Troubleshoot: iPhone 6 Home button return function failure

We received an iPhone 6 to repair, the prblem of this iPhone is the home botton doesn't implement the return function effect, which means the iPhone home button not working.  We need to fix it!

After checking, we've ruled out external issues, we excluded the peripheral accessories issues and decided the problem is on the iPhone motherboard.

Use multimeter to measure whether the iPhone motherboard fingerprint socket J2118#3 pin has resistance, the data is normal. When measure the voltage, we found the BUTTON_TO_AP_MENU_KEY_L_CONN only has 0.6V, it is obviously been pulled down, the normal voltage is around 1.3V. You can check those pins on phone circuit diagram.

R0313 starts with 392K, now we change it to 10K resistance, and then measure it again, we found the voltage reached 1.4V, almost normal. So we assemble the iPhone and test it, we found it's still no return function after we install the fingerprint button. However, when we use tweezers to press the J2118#3 pin ground, it can return. We suspect it is a fingerprint key problem.

After measuring, we found there is a 20K current limiting resistance on the BUTTON_TO_AP_MENU_KEY_L_CONN of fingerprint key. Decisively remove that resistor, and then use the phone soldering station to directly short connect them. 

After finish the above steps, use phone screwdrivers to install the iPhone, power on it,  enter the IOS system,  and test the home button return function, not it works perfectly.

How to fix iPhone 6 cannot boot—need retain data

The iPhone 6 doesn't boot, and the boot current is 700mA. We need to fix it without delete the phone data.

Repair Process

1. Disassemble the iPhone by phone opening tools, take out the iPhone motherboard. Connect it to DC power supply, the boot current shows 700mA, which means there is a power supply short circuit.

2. Open the phonecircuit diagram and check it, we can find that the diode data of PP1V8_SDRAM is low.

3. Measure the diode data the PP1V8_SDRAM with multimeter, the data only have around 100, it is lower than normal data.

4. According to the repair experience, this group abnormal power supply was caused by damaged capacitor at lower right corner of iPhone CPU. As shown in picture 9-13-5. We directly pick it off.

5. After remove it, measure the diode data again, now the data is back to normal.

Finally, assemble the iPhone and test it, now it can be successfully powered on and smoothly into the IOS system.

Troubleshoot: there is no service on iPhone 6

Customers sent us an iPhone 6 to repair; the faulty is that there is no service on iPhone 6. It's been repaired, but it's not fixed.
After we received the iPhone 6, we started checking the iPhone. We can't find the operator in manual condition. As shown in picture 8-3-1.

 Disassemble the iPhone 6 by phone opening tool, take out the motherboard, we can found that the colleague has been repaired RF parts, now we need to fix it step by step.

Let's start with the easiest. Soldering jump wire on U1、V1 pin, still no service. Because the colleague repaired too many chips, as long as the chip on the RFFE bus has problems, it will affect this. Remove all chips except 2G power amplifier on RFFE bus, the iPhone still no service. Then we replace the antenna switch and RF IC, the problem still the same. It seems that colleagues have amplified the problem.

Now we use multimeter to measure the power supply on RF IC U_WTR_RF, we found that the resistance at both ends of the R38808_RF resistor on VDD_XO_2V power supply is incorrect, one side it 438, the other side is 564. U_WTR_RF and R38808_RF in the circuit diagram position as shown in 8-3-2 and 8-3-3.

When we use multimeter Lead Probe to press it, it's back to normal, so we can judge that the resistance is virtual welding. Now we find the problem, so we solder it with soldering station. After finish it, we assemble the iPhone and test it, the signal was back.
Finally, we put the removed RF IC back in iPhone motherboard. The repairs end here!

 

Real solution for iPhone 6 reports iTunes error 9 56

 According our experience, after the iPhone drop into ground, and then it reports iTunes error 9 and 56 when we root it.  Most of this case is caused by disconnection from CPU to logic IC and NFC IC.  The main CPU chip and PCB board  has the bad connect after iPhone dropped, so the iPhone will shows situation of not boot or iTunes error code .

The iPhone 6 reports iTunes error 9,  disassemble the iPhone by repair toolkit, and check the line from logic epprom IC to CPU, there is a test point with false soldering.  Soldering jump wire directly from CPU to logic epprom IC. As shown in picture 1.

 

Scraping the CPU off slowly and find the signal point to solder jump wire. As shown in picture 2.

Soldering jumper on the position where the chip are connected, and the iPhone can be directly switched into the system after the connection is made up. After the customer go back for a few days, the device reported error 56 again, error 56 is caused by the broken wire from NFC to CPU or damaged NFC chip, firstly we remove the NFC chip. As shown in picture 3.

NFC chip is diconnected and most of solder points are dropped, it's all blank for the places without wire end, so soldering the useful two points with solder iron. As shown in picture 4.

Reload the chip, and then root it again, the iPhone 6 can work normally.