Ipkbl-sr 35w Schematic -

A. Power Supply Section

B. Matrix Scanning (Key Switches)

C. Smartcard Reader Interface (The "SR" suffix) ipkbl-sr 35w schematic

D. USB Output

Since a factory schematic is unavailable, we infer the circuit using standard Flyback Converter design. Below is the logical block diagram and signal flow. Since a factory schematic is unavailable

This is the most challenging part. OEMs like Lenovo actively file DMCA takedowns against public schematic sharing. However, here is a tiered approach to finding the file (which is typically a PDF or .BRD file for BoardView software). D. USB Output