Generic file named index2, a very small 20.9 KB PDF catalogued as a schematic. The name reveals nothing about the device, brand or board, so open it and identify the content before use. A document this size is likely a single page, perhaps an index or one diagram sheet. If it turns out to be a schematic, match any model or board number shown on it to the equipment on the bench, and only then use it to trace supply rails or locate components.
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 @pdf_servicemanual. 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.
Any PDF readerSumatraPDFFirefox / ChromeFlexBV (links PDF to boardview)