Chosen Solution
Hi Sorry for my english i have an iphone 6 that was shorted on vcc main, solved after removed c1552 cap . even though there are no more short , he still does not boot.nothing happens on dc power supply when i try to turn it on with the ipower cable, it stays on 0.000 i checked the current that came to the battery and it was 0.69, then i changed the u2 (tristar) and the current is back to the normal 4.2 but still nothing happen in dc power supply when i prompt to boot the phone I finally replace the tigris and the q1403 but the same result I check the power on vcc main and is correct 4V
When dealing with a “dead” phone, there is no “silver-bullet” solution. You have to probe the board to get a better understanding of what is working properly and what is not. It may be a simple solution or a complex one. Sometimes we see a visibly blown cap, replace and all is well. Other times, everything looks perfect yet the phone won’t boot. You have to start at the beginning and check PP_BATT_VCC, PP_VCC_MAIN and PP5V0_USB. If you are measuring the proper voltage, then you move onto the PMIC and check the voltage rails it generates. The PMIC generates ~15 voltage rails. They are all important (for obvious reasons) but the ones to check first are as follows: PP_CPU & PP_GPU – These rails supply the CPU & GPU. They are low resistance rails so they may “beep” when you test them on your multimeter in continuity mode. It’s important to look at the reading and not focus just on the beep. You will typically measure something around 20-100 Ohms on these lines.PP1V8_SDRAM & PP1V2_SDRAM – These rails supply the SDRAM (which is sandwiched with the SoC/CPU).PP_VAR_SOC & PP0V95_FIXED_SOC – These rails supply the rest of the System on a Chip. What we commonly refer to as the CPU is actually a SoC.PP3V0_Tristar & PP3V0_NAND – These rails supply Tristar & the NAND chip.PP1V8_ALWAYS – This is an “always-on” voltage rail that is used for the bootstrapping of the devicePP1V0 – Supplies the High Speed Digital Communications via the SoC
Hi i did the tests you suggested and here are the results.j hope you can help me thanks again Pp_cpu 0V and 119 in diode mode Pp_gpu 0v and 59 in diode mode PP1V8_SDRAM 0V and 772 in diode mode Pp1v2_sdram 0v and 415 in diode mode PP_VAR_SOC 0v and 157 in diode mode PP0V95_FIXED_SOC 0V and 196 in diode mode PP3V0_Tristar 0V and 1400 in diode mode PP3V0_NAND 0V and 1304 in diode mode PP1V8_ALWAYS 1.82V Founded and 1451 in diode mode Pp1v0 showing unstable current from 0.23 to 0.95 looping
