Since a transformer does not create power, the power output from the secondary of an ideal transformer can only equal (and in a real transformer only be less than) the power input to the primary. Black was the primary connection, red secondary for the B+ (plate voltage), red with a yellow tracer was the center tap for the B+ full-wave rectfier winding, green or brown was the heater voltage for all tubes, yellow was the filament voltage for the. Conversely, a transformer with a turns ratio of 1:2 would be called a step- up transformer since its secondary voltage would be twice that of the primary. Not all transformer makers use these color codes, but it is good guidance if you have no clue about the transformer. Power transformers used in North American vacuum-tube equipment often were color-coded to identify the leads. As for replacements pretty much any push pull output transformer should work, except if it's for 41/6K6 tubes, the primary impedances are pretty close between 45s, 47s, 42s/6F6s, 6V6s, 6L6s, and 6BQ5s, it isn't that critical.The typical wiring found on a lot of power and audio output transformers. The existing transformer could also be miswired, the B+ should always go to the center tap of the primary, so it's worth disconnecting and rechecking.
Other threads lead me to believe it will work in this context.
I'm looking at the Hammond 125C as a replacement for this transformer.
Does anyone have any info on which is primary/secondary and start/finish/center tap? One side has a black center wire, the other is red (or orange?). There are 2 end connection lugs on each side with center wires also on each side. Checking continuity between leads shows pretty much everything open. The transformer is a Jefferson Electric 2766J but I have no info on its wiring layout. I'm convinced that the wiring is not correct and also that the output transformer is bad. Lack of plate voltage to the first 45 (the second 45 is getting 243V at the plate) led me to look at the speaker output transformer wiring. I was not impressed with the quality of the previous work. It was recapped but not working when I received it. (03-02-2016, 02:52 AM)rrova Wrote: I'm working on restoring a Philco Model 90 (2 45's for output, Min-max switch, March 1931).
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