By now many of you have heard of several iconic problems in repair:
Lately, we've been hearing about the "Blue Screen of Death" in the iPhone 5S--
Tonight, I have a warning for you. This may not end up being an iconic problem, it may be coincidental damage. In any event, I want to share this case with the repair community.
iPhone 6 No Backlight after simple screen replacement:
An iPhone 6 comes in to a shop for what seems like a straightforward screen replacement. However, the new screen does not light up.
After component failure was ruled out, this phone found its way to my microscope.
I confirmed the phone was turning on, but showing no display--not even on an original iPhone 6 display. This seemed to be a straightforward backlight repair. Raise your hand if you know what component(s) should be replaced to solve a standard backlight failure in this situation? If you said "the coil" or "the backlight ic" punch yourself in the face and read Backlight 101.
Given the history, those of you who read Backlight 101 will recognize that this will most likely be connector damage or a bad backlight filter. I have repaired a backlight from a water damaged iPhone 6 before, so I'd already mapped the backlight filters.
I opened the phone and found very minor damage at the edge of the LCD connector, but all the pins intact. I believe the connector is okay. I uncovered the backlight filters and found that they showed no signs of damage, and had continuity as normal.
I even used my new FLIR One infrared camera to make a heat map comparing this iPhone 6 to a normal iPhone 6. Spot temperature measurements were largely the same. No hot spot, so therefore no short circuit.
Since the history tells us the display was working fine after the drop and before the screen change attempt, what could be the problem?
Making a connection to the recent BSOD problem on the iPhone 5S, I took a hard look inside the screw brackets. In a normal phone, the bottom of the screw bracket is nothing but the clean black coating of the solder mask applied to all non-conductive surfaces of the board. Sometimes you can see blue plastic along the edges of the screw bracket from the plastic coating on the shaft of the screws.
iPhone 6: Normal LCD connector area MIDDLE SCREW
iPhone 6: No backlight after screen replacement - MIDDLE SCREW long screw damage
In this phone, I could see copper. Copper at the bottom of a screw bracket is bad--it means that the wrong screw was tightened in the bracket until it pierced the solder mask and continued to churn into the board. Without the schematic or an x-ray machine, I can't be sure of any relationship between screw damage and the no backlight problem in this phone. This might just be purely coincidental.
However, with no other findings for an iPhone 6 that has sudden onset of backlight failure with intact connector and filters----this could mean that more than ever we need to watch our P's and screws when doing screen replacements.