It's an ATX-style 525 W power supply used in Dell Precision T3500 workstations (and others).
Given that it is a proprietary design, finding a circuit diagram floating around is going to be difficult, but probably not impossible.
However, it isn't something that is really fair game for us to help with, given that it IS proprietary and protected by copyright.
Contact Dell or a Dell service dealer and see if they can point you in the right direction. I don't know about Dell specifically, but some manufacturers are tolerant of third-party sites providing technical documentation for some of their products for personal use, particularly those that are commonly repurposed (such as to make a hobbyist bench supply) and will even direct you to some of those sites.