Troubleshoot USB keyboard and mouse failures

"Unrecognized USB device", you've probably all met. There is such a situation of the system's USB device: USB mouse, USB keyboard can not be used. Still cannot be resolved after reboot. Such failures are usually affected by the following three factors:

A. BIOS setup issues

The default "USB Keyboardsupport" entry for the earlier part of the motherboard is "Disable". At this time can borrow other people's (PS/2) keyboard into the BIOS to modify the parameter to "Enable", or the use of the manufacturer to provide USBPS/2 interface access to the PS/2 port installation system can be. And the new motherboard generally will this default to open, of course, can only be inserted in the motherboard from the USB port, can not be inserted in the expansion of the pciusb mouth, or the same may occur unrecognized situation.

Two. Software issues

Check if the computer is damaged by the virus. USB2.0 driver is not well installed or version incompatible. There is no software conflict (solve the software problem first) general situation out a driver installation prompts.

Three. Motherboard issues

We first use a multimeter to measure the USB four lines (red +5v white data-data-green data-data-lacquer line) multimeter Red table pen to the ground black pen measurement (white line and Lu Liling line. The resistance of 50 euro, the two lines are from the South bridge out, if the resistance changes too large can be judged is the South bridge problem. Description USB module burned inside the South bridge.

Look outside the USB device now a lot of the driver. Even if there is no driver, it will not come out unrecognized. There are several cases where there is no recognition.

1.USB data line or bad contact generally contact the place because of the long time may rust there is swelling things may also have something in the inside blocked.

2.USB line is not up. The red line does not have any reaction also will not have, the white wire is unable to recognize. The Green Line is not recognizable. The white line and the Green Line cannot be reversed. is not recognizable. The black line and no response, this method of measurement has been mentioned.

3.USB board internal problems, usually the following several effects: 1 crystal oscillator is bad, do not start vibration. 2 The crystal oscillator capacitance is bad (20P) has two 3) the reduction capacitor resistor is bad, the reset voltage is on the high side. 4 The three-terminal IC is not enough for IC supply voltage. 5 main IC bad.

USB keyboard and mouse can not identify the fault, according to the above method can be completely solved, but this failure or the first from the software to find out why. After all, the probability of bad hardware is also relatively small.