Schematic in PDF form for the IBM ThinkPad R40 notebook, around 1.45 MB. No board number or revision is given in the name, so check the drawing's title block against the marking on your system board. Circuit diagrams like this let a technician trace power rails from the adapter input through the regulators, check enable and power-good logic, identify parts on a shorted net and locate useful measurement points. Any standard PDF viewer opens the file, and text search helps jump to specific nets or part references.
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 @alischematics. 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.