1. The front USB cable is connected incorrectly. This kind of fault will happen when the USB cable on the motherboard is connected to the front USB interface on the chassis, which is also very dangerous, because the positive and negative connection is likely to burn out the USB device. So try to use the USB interface on the back of the chassis and use less extension cables. There may be something wrong with the fracture. Look at the other USB port.
2.USB interface voltage is insufficient. When the mobile hard disk is connected to the front USB port, the system may not recognize the device. The reason is that the power of the mobile hard disk is relatively large and the required voltage is relatively strict, and the front-end interface may not provide enough voltage. Of course, inferior power supply may also cause this problem. The solution is not to connect the mobile hard disk to the front USB interface, replace the inferior low-power power supply or try to use the hard disk box with external power supply, if possible.
3. Compatibility between motherboard and system. Hehe, the most famous fault is the compatibility between NF2 motherboard and USB. If you encounter this problem on the motherboard of NF2, you can first install the latest USB2.0 driver and patch of nForce2, the latest motherboard patch and operating system patch, or try to refresh the BIOS of the motherboard, which can generally be solved.
4. System or BIOS problems. When you disable USB in BIOS or operating system, the system will not recognize the USB device. The solution is to turn on the options related to USB devices. That is, press F2 or DEL to boot, enter BIOS, and select Enable usb device.
5. Be careful when plugging and unplugging. Never unplug it when reading or writing, or it may burn the chip. There are more USB device icons in the taskbar of XP. When you open this icon, USB devices will be displayed in the list. Choose to disable this device, and then you can unplug it, which will be safer.
In fact, judging software and hardware problems is very simple. Just try it on another machine or another system. Some minor problems may be formatted with special software first. And remind everyone to choose FAT instead of FAT32 when formatting under WINDOWS.
Prompt unidentified USB device maintenance
The fault prompt is as follows:
Unrecognized USB device: unknown USB device. Many people have encountered a problem. For the operating system, the so-called "unrecognizable" is either a problem with the degree of driving, a problem with the USB device, or a failure in the connection between the computer and the USB device. The solution to the problem also starts from these points.
Different devices will have different treatment methods. It is helpful to know the conditions required for the normal operation of USB devices and some factors that may affect the normal operation of USB devices.
The following are some conditions to ensure that the USB device can work normally: (1) There is nothing wrong with the USB device itself-it can work normally when tested on other computers; (2) There is nothing wrong with the USB interface-you can test it on this interface by connecting other USB devices; (The driver of USB device has been installed correctly. If there is a detailed USB device, be sure to carefully check the corresponding documents and install the corresponding driver according to the instructions; Operating systems after Windows 2000 can recognize most USB devices, and operating systems before Windows 98 can install USB device drivers or universal USB device drivers.
The following are some situations that may affect the normal work of USB devices: (1) The USB device is out of order (the same situation was used normally before, but now there is a problem); (2) There is something wrong with the USB interface. For example, a. The polarity of the USB front interface is reversed, which may cause the USB device to burn. Be sure to read the motherboard manual carefully to prevent the wrong connection; B. insufficient interface voltage. This problem often occurs on some mobile hard disks. The USB interface behind the host is often more reliable than the USB interface in front. C. there is a problem with the compatibility between the motherboard and the operating system. Installing the latest motherboard driver can avoid such problems to the greatest extent; D. USB devices are prohibited in BIOS, which may be solved by changing the corresponding settings in BIOS; E. operating system problems can be solved by reinstalling the operating system; (3) There is something wrong with the USB driver: If there is something wrong with the driver, you should make sure that the latest driver of the corresponding model of the device is installed or make sure that the operating system does not need to install a special driver. The latest drivers can be found on the home page of online equipment manufacturers.
When there is a problem with the USB device, we should not only find a solution according to the actual error information, but also carefully check the specific brand, model and manufacturer of the USB device, and incorporate this information into the search results, so that it is easier to find the corresponding solution. For example, when some frequently connected USB devices are difficult to plug in and out, and the operating system keeps displaying annoying prompts such as "Unrecognized USB devices", you can temporarily close the corresponding USB ports in the universal serial bus controller or disable the corresponding USB devices in the device manager.
About unrecognized usb devices
Computer settings
After insertion, some information that the computer is trying to connect to this USB device will pop up in the lower right corner, and sometimes a dialog box will pop up for the user to choose. Some users clicked No without seeing it clearly, or some functions of USB were banned because of some initial setup problems of the computer.
Solution: Right-click my computer and select Properties-Hardware-Drive Signature. Select Ignore here, and then click OK. Then plug in MP3. If you still can't connect, right-click My Computer-Properties-Hardware-Device Manager to find the USB controller, right-click and scan for hardware changes.
The voltage problem of the equipment itself
Because the current trend of MP3 is to do everything possible to reduce costs, the company constantly adopts new schemes, new controllers and new FLASH chips, which does not mean that these new things will cut corners. The problem is that these new things often need to be debugged for a long time to do their best, and the market situation can only allow MP3 factory testing to be put into production on one interface of a computer, so disconnection and disk dropping often occur.
In this case, users need to try several times, plug in different USB ports, and match a good quality USB cable separately (generally, the thicker the better, the copper is better than the iron), and then ensure the normal power supply of MP3 (try again with a charger).
The system reports "Unrecognized USB device"
Fault phenomenon: The computer accidentally loses power when using the USB flash drive, and the USB flash drive can't be used normally after restarting. After insertion, the system will report "Unrecognized USB device". Using other USB interface devices that can work normally will also prompt the same error message. Plug USB devices into other USB interfaces of the computer, and they can all work normally.
Fault analysis: Phenomenologically, the interface between USB device and motherboard is not damaged, and it is suspected that the accidental power failure caused the system setting error.
Solution: Enter the window of adding and deleting hardware from the Control Panel, delete all USB devices and reinstall the required USB device drivers. Restart the computer, and USB devices such as USB flash drive can work normally when plugged into the original fault interface. Unrecognized USB devices-notebook hard disk failure and mobile hard disk, plugged into the front USB interface, are unrecognizable.
This situation is largely due to power supply problems. Because USB hard disk also needs to consume a certain amount of electricity when it is working, if it is accessed directly through USB interface, it is likely that there will be insufficient power supply. Therefore, almost all mobile hard disks are equipped with independent external power supply or PS2 adapter, which is powered by keyboard. At this time, as long as the external power supply is connected in advance or the keyboard is connected through the PS2 adapter, try again after ensuring sufficient power supply for the mobile hard disk. You should be able to use it normally at this time. Need to remind everyone that it is recommended to ensure sufficient power supply before using the mobile hard disk, otherwise it is likely to damage the hard disk due to insufficient power supply.
For friends who have never used a USB external device, even if the driver is installed correctly, the system may not be able to detect the USB hard disk. This is mainly because the default CMOS port of the motherboard is closed. If it is not set to the open state, then Windows naturally cannot detect the mobile hard disk. To solve this problem, we can restart, enter the CMOS setting window, and set the item "Assign IRQ to USB" to "Enable" in the column of "PNP/PCI configuration", so that the system can assign available interrupt addresses to USB ports.
It is also possible that the USB interface type does not match, which makes the mobile hard disk unusable. For example, the USB interface configured by the computer is 1. 1 standard, and the purchased mobile hard disk is USB 2.0 standard interface, which requires that the cable connecting the computer and the mobile hard disk must support USB 2.0 standard. Because high-speed mobile devices are plugged into low-speed hubs, they may not be installed normally. Some friends use USB flash drives while using mobile hard disks. For convenience, they directly use the USB 1. 1 standard cable attached to the USB flash drive, which makes it impossible to correctly identify the USB 2.0 standard mobile hard disk. This fault can be solved by replacing the connecting cable with USB 2.0 standard.