At 469 KB, this PDF carries just the transistor designation 2SC4844 and is filed in the schematic category. Under JIS naming, 2SC marks an NPN bipolar device, so the file is most likely its datasheet, with the maker and package unstated in the name. Use it to read lead assignment and absolute maximum ratings, which you need for diode-mode testing and for selecting a replacement. Neighbouring numbers in the same series may look similar, so compare the exact code printed on the component.
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.