Family datasheet for the 1N5817, 1N5818 and 1N5819 Schottky rectifiers, 1 A devices rated 20, 30 and 40 V. The Phi tag in the name probably points to a Philips edition, but treat that as likely rather than certain. The 70.1 KB PDF sits in the schematic category and contains ratings, curves and package drawings. Technicians use it to choose a voltage grade when a Schottky in a low-voltage supply has failed. Pick a grade no lower than the original and confirm cathode orientation.
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.