Part number 2SC3449 names this 113 KB PDF, filed under the schematic type. In the Japanese semiconductor registry the 2SC prefix covers NPN bipolar transistors, so this is probably a datasheet rather than a board diagram. It lets a repairer verify pinout, compare ratings with a proposed substitute and understand the device's intended role. No package, maker or grade is given in the name, so inspect the printed code and case on the faulty part before trusting the match.
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.