1033 transformer schematic

[Bob.M]

lionelsoni

......

  You must have a voltmeter with a high input impedance.  .....

 

10 Megohms. Sometimes using a "fancy" Digital Voltmeter on a 1950s electrical device is not only overkill, but can be misleading. Using an older VOM with 20,000 ohms per volt produces the more accurate results you describe. Looking at the schematic for the Xfmr, I can see why it goes from 11 vac down to zero.

[lionelsoni]

Maybe I can help with that mystery.  You get zero volts between U and C with the handle clockwise because C is just a tap at the clockwise end of the 11-volt winding; so, in that handle position, both U and C are connected together to the same point on the winding.

With the handle fully counter-clockwise, the U terminal isn't connected to anything; so I guess that what you're seeing is some stray voltage capacitively coupled to the wiper and the whistle components.   You must have a voltmeter with a high input impedance.  Try turning the handle just a little, so that the wiper moves onto the end of the 11-volt winding.  Then you should see a solid 11 volts.  As you turn the handle farther, the U terminal's connection to the winding will get closer to the C end and the voltage between those two terminals will decline to zero.

[Bob.M]

 Thanx, Rob. Maybe now I will understand it. I see that the "slider" goes from one end of the 11 volt winding to the other, and you can add in another 5 volts by using the "A" terminal as common. Later on in the day, when I am more awake, I will try to figure why I get ~6vac from terminals U to C with the handle full ccw, and it goes down to about zero at "full throttle".

[ADCX Rob]

Bob.M

 ... A schematic may help me to understand the oddities of this model. i.e. Using the "U" terminal for the center rail, etc.

 

Not an oddity, per se, just the norm.  Multi-train transformers used "U" as common, singles use "A"(or other optional commons).

Rob

[lionelsoni]

http://pictures.olsenstoy.com/searchcd31.htm?itm=640

N.b. that the rectifier diode symbol is reversed in the schematic diagram.  This is typical of Lionel postwar schematics.

[Bob.M]

 Does anyone have a working link to the Service Manual for this transformer? I don't currently have a problem with the transformer, but I have one sitting around not being used. A schematic may help me to understand the oddities of this model. i.e. Using the "U" terminal for the center rail, etc.