Fault Description: iPhone 7 happens broken seriously and caused to cannot be turned on.
Meanwhile, during we check it, we found that the screw posts fell off. But we check the current, which shows the motherboard works well, so we need to check other place.
First, try to power up, we found a large current leakage, and continue to test by digital multimeter , we know the 3V power supply short circuit. Observe seriously, the motherboard card slot position is bent, and the short circuit may be in this position. Remove the two capacitors next to the NAND flash by QUICK 861DW Hot Air Rework Station and power on, the phone turn on normally.
Test function after turned on, we found no Wifi, sometimes stuck when enter the settings. When check, the Wifi clock signal R0807 end has 1.8V, the other end through the Wifi module 17 pin have no voltage, we replace the resistor, but the fault remains. Remove the iPhone Wifi IC, the soldering pad drop the point.
Originally, we plan to turn on phone without install the Wifi module, and test its function. But there is leakage when power-up, we have to apply rosin. After removing the heating capacitor and test, the setting function is normal, no longer stuck, next install the WiFi module.
After the installation, test again, WiFi appears, and the problem of stuck setting have been solved, but sometimes appeared restart. Considering that the middle position of the motherboard occues bent, the iPhone Audio IC will cause a restart phenomenon, so we have to disassemble the audio. After replanted fly line, all functions tested normal. The next step is to change the match.
Replace the iPhone fingerprint flex cable on the phone. Then install the repaired motherboard, test function after turned on, all function recovers normal, phone fault repair end.
Thursday, December 13, 2018
Solutions for iPhone 6S Plus No Service
Fault Description: iPhone 6S Plus happens no service when insert the SIM card.
While the attached file described it is possible to be caused by the WiFi failure, cause he did the repair work before by himself. Meanwhile, we have tried to insert the SIM card, it is true like he said.
So here comes the question, we need to continue the testing. Following the test process.
Continue testing, the signal is normal when you turn on 4G in Cellular Data, it can connect to the 4G network. It's normal to make phone calls and browse the Web，but the signal is bad. Turn off 4G, and then choose 3G and 2G, both of them are showed no service.
The 4G signal can be searched normally, but 2G and 3G are no service, we suspected that the fault should be an iPhone antenna switch or a 2G amplifier.
Is it an error in the antenna switch frequency selection? We decided to replace the antenna switch and test it. After remove the antenna switch, use digital multimeter to measure the diode data, we found the 21th PP_2V8_LD014 power supply of the ULASM_FR antenna switch is grounding short-circuited.
Open the WUXINJI Dongle to check the iPhone schematic diagram, we found the PP_2V8_LDO14 is connected to many places, one of them was sent to the filter U_VOX_RF next to the iPhone WIFI IC.
Measuring the diode data for all the power supply of filter, we found there are several power supply circuit are short-circuited.
According to the description of the customer, we judged that the fault is that the tin ball of the filter next to the iPhone WIFI IC was burned when he repairing the iPhone WIFI IC.
Use QUICK 861DW hot air rework station and Titanium Alloy Tweezers to remove the U_VOX_RF directly，and then turn on iPhone to test, now the 2G, 3G and 4G signal can be searched normally, and the signal tested is normal.
After re-installing the U_VIX_RF, all functions are normal, the repairs end!
While the attached file described it is possible to be caused by the WiFi failure, cause he did the repair work before by himself. Meanwhile, we have tried to insert the SIM card, it is true like he said.
So here comes the question, we need to continue the testing. Following the test process.
Continue testing, the signal is normal when you turn on 4G in Cellular Data, it can connect to the 4G network. It's normal to make phone calls and browse the Web，but the signal is bad. Turn off 4G, and then choose 3G and 2G, both of them are showed no service.
The 4G signal can be searched normally, but 2G and 3G are no service, we suspected that the fault should be an iPhone antenna switch or a 2G amplifier.
Is it an error in the antenna switch frequency selection? We decided to replace the antenna switch and test it. After remove the antenna switch, use digital multimeter to measure the diode data, we found the 21th PP_2V8_LD014 power supply of the ULASM_FR antenna switch is grounding short-circuited.
Open the WUXINJI Dongle to check the iPhone schematic diagram, we found the PP_2V8_LDO14 is connected to many places, one of them was sent to the filter U_VOX_RF next to the iPhone WIFI IC.
Measuring the diode data for all the power supply of filter, we found there are several power supply circuit are short-circuited.
According to the description of the customer, we judged that the fault is that the tin ball of the filter next to the iPhone WIFI IC was burned when he repairing the iPhone WIFI IC.
Use QUICK 861DW hot air rework station and Titanium Alloy Tweezers to remove the U_VOX_RF directly，and then turn on iPhone to test, now the 2G, 3G and 4G signal can be searched normally, and the signal tested is normal.
After re-installing the U_VIX_RF, all functions are normal, the repairs end!
Wiser Mind for iPhone 6 Flickering Issues
The next one, iPhone 6, it is a perfect machine, at least i think so, while i have used many models iPhone, but i like this one, only.
Anyway, as a phone repair shop, we need to fix everything we need on phone problems. According to the attached file, we know there happens a flickered faults, so we need to disassemble it and check the IC.
Well, we need to test it again. Connect to the DC power supply, the screen flickering as before described. According to past maintenance experience, the problem of iPhone multi-touch usually resulted from signal interference or unstable touch screen IC power supply.
Use Fluke digital multimeter to test the power of PN5V7_SAGE_AVDDN, PP5V7_SAGE_AVDDH, PP5V1_GRAPE_VDDH on the touch screen controller IC and touch screen processor IC, the voltage is normal.
Then we measure the diode value between the coupling capacitance of the touch screen control U2401 and the touch screen control IC U2402 . It is still normal.
Judging from the customer's description, we conclude that the fault may be related to the replaced touch screen IC itself. According to our experience, touch diseases caused by the touch screen controller IC will cause the touch to not work.
Although a faulty touch screen processor IC will only result in a partial unresponsive touch. Therefore the touch processor may be the faulty part. We remove the touch screen processor IC with YH898D soldering station and replace the new one.
To our surprise, when we test the iPhone after the replacement, the fault still exists. We guess that there is only one type of interference that can cause such touch of the disease - some kind of high frequency signal. The NFC IC next to the touch screen processor is most likely because the high frequency signal it outputs interrupts the normal operation of the touch screen IC.
Next step is to replace and test with the new NFC IC. Great, the fault is cleared thoroughly.
Anyway, as a phone repair shop, we need to fix everything we need on phone problems. According to the attached file, we know there happens a flickered faults, so we need to disassemble it and check the IC.
Well, we need to test it again. Connect to the DC power supply, the screen flickering as before described. According to past maintenance experience, the problem of iPhone multi-touch usually resulted from signal interference or unstable touch screen IC power supply.
Use Fluke digital multimeter to test the power of PN5V7_SAGE_AVDDN, PP5V7_SAGE_AVDDH, PP5V1_GRAPE_VDDH on the touch screen controller IC and touch screen processor IC, the voltage is normal.
Then we measure the diode value between the coupling capacitance of the touch screen control U2401 and the touch screen control IC U2402 . It is still normal.
Judging from the customer's description, we conclude that the fault may be related to the replaced touch screen IC itself. According to our experience, touch diseases caused by the touch screen controller IC will cause the touch to not work.
Although a faulty touch screen processor IC will only result in a partial unresponsive touch. Therefore the touch processor may be the faulty part. We remove the touch screen processor IC with YH898D soldering station and replace the new one.
To our surprise, when we test the iPhone after the replacement, the fault still exists. We guess that there is only one type of interference that can cause such touch of the disease - some kind of high frequency signal. The NFC IC next to the touch screen processor is most likely because the high frequency signal it outputs interrupts the normal operation of the touch screen IC.
Next step is to replace and test with the new NFC IC. Great, the fault is cleared thoroughly.
Solutions for iPhone X 4013 Errors
While iPhone X has been out of warranty, we have received more and more iPhone X. Today, we will talk about how to fix iPhone X 4013 errors after water damaged.
The first step we need to do is to restore the data, then we boot it normally, but we found there reports an unknown error 4013, same with the file description.
So we have to quit it and use the professional tools to disassemble the iPhone, and connect it to DC power supply to check the iPhone current. The iPhone X can enter the IOS system when the iPhone screen isn't connected, and the iPhone can be turned on smoothly when the front receiver flex cable isn't connected.
Observe the iPhone display screen under the Stereo Zoom Microscope, we found the iPhone receiver has the trace of the water.
Remove the front receiver sensor flex cable, we found the photosensitive lens also has the traces of corrosion. Use QUICK 861DW rework station to separate the light sensor, the solder pad has been corroded.
Handling the corroded solder pad, apply the tin, and use green UV oil to cover the area where the copper is leaking, and then install the light sensor back to the solder pad.
Assemble the iPhone and test it, the iPhone is turned on successfully, and it can enter the IOS system properly, the functions tested are normal, the light sensor is normal, the Face ID is normal.
Summary: this failure is caused by the short circuit of the corroded iPhone X front receiver light sensor, and then caused iTunes unknown 4013.
Wednesday, November 14, 2018
How to fix iPhone 6P Wi-Fi turn on failure
The iPhone 6 Plus WIFI switch won't turn on after dropping, which means the iPhone WIFI function can't be used, we need to repair it.
Power on iPhone 6 Plus, get into IOS to test iPhone, all function works good, except iPhone WIFI, the iPhone WIFI icon can't be turned on.
First, use phone opening tools to disassemble the iPhone 6 Plus, remove the iPhone display assembly, disconnect the iPhone battery, and then take out the iPhone motherboard.
Put iPhone motherboard under the Stereo Zoom Microscope to observe, we found the iPhone WIFI IC has some problem.
Use QUICK 861DW hot air rework station to heat the iPhone WIFI IC, and then use tweezers to remove the iPhone WIFI IC, there are 18 pieces pin are missing, one of them is an empty pin, no need to fill.
Clean up the solder pad, and then use fill the missing pins, apply some green UV oil to those pins, use UV lamp light to solidify them.
Pic 1
Now, install the iPhone WIFI IC to the iPhone motherboard, and then assemble the iPhone motherboard.
Finally, power on iPhone, test the iPhone WIFI function, the iPhone 6 Plus WIFI switch is turning on smoothly and the iPhone WIFI function works perfectly.
How to fix iPhone 7P turn on failure
Fault Description: iPhone 7P can't be turned on while the charging current shows 200 mA
We disassemble the battery, use the latest iPower DC power supply cable to detect the charging current, but we found it still keeps jumping, connect to the LCD screen, no any display shows.
Next, disassemble the machine and connect DC Power Supply, we find no current. There is no leakage on the front side, triggering a large current, which reaches 1.9A. Then, it’s easy to spray rosin to power on, current appeared.
When we saw this, we all feel frustrated. Does the main power supply has failed? We decide to open the circuit diagram. And open the hot spot, we find there is the NAND flash power supply. Test whether there is a short circuit in the NAND flash! Without surprise, the fault from here after testing with digital multimeter. Because the 6s machine has many problems, what can we referred to is NAND flash at first. Click a few points, we thought this point probably have fault, and measured it, it is the fault one.
The next step is simple. Use the iphone Scraper to remove the power supply capacitors around the NAND flash. Plaster on rosin, adjust the current meter to 3V and operate directly.
We found this capacitor shorted and use the crowbar to open it.
Then test it ,we found that there is no short circuit.Turn on and test the battery's electric light is shine. Put it on the activation board and add some power, then turn it on again.
There should be no problem here, we should notice: it is not necessarily that the hot one fault. I think that many people will move the main power supply when repair this iphone. But my advice is to check the circuit diagram with WUXINJI Dongle to test if the power supply is short-circuited. Such short-circuits outside often occur. Many of the first pictures are short-circuited by the main power supply itself.
We disassemble the battery, use the latest iPower DC power supply cable to detect the charging current, but we found it still keeps jumping, connect to the LCD screen, no any display shows.
Next, disassemble the machine and connect DC Power Supply, we find no current. There is no leakage on the front side, triggering a large current, which reaches 1.9A. Then, it’s easy to spray rosin to power on, current appeared.
Picture 1
When we saw this, we all feel frustrated. Does the main power supply has failed? We decide to open the circuit diagram. And open the hot spot, we find there is the NAND flash power supply. Test whether there is a short circuit in the NAND flash! Without surprise, the fault from here after testing with digital multimeter. Because the 6s machine has many problems, what can we referred to is NAND flash at first. Click a few points, we thought this point probably have fault, and measured it, it is the fault one.
Picture2
The next step is simple. Use the iphone Scraper to remove the power supply capacitors around the NAND flash. Plaster on rosin, adjust the current meter to 3V and operate directly.
Picture 3
We found this capacitor shorted and use the crowbar to open it.
Picture 4
Then test it ,we found that there is no short circuit.Turn on and test the battery's electric light is shine. Put it on the activation board and add some power, then turn it on again.
Picture 5
There should be no problem here, we should notice: it is not necessarily that the hot one fault. I think that many people will move the main power supply when repair this iphone. But my advice is to check the circuit diagram with WUXINJI Dongle to test if the power supply is short-circuited. Such short-circuits outside often occur. Many of the first pictures are short-circuited by the main power supply itself.
How to fix iPhone 8 no boot fault
Fault Description: iPhone 8 can't boot though it is showed power on
After we got this phone, we use the DC power supply to charge it, but we found that the current is 250mA when the iphone 8 is powered on, then goes back to 0 and continues to cycle. Based on past repair experience, we judged that it is related to the USB charging part.
The way to disassemble iphone 8 is similar to the 7th generation. Using the HYT 888D ESD digital desoldering station to disassemble the motherboard, we found that the counterparts have soldered the charging part, while the 8th generation U2 (6300) is still located at the bottom right of the NAND flash, which is not common with previous models.
Picture 1
Picture2
Remove the U2 with desoldering tool, and use Fluke digital multimeter (VC712) to measure the pad resistance, there is no any abnormality. when the machine powered-on, the current is also normal without U2. Replace the new iphone U2 chip and test machine, we found that iphone can enter the system. And then insert the charger, iphone can not trigger the boot, and can not charge too.
After we replaced the iphone 8 tail plug flexible cable, the problem still existed. Then we measured that the 5V power supply from the charger, which was different from that of the previous generation. There is no Q protection tube, and the tail plug is directly sent to the U3300 charging tube.
Picture 3
We use the digital multimeter measure the voltage has been sent to C3301. Is it because the faulty charging tube resulted in no voltage output? We have to remove the U3300 charging tube and measure the foot with normal resistance. The U3300 chip is also different from previous models. Replace the new iphone 8 IC and test the current have recovered normal when power-on. There is a voltage of 4.2V on the electronic carrier, and the retesting machine is restored to normal.
Summary
The fault that this iphone 8 can not boot is caused by the charging part. When we encounter an iphone with a charging fault, we could eliminate the external distribution at first and then test the line to judge the cause of the fault.
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