The Haunted Face Proximity Sensor after LCD replacement- Im STUMPED!

Discussion in 'iPhone Tips, Help and Troubleshooting' started by jraemt86, May 23, 2010.

  1. jraemt86 macrumors newbie


    May 23, 2010
    Home: NJ, School: NY
    Hello world - I would like to tell you a brief story on what the hell is going on with my iphone(s) 3g 16mb. I challenge only the most technically skilled with this one.

    Please visit this website to see photos of everything documented.

    So I drop my iphone-->cracked glass. So I go on, order a new digitizer/glass. All works well. Successfully replaced and everyone is happy. A week goes by, and again, dropped -->cracked, this time, LCD goes with it. So I go on and order the LCD, screen with digitizer. Replacement runs smoothly. Everything goes back together just fine. Everything works except when receiving/making a phone sound from the earpiece. So first I say, lets rule out cable #3 being the problem. Checked, checked and rechecked. Cable 3 is snug and secure with no damage. So I test to see if when in a phone call the screen turns black when i put my hand over the entire upper black portion of the phone. Nope - the screen stays on. So next step is to see if maybe I damaged the face proximity sensor.


    [​IMG] [​IMG]

    So in the meantime I buy a used, scratched up (but working and I tested it-fully functional) iphone 3g 16mb from my ex girlfriend. I remove the face proximity sensor from it and replace it into my phone. The problem persists. Face proximity sensor is ruled out as a possible problem.


    I have now ruled out a cable 3 malfunction, a face proximity sensor mechanism problem, the only thing left is maybe the main-board insertion connector. I noticed after repeated attempts inserting cable three i had nicked a piece of the plastic exposing 3 of the wire inserts.

    So what do I do next you ask? I remove the mainboard (notice in the pic below the mainboard is now blue [new]) from the scratched up phone and REPLACE the entire mainboard onto my phone. Guess what? the problem persists with a new face proximity sensor and new mainboard.


    At this point the only possible thing left is maybe a dysfunctional internal speaker earpiece is causing the entire face proximity sensor to be defective?

    So what do I do? I replace the entire front face. Meaning I disconnected the first 3 wires that you must when you FIRST open the phone, and I immediately transferred the entire thing to my phone. The problem still persists. I have now ruled out a speaker problem.


    The only possible thing left is some kind of short within the circuitry attached to the backplate by the battery. next step is to then say screw it and put back together all of the original parts of both phones.

    Now I currently have TWO iphones that do not activate the speaker when I cover the phone. Either I am missing something, or I am being haunted by a really nasty and mean face proximity sensor goblin.


    Can someone please help me out? I am honestly confused

    What I am basically looking for is to how to get my face proximity sensor/internal ear speaker to work since I cannot seem to figure it out with TWO sets of parts.

    Mainboard: no resolution
    LCD: no resolution
    Cable 3/face proximity sensor: no resolution
    THE ENTIRE PHONE: no resolution

    There has GOT to be an answer.
  2. Gadgetgeezer macrumors regular

    Oct 4, 2009
    You won't like me saying this, but I fix iPhones as a small business:

    1. If you have broken the plastic on connector 3, you aren't being delicate enough - tweezers and a steady hand is required with plenty of light to see;
    2. You should be wearing an anti-static wrist strap when doing repairs;
    3. The proximity sensor cable is very very delicate and is easily broken. I would buy another brand new OEM part and try again, but with that broken connector 3 on the logic board, it may never work - I have worked with these myself and can't always get them working once the casing on connector 3 is broken.

    Often the earpiece will work though since it is supplied by the two far right connections on the ribbon which is away from the normal damage area as with yours. If you ever doubt that the earpiece has continuity, the resistance reading onto the ribbon is about 28 Ohms. I always check before reassembly of customers' phones.

    I say no more, hope this is some help.

  3. jraemt86 thread starter macrumors newbie


    May 23, 2010
    Home: NJ, School: NY


    Thanks for taking the time to read my problem and giving me some advice. I really appreciate it!

    After replacing the entire mainboard and proximity sensor, I am still experiencing the issue. So I guess what I am leaning toward is maybe I should be especially looking out for something that I may be doing wrong which could cause this issue (if and when the hardware is not faulty).

    Thanks again

  4. Gadgetgeezer macrumors regular

    Oct 4, 2009
    If you were local to me (in the UK) I would help you. It's hard to diagnose problems from afar. I have every spare part for iPhones so I would do some electrical tests and swap out parts until solved.


  5. DEE9299 macrumors 6502a


    Oct 3, 2009
    Boston Mass.
    as far as the board with the broken #3 connector a guy on here named hectordtruong can fix them..he has fixed a couple for me before....and in the process you may have damage the sensor cable as well
  6. hectordtruong macrumors member

    Nov 11, 2009
    Thanks Derek!

    Hey John, if you want to send me the phone I can diagnose it for you for free. If it is the #3 connector, then I can replace it for you. I just did my blog, and here is a run down of how the repair goes:

    Let me know if you want me to check out your phone, I know these things are headaches, but it is usually something minor if you have all the right parts and its just not in sync with each other. Opening an iphone is almost synonymous to opening a can of worms lol.
  7. amann76 macrumors 6502


    Jun 16, 2009
    MacWorld USA
    i'm not surprised that a person who can't manage to hold on to a phone without dropping it can't manage to solve and fix the problem...

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