I need to replace the power transformer in a Crosley model 25 floor console radio.
I need someone to tell me the part number of the origional transformer.
The old one is completely charred and I can't tell much from it.
I have a small copy of the rider's schematic which tells me it should have 630 vac across the diodes of the 5y3. I think I am comfortable with the filaments and filters. It uses the speaker field as a choke.
I am going to have to find a replacement in the junk box or get savvy enough to select one from a catalog.
I just need some reassurance.
This radio belongs to a friend and I am nervous I might create a time bomb.
Any help will be greatly appreciated.
Ivan Copas. Amatuer engineer.KB8RSJ
ww7120@dragonbbs.com

Ivan, you'll need a xfmr with 3 secondary windings: 630V CT, 5V, and 6.3V, right? Here's the schematic: http://www.nostalgiaair.org/PagesByModel/321/M0003321.pdf

It appears that this is a horizontally mounted xfmr (with the xfmr sort of laying on it's side and the wires coming out the bottom.

Here's, at first glance, a possible replacement: RadioDaze Cat. HX273AZ. You'd have to check the dimensions to see if it will physically fit. The high voltage winding is 650V CT, which should be OK. However, this xfmr is rated at only 35VA, and I note that your set is rated at 65W (which includes the record player?) Well maybe this xfmr is too scrawney, so look at other options on the RadioDaze catalog/website. You have more options if you can make a vertical mount xfmr fit, physically.

What you need to address is why the original xfmr blew up in the first place. There might be a short somewhere - they seldom burn up on their own accord. Of course, you should replace the filter caps before energizing a replacement xfmr and add a fuse to the primary. And then bring it up slowly and carefully on a variac or with a dim-bulb tester.

:Ivan, you'll need a xfmr with 3 secondary windings: 630V CT, 5V, and 6.3V, right? Here's the schematic: http://www.nostalgiaair.org/PagesByModel/321/M0003321.pdf
:
:It appears that this is a horizontally mounted xfmr (with the xfmr sort of laying on it's side and the wires coming out the bottom.
:
:Here's, at first glance, a possible replacement: RadioDaze Cat. HX273AZ. You'd have to check the dimensions to see if it will physically fit. The high voltage winding is 650V CT, which should be OK. However, this xfmr is rated at only 35VA, and I note that your set is rated at 65W (which includes the record player?) Well maybe this xfmr is too scrawney, so look at other options on the RadioDaze catalog/website. You have more options if you can make a vertical mount xfmr fit, physically.
:
:What you need to address is why the original xfmr blew up in the first place. There might be a short somewhere - they seldom burn up on their own accord. Of course, you should replace the filter caps before energizing a replacement xfmr and add a fuse to the primary. And then bring it up slowly and carefully on a variac or with a dim-bulb tester.

::Ivan, you'll need a xfmr with 3 secondary windings: 630V CT, 5V, and 6.3V, right? Here's the schematic: http://www.nostalgiaair.org/PagesByModel/321/M0003321.pdf
::
::It appears that this is a horizontally mounted xfmr (with the xfmr sort of laying on it's side and the wires coming out the bottom.
::
::Here's, at first glance, a possible replacement: RadioDaze Cat. HX273AZ. You'd have to check the dimensions to see if it will physically fit. The high voltage winding is 650V CT, which should be OK. However, this xfmr is rated at only 35VA, and I note that your set is rated at 65W (which includes the record player?) Well maybe this xfmr is too scrawney, so look at other options on the RadioDaze catalog/website. You have more options if you can make a vertical mount xfmr fit, physically.
::
::What you need to address is why the original xfmr blew up in the first place. There might be a short somewhere - they seldom burn up on their own accord. Of course, you should replace the filter caps before energizing a replacement xfmr and add a fuse to the primary. And then bring it up slowly and carefully on a variac or with a dim-bulb tester.

:::Ivan, you'll need a xfmr with 3 secondary windings: 630V CT, 5V, and 6.3V, right? Here's the schematic: http://www.nostalgiaair.org/PagesByModel/321/M0003321.pdf
:::
:::It appears that this is a horizontally mounted xfmr (with the xfmr sort of laying on it's side and the wires coming out the bottom.
:::
:::Here's, at first glance, a possible replacement: RadioDaze Cat. HX273AZ. You'd have to check the dimensions to see if it will physically fit. The high voltage winding is 650V CT, which should be OK. However, this xfmr is rated at only 35VA, and I note that your set is rated at 65W (which includes the record player?) Well maybe this xfmr is too scrawney, so look at other options on the RadioDaze catalog/website. You have more options if you can make a vertical mount xfmr fit, physically.
:::
:::What you need to address is why the original xfmr blew up in the first place. There might be a short somewhere - they seldom burn up on their own accord. Of course, you should replace the filter caps before energizing a replacement xfmr and add a fuse to the primary. And then bring it up slowly and carefully on a variac or with a dim-bulb tester.

Doug Criner. Hi, I appreciate your response very much. As you may have noticed it took me some time to get this response to work. That darn software.
I think I am beginning to understand a little bit how this tube; rectifier filter set up works. Pity that poor radio. I have found a number of transformers that almost fill the bill. Both in catalogs and various junk boxes. I am not comfortable with my power calculations as yet. It seems one may fne tune the DC output by adjusting the filter value. I don't know just how much leeway there is. As you may have noticed I am suffering anslysis paralysis.
Thanks again for your reply.
Ivan Copas