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Thread: How to resolder Teensy LC USB connector?

  1. #1
    Senior Member+ MichaelMeissner's Avatar
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    Question How to resolder Teensy LC USB connector?

    I was doing a neopixel suspender for a local steampunk event, and I did a quick job to solder some wires to the Teensy LC (Vin, the pin 17 level shifted, and ground). Afterward the show, I noticed the micro USB-B socket had come off. This was very much a jury-rigged prop. I didn't have time to properly secure the Teensy to the suspender (hey, it was 4am in the morning at that point). I likely had the Teensy hanging by the USB cable (or the USB battery hanging from the Teensy). Presumably something twisted and turned and the USB connector broke off. I do have the USB connector, as I found it still attached to the USB cable. I bought two more LC's at microcenter, so at the moment, I'm not hurting for boards.

    I normally haven't done much SMT soldering. In the past, I did 1-2 psram's for the Teensy 4.1, and a few SN74AHC1G125DBVR's onto a SOT23 to DIP breakout board, but mostly I only do through hole solder. Now in the SMT soldering I've done, I could solder thin solder onto the pad, and then carefully place the chip on top of this solder, and heat the solder until it melts. But with the USB micro-B socket, I can't see where the solder meets the metal. Is there a way to do this soldering? I assume I want to put solder on the 4 pads, and possibly use a heat gun to lightly melt the solder, but with a heat gun, I would worry about unsoldering other components.

    <edit>
    As an aside, I had problems with all 3 of my neopixel props. The goggles prop had 2 rings inside of goggles with a small microprocessor (Gemma M0 in this case), and a lipo battery that is small enough to fit inside of the goggle. Unfortunately one of the wires to the lipo battery came out between the time when I left the house and when I got to the event.

    I also have a wooden bowtie that has a Teensy 4.0 behind the tie, and lipo battery and a single 16-LED ring. In this case, the prop actually worked. The problem was my shirt collar is no longer tight to my throat (due to weight loss), and the tie kept moving down, so it would still work, but you couldn't see the ring or the tie. I think I need to rework the tie so it has clips on either side to attach to the collar so the tie keeps up. I'm thinking about moving the Teensy and battery off of the tie, and just put the microprocessor in a pocket and use an extension cable.

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    I just took a look at my LC. The microUSB has two surface tabs that can be soldered by hand. First you want to check the solder pads (2 for the tabs and 5 for the connection) on the board to make sure they are all there, instead of broken off. If the pads all look good, you can start by soldering the connector's tab. For the 5-pins, I would use some tacky flux with them. Have some small amount of solder on my small iron tip, touch the 5 pins with flux and the solder will go where it should.

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    Senior Member+ MichaelMeissner's Avatar
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    Quote Originally Posted by liudr View Post
    I just took a look at my LC. The microUSB has two surface tabs that can be soldered by hand. First you want to check the solder pads (2 for the tabs and 5 for the connection) on the board to make sure they are all there, instead of broken off. If the pads all look good, you can start by soldering the connector's tab. For the 5-pins, I would use some tacky flux with them. Have some small amount of solder on my small iron tip, touch the 5 pins with flux and the solder will go where it should.
    My problem is with the USB header on place, there is no way to touch the tabs with the iron since the usb header is sitting on top of it. With PSrams and such, I can still see the top of the chip's feet and touch the iron to that and melt the solder underneath it. With the header obscuring where the solder pads are, I don't have the option of using the tip of the iron to heat just the one leg being soldered. I don't see how to use the iron to just target the one pad I want to work on. I don't have a heat gun that can target the air flow directly at a single small spot. The heat gun I have tends to be more wide angle.

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    If the tab completely covers the pad, you have to either use a heat gun or maybe have your iron on the tab for some extended amount of time to try to melt the solder under the tab. I might add a bit of solder paste to the pad and apply heat with iron on the tab. If you don't do SMD parts, you don't have solder paste either. These things aren't meant to be easily serviceable. I once was given a VEX controller because I have a name for fixing up things. But the device wasn't designed to be repaired and before I could get the microUSB port desoldered, the hot air started deforming plastic sockets etc.

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    Food for thought?
    Click image for larger version. 

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    Senior Member+ MichaelMeissner's Avatar
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    Quote Originally Posted by liudr View Post
    If the tab completely covers the pad, you have to either use a heat gun or maybe have your iron on the tab for some extended amount of time to try to melt the solder under the tab. I might add a bit of solder paste to the pad and apply heat with iron on the tab. If you don't do SMD parts, you don't have solder paste either. These things aren't meant to be easily serviceable. I once was given a VEX controller because I have a name for fixing up things. But the device wasn't designed to be repaired and before I could get the microUSB port desoldered, the hot air started deforming plastic sockets etc.
    Thanks. Yes, I don't have solder paste or a heat gun that isn't that directional. I'll maybe play with it, but as I said, I did recently pick up some more Teensy LC's. Fortunately, you can still get Teensy LC's (at least for now).

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    Senior Member+ MichaelMeissner's Avatar
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    Quote Originally Posted by MatrixRat View Post
    Food for thought?
    Cute. Though I'm having trouble thinking that a soldering iron would be made where the tip can't stand the temps. produced. But you never know these days.

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