Catalogued as a schematic, this 87.6 KB PDF is named only with the part number 2SC3808, which follows the Japanese JIS scheme where 2SC marks an NPN bipolar transistor, so it is most likely a component datasheet rather than a board drawing. The name gives no maker, package or ratings. Technicians use such a sheet to confirm pinout, voltage and current limits and to choose a substitute when the original is burnt or unobtainable. Check the marking on the actual part before relying on it.
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.