K72JK mainboard schematic in PDF, 2.02 MB, for the laptop model of that name; no revision or board number is included in the name. Use it to work through a no-power or no-boot fault: follow the adapter input, charger IC, standby rails and main converters, then check enable and power-good signals. It also shows connector pinouts and where discrete graphics, memory and I/O circuits sit. Make sure the board revision marked on the PCB corresponds to the one printed in the schematic title block before relying on component values.
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.