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I just unpacked a 6-30218, Polar Express, ready to run set. The power pack gives me 39 Volts on the Fastrack by attaching my Volt meter to the center and side rails. I tested the power pack directly by inserting the probe into the end and attaching ground to the outside edge of the plug and it give out 39 Volts. Do I just have a malfunctioning power pack or am I missing something? The engine and tender work great on my Legacy layout at 18 volts. power supply model # YF18020000K3-UL.

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Last edited by Quizshow904
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Confirm you're using the DC mode on your meter.   In the AC mode, some hobby-grade meters simply make a DC reading and double it assuming that that the voltage must be alternating + and - and hence be twice the size.  

If anyone is curious about their own meter, you can try this at home too!  Measure, say, a 9V battery in AC mode and DC mode.  Hopefully you'll measure +9V DC and -9V DC (if swapping leads).  Some meters will read 18V AC (or so) when measuring the battery in one polarity but 0V AC if you swap the leads.  Gold star if you can think through why this happens.

DC coupled half wave rectifier will give the performance you describe.

It is a shame that small moving-vane meters are so hard to find. Polarity insensitive, can be designed to accurately read AC, DC, AC + DC and true RMS all the while. Actually, there is a clamp-on ammeter intended for utility applications, the Columbia Tong Tester, that works like that. Purely magnetic, no coils or windings or transformers. They also work well in strong electric fields such as you would encounter when clamped around 4.16 kV or 13.8 kV power lines where most electronic and microprocessor designs struggle. Pity they don't make a small version for model train guys. Would remove all doubt...

Actually, I'm pretty sure Stan cracked the code, he's using the AC scale and he has a cheap meter.  I did the experiment, I finally found an old Harbor Freight meter that would demonstrate the indications he's getting.  The LC power supply is actually regulated, so you don't need a load to get an accurate reading.  When I measure one with a DC meter, I get 18.5, but when I measure with the cheap meter set on AC, I get 38.5 volts, swap the leads and I get nothing.

Quizshow904 posted:

Question,,,how would I know it is a DC output?? The label only says 18 V output 2000ma. 

That's a very good question to which I don't think there's a universal answer.

Here's a similar brick-shaped adapter.  It says "AC Adapter" but it has a DC output.  It says AC because it plugs into the AC wall outlet.  But I'd say half of the time you'll see this kind of adapter referred to as a "DC Adapter" because it puts out DC.

One clue is if it has the symbol on the right with the + and - symbol.  This shows the polarity (presumed DC output) of the plug.

I'd guess your brick might at least have the parallel / dashed-line symbol shown where it says OUTPUT:12V.  This symbol indicates DC though I can't think of where one learns this.  That's as opposed to the squiggly tilde ~ shown above after INPUT.  That symbol indicates AC.

This pack then explicitly states OUTPUT: DC at the bottom which yours apparently does not.

IMG_0370

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gsvoboda posted:

How?  VA 31.5 equals 31.5 watts.

Reread my response again.  Do you know what the Power Factor is?  The Power Factor of an AC electrical power system is defined as the ratio of the real power flowing to the load to the apparent power in the circuit.  As I said, only with a perfectly resistive load is the power factor 1.0, with any inductive or capacitive element, the power factor will be less than 1.0, and the VA and watts will not be equal.

Last edited by gunrunnerjohn
gsvoboda posted:

Ok, so the suggestions of putting load on the tracks works, but does not explain 38 volts to the meter. 

 It's due to the fact that you are using a cheap meter and you're using it on AC instead of DC.  The method of measuring AC with inexpensive meters results in doubling the indicated voltage if you're reading DC on the AC scale.

Stan explained this quite well some time back in this thread.

It's a Federal requirement that is supposed to more accurately assist the end user in determining the maximum load on a device for safety purposes.

DC voltamps does equal the watts. But, calculate the formula for AC-not always the same.

The end user doesn't know from anything. They just plug in whatever, wherever and complain if it doesn't work.

In another thread I did the homework on this one, and the basic information I found was that in DC watts=VA.  In AC, however VA is the maximum watts theoretically possible.  This has to do with the way watts are measured in AC devices.   for practical terms, the VA rating is typically the output side rating; How much power can the device supply.  Where as in the world of our train transformers, devices rates in Watts are giving you the maximum Input side power load.  

For those 2 stars, Watts when used as a proper term, is only useful as a precise, real time measurement of power consumed, and really only important in the grand scheme of things in billing you for electricity.  Volt-Amps, on the other hand if of greater use, as it denotes what the maximum power provided is on the output side, and is useful in determining what size wire you need, and what sort of protection circuitry is needed.  VA as a proper term is a more useful figure almost all of the time.

That said, if you are looking at the same, input or output, side of a device, a maximum rating in VA or watts is interchangeable.  VA has just become industry standard because it is a better system that watts to measure output side power availability, and is easier to understand.   

JGL

Last edited by JohnGaltLine
illinoiscentral posted:

Don't put 39V to your track.

It's already been pretty well established that the 39V was a measurement error, not the actual powerpack output, there's no issue with his power.

ADCX Rob posted:

I say plug it in and let it RIP!

Everyone else who got a LionChief set for Christmas and didn't check it, improperly, with a cheap $4 meter, is out there running their train.

 

Right on, let's see the smoke!

Power supply LIonel ChiefHere is a picture of the power supply...Lionel Chief Polar Express. Sorry it isn't clearer but it says...output 18v  2000ma    .85amp.  Don't worry the train is already running on the Legacy layout, I am not sure I can hook it up to run on Fastrack using this power supply. The other type of power hookup with Fastrack that just has 2 wires hooks up to my transformer and gets 15 volts just fine on the Fastrack loop.

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