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Hello everyone, today we will learn about the common problems of these models of Apple laptops

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The A1465, A1466 and A1502 models do not start up

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or sometimes can be turned on and sometimes cannot be turned on

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This kind of failure is mostly caused by the abnormal standby reset signal of the EC

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We can replace the U5110

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U5110 provides reset signal to EC

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The third pin VIN of this chip comes from the standby power supply of EC

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The first pin is specially used to check whether the EC standby power supply is normal,

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and the detection threshold is 3.0V

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As long as the voltage of this pin exceeds 3.0V,

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it will internally open-drain and output the EC standby reset signal,

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which is pulled up externally to a high level

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If the signal is abnormal, it is either because of the internal short circuit of the chip,

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or the damage of the pull-up resistor,

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or the EC short circuit pulls the signal down,

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and a small part is the leakage of the mainboard circuit

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Our solution is to replace the U5110, or directly connect this pull-up resistor,

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try to see if it can solve the problem

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If it can't be solved, we will try to replace the EC

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The second fault, the power-on current rises from 0.015A to 0.05A or 0.2A,

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and the power-off restarts repeatedly

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This is usually due to lack of power to the mainboard

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We focus on checking whether the main power supply of each channel is normally generated,

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which can be measured with an oscilloscope

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Check whether the back-end output voltage of each inductor is normal

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We can re-flash the BIOS

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This failure can also be caused by a problem with the BIOS program

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The CPU is soldered falsely or the CPU is damaged,

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which will also cause repeated power failure and restart

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We need to reball the CPU, or replace the CPU

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If the A1465, A1466, and A1370 models have 3 alarms when they are turned on,

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it is generally necessary to replace the memory chips first,

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because it is usually caused by memory damage

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If changing the memory still does not solve the problem,

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consider replacing the CPU or PCH

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If it is a machine with liquid or a machine that has been dropped,

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the possibility of disconnection of the board cannot be ruled out

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This is the most difficult to repair

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After the models like A1465 and A1466 have water ingress, the backlight circuit is also prone to problems

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The fault phenomenon is usually a dark screen when the power is turned on, and no display

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The solution is to focus on troubleshooting these fault points

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Check if the screen interface is corroded,

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and if the backlight boost control chip is damaged

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We remove the backlight driver chip, we can find that

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there are traces of mold on the bottom, and even some solder points have disappeared

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The FB feedback pin of the backlight chip is disconnected,

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and it is easy to cause the dark screen to not be displayed after booting

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Ok, these are the common problems of these models from Apple laptops