A customer sent an iPhone 6S device with booting failure, he said the iPhone motherboard was fixed before, after receiving it, we disassemble to test with DC power supply, like shown in picture 10-10-1, the logic board measured with high current and CC light shows up.
High current is usually caused by damaged components on iPhone battery voltage VBATT or on the VCC_MAIN circuit. The VBATT resistance value is measured normal, and the voltage of the VCC_MAIN is measured to 0. As shown in picture 10-10-2.
Power on and increase the current, we find the iPhone charging chips and bell ring amplifier under the motherboard burn hot, so dismantle it directly then measure the value, it also makes short circuit to the ground, and still we can feel hot around. In order to find out the trouble spot accurately, fumigate the rosin and find that the charging tube is hot, which indicating that the short-circuit is not caused here.
After checking on iPhone bitmap, we find that the iPhone backlight chip is very vulnerable for the connected components in the VCC_MAIN , directly remove the motherboard shield, we find this part was repaired before since both inductor and chip are get some broken. Take off the chip which is measured with normal value, then we replace with new chip and inductor. As shown in picture 10-10-4.
Now the iPhone 6S can be turned on properly, as shown in picture 10-10-5.
More cell phone repair knowledge, please click www.vipfixphone.com
High current is usually caused by damaged components on iPhone battery voltage VBATT or on the VCC_MAIN circuit. The VBATT resistance value is measured normal, and the voltage of the VCC_MAIN is measured to 0. As shown in picture 10-10-2.
Power on and increase the current, we find the iPhone charging chips and bell ring amplifier under the motherboard burn hot, so dismantle it directly then measure the value, it also makes short circuit to the ground, and still we can feel hot around. In order to find out the trouble spot accurately, fumigate the rosin and find that the charging tube is hot, which indicating that the short-circuit is not caused here.
After checking on iPhone bitmap, we find that the iPhone backlight chip is very vulnerable for the connected components in the VCC_MAIN , directly remove the motherboard shield, we find this part was repaired before since both inductor and chip are get some broken. Take off the chip which is measured with normal value, then we replace with new chip and inductor. As shown in picture 10-10-4.
Now the iPhone 6S can be turned on properly, as shown in picture 10-10-5.
More cell phone repair knowledge, please click www.vipfixphone.com
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