Possible Schottky?

Several manufacturers (Vishay for instance) use codes like U3J and S3J, for ultrafast and standard rectifiers respectively [package marking same as part code]. The 3 is 3A and the J indicates 600V. It's possible you might find a manufacturer that uses 3J for the standard part without a prefix, but I think they would be physically bigger than the part you show.

What leads you to think it's a Schottky? Have you measured the forward voltage?

To help narrow your search down a bit, you could measure the package and work out what it is.

Other than that it's difficult to help. With everyone making up their own codes and not even publishing sensible lists of what they are it's painful trying to identify parts.

Several manufacturers (Vishay for instance) use codes like U3J and S3J, for ultrafast and standard rectifiers respectively [package marking same as part code]. The 3 is 3A and the J indicates 600V. It's possible you might find a manufacturer that uses 3J for the standard part without a prefix, but I think they would be physically bigger than the part you show.

What leads you to think it's a Schottky? Have you measured the forward voltage?

To help narrow your search down a bit, you could measure the package and work out what it is.

Other than that it's difficult to help. With everyone making up their own codes and not even publishing sensible lists of what they are it's painful trying to identify parts.

It measures as a DO-214AB package, the circuit is with a LM2596 and all the other components match the Adjustable output series Buck regulator.  That circuit from TI indicated that it is a 1N5825 but because of the marking I want to make sure that is what I have.