Schematic for a Lenovo E390 laptop in PDF format, 1.49 MB. The file name gives only the model, with no board maker, board number or revision, so you need to confirm against the documents' title blocks and the markings on the motherboard itself. Lenovo used the E390 name in more than one product line, which makes that check especially important. Once matched, the pages serve to trace power and signal nets, find the components behind a dead or shorted rail and look up part values when repairing damaged areas.
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 @smschematics. 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.