Filed as a schematic, this 52.9 KB PDF is named after the 2SB1668, a PNP bipolar transistor according to Japanese JIS numbering; the contents should therefore be its datasheet. It likely belongs to the same document set as the nearby 2SB167x files of nearly identical size. Look here for the package drawing, terminal order, maximum ratings and gain data. Compare these with any proposed equivalent, and confirm the marking on the physical part, before relying on the sheet during a repair.
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.