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Thread: Teensy++ accidentally desoldered a resistor

  1. #1

    Teensy++ accidentally desoldered a resistor

    Hi,
    I was trying to desolder some header pins from my Teensy++ and a resistor(?) that was very close to the header also got removed.

    I haven't tried to use the board after this but I'm pretty sure I'm going to run into issues.

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    The picture above is a screenshot from the Teensy++ product page. But on my board the resistor is almost touching the GND (unmarked pin) and AREF ('R' pin).

    Is there anything I should do at this point? or just try using it as is? I don't have the ability to do surface mount work because it just too tiny.

    I'm trying to use the teensy to run QMK software to use as a controller for a keyboard.

    Thanks

  2. #2
    Senior Member PaulStoffregen's Avatar
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    That part is capacitor C5, which connects between AREF and GND. Teensy++ 2.0 will work without it, but the quality of analog measurements will be degraded. If you never use analogRead(), just leave it alone and don't worry. If you do need analog input, just solder a capacitor to the nearby GND and AREF pins.



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  3. #3
    Thanks Paul. I appreciate your quick response. I'll try it out as is and report back.

    I'm not doing any analogRead's (or at least I'm not aware that QMK is trying to do that).
    Just driving a switch matrix for my keyboard and sending keypresses over USB.

    Thanks again.

  4. #4
    I was just going to ask out of curiosity if I did want to put a capacitor across the two pins what value cap should I use.

    Then I looked closely at the schematic and noticed that it was labeled.. 0.1 uF

  5. #5
    Senior Member PaulStoffregen's Avatar
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    The type of capacitor material matters more than the actual capacitance. Use a X-type ceramic like X7R or X5R. Don't use Z5U or other non-ceramic types.

    But again, if the capacitor is only needed if you use analog inputs.

  6. #6
    Thanks, I tried out the teensy as it was and it works perfectly.
    As a matter of fact, I'm typing this message with the same teensy running as the controller.

  7. #7
    Senior Member
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    Quote Originally Posted by pepsiplease69 View Post
    Hi,
    I was trying to desolder some header pins from my Teensy++ and a resistor(?) that was very close to the header also got removed.
    FYI: surface mount resistors are identifiable as they are nearly always black on top with white printing on them
    showing the value (unless really tiny) they also have metal endcaps.

    Brown/tan coloured components like this one with metal endcaps and no printed markings are ceramic multi-layer
    capacitors. Other ceramic capacitors (of lower value) can be white to grey in colour.

  8. #8
    Thanks, good to know.

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