1. If it is plug and play, there is no problem. If there is a problem if your controller needs to install the driver, you should try to see if there is a conflict, and try one by one.
2. You can find another USB device to test and see if your computer can be used normally. Test to see if there is any problem with the computer port. If it is a computer problem. Is your computer damaged by a virus? The USB2.0 driver is installed well or the version is not compatible. Is there a software conflict (solve the software problem first) Generally, a prompt to install the driver will appear.
If it is a computer hardware problem. We first use a multimeter to measure the four USB lines (red +5V white DATA-data-green DATA-data-black ground wire). The red test lead of the multimeter is measured against the ground and the black test lead (white line and Lu line. The resistance value does not differ by 50 ohms, These two lines come from the South Bridge. If the resistance changes too much, it can be judged as the South Bridge problem. It means that the USB module inside the South Bridge is burned.
Many external USB devices now require drivers. Even if there is no driver, there will be no unrecognized situation. There are two kinds of unrecognized situations: the USB data line is blocked or the connection is poor. I usually touch that place for a long time because there may be rust and swelling inside, or something may be blocked inside.
3. The USB cable is blocked. If the red line is blocked, there will be no response, and the white line is blocked and cannot be recognized. If the green line is blocked, it cannot be recognized. The white wire and the green wire cannot be reversed. It is also unrecognizable. The black line is blocked and there is no response. This measurement method has been mentioned above.
Note: The low 5V voltage of the red wire can also cause unrecognition.
4. Internal problems of USB board
a. The crystal oscillator is not good and can't shake;
b. There are two bad crystal capacitors (20P);
c. The resistance of the reset capacitor is poor, and the reset voltage is too high;
d. The three-terminal IC is not good enough to provide the IC with insufficient voltage;
e. The main IC is bad.
