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iPhone 6 died all sudden, heats up under the back camera

We have a customer who drop his phone couple times and when he was using it one day it decides to die all the sudden, with a lot of heat come out from the back under camera lens and doesn’t matter how he reset the phone or plug into the computer, the iPhone 6 is still dead. He brought it to several repair places all getting quoted AUD $300+ for motherboard replacing, others reckon motherboard issues are not cureable. He really needs his data inside the iPhone so he came to us.

Is it true motherboard issues are not fixable? Of course NO. Sounds like a very typical iPhone 6 issue.

From what he told us, we suspect it could simply be a broken capacitor/ IC under the camera, causing the phone shortening all battery power to the ground, the reason why it turns off it self instantly before the overheating took place is most likely be caused by circuits linked directly to battery power.

Simple? Sounds like it!

First off, we pull the screen off, removed the battery. plugged the board directly into directly power supply. Damn instantly shortened. Lucky we have a short circuit protector built into the power supply.

We then removed the EMI shielding on the circuit board, sprayed some freezing spray onto the main circuit board components, to freeze the board down to -50 degrees, which makes it easier for us to find the overheating source.

Freezing Spray for mobile phone repairs - www.fixiphone.com.au

Freezing Spray for mobile phone repairs

Then plug the circuit board again into the power supply, but this time start with lower volts, slowly turn it up. At around about 1.9V, bravo we found the component that is overheating:

Location of U1502 Backlight Driver IC, overheats when damaged - fixiphone.com.au

Location of U1502 Backlight Driver IC, overheats when damaged

This is the U1502 aka backlight driver IC, it generates around about 17V for the screen backlight to light up, takes in directly battery power (VCC_Main circuits), if it is crack damaged, chances it will cause the whole phone to short out, which sounds like exactly what happened to the poor customer.

iPhone 6 U1502 Backlight Driver schematic, shows how battery power is converted to backlight power - fixiphone.com.au

iPhone 6 U1502 Backlight Driver schematic, shows how battery power is converted to backlight power

Before we go ahead with the U1502 replacement, 2 things all the repairers need to know:

1. check the circuit resistance of VCC_Main, the battery power circuit may be shortened than the Backlight driver itself.

2. If you have a UMT branded iPhone 6 motherboard, be ultra careful at temperature control when removing/installing. The UMT types of motherboard is ultra weak against heat/force and because the driver is right next to the CPU and glued down as well, you will have a ultra high chance of damaged CPU after repair end up having to replace/resolder the CPU.

iPhone 6 UMT motherboards are weak and vulnerable to heat. Causing many weird issues. - fixiphone.com.au

iPhone 6 UMT motherboards are weak and vulnerable to heat. Causing many weird issues.

 

Typical how physical damage can easily destroy UMT motherboards. - fixiphone.com.au

Typical how physical damage can easily destroy UMT motherboards.

Plug into power after the replacement, no sign of shortening or leaking anymore, Let’s turn it on, Job done! Time to test the rest.

iPhone 6 Backlight Driver Replaced! www.fixiphone.com.au

iPhone 6 Backlight Driver Replaced! www.fixiphone.com.au