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Discussion Starter · #1 ·
I have a large loft layout which I am converting to dcc, my problem is that I can run one loco but when I try to run two locos there does not seem to be enough power to drive the two, ( almost as though the track is dirty and the locos are sticking.
I am gradually adding drop down wires from the track but at the moment the average is about one every six feet, and I can run one loco fine on the feeds I have installed,
The system I have I regard as a starter system and is the basic Hornby dcc with a 4 amp transformer.
Can anyone offer me any tips on what to look for?
 

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Hi Dennis

I don't do DCC myself but I have gleaned some information in the past so here goes!

Your problem may be in the length and distance of your dropper wires! I think you need them about every 3 feet or so. You also need to make sure you have a good ampage carrying main wire under the layout.

I hope this helps and if I am wrong I am sure someone will let you know. I do know there is one such expert (in my opinion anyway) on this forum as he helped me with my wiring on my DC layout.

Kind regards

Paul
 

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I don't think that it is the distance between the dropper wires. I've got mine that far apart but connected to really thick bus wires and my system works well. Mine is the basic Bachmann EZ and I can run three trains with no problem. It really looks as though there is a fault with your system.

Hope you get it sorted out quickly as, now that I've tried DCC, I will never use anything else. Cheers, Robert.
 

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In theory yes I would drop a pair of feeders for every yard of track. Are you trying to run the locos as separate locos or consisted together? How large is your layout? and how clean is the track. Dirty track is the bane of every DCC user and while track that operates okay on DC may not work well on DCC. How far have you progressed with your DCC conversion ie: have you completed the layout or just part of it. Is part of your layout still running under DC. Remember not to mix the two systems or strange things will result usually culminating in the factory smoke escaping. A basic Hornby system would be the "Select"? and at 4 amps you should have sufficient power to run more than two locos. I'm not familiar with the system but I know I would avoid it like the plague. Other things to check are points to ensure you don't have a short that's not tripping the system, and that the decoders to ensure that the DC bit is turned off in CV29.

Charles Emerson
Queensland
Australia

QUOTE (dennis1 @ 27 Mar 2009, 20:59) <{POST_SNAPBACK}>I have a large loft layout which I am converting to dcc, my problem is that I can run one loco but when I try to run two locos there does not seem to be enough power to drive the two, ( almost as though the track is dirty and the locos are sticking.
I am gradually adding drop down wires from the track but at the moment the average is about one every six feet, and I can run one loco fine on the feeds I have installed,
The system I have I regard as a starter system and is the basic Hornby dcc with a 4 amp transformer.
Can anyone offer me any tips on what to look for?
 

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Discussion Starter · #5 ·
in reply to ozzie21 the layout is quite large covering an area about 10 metres by 4 metres with 4 main lines and sidings, the track was very dirty through a long lay-off and I am constantly cleaning track, no part is operating on dc and only part has so far been wired for dcc. The 4 amp transformer should operate several locos. Thanks for the comments received so far, Dennis
 

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Hi
First off you don't get 4.0 Amps to the track with the Hornby DCC system. 1.0 Amp is reserved for non DCC use via 15volt dc output accessory outlet.
So, 3.0Amps is available to the track, which for most small to medium sized layout will be fine.
If more power is later needed then sectionalise the layout by fitting Insulated rail joiners to all tracks after a chosen place and then wire a Power Boaster to the new section(s) of track. Note the boosters tracks are not connected electrically to the consoles fed tracks.

Next, assuming all your rail tops and loco wheels are clean, and your system is working correctly (Try it on a yard length of track with two locos etc) your power loss may be due to poor metal rail joiners causing high resistance (HR) connections rail to rail, assuming you're relying on those for transfer of power, pending installing a full DCC bus and dropper wires.
Try gently squeezing up the bottom sides of all the metal joiners on both end of the abutting rails they make connection to. Use a pair of pliers to squeeze the ends of the joiners.
 

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Forgot to mention in my earlier post that there is one fool-proof way to check whether it is the control system at fault.
Try both locos on the same section of track (having thoroughly cleaned it first) that has a direct electrical feed - if they behave in the same way then it has got to be a system fault.
 

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Hi Dennis
I have a similar size layout with a 4 Amp Power unit and it can handle up to 6 trains at once easily so you definitely seem to have an issue. I used a copper strip which I was concerned would not be adequate but I have soldered the rails to it approx every metre with no problems . I had the misfortune to have to drill through the copper ( to carry out repairs underneth) and it had no adverse effect.

It really sounds like

1. A bad connection or
2. A faulty output from the controller.

Do you have anyone you could swap controllers with to see if that cures it as it sounds like a trial and error scenario to try and locate something which is obviously a fault in delivering the power to the locos.

Another check could be CV 5 is it set as high as possible (255) as possibly this could be an issue,
best of luck with this, its a sod when you struggle and its most probably something very simple when you finally crack it.
 

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Probably worth checking each section of track by putting a short circuit on the rails - a coin is the usual method. If the command station doesn't cut out then there is too much resistance in the feeds for whatever reason. If so you layout could potentially overheat if a short circuit does happen, so it's worth finding and sorting the problem! If you repeat this on nearby sections you may be able to pin down the problem a bit, though if the same thing happens across the layout then it could be near the command station.

What size wire are you using for your main bus, and how big is the layout?
 

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***If the effect is that the loco's are slowing then it most definately sounds like a voltage drop problem. If they are running erratically then it could be that you have other wiring issues you will have to sort out.

Techincally its easy to change DC to DCC but if initial wiring was light weight then power transmission problems will be an issue.

for example:
twin light gauge wire used as a bus or two separate wires that are too close together causing a problem with the waveform. Bus wire should be heavy and if separated wires, run about 100mm apart/ twin should be twisted about 4 turns per foot for a large layout

lots of intermittent shorts via insulfrog points - this will cause all loco's to twitch a bit if it doesn't shut the system down.

inadequate power feeds causing voltage drop

pickups/wheels/track needing cleaning

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Wire for the power bus should be reasonably substantial (32/.2 or larger), and finer wire droppers should be short - say 300mm.

an easy test of your wiring:

WHile a meter will not read accurately under DCC conditions, take all loco's off and read the voltage at the controller output.

attach a load (a 100 ohm resistor would be good) or a car tail-light bulb (any low voltage bulb 10~20 watts) or similar across the rails at the point furthest from the controller and then re-read it with the meter.

I am guessing that the voltage will be lower. The answer is heavier wire and more droppers.

another easy test. Take all loco's off. Put the controller where you can see its short circuit indicator.

short the track briefly every meter and look at the controller as you do it - if the system shuts down immediately power is probably OK, if not, then wiring needs boosting at that point.

Neither of the above two tests are foolproof but are good indicators that may help diagnosis.

-----------------------------------------------------------------------------

Worth adding and very low cost:

get a couple of 150 ohm 1 watt resistors and 0.1microfarad ceramic or monolithic capacitors and wire one of each in series with each other. Then wire the two unused leads (one on the capacitor, one on the resistor) to the power bus. This will suppress/filter some of the problems related to voltage issues created by momentary shorts and also keep the DCC waveform in better shape.

regards

Richard
 

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QUOTE (Richard Johnson @ 28 Mar 2009, 03:34) <{POST_SNAPBACK}>WHile a meter will not read accurately under DCC conditions, take all loco's off and read the voltage at the controller output.

attach a load (a 100 ohm resistor would be good) or a car tail-light bulb (any low voltage bulb 10~20 watts) or similar across the rails at the point furthest from the controller and then re-read it with the meter.

Good advice here from Richard. Just to be clear on the one above, I think he intends that the re-reading should be across the rails at the point furthest from the controller, not back at the controller output. Voltage won't change much at the controller output unless there is a problem with the controller itself. Also the 100 ohm resistor should be a high wattage type (at least 3 watts) otherwise it will get very hot and probably burn out.
 

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hey folks ...

the tracks are finally laid after 4 days of working away at it on the 1st level of my german winter setting layout!. its been hard going with lots of measuring and cutting and sore fingers from fishpplate fitting!.

last night i wired up just a fleischmann profi boss with a start set transformer (with the thinnest wires iv ever seen come out a controller!) to the rails for a test run. using a trix e-lok it ran flawlessly around all the track with no derailments except in reverse, the end passneger carriage jumped of the rails at one curved point where the rail joiner looks to be a little out.

theres approximately 50 metres of track there. only 2 tiny wires from the controller to the rails in 1 corner. no feeders/droppers etc etc... ull laff at this, but the inner circuit of track (about 20 meters of track) gets its power thru the curved electro frog points at either end of the layout from the outer circuit.

so how come it runs so well with no loss of speed/power to anywhere on the layout? ok, so im only running 1 loco + 4 passenger carriages, hardly a 16 car ice 1/2 set, tonight, ill try 2 locos (about max the start set power pack will handle) and see how it runs.

my question is this :- isnt there a degree of over - engineering going on with some folks set-ups? are all those extra feeders and droppers really necessary or do some folks just like having lots of wires?

my next step is to start construction of the 2 level of my layout, with a thru mainline station. the 2nd level is planned to be a separate power district with the fleischmann booster ready to go in. but if it all works with just a single track feed, why put in any extra ones?

if running were troublesome then sure i wud, but if it runs fine as is, then why go to all the bother? (im not a wire counter lol - if u know wot i mean! .. not trying to replicate deutsche bahn's wiring system too!)
 

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QUOTE (db ice 3 @ 28 Mar 2009, 12:15) <{POST_SNAPBACK}>my question is this :- isnt there a degree of over - engineering going on with some folks set-ups? are all those extra feeders and droppers really necessary or do some folks just like having lots of wires?

Possibly so, but it's not too difficult to do things properly from the start and could be very difficult to improve them later if they turn out not to be good enough. It's not always easy to tell how good is good enough for a particular layout setup, as it depends on all sorts of factors.

In your case you have a short feed through thin wires and then the rails act as the feed to the rest of the layout. So there shouldn't be a problem with voltage drop as the rails are quite thick. However you are relying on rail joiners to conduct the current - this may work now with new track but will it work when the track has been down for a while and got a bit tarnished, perhaps soaked with glue during ballasting?

There can also be situations where everything seems to work but there is enough resistance in the system for the short circuit protection no longer to be effective (the short circuit current may be just less than the trip value). Then if you have a short circuit there will be maybe as much heat as a 60 watt light bulb being generated in a small part of your layout - not surprisingly things can then start melting pretty quickly.
 

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An older part of my layout which does not have droppers has a dodgy fishplate connection which resists all my attempts to tighten it up. Locos regularly slide to a halt in this area which becomes rather tiresome. The section will be replaced one day but it's the reason why I use droppers on each separate section of rail and don't rely on fishplates.

David
 

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Discussion Starter · #15 ·
I think I finally found the cause of my problem. I found a point , one blade of which was loose , removing this point and replacing seems to done the trick and I can now run three locos at the same time (possibly more) My grandson could hear a faint humming sound coming from the location of this point although it never shorted out..Thank you all for your suggestions., Dennis
 

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I still smell a rat here. If the locos plus faulty point are drawing too much current the command station should cut out. I suggest you short out the track with a coin in the area where the point used to be, and check that the command station cuts out straight away. If it doesn't then the reason is probably too much resistance in the feed to that part of the layout, and you may be at risk of a short circuit in this part of the layout causing serious damage!
 

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*** Good advice - I agree

Richard

QUOTE (Edwin @ 10 Apr 2009, 05:49) <{POST_SNAPBACK}>I still smell a rat here. If the locos plus faulty point are drawing too much current the command station should cut out. I suggest you short out the track with a coin in the area where the point used to be, and check that the command station cuts out straight away. If it doesn't then the reason is probably too much resistance in the feed to that part of the layout, and you may be at risk of a short circuit in this part of the layout causing serious damage!
 
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