[SOLVED] SMPS flyback transformer question

[kkeeley]

Hi,

I have been working on re-producing an exisiting 350W ATX SMPS from a pc. The power supply was in good working condition at the time. I have removed the transformers so that I can re-use them as I felt this would save me time and money by not having to wind my own. Un-fortunatly I have damaged one of the small transformer used by the flyback standby component of the power supply. It was an EE-19C, I burnt out the primary winding during testing my re-produced circuit.

I have found other power supplies that also have a EE-19 transformer used as a flyback in the standby circuit, can I use them? From what I have found so far most of the ATX SMPS use a flyback transformer to produce the +5V standby power, along with a 12-20V circuit to power the main PWM circuit. There is also a bias winding for the regulation of the +5V standby circuit and it appears to be this bias voltage that can be different between power supplies. What effect will this have on my exisiting circuit? My current circuit use two BJT transistors to drive the flyback transformer, some of the other power supplies I have found that also contain a EE19 transformer use FET's instead. Will this make a big difference?

Would I just be better off rewinding the orignal transformer? I have managed to disassemble the damaged transformer and in the process I counted the number of turns for each layer and the gauge of the wire used. I recorded which pins where used for each winding, both start, end and middle where used. I also counted the number of layers of tape between each winding. I also measured the spacers used on the outer legs to produce the center air gap. Will this be enough information to rewind the transformer? What information have I not gathered about the transformer before I can rewind it?

Thanks
Kenneth

 

[exnol]

You can use same transformer from a similar circuit. Just make sure both the circuits are similar. Here is a link to common SMPS schematics : **broken link removed**

 

[kkeeley]

Thanks for the reply exnol,

You can use same transformer from a similar circuit. Just make sure both the circuits are similar.

Ok, I'll only use the transformers from SMPS that use the TL494 circuit design, as that is what the original circuit I'm using contains.

Here is a link to common SMPS schematics : **broken link removed**

Thank you for the link, I had already managed to find the circuits shown by my own searching, but at least it shows I'm going in the right direction.

Thanks again,
Kenneth