We received a iPad mini 2 from our
colleague, the problem is that it cannot boot. Colleague said he accidentally
supply power 15V when replacing iPad screen, the iPadlogic board is short circuit.
First, we test power supply, starting at
0V, and then slowly increase the voltage. When added to 1.5V, the current
reaches 2A. Remove the power supply pipe, we can found that the B+ is short
circuit, as shown in picture 8-7-1.
Secone, take out the iPadpower IC, the B+ voltage still shows short circuit. In this case, we can use "Paint Rosin Method" and supply power on it. As shown in picture 8-7-2.
Third, because the B+ involves too much IC and
capacitance, we can't make sure that which component is broken. In order to perceive
the temperature, we use hand to touch it, and found the temperature of rear big
audio IC is higher than others.
Fourth, remove the iPad big
audio IC and measure the B+ circuit again, we found
that the short circuit fault has disappeared. And the power supply point of big
audio has obvious signs of burnout. We can check it clearly under the microscope, as shown in picture 8-7-4.
Fifth, install the power IC, power on iPad and
test it, the problem is solved, the iPad mini 2 can boot now. As shown in
picture 8-8-5.
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