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Hello fellow RRers,

When phasing two Lionel ZW transformers, is it sufficient to run one wire from one common post to the common post on the second transformer or do I also need to run wires between each power post a, b, c, d on the second transformer? Thanks for the feedback.


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After connecting commons connect a long wire to one A post, set both A handles at same voltage. follow directions below for "spark" test used only for postwar transformers.

For extensive phasing information see my website, Phasing Transformers

Phasing Postwar Transformers Only

If you are phasing only postwar transformers (those without electronics such as a postwar ZW) you can do so with the spark test as follows:

  • Set up transformers as described above.
  • Connect a long wire (if needed) to the variable voltage post you will use for comparison to the Master transformer.
  • Touch the long wire from Master transformer to the variable voltage post on the second transformer. There should be no sparks. If you get sparks, turn the power plug over in the power socket and check again.

1) Run a heavy wire from a 'U' terminal from to the first transformer to a 'U' terminal of the second. Do not connect any other terminals together.

2) Plug both transformers into a power strip and turn on. Just because they're on the same strip, DOESN'T GUARANTEE they're in phase. Proceed to step 3 regardless.

3) Turn voltage up on both transformers to about the same voltage. Doesn't really matter WHAT voltage, just so they're the SAME voltage. Use the AC setting on a voltmeter to measure, even an elcheapo digital voltmeter will do. No spark testing!. I usually go around 12VAC each.

4) Measure between the two outputs. If the outputs are near or at ZERO then PHASED. If Outputs are near double the setting in (step 3) then OUT OF PHASE.

5) If out of phase, reverse the plug to the power strip of ONE transformer, then measure again. Put a small mark on the plug of both transformers to remember how they plug in.

@Lyle S posted:

Well I have a couple of freaky ZW's then. Because no matter what way I turn the plugs in my power strip they stay phased.

i vote with mellow mike but this is worth exploring how this happens.

Do these transformers have polarized plugs? My guess is no since you can turn them. Do you change both at the same time? Try changing only one, you should get sparks.

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