Wright writes.....

[coachmann]

When it came to adopting DCC sound decoders, it is just another skill set that one acquires like soldering. The more you do it the easier it becomes.

 

I depended 100% on a pal initially, but when dependency changed to guilt, I bought a further handset and learned to set the CV's for myself at home. He had set me on the right path though and stressed the importance of putting on paper every change of CV value.  This is vital if one is to learn which ones to alter and why.

Edited August 14, 2017 by coachmann

[RThompson]

It would seem loco kit-building articles are nowhere near as popular as they once were in the press. A sign of the times? 

 

Regards,

 

Tony.

 

For me, the lack of locomotive and rolling stock construction articles (plus scale drawings) puts me off from buying magazines these days. These from a young age taught me quite a bit and actually made me want to build something which I did on my 14th birthday, a SEF secr class C. Then a secr H just after Christmas within a week of each other (glad both was not rolled into one then) but sold that built onto a friend. Before then I was scratch building locos in plastic card so it shows the value to me of such articles.

[Michael Edge]

Interesting that it is possible to do this, I had no idea, thinking that ANY short would immediately trip a DCC system. 

 

We use NCE EB1 circuit breakers, they are adjustable for amperage by moving a shunt, the delay is programmed by the loco controller.

[Barry O]

I use a SPROG linked to my laptop to set up decoders. The CVS are all kept as a record on the laptop. When I get the odd loco back I can very quickly tell if someone has been changing CVs. It also lets me set a number of the same type of loco very easily.

 

Baz

[stewartingram]

I know you don't personally care Tony, but for sake of completeness the matter of dead chassis and motor for DCC installation is an absolute. Anything else is asking for trouble and DCC manufacturers say it enough times in the destructions. People still do it.....and fry decoders unnecessarily. Then return them to us for replacement because they don't work......harrumph.

 

I'm looking forward to the A7 build too, especially bogie ideas.

 

As a complete DCC numpty, but one who works in electronics, and used to be a Hornby service engineer that fitted Zero 1 chips, can I ask why the chassis has to be dead? I have no interest in DCC, just like Tony, but would like to know the reason why, as we obviously fitted Zero 1 in live chassis.

 

Stewart

[jacko]

As a complete DCC numpty, but one who works in electronics, and used to be a Hornby service engineer that fitted Zero 1 chips, can I ask why the chassis has to be dead? I have no interest in DCC, just like Tony, but would like to know the reason why, as we obviously fitted Zero 1 in live chassis.

 

Stewart

At a guess it's probably because any short will shut down the DCC controller or ( in the case of my prodigy advance) set the running loco to full power and lock the handset. however, Michael (above) has pointed to a useful method of delaying the short enough to avoid locking up the controller. 

 

Graeme

[stewartingram]

At a guess it's probably because any short will shut down the DCC controller or ( in the case of my prodigy advance) set the running loco to full power and lock the handset. however, Michael (above) has pointed to a useful method of delaying the short enough to avoid locking up the controller. 

 

Graeme

 

I understand that, but a s/c can occur with a live or dead chassis. Take a Hornby loco 4472 for example - with a cast block chassis that is live. Properly constructed, it works, no s/c. That can only occur if say a track pin is picked up. I accept that the construction of one of Tony's all metal locos (no offence intended) with a live chassis and limited clearance on say brake parts offers more chance of a s/c, but, if assembled correctly there isn't any s/c. So why can't a live chassis be used? Or is it just the fear of an off chance s/c occurring?

Sorry to be pedantic, but I see no real technical reason for saying it is not possible.

 

Stewart

[grob1234]

The information regarding circuit breaking on DCC set-ups is heartening, as I was beginning to think that with quite a few kit built items of stock, I would have trouble getting them to be 100% short free. This would (I thought) severely limit what I could do with DCC (my preferred choice at the moment). So that is very useful info for me going forward.

 

In the meantime, I have virtually completed the J3. Just coupling rods and globe lubricators, courtesy of ArthurK to fit. Next time you see her, she will be primed then painted. More information on my workbench thread.

 

 

 

[Barry Ten]

This King (Tony took the picture, so I hope it's OK to post it again) has a live chassis, with only one set of wheels having pickups. The decoder is in the tender, mounted on a bit of insulation, so there's no real chance of catastrophes.

 

 

Most DCC systems will tolerate a very brief short circuit and there may not be any detectable interruption in the running, beyond what would happen in DC anyway. Unless these short-circuits continue and the full current of the DCC system keeps pumping into the track (which won't happen if there's a circuit-breaker in the system) the decoder won't come to any immediate harm. The only foolproof way to blow a decoder for good is to have track voltage (what should go through the red and black wires) come into contact with the motor wires, the orange and grey ones. Provided the decoder is properly installed (always check on a programming track first, as that will identify a problem without imposing a damaging current/voltage on the decoder) and the motor contacts arranged so that they can't come into contact with the wheels, frames or pickups, all should be well. It is certainly sound advice to make the chassis electrically dead if you are starting the kit from scratch, but a locomotive with a live chassis doesn't have to be discounted for DCC conversion, provided care is taken with the installation.

 

I'm not a DCC zealot and enjoy building and operating locomotives to run on DC as well. In fact the final decision often doesn't come until the painting stage. What I tend to find is that if I've eliminated all obvious shorts in DC, there'll be no problems running in DCC. Obviously there may be the occasional, once-in-a-blue-moon situation where something touches something at the same time as something else, but those cases are just as likely to cause  sparks or twitches in DC.

 

Alastair

[Tony Wright]

I understand that, but a s/c can occur with a live or dead chassis. Take a Hornby loco 4472 for example - with a cast block chassis that is live. Properly constructed, it works, no s/c. That can only occur if say a track pin is picked up. I accept that the construction of one of Tony's all metal locos (no offence intended) with a live chassis and limited clearance on say brake parts offers more chance of a s/c, but, if assembled correctly there isn't any s/c. So why can't a live chassis be used? Or is it just the fear of an off chance s/c occurring?

Sorry to be pedantic, but I see no real technical reason for saying it is not possible.

 

Stewart

Thanks Stewart,

 

When you say Hornby loco 4472, which one do you mean, please? The old(est) Tri-ang Hornby one, the tender drive one or the latest manifestation? If it's the last-mentioned, then that has a dead chassis (or at least pick-ups both sides). 

 

I don't think it's the the problem of a stray short on a live chassis that might affect DCC, but the chance of the chip touching the inside of an all-metal loco's boiler/tender/wherever it's installed. With a dead chassis, the loco's body is dead as well, though that won't stop two separate bits on a chip touching the inside at the same time. 

 

When I did a DVD on fitting decoders to (older) Hornby locos (with plastic bodies, but with live chassis), I acted as the 'dunce' - asking really daft questions. Actually, I didn't act at all - the questions just came naturally! It was impressed on me the need to 'sleeve' the chip in some non-conductive material. A DCC expert subsequently told me that that was poor advice, because the decoder might overheat.

 

As is well known, my experience in fitting/using DCC is very limited, though my disliking of it is vast. I have fitted decoders in metal kit-built locos with both live and dead chassis for customers I've built engines for (though I'm still puzzled why they couldn't do this for themselves - I could). Because I'd fried at least five chips by their touching the inside of the body, I adopted the following 'safety regime'. I subsequently made every chassis electrically-dead. Not only that, I made sure the area surrounding the chip was insulated as well, by either smearing a thin layer of Araldite inside the loco body or by using a strip of insulation tape - the former method is preferred because it never comes off.

 

A major difference between a kit-built loco and a (more modern) RTR loco is that the latter will have a socket ready-installed, either in the loco or the tender. This allows the simplicity of 'plug & play' to take place (but even some I know can't even do this!) and the chip is securely held in place at source. The kit-built loco (usually) has the decoder solder-fitted, and it tends (in my experience) to rather flop about inside the body - hence the need for internal insulation.

 

All this, of course, is not even academic to non-users of DCC. I just build a live chassis, install pick-ups on just one side, taking care that the 'insulated' motor brush is far away from the inside of the loco's body (either by having it at the bottom of the can, or, if it's at the top, by insulating the body around it if necessary - not at all in big-boilered locos). I just have one insulated wire from the pick-up to the motor and a live wire (a joggled piece of .45mm brass - the joggle allows the motor/gearbox to find their sweet spot) to the other brush - which also acts as a stay to the motor. I have no need for 'delay' facilities if a short is detected (though any chances of them are eradicated at source during the build), I save myself masses of dosh, if I want to run a loco I just set the road, flick a switch and turn a knob/slider and away it goes. Any spare space in an etched brass boiler can be packed with lead, and that's that. What's best is that I can do it all myself.

 

Despite what others might say, I believe you (the generic 'you') need a fair bit of know-how to install DCC at every stage (see the post above), or pay someone else to do it for you. Then, when it goes wrong, you're stuffed! But then, I'm a Luddite.    

Edited August 15, 2017 by Tony Wright

[Tony Wright]

This King (Tony took the picture, so I hope it's OK to post it again) has a live chassis, with only one set of wheels having pickups. The decoder is in the tender, mounted on a bit of insulation, so there's no real chance of catastrophes.

 

 

Most DCC systems will tolerate a very brief short circuit and there may not be any detectable interruption in the running, beyond what would happen in DC anyway. Unless these short-circuits continue and the full current of the DCC system keeps pumping into the track (which won't happen if there's a circuit-breaker in the system) the decoder won't come to any immediate harm. The only foolproof way to blow a decoder for good is to have track voltage (what should go through the red and black wires) come into contact with the motor wires, the orange and grey ones. Provided the decoder is properly installed (always check on a programming track first, as that will identify a problem without imposing a damaging current/voltage on the decoder) and the motor contacts arranged so that they can't come into contact with the wheels, frames or pickups, all should be well. It is certainly sound advice to make the chassis electrically dead if you are starting the kit from scratch, but a locomotive with a live chassis doesn't have to be discounted for DCC conversion, provided care is taken with the installation.

 

I'm not a DCC zealot and enjoy building and operating locomotives to run on DC as well. In fact the final decision often doesn't come until the painting stage. What I tend to find is that if I've eliminated all obvious shorts in DC, there'll be no problems running in DCC. Obviously there may be the occasional, once-in-a-blue-moon situation where something touches something at the same time as something else, but those cases are just as likely to cause  sparks or twitches in DC.

 

Alastair

And, that 'King' ran beautifully around Little Bytham! 

[Focalplane]

All my kit built brass or nickel silver locos have live chassis and DCC sound. Once run in on DC, which I consider imperative, and checked on reverse curves, etc., I install the DCC chip and speaker. These days I always install the decoder using an 8 pin socket mounted on a small piece of printed circuit board fully insulated from the frames. This allows the decoder to be easily removed and still maintain its warranty. I no longer hard wire decoders as this can prove disastrous.

 

This way, using a blanking plug, the loco can be run on either DC or DCC sound. On my 4F i have the decoder and speaker mounted in the tender with two twin leads running from the pickups and motor. One lead has male/female from engine to tender, the other female/male from engine to tender. In this case DC running is possible simply by disconnecting the tender leads and connecting the two leads from the engine to each other, male to female.

[allan downes]

When I first encountered clockwork technology I thought noting could possibly improve on this where a busted spring was your only fear. Now, a lifetime later, and non the wiser, it seems that all it takes to immobilise anything is just a spark !

 

 

Just thought a little sophisticated in put wouldn't go amiss.....

 

Allan

Edited August 15, 2017 by allan downes

[jjb1970]

I think the problem with DCC and people using it who don’t know what they’re doing is that it was, and tends to still be, marketed as a simple solution for those who don’t want all the complications of wiring a layout. Just connect two wires and Robert is ones uncle and all that. Clearly that is at best a simplification, and some would argue it is outright misrepresentation.

[unclebobkt]

For HMS Hood fans I'd strongly recommend the below book for any who haven't already got it:

 

https://www.amazon.co.uk/Battlecruiser-HMS-Hood-Illustrated-Biography/dp/B00SLSPWQK/ref=tmm_hrd_swatch_0?_encoding=UTF8&qid=1502482184&sr=8-3

 

        Surely the main point to remember, which Beatty forgot at Jutland, is that the  so-called Battlecruisers were NOT Battleships and were not designed to enter the line of Battleships and to take-on enemy Battleships - they were highly specialised cruisers designed for scouting and for reporting back to the main battle-fleet the enemy's courses & speeds.

  True they had large calibre guns and high speeds,  but both were incorporated to get them OUT of trouble as fast as possible, should that be necessary.

 

        

[asmay2002]

        Surely the main point to remember, which Beatty forgot at Jutland, is that the  so-called Battlecruisers were NOT Battleships and were not designed to enter the line of Battleships and to take-on enemy Battleships - they were highly specialised cruisers designed for scouting and for reporting back to the main battle-fleet the enemy's courses & speeds.

  True they had large calibre guns and high speeds,  but both were incorporated to get them OUT of trouble as fast as possible, should that be necessary.

None of the British battlecruisers sunk at Jutland were sunk by Battleships.  They were all sunk by German Battlecruisers which survived numerous hits from duff RN shells.

[thegreenhowards]

Thanks Stewart,

 

When you say Hornby loco 4472, which one do you mean, please? The old(est) Tri-ang Hornby one, the tender drive one or the latest manifestation? If it's the last-mentioned, then that has a dead chassis (or at least pick-ups both sides). 

 

I don't think it's the the problem of a stray short on a live chassis that might affect DCC, but the chance of the chip touching the inside of an all-metal loco's boiler/tender/wherever it's installed. With a dead chassis, the loco's body is dead as well, though that won't stop two separate bits on a chip touching the inside at the same time. 

 

When I did a DVD on fitting decoders to (older) Hornby locos (with plastic bodies, but with live chassis), I acted as the 'dunce' - asking really daft questions. Actually, I didn't act at all - the questions just came naturally! It was impressed on me the need to 'sleeve' the chip in some non-conductive material. A DCC expert subsequently told me that that was poor advice, because the decoder might overheat.

 

As is well known, my experience in fitting/using DCC is very limited, though my disliking of it is vast. I have fitted decoders in metal kit-built locos with both live and dead chassis for customers I've built engines for (though I'm still puzzled why they couldn't do this for themselves - I could). Because I'd fried at least five chips by their touching the inside of the body, I adopted the following 'safety regime'. I subsequently made every chassis electrically-dead. Not only that, I made sure the area surrounding the chip was insulated as well, by either smearing a thin layer of Araldite inside the loco body or by using a strip of insulation tape - the former method is preferred because it never comes off.

 

A major difference between a kit-built loco and a (more modern) RTR loco is that the latter will have a socket ready-installed, either in the loco or the tender. This allows the simplicity of 'plug & play' to take place (but even some I know can't even do this!) and the chip is securely held in place at source. The kit-built loco (usually) has the decoder solder-fitted, and it tends (in my experience) to rather flop about inside the body - hence the need for internal insulation.

 

All this, of course, is not even academic to non-users of DCC. I just build a live chassis, install pick-ups on just one side, taking care that the 'insulated' motor brush is far away from the inside of the loco's body (either by having it at the bottom of the can, or, if it's at the top, by insulating the body around it if necessary - not at all in big-boilered locos). I just have one insulated wire from the pick-up to the motor and a live wire (a joggled piece of .45mm brass - the joggle allows the motor/gearbox to find their sweet spot) to the other brush - which also acts as a stay to the motor. I have no need for 'delay' facilities if a short is detected (though any chances of them are eradicated at source during the build), I save myself masses of dosh, if I want to run a loco I just set the road, flick a switch and turn a knob/slider and away it goes. Any spare space in an etched brass boiler can be packed with lead, and that's that. What's best is that I can do it all myself.

 

Despite what others might say, I believe you (the generic 'you') need a fair bit of know-how to install DCC at every stage (see the post above), or pay someone else to do it for you. Then, when it goes wrong, you're stuffed! But then, I'm a Luddite.

 

Tony et al,

 

I think there are two related DCC issues which we are dealing with here:

1. Reliable running; and

2. Frying chips.

 

I can honestly say that I've never fried a (DCC!) chip ( although you know about frying a chip-fitted Portescap which the chip survived after a reset!). As I understand it this does not happen through short circuits as the DCC protection will cut power pretty quickly. As you say it could happen by touching the chip on a metal body - live or neutral , but live might only take one terminal to touch.

 

The key issue for me is reliable running. On DC 'micro shorts' can go unnoticed and the loco will run with no obvious issue or maybe a minor stutter. On DCC a minor short will bring the whole shooting match to a stop, and is therefore a no-no. For a short on a neutral chassis loco you would need two opposite parts of the wheels to touch the body at the same time - pretty unlikely! Whereas on a live chassis, just one passing touch of say the neutral side bogie wheel on the cyclinder would cause a short and stop the system. Obviously this shouldn't happen, and can be eliminated by careful adjustment and judicial use of araldite, but the risk is greater.

 

For this reason, I would always prefer a dead chassis, and if I'm building from a kit will always go that way (the Wolf you helped me build performs faultlessly) but I don't regard it as an absolute. As you know I have a few live chassis kit built locos, some of which you sold me, and they all run fine now - but in every case they have taken some fettling. One thing I don't understand is why you think American pick ups are much worse than standard live chassis pickups. As far as I can see, both have the same problem of a live chassis, and the only additional issue with the American system is the loco touching the tender which should be easy enough to prevent.

 

I have to admit that, when I'm struggling with a short, I occasionally question my wisdom in going for DCC, but then I run round my sound fitted Deltic or A3 and I'm in no doubt! Not everyone's cup of tea, but I love it.

 

Regards

 

Andy

[grob1234]

OK, so I certainly agree on the dead chassis principle for DCC locomotives.

 

But, what about coaches? I'm thinking about kit built coaches, fitted with for example MJT brass bogies, in particular the compensated ones.

 

If you build them and they are not 100% tight against the axles, there is a chance the wheels can move within the frame from side to side and touch the brass frame, which would cause a short I believe. No issue on DC, just a couple of sparks, but what about DCC and kit built coaches? Any issues there?

 

I'm only asking because, A) I have not used DCC, but intend to in the future, and B) I am trying to DDC ready all my kit built stock to avoid a massive programme of DCC readying when I eventually build my layout.

Edited August 15, 2017 by grob1234

[unclebobkt]

       ... .  

  It is even said the torpedo planes which crippled her rudder escaped destruction because they were too slow for the AA fire-control systems to track them!

 

        That joke amongst the crews of the obsolescent Fairy Swordfish torpedo-bombers, which, fully laden could just about stagger along at 100kts. under ideal flying conditions,  was that to hit them the Boche had to aim astern!    Just how often were flying conditions ideal?.

  Torpedo-bombers were sitting ducks when it came time to launch their torpedoes, having to fly on a constant course, at a constant speed and at a constant height, (the anti aircraft 'Balance of time.'), to allow their torpedoes to be launched under their most favourable conditions to ensure that they stood a reasonable chance of hitting their targets.

 

  Read about the 'Channel dash.' and the pathetic effort made by Cdr. Esmonde RN. and his three Swordfish to sink either the KM. Gnaisenau or the Scharnhorst in Feb. '42..

  Alas a far cry from the Swordfish's success at Taranto in Nov. '40..

Edited August 15, 2017 by unclebobkt

[St Enodoc]

Much of my modelling work looks better in the dark...

A bit worrying to see that Mike and Rod "agree" with this. You can go off people you know...

[The Fatadder]

Thanks Stewart,

 

When you say Hornby loco 4472, which one do you mean, please? The old(est) Tri-ang Hornby one, the tender drive one or the latest manifestation? If it's the last-mentioned, then that has a dead chassis (or at least pick-ups both sides). 

 

I don't think it's the the problem of a stray short on a live chassis that might affect DCC, but the chance of the chip touching the inside of an all-metal loco's boiler/tender/wherever it's installed. With a dead chassis, the loco's body is dead as well, though that won't stop two separate bits on a chip touching the inside at the same time .

 

I think with the current version of the Hornby A3 there is a live chassis block which is connected to the pick up strips, in my mind the worse of all worlds having both the risk of a short circuit and the drag of an unnecessary set of pickups. This is certainly true of my one which I was rebuilding last night (which is now hard wired between both pickups and the motor). Of course more recent examples may well have had the wiring changed.

 

When I fit the decoder I am likely to hard wire it into the space containing the existing 8 pin socket (in order to try and fit in some extra weight to help it pull 8 brass sided pullmans). Your point re the decoder touching the live block certainly gives a further good reason to rewire the live side.

 

Now what exactly a 2005 condition 4472 is doing going through 1947 Brent I am slightly less sure, but it keeps my 3 year old happy. She has a lot to learn about the correct colour of green for a locomotive (and for that matter the correct number of wheels.)

[The Stationmaster]

A bit worrying to see that Mike and Rod "agree" with this. You can go off people you know...

 

Isn't the English language wonderful.  Actually my 'agree' was in respect of my modelling (some of it?) looking far better in the dark and if you were to see a picture of  Hornby Dublo 'Castle' I converted to 2-rail using Hamblings wheels (well they did look good before I started) you would no doubt also tick 'Agree'. 

[thegreenhowards]

OK, so I certainly agree on the dead chassis principle for DCC locomotives.

 

But, what about coaches? I'm thinking about kit built coaches, fitted with for example MJT brass bogies, in particular the compensated ones.

 

If you build them and they are not 100% tight against the axles, there is a chance the wheels can move within the frame from side to side and touch the brass frame, which would cause a short I believe. No issue on DC, just a couple of sparks, but what about DCC and kit built coaches? Any issues there?

 

I'm only asking because, A) I have not used DCC, but intend to in the future, and B) I am trying to DDC ready all my kit built stock to avoid a massive programme of DCC readying when I eventually build my layout.

Tom,

 

I was worried about that but so far I have had no problems using MJT fixed or compensated bogies.

 

Andy

[grob1234]

Tom,

 

I was worried about that but so far I have had no problems using MJT fixed or compensated bogies.

 

Andy

 

Andy that is great to hear, though I'm sure you have built yours better than mine. I have concerns that the axles in some bogies are too loose. Are all yours nice and snug?

[Barry O]

Tom

 

JW has had a short on one of his MJT bogies but he fixed it. In dc it can bring things to a dead stop if its really bad.

 

Baz