How to fix iPhone XS Max Touch Not Work | Motherboard Repair

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In our daily life, your iPhone is easy to get touch function damaged. Sometimes it is because of poor quality screen, but sometimes it is caused by motherboard issue. Today we will show you how to troubleshoot and fix no touch motherboard issue. Hope you will like our sharing, and welcome to subscribe to us.

Step 1 Function Test

Boot up the iPhone XS Max and test, the touch function is not working.

Step 2 Diagnosis

Take off the motherboard and place the motherboard under the microscope. Use the multimeter to measure the diode resistance of the touch connector J5800. Both the touch connector pin 18 and the corresponding inductor FL5802 end are measured open circuit.

This is an INT signal from touch IC to the CPU, therefore, the reasons can cause no touch issue are: motherboard poor soldering, CPU poor soldering or touch board failure. In order to confirm the problem, the bottom motherboard layer INT signal line and upper motherboard layer CPU signal line need to be troubleshot.   

Step 3 Troubleshoot

Separate the motherboard for further troubleshoot. The bottom motherboard layer INT signal line is measured normal, we can therefore rule out the touch board failure.

The upper motherboard layer CPU line also measured normal, so the no touch issue is not caused by CPU poor soldering.

Therefore, we can tell the touch failure is caused by motherboard layers poor soldering

Step 4 Repair

Put the motherboard bottom layer on the heating station, add solder flux, then align and heat the motherboard.

Step 5 Reassemble and Test

Install the motherboard, boot up the iPhone XS Max and test. Touch function works properly, repair completed.

Please refer to below detailed video:

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Tools and Materials Used in This Video:

Spudger

Motherboard fixture

DC Power Supply

Heating station

Microscope

Tweezers

Solder flux paste

PCB cleaner

Cleanroom wipe

Multimeter

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