Schematic in a compact 464 KB PDF, named PA-1650-56LC, a code that appears to be a power adapter model number; the file name gives no brand or further details. Check the label on the adapter before using it for repair work. A charger diagram like this lets you follow the mains input, the rectifier and bulk capacitor, the PWM controller and switching transistor, the transformer, and the optocoupler feedback that sets the output voltage. Discharge the high-voltage capacitor before measuring anything on the primary side.
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 @BoardSchematic. 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.