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iphone 7 vdd main pp batt vcc difference
I don't know what Q2101 is off the top of my head, but I'm assuming that they want you to bridge vcc_main with vbat. I'm not sure why they would want you to do that if you have a short on vcc_main. I would look to relieve the short. In order to do that, you should use the freeze spray method or perhaps a thermal camera.
To use the freeze spray method, apply 4V 2A to multiple vcc_main points on the logic board, while using the freeze spray. The capacitor that heats up before the others is usually the culprit.
I am a little late to the party. Shorting Q2101 MOSFET does make sense to find bad components, but please, PLEASE! be careful not to short data lines in the MOSFET, It is a way to inject voltage to PP_VDD_MAIN. I have attached a photo so you can see how it is done.
You can later witch hunt the bad component/s. I have seen in a lot of videos, the guilty components are the ones at the top of the board (C2609??)
Please keep us informed. Gd Luck!
You are basically looking for the component that is making the line go to ground, most of the cases it is a capacitor.
Shirting the MOSFET in the source and drain is the same as injecting voltage to the line. Sorry I forgot to upload the picture I will in this one.
After you short it it will be easier to identify the component that is hot and consequently the faulty one.
I've never had to short the mosfet. To inject power into vdd_main, just use your dc power supply and probe different points on the logic board with 4V 2A on the vdd_main power line while using freeze spray. What you're looking for is the a bigger capacitor that gets heated first before the others.
I am just learning. I just said that the technique you asked for does makes sense. Although I have never tried. I would take Mike’s advice injecting voltage in the line. It is way simpler.
I can give you my contact number but I won’t be of much more help.
Here are the steps to inject voltage:
limit your current to 2 Amps (Short the two probes of your power supply and keep the current increasing until 2 Amps)
Set the voltage to 4.1 volts
black probe in any ground and red probe in any PP_VDD_MAIN (See images)
look for hot components with freeze spray or any method you like and remove component.(Most likely you are going to need to remove shields)
check the line to see if short is gone.
This is the Plis bro solution you might need to take a look into the schematic/board view