Teach you to quickly identify U disk Master control is a good trick

phenomenon One, U disk Insert computer, prompt "Unrecognized device" fault

Cause analysis: With the computer communication problems, specific have the following points to check:

(1) U disk Interface circuit, this circuit is two data line d+ D, so in the examination of this circuit as long as the data line to the main control of the line between the normal can, generally in the data line and the main control circuit will be strung between two small resistance resistors to play a protective role, so to check the resistance of these two resistors is normal.

(2) clock circuit, because U disk and computer communication to be in a certain frequency, if the U disk work frequency and computer can not be synchronized, then the system will think that this is an "unrecognized equipment", so this time will change the crystal vibration;

(3) master control, the above bright spots are normal, then you can judge the main control damage.

　　Phenomenon two, U disk plugged into the computer after no response

Reason analysis: Such a failure, is the U-machine does not work, and U disk tools to have the necessary conditions is the focus of our maintenance. So any maintenance program in the U disk want to work must have the following conditions:

(1) clock, because the main control to work at a certain frequency, with the flash communication also with the clock signal transmission, so if the clock if there is no signal, the main control will not work, so in the examination of the circuit, in fact, the clock generation circuit is very simple, only need to check the crystal oscillator and its peripheral circuit, crystal vibration afraid of brush The U disk compact very easy to fall on the ground caused by crystal damage, so as long as the replacement of the same crystal vibration can be. Hint: Crystal oscillator is unable to measure, the best way to judge its quality is to replace a good crystal vibration to judge.

(2) power supply, divided into the main control of the required power supply and flash required power supply, these two are the key, and U disk circuit is very simple, if there is no power supply is generally damaged or 3.3V voltage regulator block damage, as long as there is no source of power supply, the problem will be well resolved.

(3) Main control, if the above two conditions are normal, it is the main chip damage, so only replace the main control.

Phenomenon III, the computer can identify U disk, but open the prompt "disk has not been formatted"

Reason analysis: Can judge U disk itself hardware not too big problem, just software problem.

Workaround: Find the Repair tool for the master solution to fix it. This depends on the U disk is what the scheme to make the decision.

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