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In this lesson, let's take a look at the maintenance of the mainboard that causes the file memory failure

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When there is a problem with the memory-related circuit of the mainboard, it may cause the file memory to fail.

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The fault phenomenon of the file memory is that the code stops after only running a few times

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After a file memory failure occurs, we need to overhaul the working conditions of the memory.

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Let's first look at the memory working conditions of DDR3 memory

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The first is the memory main power supply VDDQ

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The main power supply of DDR3 memory is generally 1.5V

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This 1.5V we need to measure at the inductor

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Next is VTT

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The voltage of VTT is generally half of the memory main power supply

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The main memory power supply is 1.5V, so VTT is 0.75V

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VTT power supply can be measured at pin 120 and pin 240 of the memory

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So where are the 120 pins and 240 pins of the memory slot?

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We must first know the division of memory slot pins

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The memory slot of DDR3 is divided into a short section and a long section by the anti-fooling port.

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The short side is the head, the long side is the tail

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The pin division of the memory slot is like this

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Here is the first pin, counting down from top to bottom

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The last one in this row is 120 pins

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The first one in the second row is 121 pins

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Then count down the last pin is 240 pins

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So the 120 and 240 pins of VTT are at the bottom of both sides

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Then down, the reference voltage

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Its voltage is generally equal to the VTT voltage

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The reference voltage is generally generated after the main power supply of the memory is divided in series.

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There are two reference voltages for DDR3, one is pin 1 of the memory, and the other is pin 67 of the memory

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The first pin of the memory is very easy to find,

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but the 67th pin of the memory is not so easy to find

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In actual maintenance, we generally only measure the reference voltage of pin 1,

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and the measurement of pin 67 is relatively small.

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Further down, SPD power supply

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SPD power supply is the SPD chip power supply of the memory

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When the mainboard self-tests the memory, it needs to read the information of the memory SPD chip first.

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If there is no SPD power supply for the memory,

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then it will not be able to read the information of the memory, and it will not be able to self-test the memory.

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The SPD is generally on the 236th pin of the memory slot,

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which is the fifth pin from the bottom to the right of the memory slot.

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This is the SPD power supply of the memory

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Next is the SM bus

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It is a bus used by the bridge to read memory SPD chips

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When this bus reads the memory SPD, there should be data transmission,

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that is, there is a waveform

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If we don't have an oscilloscope, we can also measure the voltage of the SM bus

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In general, the SM bus is 3.3V

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It is also very easy to find on pins 118 and 238 of the memory slot

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The last one is memory reset

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Its voltage is 1.5V and is pulled up by VDDQ

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Of course, memory reset is not always a high level of 1.5V under normal circumstances.

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But if you don't have an oscilloscope, you can use a multimeter to measure the memory reset

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As long as there is 1.5V on it

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If we have tested all the above conditions, they are all normal, but the memory is still blocked.

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Then we have to measure whether the other data lines of the memory slot are connected to the CPU.

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The measurement method is to install the CPU and use the memory slot value card to value each data line

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Or you can refer to the drawing

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Make sure that each data line is not broken

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Of course, the premise is that the replacement method has been used to confirm that

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the fault of the file memory is caused by the mainboard,

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and the mainboard has no external faults.

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These are the maintenance methods of DDR3 memory