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Originally Posted by grayga
Would someone please explain to this newbie how/why that tube (5U4G?) is mounted ON the power transformer? Is this common?
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It cuts down on the necessary "real estate" needed on the rest of the chassis. Area the tube would otherwise occupy. Also gets the heat the 5U4 generates up and away from other circuits. Also the transformer manufacturer sells it as a unit piece, and it's a few less things the TV manufacturer has to assemble.
How the internal hookup is done: The high voltage secondary is center-tapped, and that tap goes to ground, under the chassis. The other two ends of that secondary connect to the tube plates. Both sections of the secondary are (some large integer number) and a half turns around the transformer core. And there's a 5V secondary to run the 5U4 filament, which is also centertapped. Have the filament secondary ends connect to the 5U4 filament, and have the filament secondary center-tap come out the bottom of the transformer. The center tap is (some small integer number of turns) and a half turn away from either end of the tube filament. Then that feeds the filter caps. Phase it right and the filament winding adds a few more volts to the high voltage secondary to produce B+.