跳至主要内容

Best Solution for iPhone 6S No Display Fault

Received an iPhone 6s with no display fault, which just show black screen.  Before repairing it, we need to test and observe first. Let's check the detailed maintenance repair steps in this article!

Disassemble the iPhone, use DC power supply to provide power on it to detect it, the current is very normal. Even if the current it normal, but the iPhone screen still doesn't display. Observe it more carefully; we can see the faint light from the side, which means that this is faulty iPhone with a light but no display.

According our experience, most of the fault points in this situation are in the display touch power supply circuit. Open the power side; we can see the iPhone PCB board is very dirty, especially in the display touch power supply tube. And after check it, we can know that this display touch power supply tube has been replaced many times.

Now we're going to use Fluke 15B+ Digital Multimeter to measure positive and negative 5.7V on the iPhone display touch power supply tube, the voltage measured is less than 2V. Next to measure the voltage of boost capacitor, the voltage only is less than 2V. Now we know the boost circuit is a problem.

Because the display touch power supply tube has been replaced on iPhone 6S, so we don't need to replace it now, the emphasis is on boosting inductance and capacitance. After measuring the inductance, we found that it was no problem. Then the problem is centered on the capacitor.

Open WUXINJI Dongle to check iPhone schematic diagram, we know this boost capacitance is C4002, we decided to replace the capacitor. With the help of QUICK861DW, we replace it smoothly and quickly.






Assemble the iPhone to test, the screen displays normally now. Continue to test other functions, all is fine, the fault has been solved. The fault is on this small capacitor.

More cell phone repair skills read at www.vipfixphone.com
标签：

评论

发表评论

此博客中的热门博文

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

Tutorial: iPhone 6S Plus Backlight Repair

Since the size of iPhone6s plus screen display  is large, it's necessary to use two sets of background lights to supply power, one is provided by U4020, the other is provided by U4050. 2  sets of circuit 1) PP_LCM_BL_ANODE,     PP_LCM_CAT1, PP_LCM_BL_CAT2 2) PP_LCM_BL34_ANODE,  PP_LCM_BL_CAT3, PP_LCM_BL_CAT4 For PP_LCM_BL_ANODE and PP_LCM_BL34_ANODE, if one of the circuit has no voltage value, it will cause the iPhone 6s Plus screen to be half bright and half dark. For PP_LCM_CAT1, PP_LCM_BL_CAT2, PP_LCM_BL_CAT3 and PP_LCM_BL_CAT4, if one of  these four circuits gets abnormal signal, it will cause the 1/4 screen to be dark. Solution: Use jumper wire  to short connect PP_LCM_CAT1 and PP_LCM_BL_CAT2 or you can also connect PP_LCM_CAT3 and PP_LCM_BL_CAT4. The control signals of these two sets of backlights, one group of inductors FL4211 FL4212 FL4213 are sent to the display interface. The other group is sent to the display interface...
1 条评论
阅读全文