Datasheet PDF for the 2SD1192 transistor, 133 KB, listed in the schematic section of the index. Its name gives nothing beyond the part number. Per the Japanese JIS convention, a 2SD type is an NPN bipolar transistor intended for low-frequency duty. A technician uses the sheet to identify collector, base and emitter and to read breakdown voltage and current limits. Those figures guide the choice of a substitute, which should equal or exceed the original ratings in a compatible package.
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.