Datasheet in PDF format for the 2SB1641, around 183 KB. By JIS convention the 2SB prefix identifies a PNP bipolar transistor aimed at low-frequency circuits such as drivers and power switching. The name carries no further detail on vendor or revision. For bench work the useful parts are the absolute maximum ratings, characteristic curves, hFE ranking and the mechanical outline with lead assignment. Confirm the marking on the suspect component matches this type before ordering a part or swapping in an equivalent device.
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.
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The standard format for schematics, block diagrams, power-sequence charts and service manuals.