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Das iPhone 6 mit dem 4,7 Zoll Display ist die kleinere Version des iPhone 6 Plus und seit dem 19. September 2014 auf dem Markt.

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No display after drop, backlight and rest of the phone still working

Hello everyone,

I just received an iPhone 6 16Gb Gold from a friend yesterday, because I offered him to look into it after he said the phone screen wouldnt be working after the phone had been dropped.

The device has a pretty apparent bend, however he is not sure whether it was already like this before it was dropped. Regardless, after some testing I figured out the LCD itself is staying blank at all times, however interestingly, the phone is still usable, it still vibrates when using the ringer switch and it is even still possible to call the device. Also, when powering the phone on, the backlight lights up, indicating the phone itself is working just fine. Also, please spare me the usual "Hard Reset" or "Swap the Display" suggestions, as I have tried both, and came to the conclusion that there might be an issue with the motherboard itself.

After inspecting the motherboard I found some liquid damage in the area I have marked in blue in the following picture.

Block Image

The chip that is affected however is just a positioning chip, either a gyroscope or magnetic field sensor, so it has nothing in common with any display circuitry. My board view software also shows no links between this area and the lcd connector.

Lastly, I noticed, while the display is supposed to be turned on, after for example pressing the home button, the LCD connector heats up rather hot while the display is connected to the motherboard, so there might be a short inside the phone, somewhere around the LCD connector.

Here are some amperage measurements of the phone:

Booting up ~ 0.7A

Idle 0,2A

When the backlight is on and display is supposed to be on ~ 0,5A

​Are there any power rails or connector pins I could measure for a specific voltage? I need to make the decision whether to keep finding a fix or selling the phone alltogether, as buying a new motherboard is not really worth it.

Perhaps this issue has surfaced somewhere before, it would be interesting to know whether such an issue is more likely to happen with the device being bent instead of being water damaged. Touch IC failure is common with a bent device, but this?

Any suggestions would be great!

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Paging @refectio for board level advice.

von

As I already said, the lcd is still working, as I have put in a working spare part that I knew is working. The issue is definitely with the motherboard itself, given that my other working screen doesn’t work on this phone

von

I have made a new discovery. Basically I took off the metal heat shield where the CPU is to further inspect the board. Allthough no apparent damage was visible, I wanted to check how hot the CPU gets when booting up the device without the heat shield. While it does get quite hot, it cools down after booting up, but I noticed that a little IC, a bit above the CPU, literally gets that hot it burned me when I touched it. Basically the chip is called the U1501 (aka. Chestnut) IC, and it is responsible for converting power which is then sent to the LCD. This IC is cool when the device is turned off, but as soon as turning the display on (which is also the case while booting as the apple logo appears), this chip instantly gets way to hot. I figured the chip might be faulty, and there could be a short while this chip is enabled when the display is supposed to be on. Even with the phone completely powered off it would draw about 0.02 Amps, removing the IC made it go down to 0.01A. Ill try replacing it soon

von

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1 Antwort

Hey Daniel, have you tried another screen? It is possible the LCD was damaged when the frame bent.

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Daniel wird auf ewig dankbar sein.
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