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Thread: 3.6 external power

  1. #1

    3.6 external power

    So i just got a 3.6 which i tested on USB OK. Now i want to power it from an external source so i flipped it over and cut the track between H and central pad.

    But it still powers up with just USB attached whereas my LC with the join removed does not

    I've made many passes with a blade between the pads and examined it with a sight glass - hard to believe there is any viable join left. Do i need to do something else ?

  2. #2
    Senior Member+ defragster's Avatar
    Join Date
    Feb 2015
    Not a clear picture form this ...'cut the track between H and central pad.'
    The card on back matches the T_3.6 bottom. I see two similar rectangle pads with a fine PCB wire between them - between USB lug and the Vin pin hole.

    Is that fine PCB wire the "H"? It is that fine wire that is cut between the two similar pads.

    When I cut to test :: When unpowered that fine wire is cut the two pads should show disconnected with DVM - measured resistance is infinite. If not cut wider/deeper to clear the connecting metal.

    And when USB connected with one DVM probe on GND, the other on one of those pads should show USB 5V { like the Vin pin and the internal VUSB nearby } and the other 'similar ZERO V.

  3. #3
    > 'cut the track between H and central pad.'

    just above pins 1 & 2 on the underside are three rectangular pads, the left most one is marked h, the right most one d and a central one unmarked. There was a fine track between H and and the central pad. i've cut this, but the device still powers on usb.

    If i cut any deeper i am concerned i'll break through to another pcb layer. i've done this before on an LC without issue and it took like 2 swipes with a blade.

  4. #4
    Senior Member+ defragster's Avatar
    Join Date
    Feb 2015
    That is the wrong board edge as far as I can tell!

    Above pins 1 & 2 I now see the "H" - that is not the right area to cut. To use USB Host you'll need to restore that trace with solder.

    The area to cut is the corner under the VIN - if you have a Teensy 3.6 card lay it down with the Teensy to get oriented when the PCB is flipped. If you don't have the card ( all T_3.x's are similar AFAIK ) - then look on and print a copy of the card for reference.

  5. #5
    yes i see what you mean - my mistake

    i saw the label and the fine track and thought was it. too much haste on my part

    thank you

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