Analysis & Summary & FIX: iPhone 6 Plus common touch problems

Here, we are going to analysis and summary the reasons of iPhone 6 Plus touch problems, and then find the solution to fix it

As we know, iPhone 6 Plus touch is very easy to get faults: unresponsive, zebra flicker on the top of the screen, etc. Before dealing with these failures, it's necessary to replace a new screen to test, if the failure still exist, you need to test the iPhone 6 Plus motherboard. First test the ground resistance of the touch pin, which can intuitively let us find out where the problem is.

At the same time, we can see that the 18 pin is the synchronous signal of CPU through the black touch M1 pin. If all these resistances are normal, voltage test should be started. By voltage test, we can more accurately judge which chip is damaged.

The voltage test must be buckled to the screen for voltage output, three power supply for black touch: +-5.7V shows power supply, and 1.8V shows it is given by power IC .

Two power supply of white touch : 5.1V display power supply, 1.8V power supply IC. It is possible to judge which IC is damaged according to the results measured.

The water damaged device shows that the power is easy to burn out so that 5.1V and white touch +-5.7V cannot be given. Broken device fault mostly shows on black touch, false welding is the most possible problem. During the soldering process, some technicians do not remove and redo but directly heat to the chip, customers can use them normally, but they will come back to repair after a while. It is better to take the chips off and replace the new ones.

The point of the black touch M1 pin is at the top of the plate layer, and it is easy to break the wire to cause the iPhone 6 Plus CPU signal to not be delivered, so we need to use the jumper wire to solve this problem. There is a point below the R2410, and the M1 pin is a circuit line, gently scraped with a blade under a VGA Camera 7-45X Trinocular Stereo Microscope, then get a little solder on the blade, blowing a small solder ball out with ESD hot air gun, it must be small, then welding the solder ball at that point scraped out with slow speed air gun, using a copper wire (can take off from solder wick) to fix on the scrape point and M1 pin, add the green oil and put under curing UV light. The process looks more complex, but the effect is very good, and it is basically no rework necessary.

In addition, take care not to damage the small components around the points, here are 2490, FL2486, C2439 three components,which are used for identifying the original screen, after you change the iPhone touch IC and install the original screen, if the screen is still not responsive but assembly screen can work, that is the problem. After installing the iPhone black touch IC, check whether the resistance of C1577 is normal, because it goes into IC, and it is surrounded by grounding pins. If the current is directly loaded onto 500mA, most of them are caused from here.

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