iPhone 7P no short, doesnt boot. - GSM-Forum

7Axis · 11-08-2018, 19:22

Hey people.

This is an iPhone 7P (Qualcomm) that won't boot when prompted, it will always remain at 0Amps on the power supply... These are the things I've checked so far.

- I've verified if PP1V8_ALWAYS is present, is it.
- I've checked PP_VCC_MAIN & PP_VCC_BATT, they both have good resistance
and proper voltage
- I've checked the flex connector for the power button(J4504) in diode mode
resistance, this is where it's interesting.
https://gyazo.com/a9f0534c6093b5923cab21e078396698

The resistance to BUTTON_POWER_KEY_CONN_L is Two times lower than what it should be, while it's estimated for 920Ohms, I barely get 400Ohms, as for the other pins, everything matches.

BUTTON_POWER_KEY_CONN_L connects to PP1V8_ALWAYS and the PMIC. This is where I'm at lost for thought, reballing the PMIC is dangerous because of the CPU right underneath, I want to be 100% sure it is the problem, so my question is how can I make sure? are there additional standby voltages I could check?

I am positive this is likely PMIC related, but how to check for sure? thx.

7Axis · 11-08-2018, 19:49

Update : I checked BUTTON_POWER_KEY_CONN_L in voltage mode and I got 124mV, while on a working work it's 1.8V (Connects to PP1V8_ALWAYS)

Yet BUTTON_POWER_KEY_L has 1.8V, and they are both interconnected via R4402 so I will try to replace that resistor and see how it goes.

11-08-2018, 19:22	#1 (permalink)
7Axis Freak Poster Join Date: Nov 2017 Location: Canada Posts: 131 Member: 2777379 Status: Offline Thanks Meter: 34	iPhone 7P no short, doesnt boot. Hey people. This is an iPhone 7P (Qualcomm) that won't boot when prompted, it will always remain at 0Amps on the power supply... These are the things I've checked so far. - I've verified if PP1V8_ALWAYS is present, is it. - I've checked PP_VCC_MAIN & PP_VCC_BATT, they both have good resistance and proper voltage - I've checked the flex connector for the power button(J4504) in diode mode resistance, this is where it's interesting. https://gyazo.com/a9f0534c6093b5923cab21e078396698 The resistance to BUTTON_POWER_KEY_CONN_L is Two times lower than what it should be, while it's estimated for 920Ohms, I barely get 400Ohms, as for the other pins, everything matches. BUTTON_POWER_KEY_CONN_L connects to PP1V8_ALWAYS and the PMIC. This is where I'm at lost for thought, reballing the PMIC is dangerous because of the CPU right underneath, I want to be 100% sure it is the problem, so my question is how can I make sure? are there additional standby voltages I could check? I am positive this is likely PMIC related, but how to check for sure? thx.

11-08-2018, 19:49	#2 (permalink)
7Axis Freak Poster Join Date: Nov 2017 Location: Canada Posts: 131 Member: 2777379 Status: Offline Thanks Meter: 34	Update : I checked BUTTON_POWER_KEY_CONN_L in voltage mode and I got 124mV, while on a working work it's 1.8V (Connects to PP1V8_ALWAYS) Yet BUTTON_POWER_KEY_L has 1.8V, and they are both interconnected via R4402 so I will try to replace that resistor and see how it goes.