Compact 125 KB PDF for the 2SC5091FT, an NPN bipolar transistor numbered under the Japanese 2SC scheme, with the FT suffix as part of the name; its exact meaning is not stated, though suffixes like this usually indicate a package or variant. Indexed as a schematic, it is most likely a short datasheet. Use a PDF viewer to read the pin assignment, ratings and outline drawing. Before swapping parts, make sure the suffix and marking on the removed device match, because packages can differ between versions.
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.