Step by step to fix iPhone 6 screen blurry fault

An iPhone 6 show a variety of blur screens after booting, the backlight slowly darkens until the black screen. When we received it and check it, it's not dropped and water damaged. We judge the fault is in the iPhone screen circuit and the touch circuit (sometimes a zebra stripe appears after booting).

According to the common problems, directly replace the U2402 deputy touch IC and U1501 screen power supply IC, the fault still exists. We have to repair it step by step, now we open the WUXINJI circuit diagram, as shown in picture 1.

Use Fluke 15B+ Digital Multimeter to measure the J2019 screen connector socket power supply, reset, open and bus, all data is normal. Then we try to remove the U2402, but the problem still the same, the repairs falling into slow rhythm. Remove the U1501 screen power supply IC, and measure the diode data of power supply, reset, I2CO bus, all is normal, directly replace it, the problem still the same. The repairs again turn into the slow pace. Is the iPhone 6 CPU dead? Measure the CPU power supply, it is normal. Measure the power supply and diode data of EPPROM IC PP1V8 and I2CO bus, all is normal. What can we do now?

Continue to repair, focus on the reasons for the slow black screen. Check to see if the PP1V8, +-5.7V, I2C2 and MIPI power supply is working properly when they fade away. Quickly measure the signal that over the J2019 when turn on iPhone, we found that the voltage of -5.7V will continue to drop during the black screen until about 0.7V, other power supply signal is normal.

-5.7 is controlled by U1501, U1501 has been replaced by two, so we can eliminate its problem, now the focus has just been on the working conditions of the U1501 display power supply IC.

After close the screen, U1501 -5.7V slowly pulled down, +5.7V is not pulled down, after remove the all -5.7V filter capacitor, the problem still the same. Check U1501 peripheral circuits, the measured resistance of CHESTNUT internal charge pump circuit (step-up 6V) that was made up of C4 and E4 pin is normal, when close the screen and supply power on it, this voltage will jump, the problem is finally found. Remove the C1554, we found that the both side solder pads were all dropped after they were heated with MFC IREWORK Heating Platform, this position is difficult to weld the jump wire or mend the solder pads.

After thinking twice, we directly remove the UF31 screw column and U1501; soldering the jump wire from C4 and E4 pin, move the step-up capacitor near the flash chip.

Summary:

May be the user was dropped the iPhone during the use and then caused the C1554 solder pad and layer line is in contact with the bad state. The resistance is normal under no boot state, but when connect the load due to the boost part of the current is very large, excessive load leads to -5.7v output instability.  The picture of the repaired iPhone 6 is as follows Picture.

Solved: iPhone 7 won't boot and almost dead after dropping

Recently, we received one dropped iPhone 7 and one iPhone with iCloud lock from our customer, the customer describes the iPhone 7 was dropped, which without iCloud, but it doesn't boot. The customer wants us to fix it, and then change it to the iPhone which with iCloud lock. But now, we need to fix the dropped iPhone first.

After checking, the iPhone is hurting a lot by a serious drop. The screws on motherboard have been dumped, as shown in picture 6-3-1.

Connect it to UD 1505TA DC power supply first, it shows large current leakage. After measuring, we found the iPhone NAND flash 3V power supply was short circuit. After observation, we found the iPhone motherboard slot position is bent; the short circuit may also be in this position. After remove the two capacitors, which on the side of the NAND flash, detecting it again with DC power supply, now it can be turn on normally.

Turn on iPhone and test functions on iPhone, we found there is no WIFI; sometimes it will be stuck when into the settings. After measuring with Fluke 15B+ Digital Multimeter, the side of wife clock signal r0807 has 1.8V, the other side which is through to wifi module 17 pin has no voltage. Replace the resistance, and weld the jump wire by QUICK 861DWrework station, the fault is still exist. Decisively remove Wi-Fi module, and then the solder pad drops points, it is common in the iPhone that dropped, weld the jump wire first, as shown in picture 6-3-3.

 The WIFI module also drop points, we can check it under the 7-45X Trinocular stereo microscope. We want to test functions by turn on iPhone without installing Wi-Fi module, but when apply power on it, it's leaking again. Now, we need to use the rosin methods to fix it.  After remove the heating capacitor, power on iPhone and test it, the setting function is normal now. Next we need to install WiFi module, after finish it, test the function, the Wi-Fi is back to normal. However, sometimes it restarts automatically.

Considering there is a slight distortion in the middle of the iPhone motherboard, the audio can cause a reboot, so we remove the audio first, also drops points. After soldering jump wire, turn on iPhone and test it, all functions is normal now.

Now we need to replace external configuration. Use JM-P01 Essential Electronics Toolkit to disassemble the iPhone that with iCloud lock, please be careful not to break the line of the iPhone. Then replace the fingerprint that on the iPhone screen, because the under of fingerprint have glue, so please be careful not to damage the IC.

Finally, install the repaired motherboard, assemble the iPhone, turn it on and test it, now all is normal. The iPhone 7 has been repaired!

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 earpiece no sound and no display issues

Received an iPhone 6 from customer, the fault described is just beginning the earpiece no sound, then not boot and iPhone screen shows black.

 

Connect it to DC power supply and boot, we found the current jumps normally, but the iPhone screen not display. After we connect it to computer, it prompts "please click on the device to trust".

Now we can judge that the iPhone 6 can boot, just the iPhone screen no display. Disassemble the iPhone and measure the resistance of the display socket; the diode data of the screen reset and open signal are all abnormal. Observe it under the microscope, we found the trace of the hitting on screws which on both sides of the left and right. Remove the iPhone screws, scrape it, and then solder the jump wire on it with soldering station, now the iPhone can display normally. Because diode data of fingerprint socket which on the right screws are normal, so we didn't scrape it.

After testing, it can record, playing a sound, the earpiece has no sound. Use multimeter to measure the diode data of iPhone front camera socket earpiece pin, the data is normal. The earpiece pin is through the inductor directly to the audio IC. Remove the iPhone audio IC, and then measure the diode data of I2S bus which is through to CPU, we found both the CODEC_TO_AP_XSP_I2S2_DIN and AP_TO_CODEC_ASP_I2SO_DOUT are infinitely large, it is open circuit.

Find an iPhone motherboard to scrape it to check the line layout, scrape and ended up on the third floor of the right screw column.

Mend the wire and put it back into the chip. Assemble iPhone and test it, earpiece back to normal, the repairs end!

Simple ways to fix iPhone 6S cannot turn on after dropping

An iPhone 6S dropped and then it doesn't boot. Disassemble the iPhone with phone opening tools, and then put it connects to DC power supply, it shows big short circuit. After measure it, we found the PP_VCC_MAIN is short circuit. Many of dropped iPhones PP_VCC_MAIN filter capacitor will be short circuit.

Remove the iPhone motherboard, and observe it under the microscope, we found the capacitance C5283_RF next to iPhone WI-FI chip turned gray, it differs greatly from the color of the capacitor next to it. This capacitance is the filter capacitor of PP_VCC_MAIN.

Now we directly remove this capacitor, and measure it again with multimeter, the resistance value is back to normal. As shown in picture 2.

Connect it to DCpower supply again, and boot it, now it shows normal, the iPhone 6s can be turned on. The repairs end!

Excellent solution for iPhone 6S home button not working

Customer sent an iPhone 6S to us, the fault phenomenon is that the iPhone home button is not sensitive and fail frequently. Get into IOS system to test it, the fingerprint function is normal. Sometimes the iPhone home button needs to be pressed several times before it can respond; we suspect there's a problem with the shrapnel button behind the fingerprint key.

Disassemble the iPhone by phone opening tools, then replace the fingerprint button and test it, now the home button function back to normal, so we exclude the iPhone motherboard error. Remove the waterproof adhesive covered by the shrapnel button, which is behind the fingerprint button. Put the multimeter on the corresponding pins, press the switch and test it, the data is normal, so we can eliminate the problem of the switch itself.

Put it under the phone repari microscope and observe it carefully, we found a rift in the edge of the line, pry the iron sheet off the power button, scrape the line, we can make sure it is disconnected. Solder the jump wire with phone rework station, this fault is resolved.

Before we pry the iron sheet, we need to clean up the solder tin in the red circle first by suction tin wire. If you don't clean it up, and directly pry it, it's easy to break the line again. Scrape the line with a sharp blade and gently scrape it, because the line is very thin, the blunt blade is easy to scrape off the line.

After the scrape, solder the tin on the pins. Find a thin copper wire and apply the tin, and then align them, heating the copper wire, finally you can fix it.

After soldering the jump wire, paint some green UV oil on it, fixed it with a UV lamp light, and then install the iron sheet in the same place. Welding the solder tin on the corner to fix it, and apply green UV oil to the edge position to fix the iron sheet.