Testing and checking on DC..... another controller needed.

[newbryford]

Reading a couple of threads regarding a loco and issues with DCC running got me thinking (dangerous, I know)

 

Whilst many of us are aware that it's good practice to check a loco on DC before installing a DCC decoder. Or put a loco back to DC if there are problems on DCC.

 

Great if you already possess a DC analog controller.

 

But......

There seems to be a reasonable number of people, either returning to the hobby, or newcomers, that are going straight to DCC and do not possess a DC controller.

 

 I must admit that I would be a bit peeved, having splashed the cash on a DCC system, decoders etc, to be then advised I need another controller on the odd chance that I may have a problem.

It may even occur that the new DCC user doesn't even have any blanking plugs - 8 pin, 21 pin and Next18 for the current crop of UK outline models, so that makes it even more difficult to test on DC.

 

Amost like buying a new car and then being advised to buy a set of spanners.

 

Cheers,

Mick

 

[jjb1970]

Nicely put.

[richard brown]

What I us for a quick test on dc is use a 9 volts battery. Cheap easy to use and easy to get hold off. But I do have a full dc controller if everything goes wrong.

[amdaley]

I can't see what the problem is.

As Richard said "Just use a 9 volt battery"

 

Reading a couple of threads regarding a loco and issues with DCC running got me thinking (dangerous, I know)

 

Whilst many of us are aware that it's good practice to check a loco on DC before installing a DCC decoder. Or put a loco back to DC if there are problems on DCC.

 

Great if you already possess a DC analog controller.

 

But......

There seems to be a reasonable number of people, either returning to the hobby, or newcomers, that are going straight to DCC and do not possess a DC controller.

 

 I must admit that I would be a bit peeved, having splashed the cash on a DCC system, decoders etc, to be then advised I need another controller on the odd chance that I may have a problem.

It may even occur that the new DCC user doesn't even have any blanking plugs - 8 pin, 21 pin and Next18 for the current crop of UK outline models, so that makes it even more difficult to test on DC.

 

Amost like buying a new car and then being advised to buy a set of spanners.

 

Cheers,

Mick

 

There was a time when you bought a new car it came with a tool kit.

Nowadays you'd need a laptop just to open the bonnet   

[jjb1970]

I think cars are a good example of a wider change in merchandise over the last few decades. Despite wailing over shoddy Chinese quality, things don't last anymore etc, people nowadays expect goods to work out of the box and not require any special skills or expertise to use. At one time cars were simple and relatively easy to work on which was good as you either needed some basic mechanic skills or enough money to pay a garage to keep the things working. Nowadays people complain about how complex cars are and how you can't work on them and kind of lose sight of the fact that you do an annual (or even less frequent) oil and filter change and a few checks and otherwise the engine and systems are pretty much "fit and forget". I remember when adding peripherals or new software to a PC was quite a scary experience, now it is all basically just plug and play and you don't need to know much about computers. Setting up my first surround sound home cinema set up was like some sort of black art, for my current one the auto set up worked perfectly well. And really, there is nothing unreasonable about expecting something to work out of the box without having to start studying new skills in order to just make it work.

[Mike Storey]

True. I do use a DC controller to test my locos before fitting a chip (apart from the very few I have bought pre-fitted). But I had also not really understood whether running locos on DCC on the 0 setting was the same as running on DC. From reading the discussion on the Class 71 and the coreless motors issue, I think I gather that it is not!

 

On the other hand, what does one do, for testing and running-in on DC, with a pre-fitted loco? It is usually simply a matter of disconnecting the chip and using a blanking plate. One of mine is hard wired, so I had to test run it on DCC. Luckily I had no problems, but what if I had?

[Nigelcliffe]

True. I do use a DC controller to test my locos before fitting a chip (apart from the very few I have bought pre-fitted). But I had also not really understood whether running locos on DCC on the 0 setting was the same as running on DC. From reading the discussion on the Class 71 and the coreless motors issue, I think I gather that it is not!

Definitely do not use address 0 for running in a DC loco. You are subjecting the motor to the full oscillating DCC voltage, with a bit of DC-bias over the top. Its fine for very short bursts of running *if* the loco has an old fashioned heavy iron cored motor (think Hornby X04). Its a very bad idea on a precision low current coreless motor.

 

On the other hand, what does one do, for testing and running-in on DC, with a pre-fitted loco? It is usually simply a matter of disconnecting the chip and using a blanking plate. One of mine is hard wired, so I had to test run it on DCC. Luckily I had no problems, but what if I had?

If the loco comes pre-fitted with decoder, then you run it in on DCC. Forget DC in those circumstances.

 

 

The "run in on DC" advice is for when fitting a decoder yourself. It comes down to two issues; ( a ) if there is a mechanical/electrical fault in the loco, find it before you might mask it with a decoder, and ( b ) in the days of "hard wiring" you had to start soldering things to the loco to fit the decoder, this probably had implications for the guarantee, so be sure its working before you start.

 

[Junctionmad]

Definitely do not use address 0 for running in a DC loco. You are subjecting the motor to the full oscillating DCC voltage, with a bit of DC-bias over the top. Its fine for very short bursts of running *if* the loco has an old fashioned heavy iron cored motor (think Hornby X04). Its a very bad idea on a precision low current coreless motor.

 

 

If the loco comes pre-fitted with decoder, then you run it in on DCC. Forget DC in those circumstances.

The "run in on DC" advice is for when fitting a decoder yourself. It comes down to two issues; ( a ) if there is a mechanical/electrical fault in the loco, find it before you might mask it with a decoder, and ( b ) in the days of "hard wiring" you had to start soldering things to the loco to fit the decoder, this probably had implications for the guarantee, so be sure its working before you start.

 

I agree , testing on DCC is just as easy . This notion that you should test on DC is really mis placed. I only go back to DC if I find I have a mechanical problem.

[Oldddudders]

I use address 00 to test basic back and forth functions. But the whistling noise - something you never hear on DC, of course - indicates that the motor is in some sort of torment, so my testing takes just a few seconds.

[amdaley]

I agree , testing on DCC is just as easy . This notion that you should test on DC is really mis placed. I only go back to DC if I find I have a mechanical problem.

 

Would it not be better to find out if you had a mechanical problem first before you fit a decoder ?

 

If you have a problem you then have to remove the decoder & go back & test on DC.

The idea to test on DC first is to stop you wasting time fitting a decoder & then trying to find out what your problem might be. Mechanical or DCC decoder.

[jjb1970]

This is something I'd never really considered before it became a topical question on a thread about a particular new release but it does raise a couple of interesting points. Most people buy a new product in the expectation it'll work out of the box and when looking at goods other than model railways I now find that recieving a dud is so rare that I really do assume everything will be tip top. I think many will apply the same expectation to trains (and like I say, it's really not an unreasonable one) and so probably would just not think that a model train should be tested to make sure it works. The other interesting point is tuning decoders for a particular locomotive. There is a difference between tuning a decoder to optimise performance and tuning a decoder in order to make the model work, personally I don't think it unreasonable to expect that a standard decoder will operate the model to an acceptable standard without having to faff about tuning the thing. If you then tune it to improve it that is one thing, but it should work to an acceptable standard without needing to be tuned I think. If there are technical reasons that is not possible then it'd be better if either the manufacturer supplied DCC versions already chipped or otherwise recommended a chip which could be used which doesn't need people to figure out how to make it work. To return to the motoring analogy, nobody would be happy buying a car then finding out you had to remap the ECU to make it work with an expectation that you can figure out how to do it via the Internet.

[34theletterbetweenB&D]

... To return to the motoring analogy, nobody would be happy buying a car then finding out you had to remap the ECU to make it work with an expectation that you can figure out how to do it via the Internet.

 The buying a car analogy I would use is the stuff you have to do with any vehicle to make it 'fit for purpose' specific to your requirements. Adjust any or all of seat, headrest, mirrors, steering wheel, pedals, seat belt, positions to provide optimum driving position, check for blind spots caused by hard structure, fool around with the onboard electronics for sat nav and other content that may be provided, blue toothery for your other devices, organise storage space in the boot and elsewhere. All very much down to individual requirements.

 

I know what I expect of movement of a model loco - and have yet to find a DCC fitted model that gets close as received - but they have all 'worked'; as in reliably goes forward and backward at command over a reasonable speed range. And judged by what I see elsewhere, for most customers that is probably good enough. Not long ago I demonstrated altering decoder settings on a loco for a really smooth transition in and out of movement, and the owner no like. He wanted that instant 'jerk away' on speed step 1 that the loco came set up with: tastes vary, so it was restored to original set -up.

[RAF96]

The run it in on DC mantra comes from the old adage that a loco must run well on DC before you convert it to DCC or chances are it will not run any better and may well be worse.

 

For a DCC fitted loco then you can run it in on DCC or DC providing DC running is enabled. No need to remove the decoder at all for DC running.

 

The point of the OP was do I need to buy a DC controller - not unless you want to carry out more than basic DC checks.

 

As stated a 9v brick battery across the wheels will check if a loco will run OK in both directions,

... and also as stated subjecting a DC loco to the torment of DCC voltage is cruel.

[CloggyDog]

Make yourself a little battery controller - PWM module, battery pack (I use 6 x rechargeable AAs), dpdt switch, few lengths of wire and a 0.2l Really Useful Box.

 

DSC_0450 by Alan Monk, on Flickr

 

Another option might be to recycle a 'wall-wart' plug in transformer of the kind used to charge phones, power small devices, etc. Select one that outputs in the range 6-12v dc, cut whatever plug is at the end of the lead off and replace with a pair of croc clips.

Edited May 31, 2017 by CloggyDog

[kevinlms]

The run it in on DC mantra comes from the old adage that a loco must run well on DC before you convert it to DCC or chances are it will not run any better and may well be worse.

 

For a DCC fitted loco then you can run it in on DCC or DC providing DC running is enabled. No need to remove the decoder at all for DC running.

 

The point of the OP was do I need to buy a DC controller - not unless you want to carry out more than basic DC checks.

 

As stated a 9v brick battery across the wheels will check if a loco will run OK in both directions,

 

... and also as stated subjecting a DC loco to the torment of DCC voltage is cruel.

It might be handy to check an unknown model first on DC. One that perhaps comes 2nd hand & doesn't have a decoder already.

 

Having said that, a simple one like CloggyDog's battery one, ought to be more than adequate.

[Crosland]

I have a short length of track driven by a decoder and use a DCC system to test unchipped  locos or chassis.

 

The drive from the decoder (Zimo, as that's what I had spare at the time) is high frequency PWM and will appear as DC to the motor.

 

You just need to take care not to short the track.

 

[edit] Forgot to mention the track has a rolling road on it, so it really is short. [/edit]

Edited May 31, 2017 by Crosland