LCD circuit page from the Samsung SM-A20S schematic, provided as a 4.63 MB PDF. It documents the display connector pinout, the display data interface lines and the supply rails feeding the panel. A technician relies on it when the phone works but shows no image, when lines on the connector need checking for shorts, or when a torn connector must be rebuilt. Open it in any PDF reader, measure voltages at the connector with a known-good panel, and confirm the model matches the SM-A20S before working.
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 @phoneSchematics. 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.