The 2SB1557 PNP transistor datasheet, a 184 KB PDF catalogued as a schematic. By JIS convention the 2SB prefix identifies PNP bipolar transistors for low-frequency use; maker, package and revision are not given. Open it with any PDF reader to check pin assignment for diode-mode testing, the absolute maximum ratings that indicate whether the part was overloaded, and gain groups for matching. Before substituting, confirm the marking on the original and choose a device with the same polarity, footprint and adequate ratings.
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.