Apple iPhone 4S schematic in PDF format, 1.34 MB in size. The name states only the phone model, without a board number or revision. Technicians rely on such diagrams to trace power rails from the PMU, follow backlight, charging and audio circuits, and find which capacitors or filters belong to a rail when a short is present. It opens in any PDF viewer. Because iPhone logic boards vary between carrier and regional versions, compare the markings on the board before depending on component positions.
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 @Schematics_Mobile. 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.