Phasing Two Lionel 180w Bricks

What we in the O gauge community refer to as phase is also called polarity.  Reversed phase or 180 degrees out of phase is a polarity reversal.

Transformer polarity can be reversed in three ways:

1. The input to the transformer can be reversed, which is what is done with postwar type transformers to phase them.  The orientation of the wall plug is swapped or turned around in the outlet to change the polarity at the output so that two transformer's outputs can be in phase with each other.  On modern transformers with polarized wall plugs like the PH-180, swapping the plug orientation is neither practical, nor advised.
2. The direction the primary windings are wrapped around the transformer core compared to the secondary windings also matters.  If they are both wrapped in the same direction, the input and output polarities will be the same.  It the primary and secondary are wrapped in opposite directions, the polarity will be reversed from input to output.
3. If the transformer's output connections are reversed this will also reverse the polarity.

It has been documented here on the forum that some early Powerhouse 180 units have a polarity reversal.  In other words, Black should normally be Hot and White should be Common or Neutral. On some units this is not the way they were wired from the factory.

The solution is to test for phase in the usual way, but instead of swapping the orientation of the wall plug, instead swap the black and white on one of the transformer's outputs so that White is Hot and Black is Common.  When done correctly, with the White wire from an in phase PH-180 connected to the black wire from an out of phase PH-180 (which we'll now call Common), there should be very little voltage measured between the other two remaining white and black wires (one from each transformer).  Also the voltage between the corrected Common (from the previous sentence) to each of the other two unconnected white and black wires should be about 18 volts.

For further reading, please see this article:

https://electrical-engineering...-group-transformer-1

Here is a brief excerpt from that article:

Polarity

An AC voltage applied to a coil will induce a voltage in a second coil where the two are linked by a magnetic path.  The phase relationship of the two voltages depends upon which way round the coils are connected.  The voltages will either be in-phase or displaced by 180 deg.

The reason why we phase is simple.

The MAXIMUM voltage for many Lionel trains and equipment is 18V AC.

If you have multiple transformers connected, and somewhere, anywhere you have higher than 18V- you run the very severe risk of blowing something sky high. Again, simple concept, if as wired your meter reads higher than 18V between any 2 nodes, then there is a chance a train might cross somehow someway those same 2 points and see higher than the maximum rated 18V thus blowing it up instantly.

So you measured 37V- at that point, you are like (Edit) from cartoon "Archer" Call Kenny Loggins because you are in the "Danger Zone".

Again,  one phasing- the transformers ADD the rated voltage so 18+18= blow up your train or something else. The other way in phase, the 2 18V null out and you get near 0V.

It's really that simple. Out of phase or "polarity", they ADD, the other way, they cancel out. You want cancel out VS blow up my trains and other equipment.

Thanks guys. Yes, one of the bricks I have turned out to be one that came from the factory with the polarity reversed.

@NJCJOE,

Remember this adaptor?  It looks like you need just one, however they're apparently sold in pairs:

Mike

You can also just go to the hardware store, buy a 120Vac plug, lop off the existing plug, swap wires, and wire up the replacement. This will hurt the resale value of your PowerHouse though. I would make sure you do the lopping on the oddball one, buy verifying build date or SN or something. It is possible you have two early and one later unit.

Don't own any MTH transformers, but I thought they went to 20Vac, and I don't recall complaints. I do have an MTH vista dome car with the interior plastic seating insert melted from running off of a 180W Lionel PowerHouse. 37Vac, yeah, that will cause problems.

I had a couple of those a few years ago.  I solved the problem by opening them up and reversing the wires internally.  I felt this was a better choice than cobbling a fix, cutting cords, or filing the polarizing plug down.

I did what GRJ did. Simple fix. To open, take a flat blade screw driver and grind a small notch in the middle of the flat blade. This will allow the screw driver to engage the screw that has the small point sticking up.

FWIW...The latest PowerHouse variant, manufactured in 2021, is out-of-phase with the Z4000, but in phase with the Z1000 when all commons are connected together. Thus it is always important to do what Joe did; i.e. always measure the hot-to-hot voltage differential before using any transformer.   

I have made mistakes in the past always trusting that connecting black terminals on some transformers (Z4000, Z Controller, CW80) with the commons on other transformers (Z1000, Powerhouse) were going to produce all properly phased "hot" outputs.  I was wrong.

Ditto to what GRJ said. Fun fact if you use a 360W legacy PowerMaster it’s not very happy with out of phase power and the bricks start shorting but the breaker is too confused to trip.

@Bruce Brown posted:

FWIW...The latest PowerHouse variant, manufactured in 2021, is out-of-phase with the Z4000, but in phase with the Z1000 when all commons are connected together. Thus it is always important to do what Joe did; i.e. always measure the hot-to-hot voltage differential before using any transformer. 

That would seem to indicate that at least one of those MTH transformers is wired incorrectly.   I know some older Z1000 bricks were not phased correctly, don't know if the the Z4000 had that problem over it's production lifetime.

GRJ,

My Z1000 brick was purchased roughly in the same old era as the Z4000. I was really surprised that that the hots of the two were out-of-phase when I connected the outer ring of the Z1000's 5.5 X 2.1mm connector with the black connector on the Z4000.

After getting the Acela and determining that a ZW was not a good way to power it, I bought a PowerHouse that included a 2021 manual. For one main line, I built a switching box to select conventional (ZW) or Legacy (PowerHouse). Imagine my dismay when I discovered that the hots on the two other main lines, powered by a Z4000, had a 38 VAC differential to the main line when powered by the PowerHouse. Fortunately, I caught the phasing issue in time before a disaster occurred.

@gunrunnerjohn posted:

That would seem to indicate that at least one of those MTH transformers is wired incorrectly.   I know some older Z1000 bricks were not phased correctly, don't know if the the Z4000 had that problem over it's production lifetime.

I have a year old Z1000 that was out of phase with an MRC 1301 Throttlepack.  Tried to open the MRC brick to reverse the wires, but after removing the 4 screws on the bottom it wouldn't come apart and there was no obvious indentation under the label on top that would hide a screw.  I ended up cutting the AC cord and reversing the wires.

John