Chosen Solution
I have a water damaged iPhone 6S, I replaced the J4200 connector because there was heavy corrosion. There is a short associated with pin 37 (PP1V8_LCM_CONN) I am getting a reading of .048V in diode mode, I have replaced the caps and filter but no such luck, the short remains. PMIC is heating up, but there was no corroson in that area so I have a hard time thinking that there is a short under there, also CPU is heating up, heating initiates right around a PP1V8 pin. I am stumped! I have visually inspected and poked around the caps on PP1v8…. Any suggestions would be appreciated! FYI, the phone connects to itunes when placed in DFU mode.
PP1V8_LCM_CONN is driven by PP1V8 via the FL4205 filter. If you have already removed and replaced FL4205C4205/C4206 and the short remains, that means the short is on PP1V8 and that would explain why the CPU and PMIC are heating up. You will need to go short hunting on PP1V8. Look at all the caps and IC’s that are powered by that line and look for visual clues. If nothing is noticeable, apply freeze spray to see what heats up first. Apply the spray, power up the device and focus on one section of the board that has PP1V8 on it. Then go to another section and repeat. Eventually you should find it but if the shorted component is tiny or hidden by the shield ribbing, you may have to start removing components one at a time.
