Troubleshoot: No WIFI and Rear Camera unavailable on iPhone 6S Plus

Please protect your iPhone, don't let it drop. Why would i say that? Last week, we received an iPhone 6S Plus, which went through a heavy drop, and then the iPhoen wifi, audio, rear camera, volum, light sensor and card settings all has problems. It took a lot of effort to fix it, the repair process as follows.

 

First, use DC power supply to test iPhone, the iPhone can be turned on smoothly, but the large is abnormal. Get into IOS to test all iPhone functions.   

Card setting. Continue to test other functions, it is true that the front flex cable, audio key flex cable, and rear camera are all broken, so we have to replace all of the spare parts. (Tips: It will get card setting if iPhone CPU can't read WiFi address, even if the WIFI is removed, the result is the same, so it's very important to firstly fix the WIFI if you meet card setting fault in the future. )

The last fault we need to confirm is motherboard: card setting, bad WiFi, audio recording is not available, bad audio and leakage. Triggered with more than 300 mA current, which means it has problem. Now we should solve the fault one by one.

Since we can't get into the setup, so we take off the iPhone 6s Plus WiFi audio first. The result is the same. There are much solder points are dropped at the bottom of WiFi, it damaged very serious. 30 pin is still on the iPhone 6sp motherboard, but the value is measured with 0L (infinity), certainly it's not normal, so we are going to use QUICK 861DW to solder the jumper wire, and also do jumpers on the other disconnected parts.

The jumpers in this repair are easy to do. A tip for new repairman: It's better to leave more jumper outside if there is enough space, so you can extend wire even there are other issues existing.

After soldering jumpers, install the motherboard to test, there is no card setting. We had always thought that only WIFI was not good and that the card was set on the board, and the WIFI would not be stuck. Today, we can see it's same if iPhone WiFi IC is removed off, after intall WiFi, the signal is very weak, it seems that the board layer is broken again, direct solder  jumper wire to the opposite track. As shown in picture 1-1-4.

Now the signal is normal, and then another iPhone 6 plusaudio IC  can be replaced, the whole repair process is finish here!

At last, asssemble the iPhone, turn it on again, enter IOS, test all iPhone functions, all works well!

Here to get iPhone 6 no backlight fault solution

A customer sent us an iPhone 6 to repair, the fault described is that the iPhone touch screen is not displayed, but the screen is good and the iPhone motherboard can also work after the iPhone boot and the button is normal too.

First use DC power supply to measure the boot current on iPhone, the boot current is normal. Tilt the iPhone screen, we can see the Apple LOGO, which means the iPhone 6 is not no display but without the backlight.

Remove the iPhone motherboard and measure the resistance of display socket backlight circuit and backlight power supply by Fluke 15B+ Digital Multimeter, we found the data of backlight power supply only has 97, but the normal data is more than 400.

Take off the iPhone CPU shield to check the components near the backlight. After check it under the VGA Camera 7-45X Trinocular Stereo Microscope, it was found that the backlight diode had been burnt, and the big inductance also is cracked and discolored. In this case, the elements on the back light path should all be damaged, we need to remove all components and replace the new.

After replacement, turn on iPhone to test, now the iPhone screen displays normally, the repairs end!

Hardware FIX: iPhone 6S no service issue

The iPhone 6S has no service issue,  but the signal of cellular is normal. We also try to solve it by rebooting iPhone or updating IOS, all is failed. So we suspect that this iPhone no service fault is caused by hardware damaged.  Now, we need to use iPhone repair tools to fix it.

In general, there are two types of cell phone faults that have no service.

1. signal receiving part;
2. signal transmitting part.

The iPhone 6s has no service with sim card but it shows operator in the setting, which indicating that there is no problem on the signal reception, so we judge the fault is on the signal transmitting part.

The signal transmitting part is sent out from the RF IC chip through the 2G amplifier chip and then through the iPhone antenna switch chip.

In iPhone repairs, the 2G power amplifier failure probability is very high, so we replace the iPhone 6 2G amplifier U2GPA_RF chip by QUICK 861DW hot rework station and related professional repair tools, but the same failure is still existing, it seems that the 2G amplifier has no problem.

 Now we suspect that it is cuase by  RF IC U_WTR_RF chip damaged.  So we have to transfer previous judgement, and  we need to replace the iPhone 6S radio frequency IC U _WTR_RF chip. 

After replacment, we install the iPhone and test it, the signal is back to normal,  you can get the phone calls and messages smoothly.

Troubleshoot Tips: iPhone 6S Plus no sound issue

 We received an iPhone 6S Plus to repair, the issue is that there is no sound  when the iPhone plays music, but after insert the earpiece, we can hear sound. What's going on?  Here is the troubleshooting tips for it.

The first step is to judge the fault, if there is no speaker voice when playing music on iPhone, generally the fault is caused by iPhone audio amplifier chips. There are 2 Audio Power Amplifiers: U3700 and U3800.

Which chip is out of problem? The previous test has said that the vibration function is not normal. The vibration function is managed by U3800 chip. Therefore, we remove the U3800 chip to measure the ground resistance of the chip pad. It is found that the E7pin I2S_AP_TO_ARC_MCLK  ground resistance is infinitely great.

In WUXINJI schematic diagram, it is known that the signal passes through the R0921 resistance to the iPhone 6s Plus CPU.

In the measurement, it is found that the CPU solder joint is broken down to the R0921 resistance layer. It is not easy to dig the route on the plate layer, so we try to borrow the 12S_AP_TO_CODEC_MCLK signal of the audio IC chip, use QUICK 861DW to solder jumper wire from the R0920 resistance to the R0921 resistor.

After finish the above step, assemble the iPhone, get into IOS to test, now we can hear sound normaly from the speaker , the vibration and recording also works good. The repairs end!