The name 1n6766 identifies a JEDEC-registered semiconductor, and this 17.1 KB PDF is likely its short datasheet, even though the catalogue lists it under schematics. Beyond the part number the filename says nothing, so consult the pages for device type, limits and package. During repair such a reference confirms what a marked part should measure, how it is oriented and what can replace it. Open it in a PDF reader and compare ratings and outline with the original component on the PCB before substituting.
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.