Apple MacBook Pro 1502 notebook does not trigger no-boot repair

Apple MacBook Pro 1502 notebook does not trigger and does not boot

[machine model] apple MacBook Pro A1502

[Motherboard Model] 820-3476-A

[maintenance process]

Pick up a companion apple.notebook,

Dismantle the machine, remove the back cover, and visually check that there is no water or the like. After the motherboard is removed, it is seen that the bottom of the USB interface has been moved by someone, and the air gun blows it. The capacitor in the standby part is dirty and has been replaced.

Apple MacBook Pro 1502 notebook does not trigger no-boot maintenance Figure 1

On, the current of 0.015-0.025-0.205-0.015 jumps repeatedly, the 3.42V measured by the probe is normal, and the L7560 3V standby jumps repeatedly. R8140 resistor S5_PWR_EN also keeps jumping. Is there a short circuit?

Apple MacBook Pro 1502 notebook does not trigger no-boot maintenance figure 2

Burning machine, L7560 disconnects the burning machine, the side with low resistance is 1V, and the burning machine has current, which is simple.

Apple MacBook Pro 1502 notebook does not trigger no-boot maintenance Figure 3

Apple MacBook Pro 1502 notebook does not trigger no-boot maintenance figure 4

Burn to a capacitor, see the point is C2951 capacitor, the source of this capacitor circuit is the conversion part, it seems that the problem is here, directly deducted.

Apple MacBook Pro 1502 notebook does not trigger no-boot maintenance Figure 5

It won’t jump when the power is turned on, but a new problem is coming. It’s too high to trigger the standby current of 0.16!

Apple MacBook Pro 1502 notebook does not trigger no-boot maintenance Figure 6

It was normal to return to the original place of measurement and test it again. As a result, when the EC was reset, the EC chip was very hot and burned.

Apple MacBook Pro 1502 notebook does not trigger no-boot maintenance Figure 7

Yes, I found one on the material board and replaced it. The standby chips were replaced together. After the replacement, I checked it again. After that, the digital power supply current automatically triggered 0.756 normal all the way.