1。 There is no response when the USB flash drive is plugged into the machine.
Maintenance ideas: according to the fault phenomenon, the U disk machine does not work, and the conditions that the U disk tool should have are the focus of our maintenance. No matter what scheme of USB flash drive wants to work, the following conditions must be met:
(1) power supply, which is divided into power supply needed by main control and power supply needed by FLASH, are two keys, and the U disk circuit is very simple. If there is no power supply, usually the fuse inductance is damaged or 3. The 3V regulator module is damaged. Speaking of regulator blocks, let's stop here. It has three pins, namely power input (5V), grounding and power output (3.3). The working principle is that when the input pin inputs 5V voltage, the output pin will output a stable 3.3v As long as we find a place without power supply, this problem will be well solved.
(2) Clock, because the host can only work at a certain frequency, and the communication with FLASH also needs to be transmitted by clock signal, so if there is no clock signal, the host will definitely not work. When checking this circuit, in fact, the clock generation circuit is very simple, just check the crystal oscillator and its peripheral circuits, because the crystal oscillator is afraid of rubbing and the U disk is easy to fall to the ground, which will damage the crystal oscillator, so just replace the same crystal oscillator. Note: the crystal oscillator cannot be measured, and the best way to judge its quality is to change a good crystal oscillator.
(3) Master control. If the above two conditions are normal, the master control chip is damaged. Just change the main control.
2。 The USB flash drive is inserted into the computer, prompting "Unrecognized device".
Maintenance ideas: for this phenomenon, first of all, it shows that the circuit of the U disk is basically normal, but there is a fault in communication with the computer. For communication, you need to check the following points:
(1) USB interface circuit, this circuit has no special components, just two data lines D+ D-, so when checking this circuit, you only need to measure whether the line between the data lines and the main control circuit is normal. Generally, two resistors with small resistance are connected in series between the data line and the main control circuit for protection, so it is necessary to check whether the resistance values of these two resistors are normal.
(2) Clock circuit, because the communication between the USB flash drive and the computer should be carried out at a certain frequency. If the working frequency of the USB flash drive and the computer can't be synchronized, then the system will think that this is an "unrecognizable device". At this time, the crystal oscillator will be changed. And there are many examples of crystal vibration damage in actual maintenance!
(3) Host, if the above two checks are normal, it can be judged that the host is damaged.
3. You can recognize the USB flash drive, but when you open it, you will be prompted "The disk is unformatted" but the system cannot format it, or you will be prompted "Please insert the disk". Open the USB flash drive, which is full of random codes, and the capacity does not match itself.
Maintenance ideas: for this phenomenon, it can be judged that there is not much problem with the hardware of the U disk itself, but there is a problem with the software.
Solution: Just find the repair tool of the master control scheme. This depends on everyone, what is the main control scheme of the USB flash drive.
The failure of U disk is generally due to the poor performance of flash memory or the phenomenon that bad blocks can't be written and stored in files. Unlike MP3, USB flash drives don't have firmware, but some manufacturers put their own software in them. If they are low, they will be gone.
Tell you a very simple method, that is, when the main control is damaged or the corresponding repair tool can't be found, you can use the USB flash drive kit to make a new USB flash drive. The method is to remove the flash of the faulty machine and put it on a new PCB. U disk kit includes (PCB with main controller (1. 1/2.0) and a set of shell), which is very simple to maintain and more convenient for data recovery.
Life of u disk
The erasable times of the USB flash drive are the normal life of the USB flash drive. Generally, the U disk with MLC particles can be erased more than 1000 times, and the life of the U disk with SLC particles is as long as 1000 times.
Maintenance of u disk
Correct plugging and unplugging of U-disk: Never unplug the U-disk when the indicator light of U-disk flashes rapidly, because the U-disk is reading or writing data at this time, and unplugging it in the middle may cause damage to hardware and data. Don't close the related program immediately after backing up the document, because the indicator light on the U disk was still flashing, indicating that the program was not completely finished. At this time, pulling out the USB flash drive will easily affect the backup. Therefore, after the file is backed up to the U disk, it will take some time to close the relevant programs to prevent accidents; Similarly, when the system prompts "Cannot stop", don't pull out the USB flash drive easily, which will also cause data loss.
Pay attention to place the U disk in a dry environment, and don't expose the interface of the U disk to the air for a long time, otherwise it will easily cause surface metal oxidation and reduce the sensitivity of the interface.
Don't always plug a long-term unused U disk into the USB interface, otherwise, on the one hand, it will easily lead to aging of the interface, and on the other hand, it will be a loss to the U disk.
The data transmission speed of U disk is generally related to the data interface and the quality of U disk, because U disk uses flash memory, unlike the storage speed of hard disk, it is only related to the interface type of USB; The USB 1. 1 and USB2.0 standards used to distinguish speeds have now been changed to USB2.0 full speed and USB 2.0 high speed, which may also be displayed as USB2.0 (FS) and USB2.0 (HS) in some testing software, so be sure to confirm that they are the interface of HS when purchasing. If the unified USB2.0 does not indicate the speed, it must be tested on site. Generally speaking, the speed of HS can reach 5~ 10M/S, while the speed of FS is below 1M/S, which is easy to distinguish.
Introduce several popular U disk brands: LG SanDisk Patriot Amber Bolesse Gold List Netac Lenovo BenQ Newman Tsinghua Hi-Tech Ziguang Digital China Ziming Youbeite IBM.
But yes, because the work of memory is very simple, the core is just a flash memory. In addition, basically all over the world will make flash memory, and Hyundai and several other factories are willing to make it and sell it. The memory particles themselves are of good quality. Therefore, memory is generally no different from any brand, and it is basically not bad. The only difference is that the products of big factories may read and write faster and have better after-sales service. It doesn't matter to us. Just stick it in for a second. Why spend tens of dollars more? At present, the inferior brand memory on the market generally provides a one-month or one-year warranty, which shows that the quality is still very good. Don't drop it as long as it doesn't get into the water. It's basically not bad.