Part reference 2SJ508 is all the name provides for this 136 KB PDF, categorised as a schematic. JIS numbering assigns 2SJ to P-channel field-effect transistors, so treat the document as a component datasheet. It is handy for identifying gate, drain and source pins, checking voltage and current limits, and reading switching data before replacing a damaged device in a power path. Open it with any PDF reader, and check the package outline against the part on the board, since suffixes can change case or ratings.
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.