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!

Help! iPhone 6 Plus has no display after screen replacement

The iPhone 6 Plus LCD screen has replaced the new, however,  when we press the iPhone power button,  the iPhone screen has no display for a long time. It can receive the calls, just no display.  Let's get help here!

Check the iPhone appearance, there is no damaege.  Replace the new LCD screen,  the problem is the same: no diaplsy and no backlight.

The measured value is completely normal, there is no current burnt traces on the iPhone backlight chip and display power supply IC, so we can start to work on its display part.  Taking off the display IC under good protection, and work on solder pad with low temperature solder, do not rush to replace the new IC, the bottom resistance should be measured before that. As shown in picture 1.

The result shows that the D3 pin I2C bus CPU has no resistance to the clock signal of the display power, and the C3 display has no resistance to the power IC signal. According to these two results, we can make sure that the lock screw is wrongly installed to cause the motherboard layer being broken. Open the 6P bottom screws column diagram,we find that C3 go through left and right sides of the screw column, D3 only go through the left, After removing the 2 screw columns, we find both of them get traces of damage (you can remove the screw columns with solder paste, hot air gun with 300 degrees and gently push then down by QUICK 861DW Hot Air Rework Station), we find there is serious disconnection on the left. As shown in picture 2.

 

First, scraping a waste main board without broken wire and observe the wire construction. Select a smaller phone fix scraper tool, gentlely scrape and try not to damage the bottom wire since there are several layers in the iPhone 6 plus motherboard. you need to pay attention if there is black layer shown up for sraping the first layer, then you can add a bit of soldering paste on it, it will be clear to see the specific location of the wire under a microscope.

We choose a similar sharp knife to throw off the location of the broken wire and find the thread. The left screw can find a resistance thread. We choose a sharp iron with professional jumpers to solder every wire carefully and try not to repair it next time.

We can solder the jumper under the microscope, as shown in picture 3, the screw column on both sides of the line have in common, the left one can not find the thread so we can use the right column to make jumpers, then we measure IC bottom pin resistance again. The resistance is normal, now solidifying with green UV oil and install display power supply to test.

Now the iPhone 6 Plus LCD screen can be lit,  you can use the iPhone normally!

iPhone 6s no display? The best solution is here!

The iPhone 6s accidentally drop into ground, we pick it up and turn it on, the iPhone screen shows black, it just no display. However, it can receive the phone call. We need best solution for this issue!

Disassemble the iPhone; take out the iPhone battery and supply power to it with DC power supply, the current is normal. Remove the iPhone screen, and then install the test screen, power on it and test it, the screen can display normally and appear white Apple interface. We thought the screen was damaged by dropping, but when we plug the original screen, it also can be light up, so we can exclude screen problem. 

The device light up, there are some problems when we are waiting to enter the IOS interface, blurry screen, grey screen, black screen, and it then cannot be wake up. Unplug the power and reboot iPhone, but the problems still exists.

Determine the fault is in the display section, remove the iPhone motherboard, use multimeter to measure the diode date of display socket, the data of all signal and power supply is normal. Reinsert screen and boot it, the white Apple still can be display, but after about 10 seconds, the screen suddenly turn into dark.

Unplug the power plug and screen test socket, measure the diode data on it, we found that the diode data of two pins on backlight is abnormal, one is more than 300, one is more than 700, the normal data of both pins should be around 600, as shown in picture 9-11-2. After a while, the data is normal, the data of these two pins also is normal in the first time, so we judged the faulty probably in the backlight part, so we replace the backlight IC. We can check it under the microscope.

After replace the iPhonebacklight IC, the boot process without any abnormalities, it can directly into the IOS. 

Finally, we input the boot password and test all functions, everything is fine. The iPhone 6s has been repaired!