[ducretet]

Hello,
I have restored a JACKSON BELL 62.
But, the power transformer is burnt. I have some transformers, but without the intermediate taps. I do not find a transformer similar to the characteristics of the 62 model.
Do you know of any builder that has this type of transformer?
I'll give you the features:

PRIMARY

230 V o 125 V

SECONDARY

760 – 0 – 760  V    (HT)
1,25 – 0 – 1,25  V    1,7  A    (tube 45)
1,25 – 0 – 1,25  V    6    A    (4 tubes 24)
5  V  1,7  A    (tube 80)

I would appreciate your help.
Regards,
Ferran

[RodB]

With a B+ of 240 volts on the 80 filament you shouldn't need more than 220-0-220 for a HT secondary.

[ducretet]

Yes, you are absolutely right. I transcribed it wrong. 

I wanted to put 380 - 0 - 380

760 is between plates.

Thanks.

[ducretet]

SUMMARIZING:

380 – 0 – 380V (HT)

1.25 – 0 – 1.25V      1.7A (tube 45)

1.25 – 0 – 1.25V      6A (4 tubes 24)

5V 1.7A (tube 80)

[MrFixr55]

I know that this is an old thread but:
- The B+ values are common.
- You should be able to find a new transformer with at least one 2.5V winding in addition to the 5V and HV windings.
- For the 24A filaments, a center tap is not really needed. one leg of that winding can be grounded.
- If a transformer with a center tap for the 45 filament can't be found, an "artificial" tap can be made by putting 2 10 Ohm resistors in
series. The Junction is the center tap. Note that the current drawn by these 2 resistors (125mA) has to be accounted for when sizing
the resistors and the winding.
- In at least one radio I found (A Studebaker 31 TRF Radio (for 115V AC), all tubes are powered by the same winding. the winding is -
center tapped and the center tap is grounded through a 500Ohm resistor and 0.5uF capacitor to provide the bias necessary for the 47
tube.
- A power transformer from a Philco 70 would provide all windings and voltages needed.
- If really desperate and if only a non-tapped secondary for 2.5V tubes is available and you find the 22 10 Ohm resistors to not -
work, convert the 45 to a 2A5. It is not too hard. However, if this is the "Peter Pan" model, nothing other than the original
transformer will do, to protect the value of the radio.

[ducretet]

Hello,
First of all, thank you very much for your comments. But, in view of the existing problems in old radios, in the sense that there are many burnt power transformers, I decided to learn how to rewind power transformers. With this you avoid making new holes in the chassis, fully respecting the original components.
Is not difficult !!!. You have to learn the basic theory of transformers. And have a rewinder. In my case of the Jackson Bell I have rewound it. Before putting it on the radio, I checked the voltages. It was a success. I am preparing an article on the theory of power transformers. But I want a person who knows English to correct it. My English is terrible. Once grammatically corrected I will upload it in the forum.
Rewinding a transformer is easier than it seems. Of course, you have to have a minimally good rewinder.
Regards,
Ferran

[GarySP]

The expertise of the Phorum members never ceases to amaze me. I look forward to reading your article. Take care and BE HEALTHY! Gary

[Ron Ramirez]

Ferran,

Please feel free to send your article to me for grammar correction. I can look over it and also have Debbie (former library director) to look over it as well.

Send me a PM to obtain my email address.

[ducretet]

Thank you very much Ron,
These days I am involved with a personal issue. I can send it to you in a month.
Regards,
Ferran

[ducretet]

Hello,
I attach the article.
My thanks to Ron and his wife for the grammar check.
I hope it helps.
Regards,
Ferran