Datasheet for the 2SB1658, filed in the index as a schematic but in practice a component data document in PDF form, 48 KB. Under the Japanese JIS naming system the 2SB prefix marks a PNP bipolar transistor intended for low-frequency work. The name gives no maker, package or revision. Technicians open a sheet like this to confirm pinout, maximum collector current and voltage, gain range and package marking before fitting a substitute on a power or switching stage. Check that the SMD code on the board matches.
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.