Hello,
I’m a complete beginner to LEDs… But I’m an avid DIY and figured jumping in would be incredibly fun. I was able to successfully solder the strip mount and sensor board. When I connect via USB to a WS2812B strip, I’m able to find and connect to my Pixelblaze with ease. However, I’ve tried switching to external power and it is not working… Attached is a photo. Any hints or leads to help me take this to the next level?
This additional photo might show you my poor soldering. 
But it’s getting data and totally being powered by USB… So IDK
The photo is tricky! I see a red, green, and white wire coming from the JST connector, but then two green and one red wires to PB?
I think the issue may be mixing those up. From the LEDs I’m guessing white is negative, green is data, and red is positive.
Just wire the barrel terminal to only the red/white pair on the strip, then connect the pixelblaze with the JST, red for VIN, white for GND, green for data.
If you have a multimeter you can see if the voltage is perhaps dropping too low and the PB rebooting/cutting out.
Few more to check:
Polarity on the power supply, if you can test with a multimeter.
Check that there’s enough wire stripped, no plastic should enter the screw terminal.
Thanks @gmcmicken - a multimeter showed me the DC plug connector was bad. Swapped it out and it’s running. 
Thanks @wizard for jumping in with comments, too.
