Ideas about an amplifier built around a 12V/300 VA transformer?

[juma]

Nothing tricky there. Nothing to open up.
You have four secondaries soldered together (all four beginnings of the windings are soldered together and all four ends are soldered together).
You just need to desolder them all and mark all the ends (E1, E2, E3 and E4) as well as all four beginnings (B1, B2, B3, B4). Use your DMM/Ohmmeter to identify four separate windings.
Then solder E1 to B2 and E3 to B4.
Then you'll have 24V AC between B1 and E2 and another 24V AC between B3 and E4. That's all - your new 2 x 24V AC transformer is ready.

 

[indaco]

Nothing tricky there. Nothing to open up.
You have four secondaries soldered together (all four beginnings of the windings are soldered together and all four ends are soldered together).
You just need to desolder them all and mark all the ends (E1, E2, E3 and E4) as well as all four beginnings (B1, B2, B3, B4). Use your DMM/Ohmmeter to identify four separate windings.
Then solder E1 to B2 and E3 to B4.
Then you'll have 24V AC between B1 and E2 and another 24V AC between B3 and E4. That's all - your new 2 x 24V AC transformer is ready.

Thanks for the suggestion, now it's very clear...the four wirings indeed come from four separate windings in the secondary, and how you said they are soldered each other at the end. After separated them I checked out and the output voltage with no load is 24.5 V for B1-E2 and B3-E4. So now I have about 6 A per wire, right?

 

[juma]

It is still 300VA

 

[JMFahey]

NOW you can build something interesting

 

[indaco]

NOW you can build something interesting

Of course, when I choose I'll let you know what is the project...

 

[AndrewT]

Your secondary will not be a single wire that big.
It will be bi-fillar, or tri-fillar, or maybe even quad-fillar.
You can open up the internal connections to end up with multiple 12Vac windings.

I understand the procedure, unfortunely each secondary has four stiff wires welded together. I must necessarely open up the transformer to see how they are linked and maybe separate them. It seems to me a little tricky

They look soldered. Separate them at both ends. Then check the 4 windings are isolated from each other.
You should then have a quad 12Vac transformer.
You can use it for 12-0-12 twice over, or for 24-0-24Vac by changing the interconnections.

 

[indaco]

They look soldered. Separate them at both ends. Then check the 4 windings are isolated from each other.
You should then have a quad 12Vac transformer.
You can use it for 12-0-12 twice over, or for 24-0-24Vac by changing the interconnections.

Yes, that's what I did following the instructions of Juma....all is fine now, thanks. Just another doubt anyway, can I replace the thermal cut-out with suitable fuse on the hot line or leave it alone?

 

[AndrewT]

Many thermal fuses are internal and when they open the transformer becomes dead.

If you are very lucky the thermal fuse may be outside the secondary winding and under the final insulation tape and can be replaced or removed.

Use a mains fuse and preferably a close rated mains fuse.