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In this lesson, let's talk about the maintenance ideas of the network card that does not recognize

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The failure phenomenon of not recognizing the network card is very clear,

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that is, the network card cannot be seen in the device manager

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We can see that there are so many network card devices in the network tester

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But the devices here are not all real network cards

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Only the two in the middle are physical network cards, and the rest are virtual network cards mapped by the system.

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We must pay attention to distinguishing them

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If the network card is not recognized,

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it is generally because the working conditions of the network card are not met,

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or the chip of the network card is damaged.

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Therefore, when we do not recognize the failure of the network card during maintenance,

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we must conduct maintenance around the working conditions of the network card

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Of course, in maintenance, we still have to follow the maintenance principle of soft first, then hard,

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easy first and then difficult.

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So we have to troubleshoot the software first,

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that is, clear the CMOS or flash a new BIOS

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Use a new system to test to ensure that the network card failure is not caused by software

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Clearing CMOS is also very simple, we only need to pull out the button battery and put it on for a while.

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Next, we need to observe whether there is any physical damage near the network card

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Observation is always the preferred method

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Because many faults can be solved by observation

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For example, there are dropped parts, corrosion and broken wires next to the network card, etc.

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These obvious physical injuries

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Use the observation method to quickly find the fault point

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Further down, we need to check whether all the power supplies of the network card are normal

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Power supply is the best test

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We must pay attention when testing the power supply of the network card,

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the power supply of the network card around 1V is generated by itself

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If not, the network card may be damaged.

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Next, we need to measure whether the crystal oscillator of the network card starts to vibrate.

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This needs to be measured with an oscilloscope.

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After the power supply and clock are tested, we also need to measure the reset signal

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The reset signal is the platform reset signal

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If the power supply, clock and reset are normal, we have to check whether the PCIE bus is normal

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There are a total of six wires on the PCIE bus.

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We need to connect the ground values separately to prevent them from short circuit or open circuit.

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But it should be noted here that there is generally a coupling capacitor in the middle of the PCIE bus,

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we must pay attention when measuring

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Coupling capacitance will lead to unmeasured value

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We should measure at the end of the coupling capacitor close to the bridge

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Going down, measure whether the clock request signal REQ is low

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In other words, has the bridge received this low-level REQ signal?

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Because it is possible that the network card has lowered the REQ,

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but this low-level REQ has not been given to the bridge

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If possible, it is best to measure the PCIE bus to see if there is any waveform on its clock line

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If there is a waveform, it means that the bridge has sent the clock of the PCIE bus,

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and it must have received the REQ signal.

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The reason why the bridge does not send out the PCIE bus clock is that it does not receive the REQ signal

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If all of the above are normal, then we can only try to replace them.

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We can replace the coupling capacitor of the PCIE bus

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Because if there is a problem with the coupling capacitor and the data cannot be transmitted,

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of course the network card will not be recognized.

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Going down, we have to replace the network card test

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The probability of actual network card damage is still very high

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If we have the same network card on hand, we don't need to check these, just change a network card and test it first.

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Finally, if the network card is changed, we have also tested the above conditions, and they are all normal,

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but the network card is still not recognized.

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Then we can only try to replace the PCH

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Well, the above are the maintenance ideas for not recognizing the network card