Part 2SC5048 is the only detail in the name of this 210 KB PDF, classed here as a schematic. In Japanese JIS designations a 2SC number is an NPN transistor, so the document should be a datasheet with electrical tables and a package drawing. Manufacturer and package are not stated. Technicians use it to identify pins, check that voltage and current ratings suit the circuit position and select an equivalent when the original is obsolete. Open with any PDF viewer.
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.