Great points / comments. Here’s a bit more background:
I powered the sensors on the Dash from the 3.3 V pin, although they have a V-USB pin available. Multiple sensors worked fine powered by 3.3 V. The Arduino 1400 is likewise a 3.3 V device.
I hear you loud and clear on the issues and risks of using flat phone cable, and an RJ11. I was probably as amazed as anybody when it worked as well as it did on the Dash and earlier Arduino units! :-). I’ve probably built 20 sensor sets with the flat phone cable, soldered and epoxy potted on the sensor and, and phone-cable tooling terminated on the other end. Out of these, not one has had a single issue with reading consistently and accurately, despite the fact that I now believe these to be knock-off sensors. These same parts work every bit as well as, in fact sometimes somewhat better than, genuine DS18 B20 sensors plugged directly in to the breadboard 1 inch away from the boron.
Regarding the above paragraph: the working “as well as” part I could maybe understand, but the “working better than” part? I have to ask if there isn’t some type of reflection going on with the sensor that close to the Boron, that maybe does not occur with the longer leads. As mentioned above, I’m going to put the scope on it and get some screenshots in the next week or so. It may also be a simple case of some genuine DS18B20 sensors being included on the leaded set I’m currently testing!
I join your suspicion that the issue may be one of poor power, particularly given that the device consistently has more issues within the first seconds of boot/1st sensor readings than subsequently. I’m probably not interpreting your note correctly on how to power this from a 5 V source, so I was hoping I could beg your indulgence and ask for a bit of elaboration (or diagram) on that, as I’m more than happy to test that configuration.