iPhone 11 Repair Cases

Released 2019, September 20. The earliest users of iPhone 11 have used the phone for more than 2 years, and there are also more and more defects happens. In this article we gonna share some iPhone 11 repair cases, to see how the phones get fixed.

<Image: GSMArena.com>

Case 1. Keep Rebooting

Defect Phenomenon: after replacing the rear glass housing, reboot every 3 minutes. 

Repair Process:

Checked with client, the phone also get battery replaced before and the two layers of motherboard also has been rebonded. 

Check the cosmetic of the motherboard, the battery connector with poor soldering. Resolder it, the every 3 minutes phenonenon gone. But after using for a few hours, the phone reboot again.

Issue may caused by the connection between the two layers, try to rebond the motherboard, issue still unresolved.

Finally, based on the panicB report code, issue get resolved by replacing the charging port flex cable.

Case 2. No Charging

Defect Phenom: phone can not be charged after dropping damage.

Troubleshooting: No charging current when test with USB Current Analyzer

                         There is a crack damage sign on the side of the motherboard.

After taking it down, we can see there are many chips. Since the issue is no charging. So we can focus on the USB IC first.

Repair Process: Replace the USB IC (U6300) with a new one then test. The charging current back to normal.

No charging issue get fixed by USB IC replacement.

Case 3. Cannot start up caused by motherboard short

Get connected with DC power, with large current. The circuit is shorted.

Seperate the motherboard and measure the diode values on the main power supplies, the measured result is 0.

Normally we should use thermal camera + DC power supply to find the short components, but in this case it’s very lucky we find out the abnormal capacitor at the upper layer, take it off and the issue get resolved!

Case 3. Cannot start up after dropping damage

Received an iPhone 11 with very serious drop damage. No response when charge with the charger, take out the motherboard and try to start up, still cannot boot, and the current jump to 300mA directly then drop to 11mA.

Like this kind of phenomenon, based on repair experience it should be the NAND related part with problem.

Use the rosin inspection method, apply voltage power on the NAND power supply rails, when apply power on the PP2V63_NAND we can see the rosin on the capacitor C2619 get melted.

Remove the capacitor, then the issue get resolved perfectly.

 * Tips: 300mA —> 11mA, this is kind of short protection after iPhone 11 series. If you see the current curve like this, then it’s means there is a short on the motherboard.

Case 4. No service after dropping damage

Phone get drop damaged and with slightly deformation.

After separating the two layers of motherboard, we can see an inductor around the Baseband CPU get lost. Solder back an inductor with the same specification and test with fixture, the network function back to normal.

The asseble back the two layers of motherboard and test again, all functions are OK. 

The no service issue get fixed by an inductor (L402_K) replacement.

Summary

Above 4 cases are for your reference, most of the issues can be caused by small components missing or damaged by dropping. Be more careful and pay more patient to check the cosmetic and run rosin inspection method.

For more repair cases and theory course, you can visit REWA academy, join us to improve your repair skills.