Dark line in display after touch IC repair
My phone had the classic touch IC issues (no touch, grey bar at top of screen, etc). Sent it off for repair (re-ball with micro-jumper). I received it back with touch input working again, but there is now a faint dark line on the display. In the attached photos, it is below the apple logo during startup.
It is most noticeable with a white background. I did some troubleshooting with an identical phone that does not have the touch IC issue. When i swap displays, neither phone shows the dark line. The issue reappears when I swap the displays back. I am at a loss because I can’t determine whether the issue is with the display or the logic board. The only thing I know is that the issue is only present when this particular display is connected to the phone with the touch IC repair.
I could just leave the displays swapped (removing and switching the fingerprint sensors, of course). However, I want to know if anyone has any other ideas or knows what is going on.
UPDATE: After a lot more swapping, I’ve analyzed the flex cables and connectors on both phones with a 10x loupe. Nothing was apparently wrong. All the pins in the connectors and cables were perfectly lined up. I also cleaned it with some IPA and applied slight pressure at different parts of the connector when the phone was turned on, but was unable to see any changes to the display.
However, I did find that there is a BARELY noticeable horizontal line when I connect the affected phone to the display from the other phone. It is in a different spot that shows up lower on the screen. For those interested, I’ve attached pictures. It is very difficult to detect in person and even more difficult to get it on camera. I’ve highlighted where it should be in one of the pictures, and it helps to zoom out or look from a distance or stare at it really hard. It also depends on how good one’s vision is.
Given that both displays show up perfect on the other phone, I have ruled out the display and its flex cable as the cause. My best guess is that the touch IC repair loosened something or introduced particles underneath the display connector and that the different tolerances in the connectors and flex cable are causing the results I’m seeing from the swap.
Nevertheless, I will be doing the touch ID and screen swap since the results are much better than before. I doubt there would be anyone still using this phone and choosing to do the repair, but I hope this can help someone!
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