Troubleshoot: iPhone 6 leakage when booting (200mA)

When booting iPhone 6, it's leaking 200mA. What's wrong? Check it and troubleshoot it!

Generally, if cell phone device is tested as 200mA electric leakage when booting, the first choice is to replace USB tube. Of course, this is not absolute, the iPhone 6 we are going to fix today is not caused by the USB tube fault.

First, we should know the leakage detection process:

We must test the function of system as possible we can in advance if we encounter the leakage, which will be repaired if any of the functions are tested abnormal, if all is normal, USB tube will be required to pay more attention. USB tube is also a problem, if it gets bad, the function will be normal and no problem can not be detected. If there is a electric leakage on the iPhone, you can first press the iPhone power button and loose to see how much the current will be. In the normal case, it is about one hundred. If it jumps to three hundred or four hundred, there must be electric leakage, and jump to two hundred or three hundred leakage is basically caused by several 3V: The 3v power supply of USB tube, the 3V of fingerprint and the 3V of compass.

Then, we start to repair 

Connecting the iPhone 6 with multimeter, the current shows 200mA. we directly replace a USB tube. The result is that the current is still in the 200mA position after waiting for a few minutes.

So we wonder if there is another fault symptom happened, the last repair technician mentioned the iPhone 6 fingerprint is not good.

When heard of this problem, we can basically judge where the problem is. Connecting multimeter and trigger the on-off current with 300-400 mA, this is not normal. There must be something wrong with the fingerprint 3V. Use the multimeter to test fingerprint 3V against the ground value, it is short. This kind of situation is generally caused by one of outside capacitance is short, dismantling it! Finally, we find out the C2133 is short circuit, pry it off with BGA Chip Remove Tool.

Finally,  reboot the iPhone 6 and retest the standby value is normal, and the fingerprint is also normal now.

4 steps can fix iPhone 6 Plus LCD no display CPU issue

Received an iPhone 6 Plus need to repair. The iPhone 6 Plus LCD screen has no display and no light, it changed the kit before. Now, we need to solve this problem step by step.

1. Measure the working condition of iPhone LCD display IC, all is normal. Then measure the display socket J2019 with Fluke 15B+ Digital Multimeter, we found the #3 pin is short circuit. 90_AP_TO_LCM_MIPI_DATA3_N MIPI image transfer data bus leads directly to CPU, the initial diagnosis is that the CPU is continuous tin or internal damage.

2. Remove iPhone CPU and then measure this signal line, we found it is the earthing short circuit, which is CPU internal damage, the kit is damaged. 6P and 6 are not the same size; the circuit design is also not the same. By analyzing the WUXINJI schematic diagram, we found the solution.

3. According to the comparison of WUXINJIschematic diagram, we found that iPhone 6 Plus has one more a set of MIPI image transfer data bus than iPhone 6, 90_AP_TO_LCM_MIPI_DATA3_P、90_AP_TO_LCM_MIPI_DATA3_N, and iPhone 6 doesn't have that line. Because the iPhone 6 only needs to display 4.7 inch images, but iPhone 6 Plus needs to display 5.5 inch images.

4. The faulty iPhone 6 Plus is 90_AP_TO_LCM_MIPI_DATA3_N short circuit, we decided to abandon the 5.5 and install the 4.7 directly. Move the CPU on this fault board to iPhone 6 motherboard, the iPhone LCD can display now！

iPhone 7 Boot without Display! Get solutions here!

 Recently, there's a strange thing happening on the iphone 7, it can be boot but withou display, the iPhone LCD screen just always black.  What's going on?  By the way, the iPhone 7 had been dropped before.

1. Disassemble the iPhone 7 by JM-P01 Electronics Toolkit,  then measure it with DC power supply, at the beginning, the current is about 350mA, and then the current drops and the iPhone reboots.  Usually, this problem was caused by iPhone Nand flash systme is damaged or it wasn't tested when loading with other peripherals.  Now, our initial judgment is that the Nand flash is empty welded or IOS problems.

2. Connect computer to flash, when it's ready to enter the normal mode, error 4013 is reported, then the phone into recovery mode. It doesn't seem like a system problem, so we remove the iPhone NAND Flash. There is no problem to test the NAND to the CPU resistance, and the iPhone NAND is read normally on the test fixture. As shown in picture 1, the NAND is welded back.

3. According to the result of above test, we can get to know there is no problem with the NAND. It seems something wrong with the baseband. CPU self check will also be some errors reported. From the picture 2, the baseband chip is removed

4. After removing the iPhone 7 baseband, no solder drop points were found. As shown in picture 3, using QUICK 861DW reworking station to weld the baseband back.

5. Reboot it again, the current is normal and the iPhone screen can be display now.  The iPhone 7  has returned to normal work.

SOLVED: iPhone 6 Plus half screen is black and the other half is bright

A customer has sent us an iPhone 6 Plus to repair, which problem is the half iPhone touch screen is dark and the other half is bright, sometimes even no display.

 

Because the customer only sent us the iPhone motherboard, after we received it, we checked it immediately. We found the motherboard repaired, and the iPhone backlight has been replaced. By the way, there is a capacitor that is not installed.

Now we directly remove the yellow insulation tape, cleaning up the repaired place, and then supply power on it to test, the left backlight is dark.

After using the QUICK861DW rework station to weld the capacitor that didn't install before, turn it on and test it, now the backlight is back to normal, it can display normally. According to check the WUXINJI circuit diagram, we know that the backlight is a step-up capacitor, if none of this; it can't boost the voltage, so the backlight is not bright.

After fixing the backlight, we also need to repair the screen sometimes display but sometimes doesn't display issue. Sometimes it can display when you press the socket with your hand, so we thought it was a problem with the socket. However, after careful examination, we found that the socket has been replaced, and the pin also is fine, now we have to check its circuit.

After testing, we found that there is no display power supply -5.7V. As we know, -5.7V is directly output by the iPhone screen display IC, testing the line, it is normal. So we decided to replace the display IC directly. After the replacement, turn on the iPhone, now the iPhone screen works normally!