In a box of "junk" I picked up at a recent train show, I found two Lionel DC transformers from the 1980's: #4065 and #4550. In both cases the constant AC output (for accessories) is 19 volts, as it should be. But also in both cases, when the speed control for the DC output is turned up, it goes immediately from 0 to 18 volts instead of slowly moving toward its maximum output. I was hoping to use the units for low voltage DC output for accessories on my 027 layout. Can they be fixed, or are these pieces truly "junk"?
John Gottcent
If you have a lighted accessory or train, hook the transformer up to them and try it. If the lights go to full brightness immediately, the DC control (potentiometer? not sure of the design on these) may be bad, or need a squirt of tuner cleaner IF these units can be opened.
Larry
That behavior suggests it's a transformer feeding a bridge rectifier, and then a rheostat. If that's the case, the voltage you would see is 18 volts minus an amount that is the product of the current drawn and the rheostat resistance. If you're looking at the voltage with a meter, there's virtually no current being drawn; so you would see the full 18 volts as soon as the wiper touches the end of the rheostat. Try loading it with some lamps and see whether you can vary the voltage.
Actually, if you use one of them to power more than one accessory and that accessory's current varies as it operates, the voltage will also vary, which could be a problem. Steadily burning lamps may be the only practical load.
Bob Nelson
Thanks, guys. I was basing my observations on a voltmeter. I'll try your suggestions and see what happens.
John
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