iPhone 7 Plus half-dark screen, how to fix it?
We received an iPhone 7 plus, and the customer said that the screen backlight problem, including no backlight, dim backlight, half backlight, or the screen can not be opened. Here, we will introduce the iPhone 7 Plus half-backlight repair case and related backlight circuit repair caused by the pseudo soldering of the display connector.
For mobile logic board repair, inspection is always the first step. Place the logic board under a trinocular stereo microscope and double check that there are no signs of water damage and deformation.
Next, let's assemble the iPhone and test it. Install the logic board and display components. Connect to the DC power supply and press the power button, the screen lights up and the Apple logo is displayed. We can see that the right side of the screen is darker than the left side. Thus, it is judged that the failure may be related to the backlight circuit.
Use phone open tools to unpack the iPhone and remove the display assembly. Take out the logic board, diode mode measurement is performed on the backlight related pins on the display connector J4502. The measured value of the needle 45 is OL, which is abnormal. The normal value should be around 450.
Next, check with WUXINJI dongle, you will see that the output voltage of the backlight IC U4601 reaches the pin 45 of J4502 through C4602, FL4601 and C4605. Therefore continue to run the diode mode measurement of the C4602. The measured value is normal. It is thus judged that the abnormal value of the pin 45 may be caused by the open state of its related circuit or the failure of the display connector J4502. Check 4502, we found that Pin 45 has been pseudo-welded.
To further confirm the fault location, remove the J4502 from the logic board. Before removing the connector, consider protection, we need to attach the heat resistant tape to the surrounding components. Then apply some solder flux paste to the J4502, then remove the J4502 with a heat gun.
After removing the connector, we use fluke digital multimeter to measure the diode value of pin 45 on the pad. The test value is normal.
Now we confirm that the fault is related to the J4502. Replace the new display connector. Heat with a heat gun, install the new display connector in place and solder with a 858D hot air gun. Next, use the PCB Fixture Platform to fix the motherboard for soldering smoothly.
Finally, assemble the iPhone and test it, install the logic board and display components. Connect the battery to turn on the power. The phone is turned on normally. The screen returns to normal, the backlight fault is resolved successfully.
If you need any help, please contact us on www.vipprogrammer.com.
For mobile logic board repair, inspection is always the first step. Place the logic board under a trinocular stereo microscope and double check that there are no signs of water damage and deformation.
Next, let's assemble the iPhone and test it. Install the logic board and display components. Connect to the DC power supply and press the power button, the screen lights up and the Apple logo is displayed. We can see that the right side of the screen is darker than the left side. Thus, it is judged that the failure may be related to the backlight circuit.
Use phone open tools to unpack the iPhone and remove the display assembly. Take out the logic board, diode mode measurement is performed on the backlight related pins on the display connector J4502. The measured value of the needle 45 is OL, which is abnormal. The normal value should be around 450.
Next, check with WUXINJI dongle, you will see that the output voltage of the backlight IC U4601 reaches the pin 45 of J4502 through C4602, FL4601 and C4605. Therefore continue to run the diode mode measurement of the C4602. The measured value is normal. It is thus judged that the abnormal value of the pin 45 may be caused by the open state of its related circuit or the failure of the display connector J4502. Check 4502, we found that Pin 45 has been pseudo-welded.
To further confirm the fault location, remove the J4502 from the logic board. Before removing the connector, consider protection, we need to attach the heat resistant tape to the surrounding components. Then apply some solder flux paste to the J4502, then remove the J4502 with a heat gun.
After removing the connector, we use fluke digital multimeter to measure the diode value of pin 45 on the pad. The test value is normal.
Now we confirm that the fault is related to the J4502. Replace the new display connector. Heat with a heat gun, install the new display connector in place and solder with a 858D hot air gun. Next, use the PCB Fixture Platform to fix the motherboard for soldering smoothly.
Finally, assemble the iPhone and test it, install the logic board and display components. Connect the battery to turn on the power. The phone is turned on normally. The screen returns to normal, the backlight fault is resolved successfully.
If you need any help, please contact us on www.vipprogrammer.com.
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