iPhone 5S can’t receive calls, the real solution is here!

No matter what electronic products are repaired, the first step is to understand the structure of the machine, and then differentiate the faults. For example, Apple iPhone is divided into two main parts:

1. AR part is the boot part.

2. BB part is baseband part, which belongs to the phone call part.

Now the fault of this iPhone 5s is it can boot, just sometimes it can call out, but can't receive calls. We can determine the fault is in the baseband section and then start measuring.

1. Enter *#06#, we can see IMEI number, which means the baseband has no problems.

2. The problem of reception and launch is generally RF power supply.

3. We can detect the SIM card, which means receive part is normal, now we need to test the launch part.

4. Open the schematic diagram, and then find the RF power supply IC U11_RF. As shown in

picture 7-7-1 and 7-7-2.

Find this chip on iPhone 5s motherboard, as shown in picture 7-7-3.

Measure the power supply and output of the chip with multimeter. Fist we measure the PP_BATT_VCC_CONN on C1215 capacitance, it has a voltage. But PP_PA has no output voltage, so we suspect the RF chip is damaged.

This chip can be replaced or directly connected (solder the jump wire between two pins under the stereo microscope). As shown in picture 7-7-5 and 7-7-6.

After soldering jumpwire, assemble the iPhone 5s and test it, everything is normal.

Repair guide for iPhone 5S shows unknown error 40 when restore IOS

There are many iTunes error code, each error code has different meaning, it means there's something wrong with your iPhone. Today, we will share how to fix iTunes error 40 on iPhone 5S. When we restore the IOS firmware of iPhone 5S, it failed and shows iTunes error 40.

Different computer may have different circumstances when root it, this is because of computer system software and other issues. We root iPhone 5S again, we found that when the progress bar goes about one tenth, as shown in picture 7-16, it reports error 40. 

 

As our experience, when the progress bar goes about one tenth, it reports error 40, which may be related to NAND FLASH. Next, remove motherboard and pry up NAND FLASH, as shown in picture 7-17.

 

Then, use JC NANDFLASH Test Fixture to test NAND FLASH, finding no series number in NAND FLASH, as shown in picture 7-18. Thus we know that the NAND FLASH was damaged.

 

Next, we need to replace the new NAND flash, as the series number is stored inside NAND FLASH, at the same time; we have to replace the series number too. Because the original NAND FLASH is damaged, I cannot know the series number from original NAND FLASH, so I have to search the series number through original motherboard IMEI.

Finally, after writing the series number, we root again and the rooting goes smoothly. The IOS of iPhone 5S can be update restore now.

Note:

The method of getting motherboard IMEI without touch any chips:

Remove a NAND FLASH from a workable motherboard and assemble it on the faulty motherboard to root. When the activation interface is shown, clicking the icon that resembles exclamation mark, we can see the IMEI. Now I can search the series number through original motherboard IMEI and write series number into the workable NAND FLASH, the operation interface is shown in picture 7-19.