Hello,

I need help identifying this transformer from a LED driver.

45C389J41

P.S. Why can I almost never find anything online from the markings on these small yellow transformers.

 

Do you know the input and output voltages, probably the only way you will find a sub, that No. is most likely a Manuf. ref No.
What is wrong with the existing? Open circuit?

 

P.S. Why can I almost never find anything online from the markings on these small yellow transformers.

because transformers are so easy to custom wind for specific projects, most people who need them in large volume order custom units. Some companies making power supplies just order the bobbins and wind them on-site. I've heard that Foxxcon and Delta wind most of their own cores. Cores are made by US companies like Micrometals, Magnetics Inc., and Arnold Magnetics - bobbins made by Pacific in the US.

here's an example of a bobbin set...
https://www.amazon.com/uxcell-Sets-Transformer-Bobbin-Ferrite/dp/B07X75YBLY

I'm not saying you should start here but, just answering your secondary thought.

 

Thanks for the replies.

It turns out I need to learn more about transformers.

That they're not like other components where I can identify from the markings and substitute.