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High current occurs when iPhone starts up

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In this video, we will learn about the repair process step 5

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If we measure a short circuit in the power supply,

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we apply the rosin on all the components connected to this line

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And trigger the boot to see if the rosin melts

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If it melts, that means it's damaged and we need to remove or replace it

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So let me demonstrate

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In the previous section, we measured a short circuit in PP1V8_S2 power supply

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A short circuit means that the components connected to the line are damaged

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Double-layer mainboard, we first need to distinguish the upper short circuit or the lower short circuit

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If the ground value of the upper layer is 0,

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it indicates that the upper mainboard is short-circuited

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If the ground value of the lower layer is 0,

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it indicates that the lower mainboard is short-circuited

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After distinguishing the upper and lower layers,

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we smoke the rosin on the components of the mainboard

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If the component is inside the shield,

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we don't have to smoke it, we smoke the outside first

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We apply rosin on the short circuit connecting components

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Then power on the switch, trigger the boot, to see if the rosin on the component is melted

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If it is melted that means the component is damaged

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The power supply will show high current after the machine is turned on

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We wait for 3 or 4 seconds,

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and then we look at the components of the smoked rosin

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We looked at the components of smoked rosin under a microscope

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We found that the rosin on this capacitor had melted

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It's possible that this capacitor is damaged, causing the high startup current

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We'll test it after we remove the capacitor

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After the capacitor is removed, we trigger the switch

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and we can see that the current changes to 80mA

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This indicates that the capacitor damage caused the high startup current

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Maintenance precautions

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If the melted component is the main power supply,

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we do not deal with it, it is likely to be caused by short circuit in the rear pole

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So that's it for this lesson