iFixit dissects iPhone Duo: detecting possible causes of screen damage due to internal impacts

Just the other day, I wrote about the iPhone Duo having a cracked screen at the hinge and suspected that Apple was repeating the mistake of the Galaxy Fold 2019. Now, iFixit has finished dissecting the iPhone Duo, including a 3D model of the hinge and CT scan, so I'll summarize it for you guys to see what they found. As mentioned before, iFixit has not confirmed the cause, but they have localized it quite clearly.

You can review my previous article here: iPhone Duo cracked screen at the hinge: will Apple repeat the 2019 Galaxy Fold?

iPhone Duo on iFixit's operating table (photo: iFixit)

The folding machine is two halves of the phone, so it is required to have a cable running through the hinge

Before talking about the crack, let me explain a little about the design, because this is what people often ask. A folding device like the iPhone Duo is essentially two halves of the device's body connected by a hinge, each half has its own components. According to iFixit, one battery is located under the back glass, the other is under the external screen, meaning one for each half. But Apple only puts the charger on one side, so the battery on the other side must be charged via the cable connecting the two halves. This cable also has to transfer a lot of image and audio data through the hinge slot. Simply put, without this cable, the two halves of the machine cannot work together.

The accordion-style pleated cable passes through the slot in the middle of the hinge, transmitting both data and electricity (photo: iFixit) In order for the cable to pass through, the hinge must leave a gap in the middle, and the cable is folded like an accordion to stretch each time you fold and open the device. That slot is where the screen support structure is changed: above is the empty slot for the cable, below is the central support bar of the hinge. And the internal screen is located right above all of this, thin and multi-layered, so wherever the support below changes, that area is susceptible to pressure.

iFixit overlays a CT image and model of the hinge onto a defective screen: the horizontal and vertical light lines of the hinge intersect just below where the cable passes through the middle of the hinge (photo: iFixit) Interestingly, iFixit says the cable isn't the culprit. The cable connecting the two halves of the folding machine is always the first suspect, but the damage they saw in the photo was not at the exact spot where the cable passes but a little lower, at the transition point from the cable slot to the central support bar, where many edges meet. iFixit's hypothesis is that if the central support bar does not lower enough when the device is folded, the curved screen inside will press on it, creating a concentrated point of force right near the location where the user reported the crack. The Verge added that this area is also located near the battery. So for me, the cable slot is not a fault, it is a must-have, but having to leave that slot makes the screen support in the middle of the hinge more complicated and can become a weak point. As for which specific batteries and components are located in which half other than the two batteries, iFixit did not make it clear, so I can't guess.

The crack is not right at the connecting cable but a little lower, where many edges meet

According to iFixit, users' descriptions are quite similar: when folding or opening the device, you hear a sound, then a small line appears along the fold and a bright line runs across the screen. Some people get it just after 6 hours of buying the device, some people get it before they've even finished setting it up. iFixit also explains that the actual damage can be much smaller than the streaks, because it only takes a local error in a few tiny electrical connections for an entire row or column of pixels to be affected. iFixit built a 3D model of the hinge from the disassembly video, Apple's patent and CT scan, then compared it to the damaged location of the devices users reported the error. As a result, the cracks are concentrated near the transition between the slot for the cable connecting the two halves of the machine and the support between the hinge. iFixit suspects:

iFixit's 3D model shows the screen bending in a waterdrop shape inside the hinge when folded (photo: iFixit) At the same time, YouTuber CuriousHagi cracked the screen of an iPhone Duo while testing its durability (putting dirt in and bending the hinge upside down), then disassembled it and saw a chain link in the middle of the hinge, thinner than the links above and below, broken right in a small groove, right where the crack started. The bottom of the screen also has scratches. This is a powerful test, so I think you should just consider it as another clue, not a conclusion. AppleInsider asked sources at the Genius Bar of 7 stores. By Sunday evening, only 1 case was recorded, so according to them the scale is still small.

The hinges are very sophisticated, less dusty than competitors but still crunchy

The iPhone Duo hinge uses gears, springs and a chain of metal links, like a watch chain, each link only rotates within a limited amplitude. The curved inner rails help the links move as if the center of rotation was inside the screen above, the purpose of which is to reduce stretching and pinching of the screen. The screen has more than 10 ultra-thin layers that can slide over each other when folded.

Spring inside the iPhone Duo hinge (photo: iFixit)

Repair score 5/10, highest for folding machines, but replacing the inner screen costs 999 USD

The two batteries of the iPhone Duo are lifted out after releasing the glue using electricity (photo: iFixit) Source: iFixit, 9to5Mac, The Verge, AppleInsider