iPhone 11 Pro Max Repair

iPhone 11 Pro Max Known Issues

Boot loop after liquid gets in at the earpiece

The 11 Pro Max has a known weak point for liquid: the earpiece opening at the top of the screen. One board repair technician describes these phones as notorious for letting fluid in that way. When it happens, the flex cable behind the earpiece takes the hit. That cable carries the proximity sensor, the ambient light sensor and the front microphone. On the phone he worked on, the result was a loop: Apple logo, black, Apple logo, black, with no end. Unplug that front flex and the same phone booted straight to the lock screen. The board could boot. The damaged sensor cable was what kept pulling it down.

A new earpiece flex means no Face ID

The obvious fix for a corroded front sensor cable is to fit a new one. The problem is that a replacement cable leaves the phone without working Face ID. That is why the technician in the case above chose to repair the original cable instead of swapping it. He lifted the proximity sensor module off the cable and cleaned the corrosion from underneath it.

Repair note: the protective coating on this flex comes away very easily once you start working on it, so cleaning has to be kept to a minimum. Scrub it hard and the traces underneath end up exposed.

Black screen, but the phone is still running

The screen goes blank mid-use, yet the phone still vibrates and charges. The obvious guess is a dead screen. In one documented 11 Pro Max case, another shop had already fitted several screens with no change, and a known-good screen showed nothing either. The fault was on the logic board. One pin on the display connector measured well off its expected reading, and that led the technician to a filter on a display power line. This is one case from one bench, not proof that every blank 11 Pro Max has a board fault. It does show why a new screen is not always the answer.

Two-layer logic board

Apple built the 11 Pro Max logic board as two boards stacked like a sandwich, held together with standoff screws. The point was to free up more room inside for the battery and the cameras. The trade-off is that the layers have a tendency to split apart, which makes this a design fault. It also makes repairs harder. In the black-screen case above, part of the display power line ran inside the sandwich, between the two layers, and the technician noted that reaching it would mean splitting the board, which is a lot of work. He checked the points he could reach from the outside first. Faults that sit between the layers are much harder to trace and fix than ones on the surface.

Fragile screen cables on the right-hand edge

Getting the screen off this phone takes heat and steady pulling, because a thick, stringy adhesive runs all round the edge as part of its water sealing. The ribbon cables that join the screen to the body sit along the right-hand side, under that adhesive. In a teardown of the 11 Pro Max, those cables were likened to paper for how easily they tear. Lever in at the wrong spot and a screen job becomes a cable job. The battery also has a second connector down by the charging port, not just the obvious one, and it is easy to miss.

Sources

• https://www.youtube.com/watch?v=1ZmNulKwsiA
• https://www.youtube.com/watch?v=xVIV_bYOgv8
• https://www.youtube.com/watch?v=dVZKn6NSmNg