No keyboard and mouse

No keyboard and mouse
Need to distinguish communication standard keyboard and mouse are PS / 2 . There is a spare USB port or just until the port ps / 2 is omitted.
In this article I just mentioned the standard keyboard and mouse PS / 2 only.

Keyboard and mouse connectors are the same, all have 6-pin plug but only four spoke only to 2 other pin (NC2, NC6: evidence for beautiful).
Chart principles:

According to the chart above shows, if off the 5V fuse surely lose both mouse and keyboard will be paralyzed. If the line Data +, Data-which was "interrupted", the results were similar. If the circuit is 5V, the probe through the Data in the SIO chip is OK. If the circuit well, read the remaining error SIO chip.
Common errors:
- End fuse -> take the 5V supply for two PS / 2.
- The data lines are bi noise filter capacitor and the convergence of this noise will leak long