[Greg Elmassian]

Very possible you have voltage drop issues on the layout, and you can have a short and still have voltage elsewhere, in fact that reinforces the theory that you have voltage drop (conductivity) issues.

The way I track these down is put a big load on the rails (I have a box that clips to the rails and draws 8 amps) and measure the voltage drop right there.

You can use thicker wire right after coming out of the dcc booster, remember the resistance (loss) from wire is a function of the wire diameter AND the length... so short sections of 14-16 gauge won't hurt.

Greg

 

[Greg Elmassian]

When you put additional motors in a loco, it does not draw much more than one single motor under load. The same goes for multiple locos. There is of course some loss of extra lights and frictional losses, but basically if you need 3 amps to pull a train with one SD45, then two SD45's pulling the same train will be about 3 amps too.

The NCE system itself (remember it does not ship with a power supply), given enough power, can put out 20 amps for brief periods.

This is not about the NCE output, it's basically on or off... It's most likely power loss somewhere, or a defective power supply (which I doubt).

Trains running well does not mean you don't have issues... double the load will show up problems you did not realize you have.

I think we've given a number of suggestions, let's hear the results of testing.

The first should be current and volts at the output of the power supply (where it is going into the NCE booster)...

Next I would suggest my load test at the far end (electrically) of the layout. If you can deliver your full 10 amps out there, that's half the battle.

Greg

 

[Greg Elmassian]

Be sure the DCC track power is OFF if you try using an ohmmeter!

Greg

 

[Greg Elmassian]

I know there are leakage issues when the rails are wet AND it's not perfectly pure water, but I have run in the rain and with completely wet rails and never had a problem, there was plenty of voltage to go around.

When I ballast / surface (prototype talk for re-leveling) track, I often do it with a train circulating (so I can see the improvement) and will hose the track down after dumping the ballast to wash the dust from the rails... never a problem...

Greg

 

[Greg Elmassian]

No, it's possible, but not a certainty.

Just stating my experience, and I did qualify it.

Greg

 

[Greg Elmassian]

While we wait on Pete's results, I'd say that you might want to check some other stuff in your S4, did you remove/disconnect the other electronics that were in there, like the voltage regulators.

I've seen decoders (Tsunami) that will shut down on "over voltage", but nothing that does what you say... it's like a short over a certain track voltage...

Greg

 

[Greg Elmassian]

Yep, sounds reasonable. My rails sit in ballast. Not sure of Pete's situation. Did not say your theory is wrong, just said it's not the only possible explanation.

I know you like the look, but probably not the best for running, since you state you have the most problems where the track is basically immersed in non-ballast.

Anyway, on layouts with ballast and drainage, I have found that while there is some resistance added between the rails when wet, it would not explain the trains slowing down.

On your layout, it probably could, depending on the conductivity of the soil, length of exposed track, etc.

Pete did not state the condition of the ballast/other material around his track as I remember...

Sorry to have upset you.

Greg

 

[Greg Elmassian]

While your voltmeter probably does not read accurately, since it needs to be a true RMS AC meter, it is sufficient to measure at the booster output and then at various places along the layout under load. Remember that reading the voltage not under load tells you basically nothing.

Anyway, take it easy, get through your personal stuff, and let us know how it progresses once you are back up to snuff.

Regards, Greg

 

[Greg Elmassian]

Sure, send it to me.. very interesting.. trying to think what the problem could be, maybe a short in an output transistor that puts a huge load on the power?

(but isn't it under warranty? I'd first see if NCE will fix for free, and if they are interested to investigate... this will probably require a call to Larry at NCE)

I've run 408's in a lot of locos with nary a problem, and conversely, I have melted a D808 down to silicon slag once... but ALL things are possible.

Regards, Greg

 

[Greg Elmassian]

Dan, when I re-read Pete's first post, the first train has a lighted caboose and 2 logos, and indeed, the second train was 4 locos with an unspecified consist.

BUT re-read the part where one train stops and shorts out, and has a burnt smell.

I believe the key here is the other train kept running. I think that's a big clue to not supplying enough current, since it would seem very likely a second train PLUS a short (enough to start burning something) should have tripped a breaker.

Combine that with the other parts of the story of trains slowing strangely and it really sounds like a power delivery problem.

Regards, Greg

 

[Greg Elmassian]

I own the same system Dan. I and many others know how an NCE system works. We know what happens when you pull max current.

He's not pulling 10 amps if there are no defects with the locos. I've run more locos with more load on an NCE system, and I'm sure his grades don't exceed my 60' of 3.5% grade. I know what locos take full slip, believe me.

FYI, the NCE works just like the zimo, and everyone else's, they run to max rated wattage/current and then shut off at overcurrent... there is no tapering off of the boosters if the power supply is a regulated supply and can put out 10 amps minimum. (By the way, if you give it enough current, the NCE will actually supply up to 20 amps for a short time, but it cannot continuously dissipate that much heat)

You do say it must be a power loss, but maybe not in the wiring. I'm confused by what you are saying? Other than the booster, the wiring and the rails, there is nothing else.

I think I've been espousing that you look for power drop at the rails under load, and trace back, and it's either bad rail connectors, or insufficient wire gauge in the feeders. (or both of course)

Anyway, a simple application of a voltmeter to the booster output and then at points further away, under load, will identify the problem very quickly.

Measuring the amps alone really will tell you nothing unless you are actually out of current. I can tell you that is not so (out of current), since even with a short on one consist, there was power to allow the other consist to operate. (the Zimo also cannot put out as much current as the NCE so if you were already out of current with a 10 amp NCE, you would absolutely be overcurrent with an 8 amp Zimo).

Here's the crux, If you were out of current already, then added a short (as indicated) , there would be nothing "left" to run a train on. But he indicated the other train kept running.

That piece of information alone makes it pretty sure it is a power delivery problem between the booster and the loco. The resistance in the system was enough that the short did not take "all" the current in the system. Surely the short circuit drew MORE current than when both consists were moving.

Thus I cannot see how the system is out of current (from the booster), so I cannot see why measuring the current tells you anything really important as compared to the voltage drop, which MUST be occurring.


Let me know if there's a flaw in the logic here, but the pieces of information provided tell you a lot actually.

(This is actually fun, so we can see what was the real problem later... seeing how to fit the data to the "theory") I could be dead wrong....


Regards, Greg

 

[Greg Elmassian]

Even an ordinary AC voltmeter can be used, just for relative measurements, you use whatever reading you get right at the booster, and then see how much it drops (under load) at the "trouble spots"... so if you see 3 or 4 volts drop, even though it's not a DCC rms meter, you know where the problem is.

And the diode bridge makes it exact, since DCC is a square wave.

Sorry Knut, we'll agree to disagree some other time hahahahaha!

Just trying to help poor Pete, he has enough on his mind, so trying not to argue with Dan, but to give Pete the most straightforward, quickest and easiest way to debug the problem. I've seen people go around and around in circles measuring stuff that really does not lead to the root problem, but just to more confusion. There's no reason to connect a completely different DCC system just to measure current, my opinion.

Regards, Greg

 

[Greg Elmassian]

I know you are not arguing... this is interesting stuff to talk about, and it's really probably the only place on the web these discussions take place where many people can read and participate.

Yeah, forgot that many AC scales are WAY high..

Most cheap meters do fine on DCC on the AC scale, in terms of relative measurements.

This is more fun than talking about the weather, and more stimulating!

Greg

 

[Greg Elmassian]

Peter, you only need 3 volts more input than the output you get... any more differential will be expended in heat, and can eventually limit your output.

For 10 amps, your power delivery system is a bit light, you need independent runs from the booster to the track, not a big loop...

For reference, I run up to 10 amps AND I use 10 gauge wire feeders, each direct from the track to the booster.

By the way, after all the effort please get a RampMeter to measure volts and amps.

Greg

 

[Greg Elmassian]

EXACTLY what Knut said... ditto ditto ditto...

Your wire is not heavy enough, and your topology (wiring scheme) for delivering 10 amps to a train. His point about the voltage drop is very important, those amp ratings you are quoting are for 110v ac supply, not 20v ac.... too much voltage drop.

If it was me, I'd upgrade the wiring. You could also buy a second booster and second power supply and split the layout into 2 power districts, that's actually an inexpensive alternative. I thing the second booster is like $150 and the meanwell can be had for $70-80.

In my case, even with 10 gauge wire right up to the rail clamp, and direct individual runs from each feed point to the booster, I am setting up for THREE boosters, 1 for each main line and 1 for the switchyard.

Greg

 

[Greg Elmassian]

Thanks for the information Peter, sounds like you are clearing out the issues.

Yes, measuring the voltage inside the booster will give you a good estimate of the DCC voltage to the rails, although this is the first time I have heard that the rails are a volt less. Larry is the guy, though, so what he says is normally 100% right.

I completely concur with your higher voltage, as you probably know from my web site, I had to determine the 3 volt drop from DC input to DCC output, and also how to get my unit modified to go over 20.1 volts output. I can get pretty close to 24 volts to the rails.

But if your system is not modified, you will most likely only get 20 to 21 volts to the rails, and with a regulated power supply, only need 24 volts input. My point is that anything over 24 volts input will be wasted, and converted to heat.

Since you are running the unit close to it's maximum (and I mean it's maximum output to not overheat) then it's not wise to run more voltage. I've considered putting some heat sinks on the back of the case... the only cooling the booster gets is radiation from the case, there are NO heat sinks on the unit...

Yep, you need that RampMeter, and connect it to your booster output, you can see how many amps you are drawing. My locos on heavy grades and heavily loaded can pull 2.7 amps each. That is really close to wheel slip and 50 cars on a 3.4% grade.

The NCE system is (unlike other systems) conservatively rated, and, kept cool, will put out 10 amps all day without complaint, and as you have found, over that...

Regards, Greg

 

[Greg Elmassian]

On the previous boosters, 27 volts was the maximum... I've had a number of friends contact NCE about getting their systems modified to output 24 volts (requiring at least 27 volts in), so maybe they changed the design a bit... will have to call Larry. That 27 volts is specified somewhere in the manual, but it was hard to find as I remember.

Peter, you can get bigger boosters, but when you start putting over 10 amps on the rails (no matter what control system) a short circuit can really melt stuff down. At that point, I think it's wiser (again no matter what control system) to break it down to separate 10 amp power districts.

If you have ever seen what 10 amps can do to a loco that has derailed, you should try 20-25!

At some point it just makes sense to go no higher... Just like your house, mostly 15 and 20 amp circuits, not a 100 amp circuit to run all the rooms... there wisdom there...

Regards, Greg