Are power transformers polalized? does it matter if the leads are reversed, does it affect rhe circut?

Hi

No power transformers are AC so windings don't have a polarity. In a circuit it doesn't matter if leads are reversed.

Phasing is important if two windings are in series or parallel.

Norm

:Are power transformers polalized? does it matter if the leads are reversed, does it affect rhe circut?

my radio has 3 heater windings, a 5 volt, and two 2.5 volt center tapped windings(one for 5 tubes and one for 2 tubes and the dial light). the transformer is completly fried , the radio is 100 watts so .8 amps , it blows 2.5 amp fuses. my new replacement has the same 5 volt, primary, and one 2.5 volt center tap, and one 2.5 volt non center tap. does the center tap do anything important in the heater circut?

Ian

Need to check how the center tap was used? It may be grounded?

You need a center tapped winding for 45 or similar filament type tubes. Heater type tubes can operate without a center tapped winding. If the center tap was originally grounded, one of the 2.5 volt leads should now be grounded.

If there is a question list the radio model. Your replacement transformer will work as long as it can supply enough current.

Norm

:my radio has 3 heater windings, a 5 volt, and two 2.5 volt center tapped windings(one for 5 tubes and one for 2 tubes and the dial light). the transformer is completly fried , the radio is 100 watts so .8 amps , it blows 2.5 amp fuses. my new replacement has the same 5 volt, primary, and one 2.5 volt center tap, and one 2.5 volt non center tap. does the center tap do anything important in the heater circut?

one center tap gose to ground , the other goes to a resistor which is tapped and one side goes to ground, The good thing about theese two radios(r-72 and r-73) is that there is a wireing diagram in the schematic

one center tap gose to ground , the other goes to a resistor which is tapped and one side goes to ground, The good thing about theese two radios(r-72 and r-73) is that there is a wireing diagram in the schematic

Hi Ian

The one where center tap goes to ground can be without a center tap. Here is a way to make your own center tap. Connect a 10 ohm resistor from each filament lead to ground. Now you have a center tapped 2.5 volt winding. Ground will be 1.25 volts from each filament lead. This keeps your circuit close to original.

Norm

:one center tap gose to ground , the other goes to a resistor which is tapped and one side goes to ground, The good thing about theese two radios(r-72 and r-73) is that there is a wireing diagram in the schematic

I installed the new transformer yesterday , and I will be plugging it in today and I’ll tell you how it goes.

When I first got it I thought it would be a quick fix, only 8 or 9 caps, everything else still there. When installing the caps, the schematic didn’t have polarity so I used the one capacitor that went to ground to determine polarity, oops. One capacitor went from negative to negative so the polarity was all wrong. But before I determined that I thought the problem might be a resistor , some of the resistors were out of tolerance by 300%. Than after all of the problems were fixed, I plugged it in again. All the tubes heated , the rectifier didn’t flash, and all of the tubes were getting the right heater voltage, then the power transformer started to pop , smoke, and smell. When I got the new transformer (no problems) I made sure the plate voltage was the same, when I tried to check the voltage on the original transformer , the piece of junk volt meter caught on fire! There’s the problem. I acquired this radio in February and thought I could get It working within the week , it’s the end of may now and it still doesn’t work.

I don't know what radio model you're working on - but only electrolytic caps are polarized. Typically, there will only be about two or three e-caps. By inspecting the schematic, you can tell which lead will be at a higher voltage than the other (whether or not the polarity is shown).

None of the other caps are polarized.

:
:When I first got it I thought it would be a quick fix, only 8 or 9 caps, everything else still there. When installing the caps, the schematic didn’t have polarity so I used the one capacitor that went to ground to determine polarity, oops.
:

the radio is from 1933 so every thing is packed in tar in a can. there are only 3 electrolitic caps but they are wired to some of the same places and other caps, therefore I had to unsolder all of them to fix the 3.

i finally plugged it in and it made horrible noises. I had fogotten abouit rhe flouresent light above my bench.then most hum went away, i can recive wjr really good, no hum or static. when i started tuneing higher there was more static and no reception. i added a large filter and recived stations.I have a small am transmitter that i sometimes put music though to my radios with, and it also helps with tuneing. i was broadcasting a song and the songs drums and instruments could be heard, but when there was singing scratching noises came out instead. the tone control will cut out all sound ,f too high or low, and the volume control also has some affect on the tone(which makes it hard to tune). do any of you know what the problem is?or how to fix it? sorry for takeing so long to reply.