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Pcb trace help

Discussion in 'PCB Layout, Design and Manufacture' started by Hemsee, Jun 14, 2016.

  1. Hemsee

    Hemsee

    2
    0
    Jun 14, 2016
    Hi,

    Hope you can help

    My wife has this usb drive, the usb connector snapped off so re-soldered the connections but the trace to which pin 3 connects came away from pcb, I cant bridge the connection to the trace and I can't find a schematic to help bridge a connection to other end of the trace either

    Is there any other way at all ?
     

    Attached Files:

  2. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    Should be able to trace at least some of it...
    That said... it's hard to see anything on this pic.
    Can you please try again in better lighting?
    Front and Back please.
    https://www.electronicspoint.com/resources/how-to-take-photos-of-circuit-boards.6/


    The two middle pins are 'data' pins, outside pins are power. That will somewhat help.
     
  3. Hemsee

    Hemsee

    2
    0
    Jun 14, 2016
    Hopefully these pictures are better

    I think I found the trace, after removing the connector i scratched away at where i thought it could be, it seems to go through to the otherside and the trace is very small

    I think I cold solder a wire to it but it would be a very fragile connection
     

    Attached Files:

  4. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    The problem though... is the 'via' that is used to take that wire from one side of the board to the other... appears to be underneath the IC...
    I think you should get your hands on a spare USB cable... cut one end off, and solder the matching wire to the 'via' that goes through the board... it's a very small connection...
    You may need to get your hands on a small 32 gauge solid core wire.. which might make it easier.

    The goal here should be 'data recovery' ...
    If you can solder a tiny wire directly to the via, then you can solder a cut-up USB cable to the other 3 pads to get your data off the the USB device.
    If you can't get that via soldered... or are worries about trying...
    Solder the 3 good contacts to the wires from a cut-up USB cable (Still with the USB end on it!)
    Solder the remaining wire to a pin, then with your hand, hold the pin on that via where it goes underneath the board...
    You can then plug in the USB cable to a laptop, or if long enough, to a desktop to copy the data off...
    Once the data is safe, you can explore methods of making a more permanent repair.

    You could also (with a multi-meter) try to determine which pin on the Microcontroller goes to that broken pad.
    The interest here is still that little dimple in the board... the 'via' .
    Measure resistance from the via on one side to each pin on the other... best of luck.
     
  5. 73's de Edd

    73's de Edd

    2,678
    1,085
    Aug 21, 2015
    Sir Hemsee. . . . . . .

    The lighting still did not permit our seeing the dedicated uP/interface chip number on the black square 48 pin device.

    However, on your USB connector proper

    #1 VCC
    #2 Tx data
    #3 Rx data
    #4 ground

    Usually there are low value series resistors from the USB connector to the Tx and Rx data lines going to the
    BLACK processor / interface I.C.

    Measure and see what values R27 and R28 and R22 might be . . 47-----68 ohms ? and if two are being of the same value, I suspect those to be the ones, and then their other ends then feed into the Rx and Tx inputs of the BLACK I.C.
    If finding two paired values, you are half way home.
    You then ohmically measure from the Intact USB tab to each resistor to find the " zero ohm " connection
    Then the floating tab will be the like path to the other companion isolation resistor.
    My repair wire choice would be a single fine wire strand pulled from some AC line cord.
    In some instances, one cluster of wires will be using bare copper while the other will be tinned copper wire.
    Choose the latter in that situation.


    Your being able to give us the magic part number. . . of the BLACK I.C. can confirm more info, after its being looked up.


    73's de Edd
     
    Last edited by a moderator: Jun 16, 2016
  6. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

    4,960
    648
    May 8, 2012
    Ed, are you sure of that pinout? I thought USB data lines are simplex Tx/Rx with differential data lines marked ...
    Pin2: Data -
    Pin3: Data +

    Chris

    [​IMG]
     
  7. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

    4,960
    648
    May 8, 2012
    Correction: Wiki describes USB as Half Duplex.
    https://en.wikipedia.org/wiki/USB
    Chris
     
  8. 73's de Edd

    73's de Edd

    2,678
    1,085
    Aug 21, 2015
    EXACTAMENTE . . . . . .
    Sir Chris . . . .one gets set in their ways . . . .in mostly seeing the former in their dealings.
    Now just rely heavily on finding that resistor / pair set.

    Also, just perchance, that this unit is using the popular ST72681 flash microcontroller of past years,
    It's connecting pins will be #'s 9 and 10.


    Setenta y tres's de Edd
     
    Last edited by a moderator: Jun 16, 2016
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