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

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A1989 and A1990 both have 4 Type-c ports,

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and A2159 has two Type-C ports

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These models with Type-C ports have a common fault: the adapter does not boost

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It is mostly because the Type-C controller is damaged

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It needs to be replaced with a chip of the same type

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If it is a mainboard with 4 Type-C interfaces, there are 4 Type-C control chips

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If any of the chips is damaged,

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all Type-C interface adapters will not boost

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For example, A2159 has two Type-C interfaces and two Type-C control chips,

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one chip is responsible for one Type-C interface

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Any CD3217 damage will cause all Type-C interface adapters to not boost

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After the A1989 is turned on, the external display can display normally,

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but the internal display has no display.

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Whether it is the water inlet machine or natural damage,

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it is basically a short circuit between pin 1 and pin 3 of the screen interface

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Pin 1 is the EDP_INT_AUX_N signal

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Pin 3 is the EDP_INT_AUX_P signal

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Pin 2 is the grounding

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These two signals are directly connected to the CPU

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If these two signals are short-circuited, first we need to eliminate the problem of the screen,

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eliminate the problem of the screen cable and the screen interface, and replace the screen to test

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If it still doesn't work, replace the CPU

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The PP3V3 inductor voltage of A2159 is easy to short circuit,

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all because the power management chip is damaged

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Replacement can be repaired, this is a common problem with A2159

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If the ground value of the hard disk power supply of A2159 and A1990 is pulled down to about 10 ohms,

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it is basically because the hard disk is short-circuited.

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The normal ground value is around 350

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If the ground value of the PP3V3_S5 power supply of A1990 is lowered to 100,

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it is generally caused by the damage of the T2 firmware,

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and you can directly flash the T2 firmware

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The ground value is normally about 300

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For Apple laptops after 2018, if the current stops at 0.06-0.08A after booting,

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it is basically because the internal firmware of the T2 is locked,

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and the T2 firmware needs to be refreshed

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The PMU chip of A2159 refers to this power chip,

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which is next to the T2 security chip

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This chip integrates multiple power supplies inside,

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and there are a bunch of power supply inductors output around it

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So it has a higher chance of damage

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Ok, here are some common problems of Apple laptops