iPhone 11 No Power Logic Board Repair
We just had our first case of repairing a no power iPhone 11. The history of the phone is that the customer dropped it, then the phone stopped working. The repair shop replaced the screen and there was no change.
After opening the phone up, we didn’t notice anything unusual with the logic board. Upon further testing, we didn’t notice any shorted power lines like vdd_main or pp1v8 or pp3v0. Since we didn’t see anything unusual, we decided to separate the two logic boards. Yes, the iPhone 11 has a sandwiched logic board with an interposer board just like the iPhone X, iPhone XS, iPhone XS Max, iPhone 11 Pro, and iPhone 11 Pro Max. The sandwiched logic boards are always a little dicey to work with, especially if there were torn pads on the logic board.
Upon separating the two logic boards, we noticed that there were two chips that were cracked. Since there are no detailed schematics available for these iPhones yet, we were uncertain about the exact function of these two chips, but we were able to make some good guesses based on past logic board repair with older iPhones.
We determined that one of the chips was the big audio chip and the other was a some sort of power chip. After replacing both of these chips from a donor board, we were tasked with the challenging task of resoldering the two separated logic boards back together.
After four attempts, we were able to get everything working once again.
Some of the challenges that we faced were the fact that the backlight dimmed out with the ear speaker flex disconnected. This was probably the biggest grief for us because we also missed a cracked backlight coil, which both contributed to the backlight not working. After replacing the broken backlight coil, we thought that we had fixed the problem, especially after getting 20v at both anode pins, but we were trolled by the ear speaker flex being disconnected.
The second challenge was sandwiching the two logic boards back together. We had to do it a total of 4 times, mainly because we didn’t tin the pads well enough and we didn’t apply enough pressure to the two logic boards after heating them up. It was mainly at the two ends of the logic boards that we were having the most problems because they tend to warp a little and bend upwards and away from the interposer board.
Anyways, I’m happy to say that after four attempts, we were able to get everything working on the iPhone 11 logic board, so I think that we can comfortably say that we’re qualified to work on these logic boards now.
If you’re interested in sending in your iPhone 11 logic board for repair, then please request a quote here.