Chosen Solution
Hi gyus, today I was working on Iphone 7. No power what so ever, does not react to a charger (0 current being drown). Plugged in to DC power supply, phone does not react to power button at all (not shorts, no reaction on power supply). However the device reacts to a lightining cable. Current goes to .010 amps and down to 0, back to 0.01, down to 0 and stays in that loop until power disconnected. When doing diode mode checks on logic board, started from bottom flex cable socket and found 2 shorted lines: pp1v8_sdram pp1v1_sdram I have injected 1.8V 1A directly to both of them, the only part that was getting warm was a CPU. Am I right the faulty part on my board is CPU RAM? Is it even worth trying to repair it? I’m pretty convenient all the tests I did eliminated other components from a “fault list”. Just wanted to confirm it with more experienced people, since my own experience in that matter is very limited, I just started my repair adventure about a month ago, learning everything from the internet :) Sorry for not the best English and Thank you :) Marcin
· What is the history of the phone? · Have you ruled out parts? · Has it had prior repair attempt? In my experience an 1V8 sd ram short would draw a constant 600 to 700mA. When testing with a DC power supply you should prompt it to boot by inserting the charger cable for three seconds than remove it. Use a proper squid not one of those red ones that has a button on it for prompt to boot. Just because something gets warm it doesn’t mean it is shorted. If in any case you were correct in your findings and the ram has multiple shorts it is a very difficult repair, it is easier than the 6 but the ram can still warp while removing and there is nothing to say you won’t have damaged pads on top of the CPU. If you want you can supply us with the diode reading of C1874 and C1823 remember red probe on ground.
