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Nexus 5 - Proximity Sensor problem

OP dalmaso

3rd May 2014, 05:07 PM   |  #1  
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Hello guys! This is something that took me a certain time so I'd like to share it to make it worth...
I was having some problems with my new Nexus 5 (D821):
- Screen never turned off during calls;
- Touch screen active during calls.
So the phone was hotter than it should be during the calls and after the calls I always discovered my ear had activated a lot of things on the touch…
Then, I was questioning myself if this would be a problem cause by software or hardware. As a microcontroller addicted, I know how trick it is to distinguish between a firmware and a hardware problem... and started to investigate the problem with a few steps:
1) Used some apps to grab the proximity sensor value (like this play.google.com/store/apps/details?id=com.gmail.macromax.vdo.sensors)
- The value was stuck in 5.00000cm;
2) Tried different ROMs and kernels with the same result;
3) Downloaded the Nexus 5 Service Manual;
4) Downloaded the sensor (Avago APDS-9930) datasheet.
So based on the new information, I have made a little experiment to make sure the problem was the hardware:
I started the app to monitor the sensor and used my TV remote control to emit the IR pulses, as I assumed the sensor had a problem with the IR emitter. Than the app started to show some measurements… confirming the sensor was the problem (more specifically the emitter).

So, I disassembled the phone getting access to the sensor and this is what I got:



The sensor was carbonized!!! There is no IR emitter anymore!!!

This is the shot from the original sensor:


It seems like the assembly production process of the phone has reached a too high temperature or has caused a mechanical damage!
Moreover, this is the biggest problem; my phone would not be the only one to have been damaged!

Hope this can help saving someone else time…
Last edited by dalmaso; 7th May 2014 at 03:54 PM.
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