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I have a customers iPhone 6 that had touch issues. The problem was not the screen but was on the motherboard. I changed touch IC U2402 and after process finish the lcd shows no image. ITunes recognize the phone, I can handle the phone through my pc, I can make a back up etch. But I don’t know what I did wrong and I can’t see the lcd image. Backlight coil is from the other side I don’t think this is the problem. Can someone help me where to look on motherboard; thank you
I would also suspect the backlight circuit (just shine a torch on the display and check if you can see the lcd image) . As already stated, when applying heat to a board where the components are so close together, the chance of disturbing an unwanted component is extremely high and there is an equally high chance of effecting the backlight circuit. When soldering Smd parts, I always use captan tape surrounding the component in question to reduce the chance of heat spreading to unwanted areas.
Hi John. That is exactly your problem. Opposite the Touch IC’s, on the front side of the pcb, is the backlight circuit. When you apply too much heat, you can either damage the backlight circuit or cause some loose solder joints. You also have to be careful because the CPU is right there as well. Being stuck in place with underfill, there is always a risk that too much heat can cause the solder balls to expand and they have nowhere to go other than short each other or get exploded out from underneath. Remove the shield over the CPU and inspect carefully for excess solder balls. Then inspect and probe the backlight circuit. You may have loose components or a defective backlight filter. EDIT (2017/02/17) Here are some snippets from the schematic. I would check the backlight circuit, specifically the diode, the decoupling capacitors and the ferrite beads (filters or some say fuses) on the anode and cathode side.
Friends, I have replace the touch ic on my iPhone 6 plus. After replacing I have black screen with light but I cant see anything else. Can you help me dear?
