Apr 29, 2020
iPhone 6s comes with a high-temperature warning screen after turning on. Usually the problem is caused by excessive running apps. Yet in our repair guide today, we are working with logic board repair. After current detecting and rosin detecting, we can confirm that the problem was caused by damaged capacitors inside the WiFi module. With our repairing experience, we adopt a new repair solution to fix the issue.
We got one malfunctioned board from a client. First thing we do is to get the logic board mounted on the phone. Then buckle the display assembly and power on. The phone turns on with normal display.
Yet, with the phone running for 3 minutes, the screen suddenly dims. And a high temperature warning screen appears. The phone then goes with black screen.
Disconnect the battery. Connect the logic board with DC Power Supply and power on. Current reading on the ammeter is abnormal and the phone keeps restarting.
Pre-judgment: abnormal boot current causes the logic board burning issue which results in high temperature warning screen on the phone.
Remove the display assembly and take out the logic board. Touch the logic board with the spare hand. A sensation of burning can be experienced on area from the power chip to WiFi module. So we can confirm the possible fault area now.
Since some components are located under shielding cover, we need to remove the shielding cover with Hot Air Gun first. Then we need to confirm the specific fault position with ‘rosin detecting’. Use Soldering Iron to smoke rosin on components of the burning area. Make sure all associated components are covered with white smoke.
Tips: Since the phone keeps restarting as powered on with power button, we can turn on the phone by battery triggering.15s later, rosin on the WiFi module starts to melt. We can confirm the fault component as WiFi module.
Burning issue of components inside the WiFi module can be related to capacitors inside the WiFi module or chips inside the WiFi module. Traditional repairing method is to replace the WiFi module and detach the NAND flash chip from the logic board. Then have the WiFi unbound.
Based on repairing experience, two capacitors are located right under the rosin melted position. The fault was caused by the two capacitors. We will adopt a new repair solution today. Confirm the rosin melted position on surface of the WiFi module at first. Then scrape off the specific surface and heat with Hot Air Gun at 330℃ for 5s. Pry up the capacitors with sculpture knife.
Once done, stick high temperature adhesive tape on the WiFi module for insulation.
Reassemble And Test
Get the logic board assembled and buckle the display assembly. Connect the logic board with DC Power Supply to power on. Current reading on the ammeter is normal this time and the phone stops restarting. The logic board also does not burn.
Continue to test WiFi function and all going well. Fault cleared.
Visit our online shop for more parts and tools.
You can also visit REWA YouTube Channel to check our video and learn how to repair the iPhone 6s overheating issue step by step.
Apr 23, 2021
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