One other thing to consider is which combination of posts are protected by the circuit breaker and which ones are not -- assuming that the breaker in an old postwar transformer still works reliably. This issue varies from one model of transformer to another.
Those of you who can read circuit diagrams may be able to determine this from the Library at Olsen's toys and/or one of the Service Manuals, such as the ones published by K-Line or Greenberg.
My safety precaution is to install an inline, fast-acting fuse in every set of posts that I use. So far, no problems....
martinden wrote:This matter of the "U" post seems to cause endless confusion, though it's actually pretty clear-cut. Here is the rule -- applicable to all postwar transformers that have more than two posts, except the "R" (which doesn't have any "U" posts). On single-train transformers, "U" is the variable post (connected to the center rail), and "A" or "B" is the common or base post (to the outer rails). I'm not sure what the story is on modern-era power supplies, but for one-train postwar transformers, this rule always applies. This includes (in numbers-first, then letters, more-or-less chronological order) the 1037, 1041, 1042, 1032, 1033, 1034, 1044, 1144, MPC 4090, Q, A, S, RW, TW, and LW. On all of these, A-U is for track power; on most, B-U gives a lower voltage range. On two-train (multi-train) transformers, the "U" posts are common, or base, and "A" and "B" (sometimes "C" & "D") are the variable posts. These include the V, Z, VW, ZW, KW,and SW. (On the first four, of course, the "C" & "D" posts are also variable.) Just why Lionel chose to use the "U" post in two different (opposite) ways is completely unclear at this point, and we'll probably never know the answer. But once you grasp the idea, it's easy to keep the "U" and "U" business straight. Martin
And Lionel has continued this tradition on the CW-80. The A post (along with the other red post - "B") is common, the U outputs are the variables. As this is a 1 train transformer, this is likely the reasoning for this scheme. Lionel still messed up the functions/labeling of the whistle/bell buttons, they are reversed when using the commons as ground on a layout.
Rob
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