Dead iPhone 6 tried everything to repair suspect CPU
I have bought a broken iphone 6 from eBay to learn micro soldering and repairs. It is all going well but this device came to me and has been worked on before. Many of the capacitors have been ripped off the board, mainly on VCC_MAIN.
I found the main fault which was a shorted PP1V8_SDRAM, the short was caused by a faulty PMIC which has been replaced. When connected to a bench PSU the phone at power on draws around 45mA and does not boot. I have checked the following and they're all OK.
VCC_MAIN
PP_CPU 0.775V-1.0V
PP_VAR_SOC 0.9V-0.95V
PP_GPU 0.9V-0.95V
PP1V8_SDRAM 1.8V CPU
PP1V2_SDRAM 1.2V CPU
PP0V95_FIXED_SOC 0.95V CPU
PP1V8 1.8V CPU
PP1V2 1.2V
PP1V8_GRAPE 1.8V
RESET_1V8_L
PP3V3-USB——A8 CPU
PP1V8_VA_L9_L67——U0900、U1601
PP3V0_TRISTAR——U1700 USB
PP3V0_IMU——U1901
PP3V0_NAND——U0604
PP3V0_PROX_ALS——J111
PP1V0——A8 CPU
PP3V0_PROX_IRLED——J111
PP1V8_ALWAYS——A8 CPU
PP3V0_MESA——U2100
Does anyone else have any ideas? Not sure what the next signal should be to the CPU to boot? I think it may be a dead or broken CPU :-( Do I need to replace all of the missing CAPs.... no long screw damage either.....everything else looks good.
Any help very much appreciated for someone learning.... loving the challenging though.....
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