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We will continue this lesson on maintenance for trigger protection

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If the rosin on the surface of the capacitor melts,

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then we directly remove it,

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and then measure the ground value to see if there is a short circuit

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In most cases, we removed the melted capacitor and then the fault was fixed

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After the capacitor is removed, we don't need to replace it

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Because it is a power supply line,

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the capacitor on the power supply line is a filter capacitor,

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it doesn't matter if we take one or two

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If the rosin on the power chip is melted,

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we remove the power chip and measure the ground value of this line

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There are two situations

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First, the line is no longer short-circuited, then we will replace the power chip

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Remove a good power supply chip from the mainboard and install it on the mainboard,

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the fault is basically repaired

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Second, if we remove the power chip and measure the ground value of this line,

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we find that it is still a short circuit

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This shows that the power chip is not damaged,

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it has nothing to do with it

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We can not rush to install the power chip

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We use the burn-in method with 1 volt to see if other places are melted

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Wherever it melts, we remove the components first,

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and then measure to see if there is still a short circuit

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Here's what to do when we find a problem with the power supply

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In the actual maintenance,

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if the surface of the CPU and hard disk is melted, we have to divide it into two situations

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First, this mainboard has not been repaired,

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it is an unrepaired machine,

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and there is no tin explosion around the CPU,

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and the mainboard has not been dropped heavily

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Because a heavy drop will cause the CPU position to be deformed

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In this case, we basically know that the possibility of CPU failure is relatively high,

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and there is basically no way to repair it

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Because the CPU cannot be replaced at will,

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it has encrypted module

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We are going to return the machine to the customer, this is irreparable

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The second situation is that when the mainboard has been repaired by maintenance personnel,

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or there are obvious tin beads around the CPU

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The reason for the existence of tin beads is that the welding method is improper,

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which leads to the explosion of tin

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So at this time, we have to re-solder the CPU

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After re-soldering, we measure the line again

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If it still has a short circuit, then basically,

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the machine has no maintenance value

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What is the reason for no maintenance value?

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It is caused by damage to the CPU, and the CPU cannot be replaced at will

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If we measure again, the supply line is no longer shorted,

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which means the fault is repaired

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what is the reason?

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It is the chip that has tin explosion, which is caused by human beings

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When soldering, the chip will explode due to the improper methods,

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and the tin will cause a short circuit

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Okay, that's it for this lesson