Component documentation for the 2SD2257 transistor, in PDF form at 180 KB. Although the index lists it as a schematic, the file name points to a single discrete part rather than a board. The 2SD designation in the Japanese JIS scheme means an NPN bipolar transistor for low-frequency circuits. A repairer would consult the voltage, current and dissipation limits, the hFE ranking and the lead order before soldering in a replacement, and should compare the case style with the original part.
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.