USB does not recognize dongle

USB does not recognize dongle

My company's computers are domain, can only use the dongle, can't use other U disk, but recently some of the dongle can't recognize, what's the problem, uninstall and reload USB, shut down and restart and can't recognize

From my maintenance experience, I can't identify. First, the computer can't identify the USB device.

Second, USB devices cannot be recognized by computers. We have to judge whether it is the computer or the USB device. We can use other USB devices to test whether the computer has any problems.

If it's a computer problem. Is your computer damaged by virus. Is the driver of USB2.0 well installed or incompatible. There is no software conflict (first solve the software problem) general situation out of a driver installation tips.

If it's a computer hardware problem. First, we use the multimeter to measure the four USB wires (red + 5V white data data green data black ground wire) and the red lead of the multimeter to the ground and the black lead (white line and other lines). If the resistance value changes too much, it can be judged that it is the South Bridge problem. It shows that the USB module inside Nanqiao is burnt out.

Let's take a look at the USB devices outside. Now many of them need drivers. Even if there is no driver, there will be no unrecognized situation. There are several situations that cannot be identified. A USB data line or poor contact, generally contact that place, because the time is long, there may be rust inside, there may be bulging things, there may be something blocked inside. Second, the USB line is blocked. If the red line is blocked, there will be no response. If the white line is blocked, it cannot be recognized. It's impossible to recognize the green line. The white line and the green line can't be reversed. It's also not recognizable. There is no response even if the black line is blocked. This measurement method has been mentioned above.

Attention. Low 5V red line voltage can also lead to unrecognizable

3. Internal problems of USB board. 1. The crystal oscillator is poor and does not vibrate. 2 crystal oscillator capacitance bad (20p) has two

3. Poor reset capacitor resistance. The reset voltage is too low and high. 4. The three terminal IC is not good enough to supply voltage to the IC. 5

Bad master IC

Good luck!