16cyq045c is the only identifier on this 51.2 KB PDF, which the index labels a schematic. The code matches the pattern of International Rectifier and Vishay Schottky rectifier part numbers, so the file is most likely a component datasheet rather than a circuit diagram. Expect pin configuration, reverse voltage and forward current ratings, and package drawings. That data helps when testing a shorted output diode or choosing an equivalent. Check the marking on the part itself before ordering a replacement.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @cyberlanelectonik. Enginerys does not host this file.
How to open a .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.