What this component is used for? no more sync..

Discussion in 'iPhone Tips, Help and Troubleshooting' started by yurann2000, Feb 20, 2010.

  1. yurann2000 macrumors newbie

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    Feb 20, 2010
    #1
  2. Gadgetgeezer macrumors regular

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    #2
    I can't say for sure, but when I test it with my meter, it certainly has a diode like characteristic so it is a semiconductor device, not a resistor.

    Spencer
     
  3. yurann2000 thread starter macrumors newbie

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    #3
    Great! Thanx!

    Is it 2 diodes there? is there any label? Do u think its possible to find one somewhere?
     
  4. Gadgetgeezer macrumors regular

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    #4
    i am not sure it is two diodes. Can't work it out. I would say it would be hard to find out without a circuit diagram. Did wonder if it is some kind of USB transceiver. Really scratching my head.
     
  5. AbblePC macrumors regular

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    #5
    looks to be a bridge rectifier... meaning a square package with four pins, probably germanium. It should measure across two pins with ~ indications of a short which would be input + - should be measured back to forward ratio of .6 ohms using diode scale. If you get .5 its silicone. if you read a short anywhere between - ~ or +~ its shorted.

    What is the issue with this particular board, had it gotten wet? is there obvious corrosion on the board etc.? If you got it wet while voltage was applied, there is a good chance it took other components out other than the obvious visible ones.

    Also, is that the data connector near by, which would indicate its not a voltage regulator of sorts but perhaps a filter instead. Measurements should be made of a good known functioning board to know for certain. The components are not always going to read the same as if not soldered to the board or "in circuit" and should be read off board if possible.

    I see now that is the Baseband Processing Circuit, where you are having this issue...

    That is the Dock Connector to the right of the component your speaking of, I haven't found a closer image yet but here is one showing more detail.
     
  6. yurann2000 thread starter macrumors newbie

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    #6
    The worst thing that this component was physically damaged and removed from board, so i cant check it.

    The board wasnt wet for sure.

    me too i think it's some kind of bridge rectifier.
    like this:
    http://www.ecnmag.com/Product/2010/02/2A100V-Schottky-Bridge-Rectifier/

    i found the bigger image:
    http://www.mr-gadget.de/wp-content/uploads/2008/07/iphone_mainboard.jpg
     
  7. yurann2000 thread starter macrumors newbie

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  8. Gadgetgeezer macrumors regular

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    #8
    To keep this going, why would you want a bridge rectifier in that area. Bridge rectifiers rectify AC power to DC power. USB is DC 5V and any of the signals on it are digital and not analogue. I am not convinced at all.
     
  9. yurann2000 thread starter macrumors newbie

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    #9
    ok, and what is your idea about what is it?
     
  10. Gadgetgeezer macrumors regular

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    #10
    Not sure but my next idea is to put a dock connector on my board and buzz it out to make sure it is definitely related to the USB data pair on the cable. Watch this space. I have a degree in electronics, but these surface mount components are hard to identifiy sometimes without a circuit diagram.
     
  11. yurann2000 thread starter macrumors newbie

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    Feb 20, 2010
    #11

    Thanx, thats a great idea if u have one working iphone 3g ;)

    i was searching for circuit but failed.

    no more sync & no more charging while "ON", when "OFF" it charges but very slow.
     
  12. Gadgetgeezer macrumors regular

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    #12
    OK so if i plug in a USB lead I get about 4 Ohms resistance between the data connector and one of the connections on the right of the component. I know that to charge from say a car charger, it has to put a voltage on those data pins (that's why some USB car chargers won't charge an iPhone) and I wonder if the component senses the voltage instead of passing it straight on to the USB controller and blowing it up. Just an idea. Of course, it is one isolated component but you need to see it in context with other components and that is the bit we are missing.
     
  13. yurann2000 thread starter macrumors newbie

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    #13
    :)... but how do u think this component is called? do u think there is a chance to find one somewhere? do u have any burned motherboard with this component or just only this component?

    what do u think of just shorting that lines?
     
  14. Gadgetgeezer macrumors regular

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    #14
    I am mystified as to what it is - you need somebody who knows surface mount components. I wouldn't short it - it is there for a reason.
     
  15. yurann2000 thread starter macrumors newbie

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    #15
    ok, may be someone else from this forum knows the answer.
     
  16. yurann2000 thread starter macrumors newbie

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  17. yurann2000 thread starter macrumors newbie

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    #17
    most schemes has such resistors : [​IMG]
     
  18. yurann2000 thread starter macrumors newbie

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    #18

    Does anyone else know smth about this?
     
  19. yurann2000 thread starter macrumors newbie

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    #19
    maybe this one?
    pic:[​IMG]
     
  20. DeadiPhone macrumors newbie

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    Jul 19, 2010
    #20
    I too am missing this part.

    I just replaced my broken glass, and now I have the same issue, My phone will not charge.

    I just looked under our scope and I too have broken off this 4 legged part.

    yurann2000, did you ever find when the part is?

    Looking at the pads under a 20x scope I see that 2 of the pads are bridged... Does this help narrow down the part?

    I have a pro-grade soldering station and hot air reflow setup I can use, But I need to know what this part is.

    Any help would be appreciated.
     
  21. randomdamage macrumors newbie

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    Dec 15, 2010
    #21
    And I just broke this part off on my iPhone 3G. :( Did anyone ever figure out what this part is? Did anyone try bridging the solder pads?
     

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