PDF schematic for a PA-1650-56LC adapter, a model code in the style of LiteOn's PA-1650 series, generally 65 W class laptop chargers. The name gives no brand of the laptop it shipped with. Technicians use such a diagram to locate the fuse, bridge, start-up circuit, PWM IC, switching transistor and output diodes, and to check the TL431 and optocoupler feedback when output is unstable. Compare the board revision and component markings to the drawing, because units within the same series vary. Always discharge the bulk capacitor before measuring.
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 @schematicslaptop. 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.