跳至主要内容

Fixed: iPhone 7 Plus No Service


After iPhone 7 Plus is inserted into the SIM card, the search state is displayed all the time, and there is no IMEI at dialing 06. Check the settings on iPhone with IM and Modem firmware numbers. After reset, the problem of iPhone network setup still exists.

If you encounter the same fault, don't flash the iPhone first, if the iPhone baseband CPU has some problem, then it will report unknown error 4013 on iPhone 6S and above, for 7 and 7P, we need to notice iPhone baseband 1.0V power supply circuit. If iPhone baseband power supply is short circuit, then basically it's caused by damaged iPhone CPU, so we need to measure the resistance for this circuit before we start to repair. For an iPhone with an iTunes 4013 error, we can heat iPhone baseband power, and then flash it.


Insert the WUXINJI Dongle on computer, and then compare with the iPhone schematic diagram and iPhone motherboard bitmap to measure the iPhone circuit line power supply. After measurement, all power supply on the iPhone baseband power tested are normal, we need to re-install the iPhone baseband CPU.

Since it's very close to main CPU, we need to do a heating insulation for the CPU. Use QUICK 861DW hot air rework station to heat iPhone CPU for a while, and then use BGA graver to gently remove the glue. We can remove the inductor on the right side fist and then insert the blade, or we can insert the blade in the slot，we'd better choose the thin blade. When heated it with hot air gun, we blow from the side of the CPU to the card slot. When we need to pay it, we can select a component around the baseband as a reference, and when the tin of reference begins to melt, we can start to pry into the baseband. 


There are many empty on the iPhone baseband CPU, observe it under the microscope, and then compare it with iPhone bitmap, there are many pins missing. Apply some lower temperature solder paste on the solder pad, and then soldering the iPhone baseband CPU with solder paste and glue, install it to the iPhone motherboard. After the iPhone motherboard is cooled, use digital multimeter to test whether the peripheral components short-circuit, so you can determine whether the chip has been installed intact.

We choose turn iPhone on by DPS DC powersupply at the first time, after everything is okay, install the iPhone, and then test the iPhone. This iPhone 7 Plus is a baseband failure caused by the iPhone baseband CPU virtual weld, after re-weld it, the fault has been solved. 

Get more mobile phone repair tools and skills on www.vipfixphone.com

评论

发表评论

此博客中的热门博文

Solution: iPhone X Won't Turn On

According to the customer's description, the iPhone X would not turn on after it drop accidentally. Then the cell phone reports error 56 when restore it. How did this happen? Let's test and repair step by step. Since iPhone X motherboard 2 layers are connected through the middle column, the solder points are very easy to get dropped. so we guess that the solder points from NFC chip to the CPU part have fell off. Disassemble the iPhone X by iPhone opening tools , remove the upper board off the main board, when separate the main board we see there is a row of points have fell off. Check the location map on WUXINJI dongle , it is surrounded by a ground wire, in fact, there are 6 useful points dropped. The ground wire does not need to be filled, the 6 useful points are added by professional phone welding tools. These are the signal wires of the NFC chip, so the iPhone X would report error 56. Then the tin of the middle column is repaired by iPhone X BGA reballing ste...
发表评论
阅读全文

iPhone 6 Display Failure after Replacing LCD

The iPhone 6 display is black after replacing LCD. After checking, the diode data of display socket is normal and all power supply for iPhone display IC  output is normal. Testing by  DC power supply , we find the iPhone current is abnormal. When press the iPhone power button, the boot current is obviously large. The current reached 100mA when press the power button. After remove the display tube, the current still the same, which means there is a short circuit. Measure the voltage output of each circuit of power supply with Fluke 15B+ Digital Multimeter , then surprised to find that there are really short circuit places. LD010 is short circuit; we suspect that the filter capacitance on the circuit has been penetrated. After remove the iPhone power control IC , we found it is ground short circuit. Open the WUXINJI Dongle  to check the iPhone schematic circuit, we found that this circuit is the display card image transmission MIPI data bus power supply. CPU brea...
发表评论
阅读全文

Solution: Why iPhone X Voltage Keeps Jumping

After getting the iPhone X motherboard to test, we observe the current value repeatedly jumps between 0mA and 50mA on DC power supply , and it is different from the normal booting current. Next, test whether the power supply of every circuit is normal. PP_VDD_MAIN is measured 4.2V; PP_VDD_BOOST measured is 4.2V. PP1V8-ALWAYS is 1.8V, all the values are normal. But when testing PP1V1_S2, PP0V8_SOC_FIXED_S1, PP1V8_S2 and other circuit voltage that output by power chip U2700 voltage are jumping constantly. According to previous experience, voltage jump is usually caused by a power supply circuit of U2700 output. Measured with digital multimeter , there is no short circuit was found for the dipole value of all power supply to ground. We repaired iPhone 7P before and know that if crystal oscillator is false welding can also cause voltage jumping, And if iPhone CPU  power supply is abnormal also can cause voltage jumping. Check the crystal oscillator we find no problem, then check th...
发表评论
阅读全文