Need help identifying a transistor

[Wuerstchenhund]

Hi!

In the fight to fix my Artesyn XL130 power supply I need some help identifying some kind of transistor. It has the following writing:

A431
756-D
94321

I guess the last row is just a production date but so far I couldn't find much with the other numbers.

Does anyone know what type of transistor this is? And maybe some alternative part I which is easier to source and which I could use instead?

[fmaimon]

It's a TL431 or similar shunt voltage reference.

[mark-r]

Unlikely to be a 2SA431 I'd have thought. That's a germanium RF transistor unlikely to turn up in a power supply. It's also been obsolete since the 70s and was in a 4 lead TO72 metal case.

[bitwelder]

The logo on top of the A431 is that one from Astec. A quick search for Astec A431 brings e.g. to this datasheet:
http://images.ihscontent.net/vipimages/VipMasterIC/IC/ASTC/ASTCD005/ASTCD005-1.pdf
(three-terminal precision adjustable shunt reference)

[Wuerstchenhund]

TL431 looks good, and they are easy to get.

Many thanks for the help!