Datasheet-type document in PDF for the 2SA1687, a Japanese JIS-registered transistor, listed under schematics at 143 KB. Parts coded 2SA are PNP transistors intended for high-frequency use. The file name gives no version or manufacturer. Open it in a PDF reader to review terminal layout, hFE ranking, maximum ratings and the mechanical drawing, then compare against the suspect component when testing junctions with a multimeter or choosing a modern equivalent for replacement.
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.