting plastic wheels - not really possible as they are required for pick up - or a complete rebuild of the kit body substituting a very thin section insulator (which would need to be all of tough, stiff and reliably bonded to) for the sheet metal, at all the vulnerable locations.

[sundodger]

sorry for the delay in replying, thank you for your help it has been very clear what I need to do, the models are kit build steam locos of various makes OO gauge.

Once again thank you

Sundodger

[paulaspinell]

Suggest investing in the Right Track DVDs on DCC matters, I did before converting my kit built locos to DCC, it is very informative & helpful. there are one or too motors out there which are a no no for DCC, I know that because I had to change two motors on my locos for ones suitable for DCC, The DVD illustrated the very motors I had!! This was not much of an issue as I have been kit building for some 40 years now, the other locos already had DCC friendly motors(more by accident than design).Hope my bit of info is of some use.

[Nigelcliffe]

Suggest investing in the Right Track DVDs on DCC matters, I did before converting my kit built locos to DCC, it is very informative & helpful. there are one or too motors out there which are a no no for DCC, I know that because I had to change two motors on my locos for ones suitable for DCC, The DVD illustrated the very motors I had!!

 

hmm...   I suspect the DVD has duff information.    Could you name the motors in question please ?   

 

There is a lot of mis-information about motors around DCC.  For example, I've lost track of the number of times people have said "can't use DCC on a Portescap motor-gearbox"  or "can't use DCC on coreless motors".  The statements are rubbish, but are regularly repeated.  DCC works fine on those motors if a suitable decoder is chosen.  Suitable decoders have high frequency PWM to control the motor, rather than very low frequency pulses.   And, for the last 10 years, just about every decoder on sale uses high frequency PWM.  (Way back in the 1990's, some early decoder designs only used low frequency pulses, these would have been bad for coreless motors).  

There are a few decoders which are superb at controlling coreless motors, they have additional settings to better regulate the motor, and specific documentation for named coreless motors.   Probably worth fitting those decoders if you've a model which is the result of many tens or hundreds of build hours. 

 

The Portescap uses a standard Swiss DC coreless motor, examples I've rebuilt for others were stamped "Faulhaber".

 

 

I have several scratchbuilt models running with small Faulhaber coreless DC motors which are DCC fitted.  In some cases they use 8v rather than 12v motors.  They run superbly on DCC.

 

- Nigel

[tarifa]

I have built 2 Comet kits, a 4F and Castle and both are fitted with Zimo sound chips.  Providing the wheels are insulated and prevented from touching the chassis and pickups are are not in contact with the chassis all should be well.  My biggest problem was finding a place to house the decoders, they are MX648.

 

Mike

[paulaspinell]

The motors I had were D13s(I cannot remember the manufacturer) and these were shown on the DVD as needing a lot of work to make them suitable so I replaced them the DS10s which work fine and less hassle than doing a conversion on the D13s(which I felt was beyond me) and like you I had heard the same of Portscape motors, but have no experience of them.

[Nigelcliffe]

The motors I had were D13s(I cannot remember the manufacturer) and these were shown on the DVD as needing a lot of work to make them suitable so I replaced them the DS10s which work fine and less hassle than doing a conversion on the D13s(which I felt was beyond me) and like you I had heard the same of Portscape motors, but have no experience of them.

 

I understand the limitation of these motors is the frame (outside) of the motor is live to one brush. So, some care in insulation will be required to ensure no contact from motor frame to pickups. That is all.  Its the same issue as converting some older RTR models where the motor was integral in the chassis, and thus live to one side of the pickups - Hornby Double-O designs, Graham Farish N until fairly recently, some Fleischmann motor bogies, and many others.

 

If a loco kit or scratchbuild has already been assembled with one of these motors, and if the motor is mounted so that the frames are live to one brush, then this could create problems with DCC. If the frames are live to the wheels on one side there is definitely an issue which needs sorting before DCC conversion.   But these are down to the build of the particular loco, and the need with any DCC installation to separate both brushes from the pickups (wheels).  I agree that the simplest fix for an existing loco may be to replace the motor with one which does not have the frame live to a brush, rather than remedial work to insulate the casing of the old motor.

 

- Nigel

[Junctionmad]

I'd disagree with a lot of comments here

All the above advice is correct.

 

In principle, if it is a satisfactorily operating 12V DC model, then conversion to DCC is straightforward. Since there is usually a wired connection to each motor brush, isolating the motor from the rails and interposing a decoder is simple, but it is not this aspect that leads to problems.

 

In practise, you may be faced with a complete PITA, but this will very much depend on any or all of: the design of the prototype, design of the kit, materials and parts used in the kit.

 

The reason for this is that DC is tolerant of brief short circuits, DCC is not.

 

An all metal construction - typical of a great many kits - is a fruitful potential location for such short circuits. I have exceedingly satisfactory all metal kit models running on DCC; and a couple which are non-stop problem children because despite brass construction for thin cross sections, the loco design puts tyres just a hairs breadth from metal surfaces which have to be present for a realistic model. What insulation can be got into the limited space available without intruding on appearance is applied; but sooner or later the wheels machine their way through, there is a spark, and the DCC system trips out. To make these into wholly satisfactory running models would require either substituting plastic wheels - not really possible as they are required for pick up - or a complete rebuild of the kit body substituting a very thin section insulator (which would need to be all of tough, stiff and reliably bonded to) for the sheet metal, at all the vulnerable locations.

I'd have to take issue with a lot of this. Firstly if you are running any sort of modern DC electronic controller it's no more or less tolerant then dcc of shorts. Intermittent short will cause poor running on any loco. DC or dcc , secondly building an insulated chassis kit is no different for dcc or DC and is entirely achievable. In fact you can quite happily run dcc on a loco with a live frame. It causes no real greater issues then the same issues on DC layouts. I wouldn't recommend it , but it can be done.

 

Many dcc boosters will have actually longer short circuit cutout times then some modern DC controllers

 

Modern dcc decoders will also make your kit perform better as they offer far better configurable motor control then DC. Decoders for dcc are available to drive a whole range of motors including core-less.

 

In my view dcc is superior to DC control in almost every aspect , especially in layout wiring simplicity.

Edited August 31, 2015 by Junctionmad

[ROSSPOP]

Putting Dcc into kit built locos be they white metal or brass is not a problem at all.

 

Modern quality decoders will tolerate accidental shorting up to a point, they will not tolerate being wired up incorrectly or metal speakers shorting against metal loco bodies.

 

So.... If you have made a crappy job in building your metal kit in the first place and it is already shorting out it will destroy any decoder.

 

If your loco already runs well it will run even better with DCC all that is required is insulating the wiring , speaker and decoder.

 

And if you can build a kit in the first place.....you won't have much difficulty in any of that...

 

Regards

John

[34theletterbetweenB&D]

...So.... If you have made a crappy job in building your metal kit in the first place and it is already shorting out it will destroy any decoder...

 

Simply not true. Never yet had a decoder destroyed by a short in the track supply on or off the loco. It just stops on losing track supply due to the short, and restarts on track supply being resumed.

 

If you read what I posted, you will notice I have satisfactorily operating DCC decoder equipped metal kit builds. But some models are very difficult due to the design of the prototype, a good example my all brass Ivatt C12 4-4-2T. The flanges of the bogie wheels run a bare 0.25mm below the brass footplating, and any applied insulation gets worn through by the flanges - I run my models a lot - and there's the short circuit potential. The only cures that occur to me are:

Plastic bogie wheelsets - yuk, and I need pick up on the bogie anyway,

Undersize bogie wheels - degraded accuracy and appearance of the model.

A very thin non-conducting sheet material replacement for the brass footplating and complete rebuild of the front end to install. Likely the flanges will quickly wear clean through this...

[AMJ]

I am of the opinion to fit a harness along with plug or socket as you can test with a standard plug on DC and then fit say a reasonable chip and if you found a suitable sound later it would then be simple to swap the chip out.

 

Remember the simple rule of red and black to the track orange and grey the other way.

 

From most harnesses they will give you the appropriate colours for the lights etc and these can be wired in at a later date.

[giralnif73]

Is it possible to reverse this process? I operate using conventional DC and have a kit built loco purchased on a well known internet auction site. The loco is a DJH kit for a BR 78xxx 2-6-0 and is fitted with a DCC chip with four wires - black, grey, red and orange. I wish to remove the chip, reverse the polarity of the motor (runs reverse when controller set forward) and fit tender pick-ups. Any suggestions would be helpful.

[Nigelcliffe]

Is it possible to reverse this process? I operate using conventional DC and have a kit built loco purchased on a well known internet auction site. The loco is a DJH kit for a BR 78xxx 2-6-0 and is fitted with a DCC chip with four wires - black, grey, red and orange. I wish to remove the chip, reverse the polarity of the motor (runs reverse when controller set forward) and fit tender pick-ups. Any suggestions would be helpful.

 

Remove chip (cut the wires, leave a reasonably amount of wire on the chip as someone else might want to use the chip elsewhere). 

Then connect Red to Grey and Black to Orange.   See if it runs the right way.  If it goes the wrong way, then change the wires to Red to Orange and Black to Grey.    

Nothing else to do.

 

(Usual convention would be Red to Orange,  but as its running backwards, chances are it may need swapping around ). 

 

 

- Nigel

[NIK]

Is it possible to reverse this process? I operate using conventional DC and have a kit built loco purchased on a well known internet auction site. The loco is a DJH kit for a BR 78xxx 2-6-0 and is fitted with a DCC chip with four wires - black, grey, red and orange. I wish to remove the chip, reverse the polarity of the motor (runs reverse when controller set forward) and fit tender pick-ups. Any suggestions would be helpful.

 

Hi,

 

If you want to reverse the polarity of the motor try connecting red to grey and black to orange (based on the DCC decoder mnemonic Red and Black come from the track, Orange and Grey go away*.

 

* to the motor.

 

Regards

 

Nick

[Phil S]

As well as the details already covered - another essential area to look at is the couplings - these need to be isolated or there is a risk of shorting to an adjacent locomotive or similar when the couplings come into contact.

This is one reason why 'commercial' couplings have become plastic - or via plastic (with a NEM box)

Many 'kit' couplings are made from wire and metal parts atahed directly to a loco body/ buffer beam .... which may then have a diect route via the chassis to the track .... which could be to either rail!

 

Although again, this would not, or should not, damage the decoder and motor - as the short circuit path is rail-chassis-coupling-chassis-rail.

And I torally agree with the problem that old, out of date, (or simply abbreviated information) results in mis-information such as that caused by the original mains-frequency-based decoders with 50-120Hz pulse rates..... being the reason for non compatibility with coreless motors  (or perhaps best not used with any motor 8-)